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{{#Wiki_filter:12 Lake On tario Salmonid Introductions 1970 to 1999: Stocking, Fishery and Fish Community  
{{#Wiki_filter:12 Lake Ontario Salmonid Introductions 1970 to 1999: Stocking, Fishery and Fish Community Influences T. J. Stewart and T. Schaner Introduction                                            were increased. In the following years, activity in the The symposium on Salmonid Communities in            recreational fishery greatly expanded. Total annual Oligotrophic Lakes (SCOL-I) (Loftus and Regier          expenditures by anglers participating in Lake 1972) provided insights on the stressors acting on      Ontarios recreational fisheries were $53 million Great Lakes ecosystem. In 2001, the Great Lakes          (Canadian) for Ontario in 1995 (Department of Fishery Commission (GLFC) initiated a second SCOL        Fisheries and Oceans 1997) and $71 million (U.S.) for symposium (SCOL-II) to synthesize new knowledge.        New York in 1996 (Connelly et al. 1997). In this As part of the synthesis, Great Lakes investigators      paper we describe the recent history (post 1970) of submitted various working papers covering a variety      salmonid introductions and the offshore boat fishery.
of topics for use at a workshop. This is paper is one    We also review and summarize information regarding such contribution and can also be found on the internet  major fish community influences of introduced at <http://www.glfc.org/bote/upload/salmonid            salmonids in Lake Ontario.
introductionsstewart.doc>. The publication of the complete Lake Ontario SCOL-II synthesis is expected      Management of salmonid stocking in 2002.
levels The initial introduction of salmonids into the Great Lakes was an attempt to control nuisance levels of          The number of salmonids stocked rapidly alewife but quickly became focused on developing a      increased during the 1970s and 1980s (Fig. 1). In the multi-million dollar recreational fishing industry      mid-1980s, the state of New York and the province of (OGorman and Stewart 1999). In early 1970s, New        Ontario agreed to limit stocking to 8 million salmonids York State and the Province of Ontario began to          annually (Kerr and LeTendre 1991) in response to establish recreational fisheries and rehabilitate lake  concerns about the sustainability of the high predator trout by accelerating the introductions of lake trout    levels, declining alewife, record fishery yields and (Salvelinus namaycush), brown trout (Salmo trutta) ,    perceived risks to the burgeoning recreational fishery rainbow trout (Oncorhynchus mykiss), chinook salmon      (Kocik and Jones 1999; OGorman and Stewart 1999).
(Oncorhynchus tshawytscha), coho salmon                      In 1992, and again in 1996, joint New York and (Oncorhynchus kisutch) and Atlantic salmon (Salmo        Ontario technical syntheses and stakeholder salar). Limited stocking of kokanee salmon              consultations resulted in changes to stocking policy (Oncorhynchus nerka), was discontinued in 1973. The      (OGorman and Stewart 1999; Stewart et al. 1999).
introductions initially failed to establish significant  Stocking levels were reduced to 4.5 million salmonids fisheries due to high parasitic sea lamprey induced      in 1996, and have been maintained at between 4 and mortality (Pearce et al. 1980). In the early 1980s, sea  5.5 million annually. In 1999, the percentage of the lamprey were effectively controlled (Christie and        total salmonid stocked by species was 39.2% chinook Kolenosky 1980) and the survival of all stocked trout    salmon, 18.8% lake trout, 17.2% rainbow trout, 12.2%
and salmon improved. Hatchery programs in both New      brown trout, 7.2% coho salmon, and 5.5% Atlantic York and Ontario were expanded and stocking levels      salmon.


Influences T. J. Stewart and T. Schane r  Introduction The symposium on Salmonid Communities in Oligotrophic Lakes (SCOL
12.2 9            TOTAL                                          considerable bi-national management attention and 8            Chinook salmon                                  public scrutiny (Kocik and Jones 1999; OGorman and Lake trout                                      Stewart 1999; Stewart et al. 1999). Stocking numbers 7                                                            peaked in 1984 at 4.2 million fish and ranged from Rainbow trout Number stocked (millions) 6            Coho salmon                                    between 3.2 and 3.6 million fish from 1985 to 1992.
-I) (Loftus and Regier 1972) provided insights on the stressors acting on Great Lakes ecosystem. In 2001, the Great Lakes Fishery Commission (GLFC) initiated a second SCOL
Brown trout                                    Chinook salmon stocking was reduced substantially in 5                                                            1994, based on a management review in 1992 Atlantic salmon 4
(OGorman and Stewart 1999), and ranged from 1.5 to 1.7 million fish annually from 1994 to 1996. Due to 3                                                            stakeholder demand, and a second management review 2
(Stewart et al. 1999), stocking was increased slightly in 1997 and has ranged from 2.0 to 2.2 million fish 1                                                            annually from 1997 to 1999.
0                                                            Lake trout 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 The history of Lake Ontario lake trout stocking, FIG. 1. Number of salmonids stocked in Lake Ontario, 1968-                           rehabilitation, management, and research is well 1999 (excludes fish stocked at a weight < 1 g).                                      documented (Schneider et al. 1983; Elrod et al. 1995; Schneider et al. 1998). Initial efforts at rehabilitation between 1953 and 1964 were abandoned, but renewed Species stocking history                                                                after initiation of sea lamprey control in 1971 Chinook salmon                                                                          (Schneider et al. 1983). Lake trout stocking policy has been directed at meeting management objectives for The resumption of chinook salmon stocking into                                      rehabilitation described in joint New York and Ontario Lake Ontario by New York state in 1969, and by                                          rehabilitation plans (Schneider et al. 1983; Schneider Ontario in 1971, followed a 35-year hiatus (Parsons                                      et al. 1998). Lake trout of nine genetic strains have 1973; Kocik and Jones 1999). Despite early failed                                        been stocked into Lake Ontario since 1972. The strain introductions in Lake Ontario, significant angling                                      composition is dominated by non-Great Lake strains returns from Lake Michigan following introductions of                                    (6 strains), two Lake Superior strains, and a brood Pacific salmon caused renewed interest in the other                                      stock developed from mixed strains of hatchery fish Great Lakes (Kocik and Jones 1999). Chinook salmon                                      that survived to maturity in Lake Ontario (Elrod et al.
was initially not the dominant species stocked (Fig. 1).                                1995). Lake trout stocking increased to 1.9 million However, angler preference for the large fast growing                                    fish in 1985, and was maintained above 2.0 million chinook along with lower hatchery production costs                                      fish annually until 1992. Changes to stocking policy to compared to other species, resulted in an increased                                      regulate predation on alewife resulted in reductions in predominance of chinook salmon. By 1982, chinook                                        lake trout stocking in 1993. From 1993 to 1999 salmon dominated the stocking of Lake Ontario                                            stocking of lake trout has ranged from 0.9 to 1.1 salmonids. From 1982 to 1999, they represented                                          million fish annually. Management efforts have between 32 to 54% of the annual stocking.                                                maintained lamprey mortality at low levels, restricted Stocking levels of chinook were influenced by                                        excessive angler or incidental commercial harvests, fisheries management efforts to regulate the level of                                    improved survival by increasing the proportion of predation on alewife. Alewife is the primary prey of                                    Seneca genetic strain, and varied stocking practices to Lake Ontario chinook salmon (Jones et al. 1993). As a                                    improve survival (Elrod et al. 1995; Schneider et al.
result of their high abundance and fast growth,                                          1998).
chinook salmon account for an estimated two-thirds of the lakewide predator demand for alewives (Jones et                                      Rainbow trout al. 1993). Consequently, management of predator                                            The rainbow trout is unique among the introduced demand required management of chinook salmon                                            salmonids as it represents the earliest to naturalize and stocking levels. As the mainstay of the recreational                                    has the longest history of successful introduction.
fishery and the associated tourism economies, changes                                    Naturalized populations were established in all five to chinook salmon stocking levels were controversial.                                    Great Lakes by the early 1900s (MacCrimmon and Chinook salmon stocking numbers received                                                Gotts 1972, referenced in Kocik and Jones 1999). In Lake Ontario Salmonid Introductions


sympos ium (SCOL-II) to synthesize new knowledge.
12.3 Lake Ontario, there were established spawning runs in    Atlantic salmon several tributaries by the 1960s (Christie 1973).            Differing and changing management objectives Despite the presence of wild runs, rainbow trout        and policies among state, provincial, and U.S. Federal stocking accelerated from 107,000 in 1972 to 1.1        agencies has influenced the history of Lake Ontario million by 1980. From 1981 to 1999 annual stocking      Atlantic salmon stocking. In the recent past (post has ranged from 570,000 to 1.3 million fish annually    1970), in the province of Ontario, management and representing from 6 to 23% of the total salmonids        stocking practices have been directed at investigating stocked. Compared to other introduced salmonids,        the feasibility of establishing Atlantic salmon.
As part of the synthesis, Great Lakes investigators submitted various working papers covering a variety of topics for use at a workshop. This is paper is one such contribution and can also be found on the internet at <http://www.glfc.org/bote/upload/salmoni d introductionsstewart.doc>. The publication of the
rainbow trout stocking numbers have received less        Stocking began in Ontario with the stocking of 1,000 scrutiny. Encouragement of wild rainbow trout            fall fingerling into Wilmot Creek in 1987. From 1988 production has recently been established as a            to 1995 between 28,000 and 76,000 spring yearlings management goal (Stewart et al. 1999), however no        and fall fingerlings, were stocked into the Credit specific stocking policies to support this goal have    River, Wilmot Creek and the Ganaraska River (1995 been developed. Much of the annual variation is due to  only). From 1996-1999, Ontario began to emphasize the stocking of a diversity of life-stage (spring        fry stocking, and between 121,000 to 249,000 Atlantic fingerlings, fall fingerlings, and yearlings) and the    salmon fry were stocked annually. In the early years, vagaries of the management of hatchery space in a        fish from both landlocked and anadromous strains multi-species fish culture program.                      were stocked. Beginning in 1991, all Atlantic salmon Brown trout                                              stocked by the province of Ontario have been from a genetic strain of anadromous fish from the LeHave Brown trout are native to Europe but have been      River, Nova Scotia.
introduced throughout the world (MacCrimmon and Marshall 1968). Self-sustaining stream resident stocks      In New York, the Department of Environmental occur in the Lake Ontario watershed but few wild        Conservation program evolved from an initial brown trout exist in the main-body of Lake Ontario      rehabilitation emphasis beginning in 1983, to an (Bowlby 1991). The stocking of brown trout              increased emphasis on the establishment of a trophy accelerated along with other salmonids during the       sport fishery (Abraham 1988). Beginning in 1996, the 1970s and 1980s and reached a peak of 0.9 million        U.S. Fish and Wild Service initiated limited stocking fish in 1991. From 1992 to 1999 stocking has been        to investigate the survival and growth of stocked relatively unchanged, ranging from 585,000 to            Atlantic salmon in selected New York tributaries. The 672,000 fish annually.                                  first stockings (post 1970) of Atlantic salmon by New York were in 1983, and from 1983 to 1990 annual Coho salmon                                              stocking numbers ranged from 25-53,000 fish. From Much of the initial excitement and development of    1991 to 1999 stocking increased to between 98,000 salmon fishing can be attributed to introductions of    and 302,000 Atlantic salmon yearlings and fingerlings coho salmon (Scott and Crossman 1999; Kocik and          annually. New York stocked Atlantic salmon originate Jones 1999). Both New York and Ontarios renewed        from four distinct landlocked strains (Little Clear interest in salmonid introductions began with an initial Lake, Grand Lake, Lake Memphremagog, and Sebago stocking of coho salmon in 1968 (New York) and          Lake) and one anadromous strain (Penobscot River, 1969 (Ontario). Coho salmon continued to dominate        MN).
the province of Ontarios stocking program until 1979.
Total stocking of coho reached its peak in 1988 with    Salmonid fisheries the stocking of 879,000 fish. The next largest stocking of coho was in 1992 at 829,000 fish. Cost                    The salmonid fishery is comprised of several considerations resulted in the discontinuation of coho  components: an offshore-boat fishery; a lakeshore stocking by the province of Ontario from 1992 to        fishery; and a tributary fishery. The only fishery that 1996. However, because of strong public sentiment the    is consistently monitored is the offshore boat fishery, province of Ontario resumed coho stocking in 1997.      which is thought to represent one-third to one-half of From 1993 to 1999, the number of coho stocked in        the total recreational fishing effort and harvest (Savoie New York and Ontario combined, has ranged from          and Bowlby 1991; T. Eckert, personal communication, 196,000 to 360,000 fish annually.                       New York Department of Environmental Conservation, Cape Vincent, N.Y. 13601).
Lake Ontario Salmonid Introductions


complete Lake Ontario SCOL
12.4 Total annual fishing effort in the offshore boat                          600                                                    5 fishery ranged from 2.2 to 4.4 million angler-hours 500                                                    4 from 1985 to 1995 (Fig. 2), with 70% of the fishery Fishing Effort (x 10 )
-II sy nthesis is expected in 2002. The initial introduction of salmonids into the Great Lakes was an attempt to control nuisance leve ls of alewife but quickly became focused on developing a multi-million dollar recreational fishing industry (O'Gorman and Stewar t 1999). In early 1970s, New York State and the Province of Ontario began to establish recreational fisheries and rehabilitate l ake trout by accelerating the introductions of lake trout (Salvelinus namaycush
6 Harvest (x 103 )
), brown trout (Salmo trutta) , rainbow trout (On corhynchus mykiss
effort occurring in New York waters (Stewart et al.                          400 2002). Fishing effort increased over the period from                                                                                  3 1985 to 1990, but declined to about half the 1990 peak                        300 level by 1995 (Fig. 2). Total annual harvest ranged                                                                                  2 200 from 153 to 548 thousand fish (Fig. 2) with 58% of the                                    Harvest      Effort harvest being from New York waters and 42% from                              100                                                    1 Ontario (Stewart et al. 2002). Harvest peaked in 1986 and declined thereafter (Fig. 2).                                              0                                                      0 1985  1987      1989        1991  1993  1995 The species composition of the harvest, in order of dominance was chinook salmon, rainbow trout, lake                      FIG. 2. Total annual fishing effort and harvest of salmonids in the offshore boat-fishery in Lake Ontario for the water of New trout, brown trout and coho salmon (Stewart et al.                    York and Ontario combined, 1985-1995 (redrawn from table 2002). Atlantic salmon harvest has been limited to                    in Stewart et al. 2002).
), chinook salmon (Oncorhynchus tshawytscha
several hundred fish (less than 1% of the total harvest) and will not be considered further. Harvest generally 824 mt in 1995 (Fig. 4). Recreational boat-fishing declined from 1985 to 1995 by 2 to 4-fold for all yields exceeded commercial fishing yields in all years.
), coho salmo n (Oncorhynchus kisutch) and Atlantic salmon (Salmo salar). Limited stocking of kokanee salmon (Oncorhynchus nerka
species but trends varied somewhat in New York and Ontario (Fig. 3). Chinook salmon harvest declined                          Examination of long-term commercial catch from a high of 224,000 in 1986 to 53,000 by 1995.                      statistics has provided much of our understanding of Rainbow trout harvest declined from a high of 120,000                  early fish community structure and function (Christie in 1988 to 40,00 fish by 1995. Lake trout harvest                      1973). Fishery yields have been used to assess changes declined from a high of 121,000 in 1985 to 28,000 by                  in system productivity and food-web dynamics 1995. Brown trout harvest declined from a high of                     (Matuszek 1978; Leach et al. 1987; Loftus et al.
), was discontinued in 1973. The introductions initially failed to establish significant fisheries due to high parasitic sea lamprey induced mortality (Pearce et al. 1980). In the early 1980s, s ea lamprey were effectively controlled (Christie and Kolenosky 1980) and the survival of all stocked trout
79,000 in 1986 to 28,000 by 1995. Coho salmon                          1987). The combined recreational and commercial harvest showed the largest decline from a high of                      yields from 1985 to 1995, expressed on an area basis 46,000 in 1986 to 6,000 fish by 1995.                                  ranged from 0.7 to 1.8 kg/ha. Recreational fishing yields reported in this study do not include harvests from large unsurveyed shore and tributary fisheries.
Commercial versus recreational                                        Including these fisheries would result in yields at least fishing yields                                                        twice as high as those documented. Matuszek (1978)
Historical commercial fisheries in the U. S. and in                determined that the maximum sustained average western and central Canada waters relied on stocks of                  annual yield from historical Lake Ontario commercial ciscoe, lake whitefish, and lake trout. These stocks and              fisheries from 1915 to 1929 was 1.25 kg/ha. Clearly, their associated fisheries had collapsed or were greatly              current fish yields far exceed historical maximums.
reduced by the mid-1940s. (Christie 1973). In eastern                  The extremely high yields in the last decade, derived Lake Ontario commercial fisheries persisted. Their                    primarily from hatchery supported recreational longevity can be attributed to lake whitefish stocks,                  fisheries, has no historical precedent.
that persisted through the 1950s and by increased reliance on warm-water species (Christie 1973). The                    Influences of introduced salmonids modern commercial fishery continues to be                              on the fish community concentrated in the nearshore waters of the northeastern part of Lake Ontario. Harvest is                              An examination of the fish community influences comprised of 15 to 20 species dominated by warm-                      of introduced salmonids in Lake Ontario must water species (American eel, walleye, yellow perch,                    consider various temporal and spatial scales. Spatial brown bullhead) and lake whitefish.                                    scales of influences range from effects of migratory salmonids on individual stream ecology (Kocik and The commercial fishery yielded 1,050 mt of fish in Jones 1999 and references therein), to impacts on 1985, but by 1995 yields had declined to 600 mt (Fig.
unique eco-regions such as the outlet basin of eastern 4). By comparison, yields from the salmonid boat-Lake Ontario (Christie et al. 1987a; Casselman and fishery peaked at 2,600 mt in 1987 and declined to Scott 1992), to whole-lake food-web impacts (Jones et Lake Ontario Salmonid Introductions


and salmon improved.
12.5 Total                                                                                Chinook salmon 600                                                                                    250 Ontario        New York      Total 500 200 Harvest (x 10 3 )                                                                      Harvest (x 10 3 )
Hatchery programs in both New York and Ontario were expanded and stocking levels were increased. In the following years, activity in the recreational fishery greatly expanded. Total annual
400 150 300 100 200 50 100 0                                                                                      0 1985  1987  1989          1991      1993          1995                            1985  1987        1989        1991  1993    1995 Rainbow trout                                                                                  Lake trout 140                                                                                    140 120                                                                                    120 100                                                                                    100 Harve st (x 10 3 )                                                                      Harve st (x 10 3 )
80                                                                                      80 60                                                                                      60 40                                                                                      40 20                                                                                      20 0                                                                                      0 1985  1987  1989        1991      1993            1995                            1985  1987        1989        1991  1993    1995 Brown trout                                                                                Coho salmon 90                                                                                    50 80                                                                                    45 70                                                                                    40 35 Harvest (x 10 3 )                                                                    Harvest (x 10 3 )
60 30 50 25 40 20 30 15 20                                                                                    10 10                                                                                      5 0                                                                                      0 1985      1987  1989        1991      1993            1995                        1985      1987      1989          1991  1993    1995 FIG. 3. Total annual Lake Ontario salmonid boat-fishery harvest and annual species-specific harvest for New York and Ontario, 1985-1995 (from Stewart et al. 2002).
Lake Ontario Salmonid Introductions


expenditures by angl ers participating in Lake Ontario's recreational fisheries were $53 million (Canadian) for Ontario in 1995 (Department of
12.6 Salmon and trout al. 1993; Rand et al. 1994; Rand and Stewart 1998a; boat fishery Rand and Stewart 1998b). Similarly, impacts of                                 3000 Commercial introduced salmonids have been investigated at the Yield (metric t) 2500                      fishery level of individual year-classes (Jones and Stanfield                          2000 1993), multi-species trend analysis (Christie et al.
 
1500 1987a, OGorman et al. 1987) and longer-term impacts of ecosystem and food-web restructuring                                1000 (Christie et al. 1987b; Eschenroder and Burnham-                                500 Curtis 1999).                                                                    0 Despite the diversity of investigations, we believe                              1985 1987 1989 1991 1993 1995 only two major biotic influences are evident: direct          FIG. 4. Lakewide yields from Lake Ontarios New York and and indirect effects on fish communities through              Ontario angling boat fishery for salmonids and from Ontarios predation on alewife and smelt; both positive and             commercial fishery, 1985-1996. The total boat-angling har-negative influences on the persistence and restoration        vest was not measured in 1996.
Fisheries and Oceans 1997) and $71 million (U.S.) for
of native salmonids. A third influence, although not strictly biotic, but a consequence of the stocking of          nutrients and zooplankton production (Millard et al.
 
large numbers of hatchery exotics into a perturbed fish        1996; Rudstam 1996). OGorman and Stewart (1999) community, is the loss of an ecological paradigm on            observed that biomass of adult alewife caught in which to base fish community management.                       bottom trawls was 42% lower from 1990 to 1994 than from 1980 to 1984. In the outlet basin of eastern Lake Predation effects Ontario, bottom trawls catches of alewife and smelt Stocking of salmonids resulted in rapid build-up of        have been variable, but declined to extremely low predator levels through the 1970s and early 1980s              levels beginning in 1993 (OMNR, unpublished data).
New York in 1996 (Connelly et al. 1997). In this
(Fig. 1). Lake-wide harvest rates of chinook salmon,           Regional variation in the timing and extent of prey fish rainbow trout, lake trout, brown trout, and coho              decline is to be expected and bottom trawling catches salmon in the offshore recreational fishery peaked in          can be influenced by changed fish distribution. Less 1985 or 1986 and declined thereafter (Stewart et al.          equivocal are whole-lake hydroacoustic estimates, 2002). Index gillnet catches of lake trout in U.S.             which demonstrate a severe and persistent decline in waters reached their highest level in 1986 and                offshore smelt and alewife numbers throughout the remained high (Elrod et al. 1995). In Canadian waters,         1990s (Fig. 5). We contend that smelt and alewife the build-up of lake trout was 3-4 years later (Elrod et      numbers remained low throughout the 1990s due al. 1995) corresponding to a 3-year lag in the initiation      primarily to high levels of predation by introduced lake trout stocking by Ontario.                                salmonids.
 
Earliest available data suggest that prior to the             The suppression of alewife and smelt in Lake build-up of predator levels (i.e. pre-1985), alewife and      Ontario during the late 1980s and 1990s was smelt were regulated by intraspecific and interspecific        associated with a number of fish community changes.
paper we describe the rec ent history (post 1970) of salmonid introductions and the offshore boat fishery.
competitive interactions, cannibalism, and weather            The alewife is considered the dominant biotic (Smith 1968; Christie 1973; Christie et al. 1987a;            influence on Lake Ontario fish communities OGorman 1974; OGorman et al. 1987; Smith 1995;              (OGorman and Stewart 1999; Stewart et al. 1999, and OGorman and Stewart 1999). The increasing                    reference therein). However, many of the food-web importance of predation by introduced salmonids and            interactions attributed to alewife (for example, other piscivores was recognized but it was not                predation on fish larvae, competition with other considered to be a dominant influence (Christie et al.         planktivores, and their importance in the diet of trout 1987a; OGorman et al. 1987).                                  and salmon) also apply to rainbow smelt (Brooks The diet of salmonids in Lake Ontario is                   1968; Christie 1973; Nepszy 1977; Brandt 1986; comprised almost entirely of smelt and alewife (Brandt        Loftus and Hulsman 1986). Alewives are ubiquitous in 1986; Rand and Stewart 1998a; Lantry 2001). By the            their distribution while rainbow smelt tend to inhabit late 1980s and through the 1990s the impact of                 deeper and colder water. Both species exhibit large-predation on alewife and smelt became more evident            scale seasonal re-distribution between the offshore and (OGorman and Stewart 1999; Casselman and Scott                nearshore. The abundance, distribution and ecology of 1992), although it was confounded with declines in             these two species result in important interactions with Lake Ontario Salmonid Introductions
We also review and summarize information regard ing major fish community influences of introduced salmonids in Lake Ontario.
Management of salmonid stocking levels The number of salmonids stocked rapidly increased during the 1970s and 1980s (Fig. 1). In the mid-1980s, the state of New York and the prov ince of Ontario agreed to limit stocking to 8 million salmonids annually (Kerr and LeTendre 1991) in response to
 
concerns about the sustainability of the high predator levels, declining alewife, record fishery yields and perceived risks to the burgeoning r ecreational fishery (Kocik and Jones 1999; O'Gorman and Stewart 1999).
In 1992, and again in 1996, joint New York and Ontario t echnical syntheses and stakeholder consultations resulted in changes to stocking policy (O'Gorman and Stewart 1999; Stewart et a l. 1999). Stocking levels were reduced to 4.5 million salmonids in 1996, and have been maintained at between 4 and
 
5.5 million a nnually. In 1999, the percentage of the total salmonid stocked by species was 39.2% chinook salmon, 18.8% lake trout, 17.2% rain bow trout, 12.2%
brown trout, 7.2% coho salmon, and 5.5% Atlantic salmon.
12.2 Lake Ontario Salmonid Introductions 0 1 2 3 4
5 6 7 8 9 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 Number stocked (millions)
TOTAL Chinook salmon Lake trout Rainbow trout Coho salmon Brown trout Atlantic salmon FIG. 1. Number of salmonids stocked in Lake Ontario, 1968
-1999 (excludes fish stocked at a weight < 1 g).
Species stocking history Chinook salmon The resumption of chinook salmon stocking into Lake Ontario by New York state in 1969, a nd by Ontario in 1971, followed a 35
-year hiatus (Parsons 1973; Kocik and Jones 1999). Despite early failed introductions in La ke Ontario, significant angling returns from Lake Michigan following introductions of Pacific salmon caused renewed interest in the other Great Lakes (Kocik and Jones 1999). Chinook salmon was initially not the dominant species stocked (Fig. 1).
 
However, a ngler preference for the large fast growing chinook along with lower hatchery production costs compared to other species, result ed in an increased predominance of chinook salmon. By 1982, chinook salmon dominated the stocking of Lake Ontario
 
salmonids. Fro m 1982 to 1999, they represented between 32 to 54% of the annual stocking.
Stocking levels of chinook were influenced by fisheries management efforts to regulate the level of predation on alewife. Alewife is the primary prey of
 
Lake Ontario chinook salmon (Jones et al. 1993). As a result of their high abundance and fast growth, chinook salmon account for an estimated two
-thi rds of the lakewide predator demand for alewives (Jones et al. 1993). Consequently, management of predator
 
demand required manag ement of chinook salmon stocking levels. As the mainstay of the recreational fishery and the associated tourism economies, chang es to chinook salmon stocking levels were controversial.
Chinook salmon stocking numbers received considerable bi
-national management attention and public scrutiny (Kocik and Jones 1999; O'Gorman and Stewart 1999; Stewart et a l. 1999). Stocking numbers peaked in 1984 at 4.2 million fish and ranged from between 3.2 and 3.6 million fish from 1985 to 1992. Chinook salmon stocking was reduced substantially in 1994, based on a management review in 1992
 
(O'Gorman and Stewart 1999), a nd ranged from 1.5 to 1.7 million fish annually from 1994 to 1996. Due to stakeholder demand, and a second management review (St ewart et al. 1999), stocking was increased slightly in 1997 and has ranged from 2.0 to 2.2 million fish annually from 1997 to 19
: 99. Lake trout The history of Lake Ontario lake trout stocking, rehabilitation, management, and research is well documented (S chneider et al. 1983; Elrod et al. 1995; Schneider et al. 1998). Initial efforts at rehabilitation between 1953 and 1964 were ab andoned, but renewed after initiation of sea lamprey control in 1971 (Schneider et al. 1983). Lake trout stocking policy has
 
bee n directed at meeting management objectives for rehabilitation described in joint New York and Ontario rehabilitation plans (Sch neider et al. 1983; Schneider et al. 1998). Lake trout of nine genetic strains have been stocked into Lake Ontario since 1972.
T he strain composition is dominated by non
-Great Lake strains (6 strains), two Lake Superior strains, and a brood stock developed from mixed strains of hatchery fish that survived to maturity in Lake Ontario (Elrod et al.
1995). Lake trout stocking increase d to 1.9 million fish in 1985, and was maintained above 2.0 million fish annually until 1992. Changes to stocking policy to
 
regu late predation on alewife resulted in reductions in lake trout stocking in 1993. From 1993 to 1999 stocking of lake trout has ra nged from 0.9 to 1.1 million fish annually. Management efforts have maintained lamprey mortality at low levels, restricted
 
exces sive angler or incidental commercial harvests, improved survival by increasing the proportion of Seneca genetic strain, and vari ed stocking practices to improve survival (Elrod et al. 1995; Schneider et al.
1998). Rainbow trout The rainbow trout is unique among the introduced salmonids as it represents the earliest to naturalize and has the longest history of successful introducti on. Naturalized populations were established in all five Great Lakes by the early 1900s (MacCrimmon and
 
Gotts 1972, referenced i n Kocik and Jones 1999). In
 
12.3 Lake Ontario Salmonid Introductions Lake Ontario, there were established spawning runs in several tributaries by the 1960s (Christie 1973).
 
Despite the presence of wild runs, rainbow trout stocking accelerated from 107,000 in 1972 to 1.1 million by 1980. From 1981 to 1999 annual stocking
 
has ranged from 570,000 to 1.3 million fish annually representing from 6 to 23% of the total salmonids stocked. Compared to other i ntroduced salmonids, rainbow trout stocking numbers have received less scrutiny. Encouragement of wild rainbow trout
 
production has recently been established as a management goal (Stewart et al. 1999), however no specific stocking policies to support this goal have been developed. Much of the annual variation is due to the stocking of a diversity of life
-stage (spring fingerlings, fall fingerlings, and yearlings) and the vagaries of the management of hatchery space in a multi-species fish culture program.
B rown trout Brown trout are native to Europe but have been introduced throughout the world (MacCrimmon and Marshall 1968). Self
-s ustaining stream resident stocks occur in the Lake Ontario watershed but few wild brown trout exist in the main
-body of Lake Ont ario (Bowlby 1991). The stocking of brown trout accelerated along with other salmonids during the
 
1970s and 1980s and reached a peak of 0.9 million fish in 1991. From 1992 to 1999 stocking has been relatively unchanged, ranging from 585,000 to
 
672,000 fish annually.
Coho salmon Much of the initial excitement and development of salmon fishing can be attributed to introductions of coho salmon (Scott and Crossman 1999; Kocik and
 
Jones 1999). Both New York and Ontario's renewed
 
interest in salmonid introducti ons began with an initial stocking of coho salmon in 1968 (New York) and 1969 (Ontario). Coho salmon continued to dominate
 
the p rovince of Ontario's stocking program until 1979.
Total stocking of coho reached its peak in 1988 with the stocking of 879,000 f ish. The next largest stocking of coho was in 1992 at 829,000 fish. Cost considerations resulted in the discontinuation of coho
 
stocking by the province of Ontario from 1992 to
 
1996. However, because of strong public sentiment the
 
province of Ontario resum ed coho stocking in 1997.
From 1993 to 1999, the number of coho stocked in New York and Ontario combined, has ranged from
 
196,00 0 to 360,000 fish annually.
Atlantic salmon Differing and changing management objectives and policies among state, provincial, and U.S. Federal agencies ha s influenced the history of Lake Ontario Atlantic salmon stocking. In the recent past (post 1970), in the province of Ontario, m anagement and stocking practices have been directed at investigating the feasibility of establishing Atlantic salmon.
 
Stocking b egan in Ontario with the stocking of 1,000 fall fingerling into Wilmot Creek in 1987. From 1988 to 1995 between 28,000 and 76,00 0 spring yearlings and fall fingerlings, were stocked into the Credit River, Wilmot Creek and the Ganaraska River (1995
 
only). F rom 1996-1999, Ontario began to emphasize fry stocking, and between 121,000 to 249,000 Atlantic salmon fry were stocked annually. In the early years, fish from both landlocked and anadromous strains were stocked. Beginning in 1991, all Atlantic salmon
 
stoc ked by the province of Ontario have been from a genetic strain of anadromous fish from the LeHave River, Nova Scotia.
In New Yo rk, the Department of Environmental Conservation program evolved from an initial rehabilitation emphasis beginning in 1983, to a n increased emphasis on the establishment of a trophy sport fishery (Abraham 1988). Beginning in 1996, the
 
U.S. Fish and Wild Se rvice initiated limited stocking to investigate the survival and growth of stocked Atlantic salmon in selected New York tributar ies. The first stockings (post 1970) of Atlantic salmon by New York were in 1983, and from 1983 to 1990 annual
 
stocking numbers ranged from 25
-53,000 fish. From 1991 to 1999 stocking increased to between 98,000 and 302,000 Atlantic salmon yearlings and fin gerlings annually. New York stocked Atlantic salmon originate from four distinct landlocked strains (Little Clear
 
Lake, Grand La ke, Lake Memphremagog, and Sebago Lake) and one anadromous strain (Penobscot River, MN). Salmonid fisheries The salmonid fisher y is comprised of several components: an offshore
-boat fishery; a lakeshore fishery; and a tributary fishery. The only fishery that is consistently monitored is the offshore boat fishery, which is thought to represent one
-third to one
-half of the total re creational fishing effort and harvest (Savoie and Bowlby 1991; T. Eckert, personal communication, New York Department of Environ mental Conservation, Cape Vincent, N.Y. 13601).
 
12.4 Lake Ontario Salmonid Introductions Total annual fishing effort in the offshore boat fishery ranged from 2.2 to 4.4 million angler
-hours from 1985 to 1995 (Fig. 2), with 70% of the fishery effort occurring in New York waters (Stewart et al.
2002). Fishing effort increased over the period fro m 1985 to 1990, but declined to about half the 1990 peak level by 1995 (Fig. 2). Total annual harvest ranged
 
from 153 to 548 tho usand fish (Fig. 2) with 58% of the harvest being from New York waters and 42% from Ontario (Stewart et al. 2002). Harvest peake d in 1986 and declined thereafter (Fig. 2).
The species composition of the harvest, in order of dominance was chinook salmon, r ainbow trout, lake trout, brown trout and coho salmon (Stewart et al.
2002). Atlantic salmon harvest has been limited to
 
several hundred fish (less than 1% of the total harvest) and will not be considered further. Harvest generally declined from 1985 to 19 95 by 2 to 4-fold for all species but trends varied somewhat in New York and Ontario (Fig. 3). Chinook salmon harvest declined
 
from a high of 224,000 in 1986 to 53,000 by 1995.
 
Rainbow trout harvest declined from a high of 120,000
 
in 1988 to 40,00 fish by 1995. Lake trout harvest declined from a high of 121,000 in 1985 to 28,000 by 1995. Brown trout harvest declined from a high of 79,000 in 1986 to 28,000 by 1995. Coho salmon harvest showed the largest decline from a high of
 
46,000 in 1986 to 6,000 fish by 1995. Commercial versus recreational fishing yields Historical commercial fisheries in the U. S. and in western and central C anada waters relied on stocks of ciscoe, lake whitefish, and lake trout. These stocks and their associated fisheries had collaps ed or were greatly reduced by the mid
-1940s. (Christie 1973). In eastern Lake Ontario commercial fisheries persisted. Their longevity can be attributed to lake whitefish stocks, that persisted through the 1950s and by increased
 
reliance on warm
-water s pecies (Christie 1973). The modern commercial fishery continues to be concentrated in the nearshore waters of the
 
northeastern p art of Lake Ontario. Harvest is comprised of 15 to 20 species dominated by warm
-water species (American eel, walleye, yellow per ch, brown bullhead) and lake whitefish.
The commercial fishery yielded 1,050 mt of fish in 1985, but by 1995 yields had decline d to 600 mt (Fig.
4). By comparison, yields from the salmonid boat
-fishery peaked at 2,600 mt in 1987 and declined to 824 mt in 1995 (Fig. 4). Recreational boat
-fishing yields exceeded commercial fishing yields in all years.
Examination of long
-term commercial catch statistics has provided much of our understanding of early fish community structure and function (Christie 1973). Fishery yields have been used to assess changes in system productivity and food
-web dynamics (Matuszek 1978; Leach et al. 1987; Loftus et al.
1987). The combined recreational and commercial yields from 1985 to 1995, expressed on an area basis
 
range d from 0.7 to 1.8 kg/ha. Recreational fishing yields reported in this study do not include harvests from large unsurveyed shore and tributary fisheries.
Including these fisheries would result in yields at least twice as high as those documented. Matuszek (1978) determined that the maximum sustained average annual yield from historical Lake Ontario commercial
 
fisheries from 1915 to 1929 was 1.25 kg/ha. Clearly, current fish yields far exceed historical maximums.
The extremely high yields in the last decade, derived primarily from hatchery supported recreational fisheries, has no historical precedent.
Influences of introduced salmoni ds on the fish community An examination of the fish community influences of introduced salmonids in Lake Ontario must consider v arious temporal and spatial scales. Spatial scales of influences range from effects of migratory salmonids on individual stream ecology (Kocik and Jones 1999 and references therein), to impacts on unique eco
-regions such as the outlet basin of eastern Lake Ontario (Christie et al. 1987a; Casselman and Scott 1992), to whole
-lake food-web impacts (Jones et 0 100 200 300 400 500 600 1985 1987 1989 1991 1993 1995 Harvest (x 10 3 )0 1 2
3 4
5 Fishing Effort (x 10 6 )Harvest Effort FIG. 2. Total annual fishing effort and harvest of salmonids in the offshore boat
-fishery in Lake Ontario for the water of New York and Ontario combined, 1985
-1995 (redrawn from table in Stewart et al. 2002).
 
12.5 Lake Ontario Salmonid Introductions Chinook s almon 0 50 100 150 200 250 1985 1987 1989 1991 1993 1995 Harve st (x 10 3 )Coho s almon 0 5 10 15 20 25 30 35 40 45 50 1985 1987 1989 1991 1993 1995 Harve s t (x 10 3 )Rainbow trout 0 20 40 60 80 100 120 140 1985 1987 1989 1991 1993 1995 Harv e st (x 10 3 )Brown trout 0 10 20 30 40 50 60 70 80 90 1985 1987 1989 1991 1993 1995 Harve st (x 10 3 )Total 0 100 200 300 400 500 600 1985 1987 1989 1991 1993 1995 Harve st (x 10 3 )Ontario New York To tal Lake trout 0 20 40 60 80 100 120 140 1985 1987 1989 1991 1993 1995 Harv e st (x 10 3 )FIG. 3. Total annual Lake Ontario salmonid boat
-fishery harvest and annual species
-specific harvest for New York and Ontario, 19 85-1995 (from Stewart et al. 2002).
 
12.6 Lake Ontario Salmonid Introductions al. 1993; Rand et al. 1994; Rand and Stewart 1998a; Rand and Stewart 1998b). Similarly, impacts of
 
introduced salmonids have bee n investigated at the level of individual year
-classes (Jones and Stanfield 1993), multi
-species trend analysis (Christie et al.
1987a, O'Gorman et al. 1987) and longer
-term impacts of ecosystem and food
-web restructuring (Christie et al. 1987b; Eschenrode r and Burnham
-Curtis 1999).
Despite the diversity of investigations, we believe only two major biotic influences are evident:
d irect and indirect effects on fish communities through predation on alewife and smelt; both positive and
 
negative influences on the persistence and restoration of native salmonids. A third influence, although not strictly biotic, but a consequence of the s tocking of large numbers of hatchery exotics into a perturbed fish community, is the loss of an ecological paradigm on
 
which to base fish community management.
Predation effects Stocking of salmonids resulted in rapid build
-up of predator levels through t he 1970s and early 1980s (Fig. 1). Lake
-wide harvest rates of chinook salmon, rainbow trout, lake trout, brown trout, and coho salmon in the offshore recreational fishery peaked in
 
1985 or 1986 and declined thereafter (Stewart et al.
 
2002). Index gillnet catches of lake trout in U.S.
waters reached their highest level in 1986 and remained high (Elrod et al. 1995). In Canadian wate rs, the build-up of lake trout was 3-4 years later (Elrod et al. 1995) corresponding to a 3
-year lag in the initiation lake trou t stocking by Ontario.
Earliest available data suggest that prior to the build-up of predator levels (i.e. pre
-1985), alewife a nd smelt were regulated by intraspecific and interspecific competitive interactions, cannibalism, and weather
 
(Smith 1968; Chris tie 1973; Christie et al. 1987a; O'Gorman 1974; O'Gorman et al. 1987; Smith 1995; O'Gorman and Stewart 1999). The increasing
 
importance of predation by introduced salmonids and
 
other piscivores was recognized but it was not
 
considered to be a dominant i nfluence (Christie et al.
1987a; O'Gorman et al. 1987).
The diet of salmonids in Lake Ontario is comprised almost entirely of s melt and alewife (Brandt 1986; Rand and Stewart 1998a; Lantry 2001). By the late 1980s and through the 1990s the impact of
 
predation on alewife and smelt became more evident
 
(O'Gorman and Stewart 1999; Casselman and Scott
 
1992), although it was confou nded with declines in nutrients and zooplankton production (Millard et al.
1996; Rudstam 1996). O'Gorman and Stewart (1999)
 
observed that biomass of a dult alewife caught in bottom trawls was 42% lower from 1990 to 1994 than from 1980 to 1984. In the outlet basin of eastern Lake Ontario, bottom trawls catches of alewife and smelt have been variable, but declined to extremely low
 
levels beginning in 1993 (OMNR, unpublished data).
Regional variation in the timing and extent of prey fish decline is to be expected and bottom trawling catches can be influenced by changed fish distribution. Less equivocal are whole
-lake hydroacoustic estimates, which demonstrat e a severe and persistent decline in offshore smelt and alewife numbers throughout the 1990s (Fig. 5). We contend that smelt and alewife numbers remained low throughout the 1990s due primarily to high levels of predation by introduced
 
salmonids.
The suppr ession of alewife and smelt in Lake Ontario during the late 1980s and 1990s was associated with a number of fish community chang es. The alewife is considered the dominant biotic influence on Lake Ontario fish communities
 
(O'Gorman and Stewart 1999; Stewart et al. 1999, and reference therein). However, many of the food
-web interactions attributed to alewife (for example, predation o n fish larvae, competition with other planktivores, and their importance in the diet of trout and salmon) also apply to rainbow smelt (Brooks 1968; Christie 1973; Nepszy 1977; Brandt 1986; Loftus and Hulsman 1986). Alewives are ubiquitous in
 
their distribu tion while rainbow smelt tend to inhabit deeper and colder water. Both species exhibit large
-scale seasonal re
-distribution betw een the offshore and nearshore. The abundance, distribution and ecology of these two species result in important interactions wi th 0 500 1000 1500 2000 2500 3000 1985 1987 1989 1991 1993 1995 Yield (metric t)
Sa lmon and trout boa t fishery Commercial fishery F IG. 4. Lakewide yields from Lake Ontario's New York and Ontario angling boat fishery for salmonids and from Ontario's commercial fishery, 1985
-1996. The total boat
-angling ha r-vest was not measured in 1996.
 
12.7 Lake Ontario Salmonid Introductions virtually all offshore fish species and many inshore fish species. Coincident with the decline of alewife
 
and smelt there was an increase in natural reproduction of lake trout, an increase in offshore abundance of native three
-spine stickleback, a recovery of native lake whitefish stocks, and some improvements in native populations of yellow perch, emerald shiner, and lake herring (Stewart et al. 1999). Other factors have contributed to these changes, but they are consistent with the hypothesis of a relaxat ion of predation and competition from suppressed populations of alewife and smelt. More recently, the
 
loss of Diporeia (deepwate r amphipod) in large regions of Lake Ontario, coincident with colonization by dreissenids, has reversed whitefish recovery and


12.7 Atlantic salmon due to an inducement of thiamine Alewife                                            deficiency (Fisher et al. 1996; McDonald et al. 1998).
Acoustic estimate (billions) 20                                                  The suppression of alewife by introduced salmonids Summer        may increase the diversity of Atlantic salmon and lake 15                                    Fall          trout diets and mitigate the loss of thiamine.
10 Existing rare native brook trout and potentially 5                                                  future stocks of wild Atlantic salmon could be 0                                                  negatively impacted by continued introductions of 1991 1992 1993 1994 1995 1996 1997 1998 1999  hatchery salmonids. Kocik and Jones (1999) summarized studies on the potential interactions of introduced Pacific salmonids (rainbow trout, coho salmon, and chinook salmon) on native brook trout Smelt                                          and on the potential for Atlantic salmon restoration.
Acoustic estimate (billions) 25                                                  Studies and field observations indicate that it is 20 possible for native and non-native salmonids to coexist (Kocik and Jones 1999; Scott and Crossman 1999).
15 However, all of the introduced non-native salmonids 10                        `                          potentially compete for spawning and nursery habitat 5                                                    and food with introduced Atlantic salmon and native 0
brook trout. The high abundance of non-native 1991 1992 1993 1994 1995 1996 1997 1998 1999  salmonids, and increasing naturalization, may limit the production of native brook trout and the future extent FIG. 5. Whole-lake acoustic estimates of abundance (number                              of Atlantic salmon restoration.
of fish) for alewives and smelt in Lake Ontario, 1991-1999.
Historically, four species of deepwater ciscoe, Coregonus nigripinnis, C. reighardi, C. kiyi, and C.
virtually all offshore fish species and many inshore                                    hoyi inhabited Lake Ontario (Christie 1972). The loss fish species. Coincident with the decline of alewife                                    of these species has been attributed to overfishing, and smelt there was an increase in natural reproduction                                increased abundance of alewives and smelt, and of lake trout, an increase in offshore abundance of                                    predation by sea lampreys (Christie 1973; Smith native three-spine stickleback, a recovery of native                                    1968). Fish management agencies have proposed the lake whitefish stocks, and some improvements in                                        reintroduction of deepwater ciscoe into Lake Ontario.
native populations of yellow perch, emerald shiner,                                    In Lake Michigan, although cause and effect are and lake herring (Stewart et al. 1999). Other factors                                  debated, bloaters (C. hoyi) increased coincident with a have contributed to these changes, but they are                                        decline in alewife and high levels of introduced consistent with the hypothesis of a relaxation of                                      salmonid abundance (Eck and Wells 1987; Kitchell predation and competition from suppressed                                              and Crowder 1986; Stewart and Ibarra 1991). These populations of alewife and smelt. More recently, the                                    conditions exist in Lake Ontario, likely favour loss of Diporeia (deepwater amphipod) in large                                          successful reintroduction of native deepwater ciscoes, regions of Lake Ontario, coincident with colonization                                  and are dependent on maintaining a high abundance of by dreissenids, has reversed whitefish recovery and                                    introduced salmonids.
may impact other species (Hoyle et al. 1999).
may impact other species (Hoyle et al. 1999).
Effects on native salmonids The introduction of hatchery salmonids may enhance re storation of native salmonids. Atlantic salmon and lake trout were native to Lake Ontario but all native gene pools were lost.
Loss of an ecological paradigm Effects on native salmonids                                                                 The initial introduction of salmonids into the Great The introduction of hatchery salmonids may                                         Lakes was an attempt to control nuisance levels of enhance restoration of native salmonids. Atlantic                                       alewife but quickly became focused on developing salmon and lake trout were native to Lake Ontario but                                   multi-million dollar recreational fishing industry all native gene pools were lost. Introductions of                                       (OGorman and Stewart 1999). In Lake Ontario, hatchery fish raised from available gene pools are the                                 efforts to rehabilitate lake trout where renewed with only way to re-establish these species. Evidence                                       increased effort to control sea lamprey. The strategy suggests that a diet high in alewives result in early                                   for the rehabilitation of lake trout, and later Atlantic mortality syndrome in the offspring of lake trout and                                   salmon, in Lake Ontario have had strong scientific and Lake Ontario Salmonid Introductions
I ntroductions of hatchery fish raised from available gene pools are the only way to re
-establish these species. Evidence suggests that a diet high in alewives result in early mortality syndrome in the offspring of lake trout and Atlantic salmon due to an inducement of thiamine deficiency (Fisher et al. 1996; McDonald et al. 1998).
 
The suppression of alewi fe by introduced salmonids may increase the diversity of Atlantic salmon and lake trout diets and mitigate the loss of thiamine.
Existing rare native brook trout and potentially future stocks of wild Atlantic salmon could be negatively impacted by continu ed introductions of hatchery salmonids. Kocik and Jones (1999) summarized studies on the potential interactions of
 
introduced Pa cific salmonids (rainbow trout, coho salmon, and chinook salmon) on native brook trout and on the potential for Atlantic salmon restoration.
Studies and field observations indicate that it is possible for native and non
-native salmonids to coexist (Kocik a nd Jones 1999; Scott and Crossman 1999).
However, all of the introduced non
-native salmonids potentially compete for spawning an d nursery habitat and food with introduced Atlantic salmon and native brook trout. The high abundance of non
-native salmonids, a nd increasing naturalization, may limit the production of native brook trout and the future extent of Atlantic salmon restoratio
: n. Historically, four species of deepwater ciscoe, Coregonus nigripinnis, C. reighardi, C. kiyi, and C.
hoyi inhabited Lake On tario (Christie 1972). The loss of these species has been attributed to overfishing, increased abundance of alewives and smelt, and predation by sea lampreys (Christie 1973; Smith 1968). Fish management agencies have proposed the
 
reintroduction of deepwate r ciscoe into Lake Ontario.
In Lake Michigan, although cause and effect are debated, bloaters (C. hoyi) increased coincident wit h a decline in alewife and high levels of introduced salmonid abundance (Eck and Wells 1987; Kitchell


and Crowder 1986; Stewart and Ibarra 1991). These conditions exist in Lake Ontario, likely favour successful reintroduction of native deepwater ciscoes, and are dependent on maintaining a high abundance of  
12.8 ecological underpinnings (Eschenroder et al. 2000;        Annual Report, Section 18, Ontario Ministry of Elrod et al. 1995; Ontario Ministry of Natural            Natural Resources.
Resources 1995; Schneider et al. 1983; Stanfield et al. CHRISTIE, W.J. 1972. Lake Ontario: effects of 1995). On the other hand, science-based management        exploitation, introductions, and eutrophication on of the recreational sport fishery has focused only on    the salmonid community. J. Fish. Res. Board Can.
the potential for over-stocking (Jones et al. 1993;      29:913-929 OGorman and Stewart 1999; Stewart et al. 1999).
CHRISTIE, W.J. 1973. A review of the changes in the The potential for a large controlling influence of    fish species composition of Lake Ontario. Great piscivores on the structure and function of the Lake      Lakes Fish. Comm. Tech. Rep. 23. 66 p.
Ontario fish community was recognized (Christie et al.
1987a; Christie et al. 1987b), but this has yet to      CHRISTIE, W.J., AND D.P. KOLENOSKY. 1980.
influence management decision making (Stewart et al.      Parasitic phase of the sea lamprey (Petromyzon 1999). The Lake Ontario fish community is largely        marinus) in Lake Ontario. Can. J. Fish. Quat. Sci.
comprised of a mix of exotic species that have no        37:2021-2038.
evolutionary sympatry. Additionally, recruitment of     CHRISTIE, W.J., K.A. SCOTT, P.G. SLY, AND R.H.
the dominant predator, and the associated top-down        STRUSS. 1987a. Recent changes in the aquatic influence on fish communities (Christie et al. 1987a;    food web of eastern Lake Ontario. Can. J. Fish.
McQueen et al. 1989) is largely controlled through        Aquat. Sci. 44(suppl. 2):37-52.
stocking levels. As a consequence, it is difficult to  CHRISTIE, W.J., G.R. SPANLGER, K.H. LOFTUS, apply conventional ecological paradigms or                W.L. HARTMAN, P.J. COLBY, M.A. ROSS, descriptions of historical fish community structures to  AND D.R. TALHELM. 1987b. A perspective on understand or predict species interrelationships or      Great Lakes fish community rehabilitation. Can. J.
equilibrium states (Christie et al. 1987b; Eschenroder    Fish. Aquat. Sci. 44 (Suppl. 2): 486-499.
and Burnham-Curtis 1999). This is not only a challenge to fisheries managers but also requires      CONNELLY, N.A., T.L. BROWN, AND B.A.
researchers to develop new conceptual models of fish      KNUTH. 1997. New York statewide angler survey community structure and function to guide                1996. Report 1: Angler effort and expenditures.
management.                                              NY State Dept. Env. Cons. 107 p.
DEPARTMENT OF FISHERIES AND OCEANS.
References                                                1997. 1995 survey of recreational fishing in Canada: selected results for Great Lakes fishery.
ABRAHAM, W.J. 1988. A draft plan for Atlantic            Economic and Policy Analysis Directorate. Dept.
salmon management in New Yorks portion of            Fish. Oceans Can. Rep. 154. 122 p.
Lake Ontario, 1990-1995. New York State ECK G.W., AND L. WELLS. 1987. Recent changes Department of Environmental Conservation.
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probable causes, with emphasis on the role of BOWLBY, J.N. 1991. Stocking assessment of brown          alewife (Alosa pseudoharengus). Can. J. Fish.
trout, rainbow trout, and coho salmon in the boat    Aquat. Sci. 44 (Suppl. 2): 53-60.
fishery of western Lake Ontario. In Lake Ontario ELROD, J.H., R. OGORMAN, C.P. SCHNEIDER, Fisheries Unit 1990 Annual Report, LOA 90.1 T. ECKERT, T. SCHANER, J.N. BOWLBY, (Chapter 4). Ontario Ministry of Natural AND L.P. SCHLEEN. 1995. Lake trout Resources.
rehabilitation in Lake Ontario. Journal of Great BRANDT, S.B. 1986. Food of trout and salmon in            Lakes Research 21 (Supplement 1):83-107.
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ESCHENRODER, R.L., AND M.K. BURNHAM-BROOKS, J.L. 1968. The effects of prey size              CURTIS. 1999. Species succession and selection by lake planktivores. Syst. Zool. 17(3):    sustainability of the Great Lakes fish community.
273-291.                                              In "Great Lakes Fisheries Policy and Management:
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12.9 ESCHENRODER, R.L., E.J. CROSSMAN, G.K.                 LEACH, J.H., L.M. DICKIE, B.J. SHUTER, U.
Loss of an ecological paradigm The initial introduct ion of salmonids into the Great Lakes was an attempt to control nuisance levels of alewife but quickly became focused on develop ing multi-million dollar recreational fishing industry (O'Gorman and Stewart 1999). In Lake Ontario, efforts to rehabilitate lak e trout where renewed with increased effort to control sea lamprey. The strategy for the rehabilitation of lake trout, and later Atlantic salmon, in Lake Ontario have had strong scientific and Alewife 0 5 10 15 20 1991 1992 1993 1994 1995 1996 1997 1998 1999 Acoustic estimate (billions)
MEFFE, C.H. OLVER, AND E.P. PISTER. 2000.               BORGMANN, J. HYMAN, AND W. LYSACK.
Summer Fall Smelt 0 5 10 15 20 25 1991 1992 1993 1994 1995 1996 1997 1998 1999 Acoustic estimate (billions)
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-lake acoustic estimates of abundance (number of fish) for alewives and smelt in Lake Ontario, 1991
AND J.M. SPITSBERGEN. 1996. Naturally              LOFTUS, K.H., AND P.F. HULSMAN. 1986.
-1999.
occurring thiamine deficiency causing                  Predation on larval whitefish (Coregonus reproduction failure in Finger Lakes Atlantic          clupeaformis) and lake herring (C. artedii) by salmon and Great Lakes lake trout. Trans. Am.           adult rainbow smelt (Osmerus mordax). Can. J.
12.8 Lake Ontario Salmonid Introductions ecological underpinnings (Eschenroder et al. 2000; Elrod et al. 1995; Ontario Ministry of Natural
Fish. Soc. 125: 167-178.                               Fish. Aquat. Sci. 43: 812-818.
 
HOYLE, J.A., J.M. CASSELMAN, R. DERMOTT,               LOFTUS, D.H., C.H. OLVER, E.H. BROWN, P.J.
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whitefish (Coregonus clupeaformis) stocks in           1987. Partioning potential fish yields from the eastern Lake Ontario following Dreissena mussel         Great Lakes. Can. J. Fish. Aquat. Sci., 44 invasion. Great Lakes Res. Rev. 4:5-10.                 (Suppl.2): 417-424.
1995). On the other hand, science
JONES, M.L., AND L.W. STANFIELD. 1993.                 LOFTUS, K.H., AND H.A. REGIER.                    1972.
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salar) in Lake Ontario tributary. Pp. 71-79. In         Bd. Canada. 29: 611-986.
The potential for a la rge controlling influence of piscivores on the structure and function of the Lake Ontario fish community was recognized (Christi e et al. 1987a; Christie et al. 1987b), but this has yet to influence management decision making (Stewart et al.
Gibson, R.J., and R.E. Cutting, editors. Production MACCRIMMON, H.R., AND B.L. GOTTS. 1972.
 
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1999). The Lake Ontario fish community is largely comprised of a mix of exotic species that have no evolutionary sympatry. Additionally, recrui tment of the dominant predator, and the associated top
Canada, Ottawa, No. 118 MACCRIMMON, H.R., AND T.L. MARSHALL.
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JONES, M.L., J.F. KOONCE, AND R. O'GORMAN.               1968. World distribution of brown trout, Salmo 1993. Sustainability of hatchery-dependent             trutta. J. Fish. Res. Board Can. 25(12):2527-2548.
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OWENS, AND D.J. STEWART. 1994. Energy                Predation and production by salmonine fishes in density and size of pelagic prey fishes in Lake      Lake Michigan, 1978-88. Can. J. Fish. Aquat.
Sci.. 48: 909
Ontario, 1978-1990implications for salmonine        Sci.. 48: 909-922.
-922. STEWART, T.J., B.E. LANGE, S.D. ORSATTI, C.
energetics. Trans. Am. Fish. Soc. 123: 519-534.
P. SCHNEIDER, A. MAT HERS, AND M.E. DANIELS 1999. Fish
STEWART, T.J., B.E. LANGE, S.D. ORSATTI, C.
-community objectives for Lake Ontario. Great Lakes Fish.
RAND, P.S., AND D.J. STEWART. 1998a. Dynamics            P. SCHNEIDER, A. MATHERS, AND M.E.
C omm. Spec.
of salmonine diets and foraging in Lake Ontario,      DANIELS 1999. Fish-community objectives for 1983-1993: a test of a bioenergetic model            Lake Ontario. Great Lakes Fish. Comm. Spec.
Pub. 99-1 56 p. STEWART, T.J., J.N. BOWLBY, M.
prediction. Can. J. Fish. Aquat. Sci. 55:307-317. Pub. 99-1 56 p.
RAWSON , AND T.H. ECKERT. 2002 The recreational boat fishery for salmon ids in Lake Ontario 1985
RAND, P.S., AND D.J. STEWART. 1998b. Prey fish        STEWART, T.J., J.N. BOWLBY, M. RAWSON, exploitation, salmonine production, and pelagic      AND T.H. ECKERT. 2002 The recreational boat food web efficiency in Lake Ontario. Can. J. Fish. fishery for salmonids in Lake Ontario 1985-Aquat. Sci. 55:318-327                                1995. State of Lake Ontario (SOLO) - Past, RUDSTAM, L. 1996 [ED.]. A review of the current          Present, and Future, pp 000-000 (accepted for status of Lake Ontario's pelagic fish community.      publication) Edited by M. Munawar, T. Edsall &
-1995. State of Lake Ontario (SOLO)
Report of the 1996 Lake Ontario technical panel.      I.F. Munawar. Ecovision World Monograph Great Lakes Res. Rev. Vol. 2 (2): 4-10.              Series, Backuys Publishers, Leiden, The SAVOIE, P.J., AND J.N. BOWLBY. 1991. Estimates          Netherlands of the total fish harvest in the Ontario waters of Lake Ontario during 1989. p. 8.1-8.4 In Lake Lake Ontario Salmonid Introductions}}
- Past, Present, and Future, pp 000
-000 (accepted for publication) E dited by M. Munawar, T. Edsall &
I.F. Munawar. Ecovision World Monograph Series, Backuys Publishers, Leiden, The
 
Netherlands}}

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12 Lake Ontario Salmonid Introductions 1970 to 1999: Stocking, Fishery and Fish Community Influences T. J. Stewart and T. Schaner Introduction were increased. In the following years, activity in the The symposium on Salmonid Communities in recreational fishery greatly expanded. Total annual Oligotrophic Lakes (SCOL-I) (Loftus and Regier expenditures by anglers participating in Lake 1972) provided insights on the stressors acting on Ontarios recreational fisheries were $53 million Great Lakes ecosystem. In 2001, the Great Lakes (Canadian) for Ontario in 1995 (Department of Fishery Commission (GLFC) initiated a second SCOL Fisheries and Oceans 1997) and $71 million (U.S.) for symposium (SCOL-II) to synthesize new knowledge. New York in 1996 (Connelly et al. 1997). In this As part of the synthesis, Great Lakes investigators paper we describe the recent history (post 1970) of submitted various working papers covering a variety salmonid introductions and the offshore boat fishery.

of topics for use at a workshop. This is paper is one We also review and summarize information regarding such contribution and can also be found on the internet major fish community influences of introduced at <http://www.glfc.org/bote/upload/salmonid salmonids in Lake Ontario.

introductionsstewart.doc>. The publication of the complete Lake Ontario SCOL-II synthesis is expected Management of salmonid stocking in 2002.

levels The initial introduction of salmonids into the Great Lakes was an attempt to control nuisance levels of The number of salmonids stocked rapidly alewife but quickly became focused on developing a increased during the 1970s and 1980s (Fig. 1). In the multi-million dollar recreational fishing industry mid-1980s, the state of New York and the province of (OGorman and Stewart 1999). In early 1970s, New Ontario agreed to limit stocking to 8 million salmonids York State and the Province of Ontario began to annually (Kerr and LeTendre 1991) in response to establish recreational fisheries and rehabilitate lake concerns about the sustainability of the high predator trout by accelerating the introductions of lake trout levels, declining alewife, record fishery yields and (Salvelinus namaycush), brown trout (Salmo trutta) , perceived risks to the burgeoning recreational fishery rainbow trout (Oncorhynchus mykiss), chinook salmon (Kocik and Jones 1999; OGorman and Stewart 1999).

(Oncorhynchus tshawytscha), coho salmon In 1992, and again in 1996, joint New York and (Oncorhynchus kisutch) and Atlantic salmon (Salmo Ontario technical syntheses and stakeholder salar). Limited stocking of kokanee salmon consultations resulted in changes to stocking policy (Oncorhynchus nerka), was discontinued in 1973. The (OGorman and Stewart 1999; Stewart et al. 1999).

introductions initially failed to establish significant Stocking levels were reduced to 4.5 million salmonids fisheries due to high parasitic sea lamprey induced in 1996, and have been maintained at between 4 and mortality (Pearce et al. 1980). In the early 1980s, sea 5.5 million annually. In 1999, the percentage of the lamprey were effectively controlled (Christie and total salmonid stocked by species was 39.2% chinook Kolenosky 1980) and the survival of all stocked trout salmon, 18.8% lake trout, 17.2% rainbow trout, 12.2%

and salmon improved. Hatchery programs in both New brown trout, 7.2% coho salmon, and 5.5% Atlantic York and Ontario were expanded and stocking levels salmon.

12.2 9 TOTAL considerable bi-national management attention and 8 Chinook salmon public scrutiny (Kocik and Jones 1999; OGorman and Lake trout Stewart 1999; Stewart et al. 1999). Stocking numbers 7 peaked in 1984 at 4.2 million fish and ranged from Rainbow trout Number stocked (millions) 6 Coho salmon between 3.2 and 3.6 million fish from 1985 to 1992.

Brown trout Chinook salmon stocking was reduced substantially in 5 1994, based on a management review in 1992 Atlantic salmon 4

(OGorman and Stewart 1999), and ranged from 1.5 to 1.7 million fish annually from 1994 to 1996. Due to 3 stakeholder demand, and a second management review 2

(Stewart et al. 1999), stocking was increased slightly in 1997 and has ranged from 2.0 to 2.2 million fish 1 annually from 1997 to 1999.

0 Lake trout 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 The history of Lake Ontario lake trout stocking, FIG. 1. Number of salmonids stocked in Lake Ontario, 1968- rehabilitation, management, and research is well 1999 (excludes fish stocked at a weight < 1 g). documented (Schneider et al. 1983; Elrod et al. 1995; Schneider et al. 1998). Initial efforts at rehabilitation between 1953 and 1964 were abandoned, but renewed Species stocking history after initiation of sea lamprey control in 1971 Chinook salmon (Schneider et al. 1983). Lake trout stocking policy has been directed at meeting management objectives for The resumption of chinook salmon stocking into rehabilitation described in joint New York and Ontario Lake Ontario by New York state in 1969, and by rehabilitation plans (Schneider et al. 1983; Schneider Ontario in 1971, followed a 35-year hiatus (Parsons et al. 1998). Lake trout of nine genetic strains have 1973; Kocik and Jones 1999). Despite early failed been stocked into Lake Ontario since 1972. The strain introductions in Lake Ontario, significant angling composition is dominated by non-Great Lake strains returns from Lake Michigan following introductions of (6 strains), two Lake Superior strains, and a brood Pacific salmon caused renewed interest in the other stock developed from mixed strains of hatchery fish Great Lakes (Kocik and Jones 1999). Chinook salmon that survived to maturity in Lake Ontario (Elrod et al.

was initially not the dominant species stocked (Fig. 1). 1995). Lake trout stocking increased to 1.9 million However, angler preference for the large fast growing fish in 1985, and was maintained above 2.0 million chinook along with lower hatchery production costs fish annually until 1992. Changes to stocking policy to compared to other species, resulted in an increased regulate predation on alewife resulted in reductions in predominance of chinook salmon. By 1982, chinook lake trout stocking in 1993. From 1993 to 1999 salmon dominated the stocking of Lake Ontario stocking of lake trout has ranged from 0.9 to 1.1 salmonids. From 1982 to 1999, they represented million fish annually. Management efforts have between 32 to 54% of the annual stocking. maintained lamprey mortality at low levels, restricted Stocking levels of chinook were influenced by excessive angler or incidental commercial harvests, fisheries management efforts to regulate the level of improved survival by increasing the proportion of predation on alewife. Alewife is the primary prey of Seneca genetic strain, and varied stocking practices to Lake Ontario chinook salmon (Jones et al. 1993). As a improve survival (Elrod et al. 1995; Schneider et al.

result of their high abundance and fast growth, 1998).

chinook salmon account for an estimated two-thirds of the lakewide predator demand for alewives (Jones et Rainbow trout al. 1993). Consequently, management of predator The rainbow trout is unique among the introduced demand required management of chinook salmon salmonids as it represents the earliest to naturalize and stocking levels. As the mainstay of the recreational has the longest history of successful introduction.

fishery and the associated tourism economies, changes Naturalized populations were established in all five to chinook salmon stocking levels were controversial. Great Lakes by the early 1900s (MacCrimmon and Chinook salmon stocking numbers received Gotts 1972, referenced in Kocik and Jones 1999). In Lake Ontario Salmonid Introductions

12.3 Lake Ontario, there were established spawning runs in Atlantic salmon several tributaries by the 1960s (Christie 1973). Differing and changing management objectives Despite the presence of wild runs, rainbow trout and policies among state, provincial, and U.S. Federal stocking accelerated from 107,000 in 1972 to 1.1 agencies has influenced the history of Lake Ontario million by 1980. From 1981 to 1999 annual stocking Atlantic salmon stocking. In the recent past (post has ranged from 570,000 to 1.3 million fish annually 1970), in the province of Ontario, management and representing from 6 to 23% of the total salmonids stocking practices have been directed at investigating stocked. Compared to other introduced salmonids, the feasibility of establishing Atlantic salmon.

rainbow trout stocking numbers have received less Stocking began in Ontario with the stocking of 1,000 scrutiny. Encouragement of wild rainbow trout fall fingerling into Wilmot Creek in 1987. From 1988 production has recently been established as a to 1995 between 28,000 and 76,000 spring yearlings management goal (Stewart et al. 1999), however no and fall fingerlings, were stocked into the Credit specific stocking policies to support this goal have River, Wilmot Creek and the Ganaraska River (1995 been developed. Much of the annual variation is due to only). From 1996-1999, Ontario began to emphasize the stocking of a diversity of life-stage (spring fry stocking, and between 121,000 to 249,000 Atlantic fingerlings, fall fingerlings, and yearlings) and the salmon fry were stocked annually. In the early years, vagaries of the management of hatchery space in a fish from both landlocked and anadromous strains multi-species fish culture program. were stocked. Beginning in 1991, all Atlantic salmon Brown trout stocked by the province of Ontario have been from a genetic strain of anadromous fish from the LeHave Brown trout are native to Europe but have been River, Nova Scotia.

introduced throughout the world (MacCrimmon and Marshall 1968). Self-sustaining stream resident stocks In New York, the Department of Environmental occur in the Lake Ontario watershed but few wild Conservation program evolved from an initial brown trout exist in the main-body of Lake Ontario rehabilitation emphasis beginning in 1983, to an (Bowlby 1991). The stocking of brown trout increased emphasis on the establishment of a trophy accelerated along with other salmonids during the sport fishery (Abraham 1988). Beginning in 1996, the 1970s and 1980s and reached a peak of 0.9 million U.S. Fish and Wild Service initiated limited stocking fish in 1991. From 1992 to 1999 stocking has been to investigate the survival and growth of stocked relatively unchanged, ranging from 585,000 to Atlantic salmon in selected New York tributaries. The 672,000 fish annually. first stockings (post 1970) of Atlantic salmon by New York were in 1983, and from 1983 to 1990 annual Coho salmon stocking numbers ranged from 25-53,000 fish. From Much of the initial excitement and development of 1991 to 1999 stocking increased to between 98,000 salmon fishing can be attributed to introductions of and 302,000 Atlantic salmon yearlings and fingerlings coho salmon (Scott and Crossman 1999; Kocik and annually. New York stocked Atlantic salmon originate Jones 1999). Both New York and Ontarios renewed from four distinct landlocked strains (Little Clear interest in salmonid introductions began with an initial Lake, Grand Lake, Lake Memphremagog, and Sebago stocking of coho salmon in 1968 (New York) and Lake) and one anadromous strain (Penobscot River, 1969 (Ontario). Coho salmon continued to dominate MN).

the province of Ontarios stocking program until 1979.

Total stocking of coho reached its peak in 1988 with Salmonid fisheries the stocking of 879,000 fish. The next largest stocking of coho was in 1992 at 829,000 fish. Cost The salmonid fishery is comprised of several considerations resulted in the discontinuation of coho components: an offshore-boat fishery; a lakeshore stocking by the province of Ontario from 1992 to fishery; and a tributary fishery. The only fishery that 1996. However, because of strong public sentiment the is consistently monitored is the offshore boat fishery, province of Ontario resumed coho stocking in 1997. which is thought to represent one-third to one-half of From 1993 to 1999, the number of coho stocked in the total recreational fishing effort and harvest (Savoie New York and Ontario combined, has ranged from and Bowlby 1991; T. Eckert, personal communication, 196,000 to 360,000 fish annually. New York Department of Environmental Conservation, Cape Vincent, N.Y. 13601).

Lake Ontario Salmonid Introductions

12.4 Total annual fishing effort in the offshore boat 600 5 fishery ranged from 2.2 to 4.4 million angler-hours 500 4 from 1985 to 1995 (Fig. 2), with 70% of the fishery Fishing Effort (x 10 )

6 Harvest (x 103 )

effort occurring in New York waters (Stewart et al. 400 2002). Fishing effort increased over the period from 3 1985 to 1990, but declined to about half the 1990 peak 300 level by 1995 (Fig. 2). Total annual harvest ranged 2 200 from 153 to 548 thousand fish (Fig. 2) with 58% of the Harvest Effort harvest being from New York waters and 42% from 100 1 Ontario (Stewart et al. 2002). Harvest peaked in 1986 and declined thereafter (Fig. 2). 0 0 1985 1987 1989 1991 1993 1995 The species composition of the harvest, in order of dominance was chinook salmon, rainbow trout, lake FIG. 2. Total annual fishing effort and harvest of salmonids in the offshore boat-fishery in Lake Ontario for the water of New trout, brown trout and coho salmon (Stewart et al. York and Ontario combined, 1985-1995 (redrawn from table 2002). Atlantic salmon harvest has been limited to in Stewart et al. 2002).

several hundred fish (less than 1% of the total harvest) and will not be considered further. Harvest generally 824 mt in 1995 (Fig. 4). Recreational boat-fishing declined from 1985 to 1995 by 2 to 4-fold for all yields exceeded commercial fishing yields in all years.

species but trends varied somewhat in New York and Ontario (Fig. 3). Chinook salmon harvest declined Examination of long-term commercial catch from a high of 224,000 in 1986 to 53,000 by 1995. statistics has provided much of our understanding of Rainbow trout harvest declined from a high of 120,000 early fish community structure and function (Christie in 1988 to 40,00 fish by 1995. Lake trout harvest 1973). Fishery yields have been used to assess changes declined from a high of 121,000 in 1985 to 28,000 by in system productivity and food-web dynamics 1995. Brown trout harvest declined from a high of (Matuszek 1978; Leach et al. 1987; Loftus et al.

79,000 in 1986 to 28,000 by 1995. Coho salmon 1987). The combined recreational and commercial harvest showed the largest decline from a high of yields from 1985 to 1995, expressed on an area basis 46,000 in 1986 to 6,000 fish by 1995. ranged from 0.7 to 1.8 kg/ha. Recreational fishing yields reported in this study do not include harvests from large unsurveyed shore and tributary fisheries.

Commercial versus recreational Including these fisheries would result in yields at least fishing yields twice as high as those documented. Matuszek (1978)

Historical commercial fisheries in the U. S. and in determined that the maximum sustained average western and central Canada waters relied on stocks of annual yield from historical Lake Ontario commercial ciscoe, lake whitefish, and lake trout. These stocks and fisheries from 1915 to 1929 was 1.25 kg/ha. Clearly, their associated fisheries had collapsed or were greatly current fish yields far exceed historical maximums.

reduced by the mid-1940s. (Christie 1973). In eastern The extremely high yields in the last decade, derived Lake Ontario commercial fisheries persisted. Their primarily from hatchery supported recreational longevity can be attributed to lake whitefish stocks, fisheries, has no historical precedent.

that persisted through the 1950s and by increased reliance on warm-water species (Christie 1973). The Influences of introduced salmonids modern commercial fishery continues to be on the fish community concentrated in the nearshore waters of the northeastern part of Lake Ontario. Harvest is An examination of the fish community influences comprised of 15 to 20 species dominated by warm- of introduced salmonids in Lake Ontario must water species (American eel, walleye, yellow perch, consider various temporal and spatial scales. Spatial brown bullhead) and lake whitefish. scales of influences range from effects of migratory salmonids on individual stream ecology (Kocik and The commercial fishery yielded 1,050 mt of fish in Jones 1999 and references therein), to impacts on 1985, but by 1995 yields had declined to 600 mt (Fig.

unique eco-regions such as the outlet basin of eastern 4). By comparison, yields from the salmonid boat-Lake Ontario (Christie et al. 1987a; Casselman and fishery peaked at 2,600 mt in 1987 and declined to Scott 1992), to whole-lake food-web impacts (Jones et Lake Ontario Salmonid Introductions

12.5 Total Chinook salmon 600 250 Ontario New York Total 500 200 Harvest (x 10 3 ) Harvest (x 10 3 )

400 150 300 100 200 50 100 0 0 1985 1987 1989 1991 1993 1995 1985 1987 1989 1991 1993 1995 Rainbow trout Lake trout 140 140 120 120 100 100 Harve st (x 10 3 ) Harve st (x 10 3 )

80 80 60 60 40 40 20 20 0 0 1985 1987 1989 1991 1993 1995 1985 1987 1989 1991 1993 1995 Brown trout Coho salmon 90 50 80 45 70 40 35 Harvest (x 10 3 ) Harvest (x 10 3 )

60 30 50 25 40 20 30 15 20 10 10 5 0 0 1985 1987 1989 1991 1993 1995 1985 1987 1989 1991 1993 1995 FIG. 3. Total annual Lake Ontario salmonid boat-fishery harvest and annual species-specific harvest for New York and Ontario, 1985-1995 (from Stewart et al. 2002).

Lake Ontario Salmonid Introductions

12.6 Salmon and trout al. 1993; Rand et al. 1994; Rand and Stewart 1998a; boat fishery Rand and Stewart 1998b). Similarly, impacts of 3000 Commercial introduced salmonids have been investigated at the Yield (metric t) 2500 fishery level of individual year-classes (Jones and Stanfield 2000 1993), multi-species trend analysis (Christie et al.

1500 1987a, OGorman et al. 1987) and longer-term impacts of ecosystem and food-web restructuring 1000 (Christie et al. 1987b; Eschenroder and Burnham- 500 Curtis 1999). 0 Despite the diversity of investigations, we believe 1985 1987 1989 1991 1993 1995 only two major biotic influences are evident: direct FIG. 4. Lakewide yields from Lake Ontarios New York and and indirect effects on fish communities through Ontario angling boat fishery for salmonids and from Ontarios predation on alewife and smelt; both positive and commercial fishery, 1985-1996. The total boat-angling har-negative influences on the persistence and restoration vest was not measured in 1996.

of native salmonids. A third influence, although not strictly biotic, but a consequence of the stocking of nutrients and zooplankton production (Millard et al.

large numbers of hatchery exotics into a perturbed fish 1996; Rudstam 1996). OGorman and Stewart (1999) community, is the loss of an ecological paradigm on observed that biomass of adult alewife caught in which to base fish community management. bottom trawls was 42% lower from 1990 to 1994 than from 1980 to 1984. In the outlet basin of eastern Lake Predation effects Ontario, bottom trawls catches of alewife and smelt Stocking of salmonids resulted in rapid build-up of have been variable, but declined to extremely low predator levels through the 1970s and early 1980s levels beginning in 1993 (OMNR, unpublished data).

(Fig. 1). Lake-wide harvest rates of chinook salmon, Regional variation in the timing and extent of prey fish rainbow trout, lake trout, brown trout, and coho decline is to be expected and bottom trawling catches salmon in the offshore recreational fishery peaked in can be influenced by changed fish distribution. Less 1985 or 1986 and declined thereafter (Stewart et al. equivocal are whole-lake hydroacoustic estimates, 2002). Index gillnet catches of lake trout in U.S. which demonstrate a severe and persistent decline in waters reached their highest level in 1986 and offshore smelt and alewife numbers throughout the remained high (Elrod et al. 1995). In Canadian waters, 1990s (Fig. 5). We contend that smelt and alewife the build-up of lake trout was 3-4 years later (Elrod et numbers remained low throughout the 1990s due al. 1995) corresponding to a 3-year lag in the initiation primarily to high levels of predation by introduced lake trout stocking by Ontario. salmonids.

Earliest available data suggest that prior to the The suppression of alewife and smelt in Lake build-up of predator levels (i.e. pre-1985), alewife and Ontario during the late 1980s and 1990s was smelt were regulated by intraspecific and interspecific associated with a number of fish community changes.

competitive interactions, cannibalism, and weather The alewife is considered the dominant biotic (Smith 1968; Christie 1973; Christie et al. 1987a; influence on Lake Ontario fish communities OGorman 1974; OGorman et al. 1987; Smith 1995; (OGorman and Stewart 1999; Stewart et al. 1999, and OGorman and Stewart 1999). The increasing reference therein). However, many of the food-web importance of predation by introduced salmonids and interactions attributed to alewife (for example, other piscivores was recognized but it was not predation on fish larvae, competition with other considered to be a dominant influence (Christie et al. planktivores, and their importance in the diet of trout 1987a; OGorman et al. 1987). and salmon) also apply to rainbow smelt (Brooks The diet of salmonids in Lake Ontario is 1968; Christie 1973; Nepszy 1977; Brandt 1986; comprised almost entirely of smelt and alewife (Brandt Loftus and Hulsman 1986). Alewives are ubiquitous in 1986; Rand and Stewart 1998a; Lantry 2001). By the their distribution while rainbow smelt tend to inhabit late 1980s and through the 1990s the impact of deeper and colder water. Both species exhibit large-predation on alewife and smelt became more evident scale seasonal re-distribution between the offshore and (OGorman and Stewart 1999; Casselman and Scott nearshore. The abundance, distribution and ecology of 1992), although it was confounded with declines in these two species result in important interactions with Lake Ontario Salmonid Introductions

12.7 Atlantic salmon due to an inducement of thiamine Alewife deficiency (Fisher et al. 1996; McDonald et al. 1998).

Acoustic estimate (billions) 20 The suppression of alewife by introduced salmonids Summer may increase the diversity of Atlantic salmon and lake 15 Fall trout diets and mitigate the loss of thiamine.

10 Existing rare native brook trout and potentially 5 future stocks of wild Atlantic salmon could be 0 negatively impacted by continued introductions of 1991 1992 1993 1994 1995 1996 1997 1998 1999 hatchery salmonids. Kocik and Jones (1999) summarized studies on the potential interactions of introduced Pacific salmonids (rainbow trout, coho salmon, and chinook salmon) on native brook trout Smelt and on the potential for Atlantic salmon restoration.

Acoustic estimate (billions) 25 Studies and field observations indicate that it is 20 possible for native and non-native salmonids to coexist (Kocik and Jones 1999; Scott and Crossman 1999).

15 However, all of the introduced non-native salmonids 10 ` potentially compete for spawning and nursery habitat 5 and food with introduced Atlantic salmon and native 0

brook trout. The high abundance of non-native 1991 1992 1993 1994 1995 1996 1997 1998 1999 salmonids, and increasing naturalization, may limit the production of native brook trout and the future extent FIG. 5. Whole-lake acoustic estimates of abundance (number of Atlantic salmon restoration.

of fish) for alewives and smelt in Lake Ontario, 1991-1999.

Historically, four species of deepwater ciscoe, Coregonus nigripinnis, C. reighardi, C. kiyi, and C.

virtually all offshore fish species and many inshore hoyi inhabited Lake Ontario (Christie 1972). The loss fish species. Coincident with the decline of alewife of these species has been attributed to overfishing, and smelt there was an increase in natural reproduction increased abundance of alewives and smelt, and of lake trout, an increase in offshore abundance of predation by sea lampreys (Christie 1973; Smith native three-spine stickleback, a recovery of native 1968). Fish management agencies have proposed the lake whitefish stocks, and some improvements in reintroduction of deepwater ciscoe into Lake Ontario.

native populations of yellow perch, emerald shiner, In Lake Michigan, although cause and effect are and lake herring (Stewart et al. 1999). Other factors debated, bloaters (C. hoyi) increased coincident with a have contributed to these changes, but they are decline in alewife and high levels of introduced consistent with the hypothesis of a relaxation of salmonid abundance (Eck and Wells 1987; Kitchell predation and competition from suppressed and Crowder 1986; Stewart and Ibarra 1991). These populations of alewife and smelt. More recently, the conditions exist in Lake Ontario, likely favour loss of Diporeia (deepwater amphipod) in large successful reintroduction of native deepwater ciscoes, regions of Lake Ontario, coincident with colonization and are dependent on maintaining a high abundance of by dreissenids, has reversed whitefish recovery and introduced salmonids.

may impact other species (Hoyle et al. 1999).

Loss of an ecological paradigm Effects on native salmonids The initial introduction of salmonids into the Great The introduction of hatchery salmonids may Lakes was an attempt to control nuisance levels of enhance restoration of native salmonids. Atlantic alewife but quickly became focused on developing salmon and lake trout were native to Lake Ontario but multi-million dollar recreational fishing industry all native gene pools were lost. Introductions of (OGorman and Stewart 1999). In Lake Ontario, hatchery fish raised from available gene pools are the efforts to rehabilitate lake trout where renewed with only way to re-establish these species. Evidence increased effort to control sea lamprey. The strategy suggests that a diet high in alewives result in early for the rehabilitation of lake trout, and later Atlantic mortality syndrome in the offspring of lake trout and salmon, in Lake Ontario have had strong scientific and Lake Ontario Salmonid Introductions

12.8 ecological underpinnings (Eschenroder et al. 2000; Annual Report, Section 18, Ontario Ministry of Elrod et al. 1995; Ontario Ministry of Natural Natural Resources.

Resources 1995; Schneider et al. 1983; Stanfield et al. CHRISTIE, W.J. 1972. Lake Ontario: effects of 1995). On the other hand, science-based management exploitation, introductions, and eutrophication on of the recreational sport fishery has focused only on the salmonid community. J. Fish. Res. Board Can.

the potential for over-stocking (Jones et al. 1993; 29:913-929 OGorman and Stewart 1999; Stewart et al. 1999).

CHRISTIE, W.J. 1973. A review of the changes in the The potential for a large controlling influence of fish species composition of Lake Ontario. Great piscivores on the structure and function of the Lake Lakes Fish. Comm. Tech. Rep. 23. 66 p.

Ontario fish community was recognized (Christie et al.

1987a; Christie et al. 1987b), but this has yet to CHRISTIE, W.J., AND D.P. KOLENOSKY. 1980.

influence management decision making (Stewart et al. Parasitic phase of the sea lamprey (Petromyzon 1999). The Lake Ontario fish community is largely marinus) in Lake Ontario. Can. J. Fish. Quat. Sci.

comprised of a mix of exotic species that have no 37:2021-2038.

evolutionary sympatry. Additionally, recruitment of CHRISTIE, W.J., K.A. SCOTT, P.G. SLY, AND R.H.

the dominant predator, and the associated top-down STRUSS. 1987a. Recent changes in the aquatic influence on fish communities (Christie et al. 1987a; food web of eastern Lake Ontario. Can. J. Fish.

McQueen et al. 1989) is largely controlled through Aquat. Sci. 44(suppl. 2):37-52.

stocking levels. As a consequence, it is difficult to CHRISTIE, W.J., G.R. SPANLGER, K.H. LOFTUS, apply conventional ecological paradigms or W.L. HARTMAN, P.J. COLBY, M.A. ROSS, descriptions of historical fish community structures to AND D.R. TALHELM. 1987b. A perspective on understand or predict species interrelationships or Great Lakes fish community rehabilitation. Can. J.

equilibrium states (Christie et al. 1987b; Eschenroder Fish. Aquat. Sci. 44 (Suppl. 2): 486-499.

and Burnham-Curtis 1999). This is not only a challenge to fisheries managers but also requires CONNELLY, N.A., T.L. BROWN, AND B.A.

researchers to develop new conceptual models of fish KNUTH. 1997. New York statewide angler survey community structure and function to guide 1996. Report 1: Angler effort and expenditures.

management. NY State Dept. Env. Cons. 107 p.

DEPARTMENT OF FISHERIES AND OCEANS.

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ABRAHAM, W.J. 1988. A draft plan for Atlantic Economic and Policy Analysis Directorate. Dept.

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Lake Ontario, 1990-1995. New York State ECK G.W., AND L. WELLS. 1987. Recent changes Department of Environmental Conservation.

in Lake Michigans fish community and their Albany, NY. 15 pp.

probable causes, with emphasis on the role of BOWLBY, J.N. 1991. Stocking assessment of brown alewife (Alosa pseudoharengus). Can. J. Fish.

trout, rainbow trout, and coho salmon in the boat Aquat. Sci. 44 (Suppl. 2): 53-60.

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rehabilitation in Lake Ontario. Journal of Great BRANDT, S.B. 1986. Food of trout and salmon in Lakes Research 21 (Supplement 1):83-107.

Lake Ontario. J. Great Lakes Res. 12: 200-205.

ESCHENRODER, R.L., AND M.K. BURNHAM-BROOKS, J.L. 1968. The effects of prey size CURTIS. 1999. Species succession and selection by lake planktivores. Syst. Zool. 17(3): sustainability of the Great Lakes fish community.

273-291. In "Great Lakes Fisheries Policy and Management:

CASSELMAN, J.M., AND K.A. SCOTT. 1992. Fish A Binational Perspective", ed. W.W. Taylor and community dynamics of the outlet basin of Lake C.P. Ferreri, pp. 141-180. East Lansing, MI:

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