ML20033A201

Soft-Shell Clam,Mya Arenaria Study

ML20033A201
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Site:	Seabrook
Issue date:	09/30/1979
From:	NORMANDEAU ASSOCIATES, INC.
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SOFT-SHELL CLAM, MA ARE R TA STUDY TECHNICAL REPORT X-3 I

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I Prepared for PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE Manchester, New Hamoshire i

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By NORMANDEAU ASSOCIATES, INC.

25 Nashua Road, Bedford, New Hampshire l

September 1979 hbk NO O

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TABLE OF CONTENTS I

PAGE 1.0 INTRODUCTION......................

1 2.0 METHODS AND MATERIALS................. 4 2.1 LARVAE TOWS...................... 4 2.2 SPAT SURVEYS......................

7 2.3 ADULT SURVEYS.....................

7 2.4 GREEN CRAB (CARCINUS MAENUS) TRAPPING........

12 2.5 HISTOLOGICAL STUDY OF GONADAL CONDITION.......

13 3.0 RESULTS.......................

14 3.1 P LAN KTON I C LARV A E..................

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3.1.1 Onshore-Offshore Distribution of M. crencria.....

14 3.1.2 Temporal Distribution of M. crer.cric Larvae..

14 3.1.3 Species Composition.................

14 3.2 SPAT AND YOUNG ADULTS................

19 3.3 ADULT STANDING STOCKS IN HAMPTON HARBOR.......

23 3.4 CARCINUS MAENAS...................

30 3.5 l#A ARENARIA REPRODUCTIVE CYCLE...........

35 4.0 DISCUSSION......................

37 4.1 GRIGIN, DISTRIBUTION AND RECRUITMENT OF lHA ARENARIA LARVAE.................

37 4.2 OTHER BIVALVE MOLLUSC LARVAE.............

38 4.3 SHELL GROWTH.....................

40 4.4 SURVIV0RSHIP AND PREDATION..............

41 4.5 PRESENT AND FUTURE STATUS OF MARKETABLE M. ARENARIA STANDING CR0P IN HAMPTON HARBOR...........

42 5.0 S U MMA R Y.......................

4 6 6.0 LITERATURE CITED...................

48 APPENDICES......................

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s LIST OF FIGURES I

PAGE 1.

Soft-shell clam Mya arenaria, and green crab, Carcinus mae n, sampling stations..............

5

m 2.

Location of at study sites................

9

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Temporal distribution of umboned #ga arenaria veligers at the intake site off Hampton Beach, New Hampshire.....

16 4.

Size-frequency distributions of young #ga arenaria from November surveys in Hampton Harbor.............. 22 5.

Length density distribution of adult clams collected in November surveys from five flats in Hampton Harbor...........................

28 6.

Estimate of Myq arenaria biomass for five tidal flats in Hampton Harbor, with approximately 95%

confidence intervals....................

29 7.

Size-frequency distribution of Carcinas maenas from Hampton Harbor Flat 2.................

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8.

Percentages of male and female #ga arenaria in each gonadel development phase during 1978.........

36

'l 9.

Means of daily minimum winter (February and March) winter temperature off Hampton Beach, New Hampshire..... 43

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LIST OF TABLES PAGE 1.

CLAM SPAT SAMPLING EFFORT................... 8 2.

ADULT CLAM SAMPLING EFFORT, HAMPTON-SEABROOK ESTUARY...........................

10 3.

GONADAL SAMPLE COLLECTIONS, 1978..............

13 3

4.

DENSITY DISTRIBUTION (INDIVIDUALS PER m ) 0F UMBONED M. ARESARIA VELIGERS ALONG THE EAST-WEST INTAKE TRANSECT.......................

15 3

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5.

DENSITIES (PER M ) 0F UMB0NED M. ARENARIA VELIGERS COLLECTED AT THE COOLING WATER INTAKE SITE (I-4)......

17 6.

PERCENT COMPOSITION OF BIVALVE UMB0NED VELIGERS I

IN OBLIQUE NET TOWS IN THE VICINITY OF THE INTAKE SITE...

20 2

7.

SPAT AND YOUNG ADULT DENSITIES (PER FT ) FOR SIX NORTHERN NEW ENGLAND ESTUARIES (SPAT: >l TO 25 un; YOUNG ADULTS: 26 TO 50 mm).................. 21 8.

SUMMARY

OF MyA ARENARIA POPULATION DENSITIES, I

ANNUAL NOVEMBER SURVEY.................... 24 9.

COMPARISON OF M. ARENARIA SHELL GROWTH (MM) IN SIX NORTHERN NEW ENGLAND ESTUARIES.............. 26

10. RESULTS OF SOFT-SHELL CLAM STANDING STOCK ESTIMATES.

HAMPTON-SEABROOK ESTUARY................... 27

11. COMPARISON OF " MARKETABLE" AND TOTAL STANDING CR0P ESTIMATES, HAMPTON-SEABROOK ESTUARY, NOVEMBER SURVEY..... 31 I

12. ESTIMATES OF CLAM FLAT PRODUCTIVE AREA (%) IN HAMPTON SEABROOK ESTUARY...................

32

13. SELECTED C. MAEJAS CATCH STATISTICS 1977-1978........

34

14. COMPARISON OF M. ARENARIA UMBONED LARVAL ABUNDANCE OFF HAMPTON BEACH WITH YOUNG-0F-THE-YEAR SPAT DENSITIES IN HAMPTON HARBOR.................

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15. RECENT HISTORY OF THE STANDING CROP 0F " MARKETABLE" SIZE ADULTa MyA ARENARIA IN HAMPTON HARBOR.......... 44 g

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I SOFT-SHELL CLAM, NYA ARE.VARIA, STUDY I

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1.0 INTRODUCTION

Normandeau Associates began providing estimates of soft-shell clam (Nya arenaria) standing crop in Hampton-Seabrook estuary in July 1969. This effort succeeded an investigation of soft-shell clam resources by the State of New Hampshire Department of Fish and Game in 1967 (Ayer, 1968). Between 1967 and 1969, standing crop estimates fell from 23,400 to 15,840 bushels (NAI, 1978). This decline continued until November 1977, when slightly more than 1000 bushels remained on 167 acres of tidal flats (NAI, 1978). Stock depletion was credited to over harvest-ing by humans, abetted by the clams' principal natural enemies, waterfowl and the green crab (Carcinus maenas), the latter having experienced a population boom during the early 1970's (Welsh, 1975; Dow, 1977).

I In the summer of 1976, juvenile clams (spat) settled on the Hampton-Seabrook flats in densities averaging almost 800 individuals per I

ft, and in some places approaching 8000 per ft Approximately 25% of the spat survived the first year. This high survival, plus a subsequent spat fall (settlement) in 1977, (approximately one fifth as intense as the previous one), augured for substantial replenishment of local stocks.

Normandeau Associates had expanded the spat (i.e., sediment I

core) sampling program in the spring of 1976 to include five estuaries within a 50-mile raf.ius of Hampton-Seabrook Estuary.

Survey results indicated similar heavy spat settlement occurred throughout the study area. Traditional clamming grounds, such as those in Ipswich, Massa-chusetts and Ogunquit Beach, Maine, which had been depleted by years of commercial and recreational digging were recovering stock even faster than Hampton-Seabrook.

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Normandeau Associates' investigations have been primarily concerned with the impact of Seabrook Station's cooling water system on soft-shell clam resources. While estimates of standing crop and spat settlement densities are crucial indicators of the welfare of this resource, the principal direct impact anticipated is entrainment of plank-tonic larvae in the intake off Hampton Beach. Normandeau Associates has I

investigated spatial and temport.1 distribution of the larvira since ' 971, although M. arenaria larvae were not reliably distinguished from larvae of a look-alike clam relative, Hiatella sp., until 1973. Since then, findings have generally supported these hypotheses (NAI, 1976, 1977, 1978):

1.

Clan flats along the Massachusetts coast, north of Cape I

Ann, supply the bulk of the larvae recruited into Hampton-Seabrook Estuary.

2.

Larvae tend to aggregate close to shore, along the open coast, the aggregations becoming progressively sparser in the offshore direction.

I 3.

The quantity of larvae at the intake site off Hampton Beach bears no relationship to the quantity of spat settling on Hampton-Seabrook flats.

This report is the eighth in a series on the status of M.

arenaria resources in the vicinity of Hampton-Seabrook Estuary. Th3 I

above mentioned hypotheses are evaluated based on these study elements:

1.

oblique plankton tows monitoring seasonal and offshore-onshore larvae distributions off Hampton Beach 2.

population surveys of spat (less than 26 mm shell length) and young adults (up to 50 mm shell length) on flats in six estuaries from Ipswich, Massachusetts to Ogunquit l

Beach, Maine 1

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l 3

'I 3.

surveys of adult standing crop in Hampton-Seabrook ia estuary

(= Hampton Harbor) 1 4.

histological examination of gonadal tissue samples to l

determine the timing of reproductive development in the j

Hampton Harbor M. arenaria.

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In addition, results are given for the first 18 months (July 1977 through December 1978) of a green crab trapping program designed to monitor relative predator pressure on M. arenaria in Hampton Harbor.

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2.0 METHODS AND MATERIALS 2.1 LARVAE TOWS To monitor temporal distribution of Nya arenaria larvae in the vicinity of the Seabrook Station cooling water intake (Figure 1), dupli-I cate, two minute, oblique net tows were made approximately twice weekly, from 18 May to 19 October; weekly tows were taken from 25 April to 8 May, and from 19 to 31 October when larvae were generally scarce or absent.

A 0.5 m diameter No. 20 (73 um) mesh net, with a 10 lb. depressor attached, was towed at approximately 1/2 knot.

The net was lowered ':o a depth of approximately 13 m (43 feet), in the first minute and returned to the surface after a second minute had elapsed ending the tcw.

A General I

Oceanics flow meter was used to record the volume of water passing through the net; in practice, this volume ranged from 4 to 11 m per tow, typically averaging 7m per tow.

Upon recovery, net contents were

.I thoroughly rinsed into a 1/2-gallon glass jar. The live material was transported immediately to the Piscataqua Marine Laboratory, Portsmouth for analysis.

To separate the live bivalve larvae from the bulk of the plankton, the sample was transferred to 1000 ml dispensing burettes and the contents allowed to rettle for 5-12 minutes. The relatively high I

density of the shells allowed the bivalves to rapidly accumulate at the bottom of the buret +.e column, and to be withdrawn for identification and enumeration. The entire s.

Le concentrate containing the bivalves was enumerated for umboned (length 145-320 um) N. arenaria larvae except when this species was particularly abundant; whereupon, the bivalve larvae were concentrated by a swirling notion, into the center of a round, 100 mm diameter, plastic culture dish. The resulting concentra-I tion of larvae was carefully divided into visually equal quadrants using a camels hair probe, viewing the operation through a dissecting micro-scope at approximately 30x; two diagonally opposed quadrants were then enumerated.

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7d' 50' 48' 70* 46' A Larvae tow stations

. l G Clam flats x Green crab trap stations il Figure 1.

Sof t-shell clam, l@a arenaria, and green crab, Carcinas maenus sampling stations. Seabrook 14c arenaria Study, 1978.

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The same splitting technique was also used to reduce the amount of larvae, representing other bivalve species, to sample frac-tions containing a total of 200 to 600 individuals. Depending on ori-ginal (i.e., field) population densities, this required from one to four successive operations consisting of concentrating the larvae into the center of the dish and then separating and extracting a quadrant. In all cases, two sample fractions were enumerated from each sample, each I

fraction having originated as one of two diagonally opposite quadrants in the initial (whole sample) larvae concentration. Principal refer-ences used as aids in identifying larvae to species were: Sullivan (1948), de Schwenitz and Lutz (1976) and Savage and Goldberg (1976).

With few exceptions, only umboned veligers were identified and enumera-ted.

Enumeration of M. arenaria straight hinge veligers was carried out only when their identity was reasonably obvious because of the large numbers involved and the paucity of straight hinge veligers of other species.

On those dates when the M. arenaria umbone veliger population density was found to exceed 50 per m, a special towing program was carried out to define the onshore / offshore M. arenaria larval density distribution in the intake vicinity. Oblique tows were made at 1/2-nautical mile intervals along a transect running east to west through the intake site (Figure 1).

Sample analysis procedures were as descri-I bed above.

Inshore / offshore transect sample data were submitted to a 2-way fixed effect analysis of variance (Sokal and Rohlf,1969) with two observations per cell. Square root transformation was used to make sample variation more homogeneous. Tukey's procedure for pairwise l

comparisons (Gaenther, 1964) was used to determine the significance of i

station differences within and across sample dates.

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7 2.2 SPAT SURVEYS To compare population densities of spat and seed clams periodic surveys were conducted on Hampton Harbor Flats (Figure 1 and Table 1) and on flats in five adjacent estuaries, in New Hampshire, northern Massachusetts and southern Maine (Figure 2 and Table 1).

With the exception of the November survey, the stations were fixed in that once established (on the basis of preliminary evidence of high productivity),

the same general locality was resampled with each survey. At each fixed I

collection site, sediment cores three or four inches in diameter, and four inches deep, were extracted in triplicate, using a section of PVC plastic pipe.

Sediments from those core samples were washed through a 1 mm mesh screen and the M. arenaria spat picked from the screen with forcops. After transfer to small fingerbowls, the spat from each core sample were enumerated and measured to the nearest 1 mm.

Spat samples were also obtained, as described above, during the annual Hampton-Seabrook clam flat survey in November; however, the November stations (Table 1) were chosen at random from a larger set of stations designated for sampling adult clam populations. While the fixed station program, with emphasis on high yield locations, gave re-lative estimates of temporal and geographical distribution, the random sampling program in November provided the best estimate of actual spat I

density over a particular flat, including portior.s less favorable for spat settlement.

2.3 ADULT SURVEYS As in past years, the five largest harbor flats were each surveyed in November 1978 for adult clams; additional surveys were conducted on Flat #2 in April 1978 (Figure 1 and Table 2).

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I TABLE 1.

CLAM SPAT SAMPLING EFFORT. SEA 3R00K NYA ARENARIA STUDY,1978.

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FIXED STATIONS NO. OF LOCATION STATIONS DATES Plum Island Sound, MA Middle Ground 5

6 Jan 4 Apr 13 Jun 11 Aug 12 Oct Lufin's Flat 3

6 Jan 4 Apr 13 Jun 11 Aug 12 Oct Nut Shoal 2

6 Jan 4 Apr 13 Jun 11 Aug 12 Oct Merrimack River, MA I

Salisbury Flat 3 5

5 Jan 6 Apr 19 Jun 9 Aug 13 Oct Ball's Flat 1 5

4 Jan 5 Apr 19 Jun 9 Aug 13 Oct Hampton Harbor, NH Flat 2 5

4 Jan 5 Apr 9 Jun 14 Aug 9 Oct Flat 4 5

5 Apr 9 Jun 14 Aug 9 Oct I

Little Harbor Channel, NH Clam Pit Island 5

13 Jan 10 Apr 16 Jun 8 Aug 6 Oct Flat, opposite shore 1

13 Jan 10 Apr 16 Jun 8 Aug 6 Oct Southern Maine York River 5

17 Jan 3 Apr 14 Jun 10 Aug 11 Oct Ogunquit Beach 6

17 Jan 3 Apr 14 Jun 10 Aug 11 Oct b.

RA.ND0M STATIONS NO. OF LOCATION STATIONS CATES Hampton Harbor, UH

.l Flat 1 14 6 Nov 5

Flat 2 7

7 Nov Flat 3 6

6 Nov

g Flat 4 11 10 Nov

E F at 5 7

7 Nov Not sampled I

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OGUNQUIT BEACH I

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4 TSt'0UTF LITTLE HARBCo H;4iPT0ii-S EAER00K ISLES OF.%

ESTUARY SHOALS

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TABLE 2.

ADULT CLAM SAMPLING EFFORT, HAMPTON-SEABROOK ESTUARY. SEABROOK lf!A ARE.7 ARIA STUDY,1978.

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TOTAL N0.

N0. OF N0. OF SURFACE SAMPLE POTENTIALLY POTENTIALLY AREA STATIONS BARREN STATIONS PRODUCTIVE LOCATION DATE (ACRES)

OBSERVED SUBSAMPLED STATIONS DUG Flat 1 6 Nov 54.91 66 10 27 Flat 2 7 Nov 24.96 33 4

14 (12 Apr)

(33)

(6)

(7)

Flat 3 6 Nov 10.54 24 3

12 Flat 4 10 Nov 51.05 51 9

22 Flat 5 7 Nov 23.69 38 4

16 All Flats 6-10 Nov 165.15 212 30 91 I

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I 11 Aerial photographs were made on 11 August 1978 at mean low water and were used to construct sampling charts as they were in 1977 I

surveys. Acreage measurements were provided by the aerial survey con-tractor, employing the "stereotemplate laydown" procedure which is standard for the preparation of tax base maps. The maximum error in computed flat acreage has been estimated by the contractor to be approx-imately 2-3%.

Random sampling procedures were employed which minimited unproductive digging in extremely depopulated areas of the flats.

Evidence of breathing or siphon holes was used as an indicator of the presence, and conversely the absence, of clams.

If, after determining the position of a sampling station, the inve.,tigator observed what was thought to be clam siphon holes, a two-square-foot area was dug thoroughly for clams. On the other hand, if no sign of siphon holes was detected within the two square foot sampling area, the investigator in most cases simply noted this fact on a field card and proceeded to the next sampling station. Several stations on each flat which showed no sign of clam I

holes were randomly selected and dug thoroughly as a check on the effective-ness of establishing the absence of clams by the absence of siphon holes (see Table 2).

Total number of samples to be observed for evidence of siphon holes was roughly determined by the surface area of the flat above mean low tide (Table 2).

To establish sampling stations, randomly generated rectangular (x, y) coordinates were plotted on charts of each flat.

Random coordinates were generated until the full quota of stations was attained for the flat.

In the field, stations were located by compass bearing and distance from the central reference point established during the beach profile survey. To delineate the sample area, a two-square-foot frame was placed on the substrate, with the left-hand corner of the frame at the investigator's right foot.

The substrate surface outlined l

by the inner edges of the frame was carefully inspected for evidence of siphon holes. If a sample was to be taken because siphon holes were evident, or if a random subsample of a "no-hole" station was required, l

the sediment outlined by the frame was dug to a depth of about 16 inches.

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m 12 Adult soft-shell clams found during excavation, or in the spoil, were picked out and placed in a plastic bag along with a tag identifying the station and flat number.

In the laboratory, clams were tallied and measured for shell length to the nearest 1 mm.

Individual sample counts and shell measurements were converted to biomass estimates (bushels per acre) using a table of clam volumes provided in Belding (1931). The overall biomass estimate for each flat was obtained using the following formula:

"1 2

n X=

X, +

X' I

n n

2 where:

n = total number of sampling stations observed n = number of stations where siphon holes were observed 2 " "-"1 = number of stations where no siphon holes were n

observed X= average biomass (bushels per acre) estimate for the entire flat X = average biomass from n samples y

y X' = average biomass from a subset of samples (n') representing I

stations where no siphon holes were observed To express reLults in terms of standing crop (bushels of harvestable clams on the entire flat), the biomass estimate was multiplied by flat surface area (acres). Variance and standard error of biomass estimates were calculated approximately, 1 sing formulae given in Hanson et al.,

1953. To obtain a rough approximation of 95 percent confidence intervals, I

standard errors were multiplied by two, as suggested by Hanson et al.,

1953.

I 2.4 GREEN CRAB (CARCINUS MAFNUS) TRAPPING From 8 July to 25 August 1977, two prism-shaped crab traps, loaned by Maine Department of Marine Resources, were hauled and reset on Flat 2 at 2 to 5 day intervals continuously, also, at least one of the two loaned traps was tended three times from 13 through 23 September.

I 13 Beginning in fall, 1977, Carcinus maenas were trapped twice a month at fo"x stations around the perimeter of Flat #2 (Figure 1); two 13 mm mesh, baited traps were set at each station so that they were awash at Mild.

After fishing for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> they were pulled in and the catch sized and sexed. Total weight of Carcinus maenas from each trap was also recorded.

I 2.5 HISTOLOGICAL STUDY OF G0NADAL CONDITION On the dates shown in Table 3 at least 20 M. arenaria with a minimum shell length of 51 mm were collected by clam fork from Hampton Harbor flats. N visceral mass (gonad, liver, gastrointestinal tract, etc.) was taken out and fixed in 10% buffered formalin. Blocks of gonadal tissue were dissected from each specimen and sent to the Univer-sity of New Hampshire Department of Animal Sciences Veterinary Diagnostic Laboratory where the blocks were: 1) dehydrated in alcohol and infiltrated (Armed Forces Institute of Pathology, 1949), 2) embedded in paraplast,

3) sectioned at 7 pm, and 4) stained in hematoxylin and eosin.

Slide preparations were then returned to Normandeau Associates for evaluation of reproductive development. Recognition of the phases of gonadal condition: indifferent, developing, ripe, spawning and spent, was based on the same characteristics as those used by other investiga-tors (Ropes and Stickney, 1965 Porter, 1974; Brousseau, 1978). Sections analyzed were from the dorsal, posterior quadrant below the heart, where Coe and Turner (1938) have claimed that maturation begins.

I TABLE 3.

GONADAL SAMPLE COLLECTIONS, 1978.

28 April 18 July 11 May 31 July 26 May 11 August 9 June 12 September 22 June

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3.0 RESULTS 3.1 PLANKTONIC LARVAE 3.1.1 Onshore-Offshore Distribution of M. arenarda on some of the dates when M. arenaria larvae were most abundant, and on average, Station I-2 had significantly higher densities than Stations I-4, I-6 and I-8 (Table 4).

Station I-8, on the other hand, had significantly lower densities t'aan any of the other stations sampled.

In addition to significant station differences, ANOVA results indicated significant differences between dates, and a significant station-date interaction; main effect differences and their interaction were signifi-cant at p 1001 (Appendix 7.1).

3.1.2 Temporal Distribution of M. arenaria Larvae In 1978, M. arenaria umboned veligers first appeared off Hampton Beach at the end of May /"iqure 3 and Table 5).

Peak values of a few hundred individuals per m were recorded during the second week of June; a rapid decline in population density followed in mid July. From I

mid July until the end of August there were never more than 5 larvae per 3

m.

The second (late summer) larval peak began abruptly with up to 1800 larvae per m recorded on 1 September (Table 4).

Densities eventually declined to near the detection limit by the third week in October. The average larval density at I-4 from 22 May to 31 October was estimated as approximately 83 individuals per m.

3.1.3 Species Composition Mya arenaria umbone veligers only occasionally dominated the bivalve veliger assemblage off Hampton Beach in late summer and early

M M

M M

M M

M M

M M

M M

M M

3 TABLE 4.

DENSITY DISTRIBUTION (INDIVIDUALS PER m ) 0F UMB0NED M. ARENARTA VELIGERS ALONG THE EAST-WEST INTAKE TRANSECT. SEABROOK NYA ARENARIA STUDY,1978.

STATION:

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SIGNIFICANCE OF STATION DIFFERENCES 2

4 6

8 DATE REPLICATE :

1 2

1 2

1 2

1 2

(@ p<.05; TUKEY'S PAIRWISE COMPARISONS) 5 Jun 234 208 80 52 50 48 46 45 I

>I and 1 2

6 8

12 Jun 415 478 260 212 318 189 275 176 None 26 Jun 120 106 99 52 50 52 52 34 None 10 Jul 133 169 40 94 146 92 102 62 None 1 Sep

'j.170 1770 210 118 111 71 3

4 I > I through 1 2

4 8

I

I 2

6 ""

8 I 8 2 ""

4 Station Mean 430 143 108 64 I

>I through I 4

8 I

<I through I 2

6

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I 1000 -

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100 -

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c.

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MAY JUNE JULY AUGUST SEPTEMBER OCTOBER COLLECTION DATE I

Figure 3.

Temporal distribution of umboned 14pa arenaria veligers at the I

intake site off Hampton Beach, New Hampshire. Seabrook lega arenaria Study, 1978.

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TABLE 5.

DENSITIES (PER M ) 0F UM80NED u. AsuARIA VELIGERS COLLECTED AT THE COOLING WATER INTAKE SITE (I-4). SEABROOK MTA g

.4ruAarA STUDY,1978.

I REPLICATE REPLICATE DATE 1

2 MEAN REMARKS E

25 Apr 0.0 0.0 0.0 1 May 0.0 0.0 0.0 I

8 May 0.0 0.0 0.0 18 May 0.0 0.0 0.0 22 May 0.3 0.0 0.1 30 May 10.0 14.0 12.0 I

5 Jun 125.0 125.0 See also Table 4 8 Jun 276.0 316.0 296.0 12 Jun 260.0 260.0 See also Table 4 15 Jun 150.0 88.0 119.0 19 Jun 48.0 39.0 44.0 22 Jun 52.0 26.0 39.0 26 Jun 211.0 100.0 156.0 See also Table 4 I

29 Jun 142.0 240.0 191.0 6 Jul 41.0 32.0 36.0 10 Jul 174.0 142.0 158.0 See also Table 4 I

13 Jul 17.0 15.0 16.0 18 Jul 3.3 3.4 3.4 21 Jul 0.3 0.5 0.4 25 Jul 1.5 4.1 3.0 I

28 Jul 2.4 1.0 1.8 31 Jul 1.4 0.3 0.8 4 Aug 1.1 5.3 3.1 I

7 Aug 0.0 0.0 0.0 10 Aug 0.0 0.5 0.2 14 Aug 0.4 0.3 0.3 17 Aug 0.0 1.8 0.9 I

21 Aug 0.0 0.1

<0.1 24 Aug 0.3 0.2 0.2 28 Aug 0.0 0.0 0.0 I

31 Aug 463.0 2250.0 1360.0 1 Sep See Table 4 5 Sep 118.0 69.0 94.0 See also Table 4 I

8 Sep 18.0 12.0 15.0 11 Sep 9.5 5.2 7.4 14 Sep 26.0 16.0 21.0 18 Sep 76.0 105.0 90.0 21 Sep See Table 4 25 Sep 21.0 23.0 22.0 (Continued)

I

.not enumerated I

18 TABLE 5.

(Continued)

REPLICATE REPLICATE DATE 1

2 MEAN REMARKS

~

28 Sep 18.0 16.0 17.0 2 Oct 281.0 326.0 306.0 5 Oct 428.0 446.0 437.0 9 Oct 50.0 105.0 75.0 12 Oct 19.0 30.0 24.0 I

16 Oct 14.0 20.0 17.0 19 Oct 43.0 45.0 44.0 23 Oct 0.8 0.5 0.7 31 Oct 1.4 1.2 1.3 Average density, 22 May to 31 October:

83.3 larvae per m I

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'I I

I 19 fall (Table 6).

Hiatella sp. was virtually the only bivalve represented from the beginning of the 1978 t ow program in late April, until early June.

Mussels, Modiolus modiolus (horse mussel) and Mytilus edulis (blue mussel) predominated from June through the end of July. There-af ter, Anonia spp. (jingle shells) assumed dominance until the end of August. Throughout most of September, veligers of Macoma balthica and Spisula solidissima (surf clam) predominated. Very few larvae of Pla-copecten magellanicus (sea scallop) were collected this year.

I 3.2 SPAT AND YOUNG ADULTS I

In Plum Island Sound, a substantial portion of the 1976 spat set had already attained " adulthood" by January 1979 (Table 7; Appendix i

7.2), the threshold of sexual maturity having been defined as 26 m l'

shell length (Belding, 1930). At Ogunquit Beach, recruitment to adult-hood followed at a slightly slower pace.

Substantial recruitment t.o the over 25 mm category did not occur in Hampton Harbor until the summer of 1978. For the first time in over three years, clams 25 to 43 mm long f

were collected from the Merrimack River estuary late in 1978. Few young adults were evident at the York River flat, even in late 1978, while none were found in Little Harbor Channel.

The spat category was composed of individuals representing the 1976 and 1977 year classes during the first half of 1978; young of the year recruitment followed in late su=mer, but was modest at all study l

sites compared to 1977 and, particularly, 1976 spatfalls (Table 7; Appendix 7.2).

This progressive decrease in young-of-the-year recruit-ment from 1976 through 1978, influenced size-frequency distributions for Hampton Harbor (Figure 4).

Two and three mm size classes overwhelmingly I

dominated the 1976 size-frequency distribution, but the numerical importance of these size classes progressively diminished in succeeding I

November surveys. Meanwhile, frequency peaks representing the three most recent spat year classes became less and less distinct as growth of later settling individuals overtook some of the slower growing earlier settlers.

I I

20 TABLE 6.

PERCENT C0t1 POSITION 0F BIVALVE UM80NED VELIGERS IN OBLIQUE NET TOWS IN THE VICINITY OF THE INTAKE SITE.

SEABROOK NYA AREVARIA STUDY,1978.

S U

I m

A E

n m

4 0

2 7

4 8

0

?

E 4

e a

R

.a 5

I

=

=

=

m 4

=

c.

o AVERAGE DENSITY 3

DATE (N0. PER M )

25 Apr 0.0 0.0 99.8 0.0 0.0 0.0 0.0 0.2 112 I

1 May 0.0 0.0 100.0 0.0 0.0 0.0 0.0

<0.1 1,330 8 May 0.0 0.0 100.0 0.0 0.0 0.0 0.0

<0.1 77 18 May 0.0 0.0 99.9 0.0 0.0 0.0 0.0

<0.1 296 22 May 0.0 0.0 99.4 0.0 0.0 0.6 0.0

<0.1 16 30 May 0.0 0.0 94.6 0.0 0.0 5.4 0.0 0.1 224 8 Jun 61.5 24.9 10.3 0.0 1.8 0.3

<0.1 1.2 120,000 15 Jun 11.8 67.2 16.4 0.1 1.2 2.0 0.4 0.9 5,900 W

22 Jun 16.0 67.6 13.1 0.3 0.8 0.1 0.1 2.0 50,300 29 Jim 17.2 52.1 27.6 0.4 1.6 0.2

<0.1 0.8 88,200 6 Jul 9.8 68.1 4.8 1.8 11.1 3.4 0.0 0.9 1,070 13 Jul 0.6 84.4 6.9 2.6 2.5 0.2 0.0 2.8 7,180 18 Jul 2.0 77.0 1.8 3.4 7.4 0.2 0.0 8.2 2,210 25 Jul 1.0 92.1 0.8 1.9 0.7

<0.1 0.0 3.6 8,980 4 Aug 4.2 44.6 5.6 31.9 3.5 1.2 0.0 3.6 278 10 Aug 4.2 31.4 5.3 51.2 1.4

<0.1 0.0 6.5 1,520 17 Aug 0.2 32.6 2.5 45.5 1.1 1.5 0.2 16.4 60 24 Aug 0.3 17.3 1.8 54.8 2.1 0.8 0.0 22.8 28 31 Aug 0.0 2.6

<0.1 0.6 1.2 85.8 0.0 9.8 1,550 8 Sep 0.6 19.4 0.2 1.2 2.0 8.0 0.0 68.6*

199 14 Sep 0.5 4.1 0.4 1.2 18.0 4.2 0.0 71.6*

525 21 Sep 4.4 17.4 0.2 7.6 9.0 23.8 0.0 37.6*

1,430 28 Sep 45.8 6.6 0.2 9.2 9.2 11.2 0.0 17.8*

159 5 Oct 12.8 6.2 0.0 2.2 20.1 35.0 0.0 23.7*

1,240 I

12 Oct 14.8 7.5 3.4 14.0 19.3 23.7 0.0 17.3*

104 19 Oct 10.0 9.5 2.9 12.4 21.2 20.7 0.0 23.3*

214 31 Oct 4.4 20.6 5.7 32.9 9.3 4.9 0.0 22.2 28 I

predominantly Macoma balthica and Spisula solidissima l

h -

2 TABLE 7.

SPAT AND YOUNG ADULT DENSITIES (PER FT ) FOR SIX NORTilERN NEW ENGLAND ESTUARIES (SPAT:

>l TO 25 m; YOUNG ADULTS: 26 TO 50 nn). SEABROOK NYA ARI'NARIA STUDY,1978.

SAf1PLE DATE JAN APR JUN AUG OCT YOUNG YOUNG YOUNG YOUNG YOUNG LOCATION SIZE GROUP SPAT ADULTS SPAT ADULTS SPAT ADULTS SPAT ADULTS SPAT ADULTS Plum Island Sound, MA 156 36 183 40 133 24 176 47 183 52 Merrimack River Estuary, MA 190 0

80 0

105 0

51 1

80 9

Ilampton liarbor, N!!

287 0

525 2

192 1

311 21 604 55 Little liarbor Channel, Nil 9

0 15 0

16 0

2 0

22 0

York River, ME 88 0

53 1

53 0

27 3

33 2

Ogunquit Beach, ME 34 8

33 21 39 17 43 25 45 18 Y

22 e

l 400 -

,l 'j l

f I

l

[

300 -

I l

5 l

i I

E 200 -

I i

Si i

1976 YEAR CLASS 100 -

i i

1976 l

40 -

,I

\\

v

\\

r

\\

/

\\

l

\\ ~, '. ~. -

/

YOUNG

\\

iiiiiiI i I

30 -

0F THE

\\

2 4

6 8 10 12 YEAR

\\

m C

I

\\

l

\\

\\'s j

20 -

g i,

\\

i,

\\

10 -,'

/

\\

I 1977

\\

l I

L

/

\\

\\

g s

s A

N,-

f I

0- '

7 il l l t

i1 t

4 i ii ij 2

4 6

8 10 12 14 16 18 20 22 24 YOUNG OF 1977 YEAR 12 THE YEAR CLASS

/'s 1976 YEAR

/ \\

s s CLASS

/

/

\\

g 10 -

i s

I

[

8-I

/

\\

\\

g

[

6-

\\

I i

\\

),

/

1978 r

)s s

4-1 s

x 05 j

s N

N 2- /

/

/

N s

.m l l'l'i s r r 3,

/

i i i iii i ei6 i6 iiiiiii1 2

4 6

8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 Size Class (mm)

Figure 4.

Size-frequency distributions of young l@a arenaria from November surveys in Hampton Harbor. Seabrook /@a crer. aria Study,1978.

~ - -

23 I

By November 1978, a few of the fastest growing representatives of the 1976 year class in Hampton Harbor had attained a shell size of up to 42 mm.

Most of these were found on Flats 4 and 5 (Appendix 7.3).

All of the Hampton-Seabrook flats, however, showed substantial increases I

in young adult population, while the spat category declined from the previous two years (Tuble 8).

As inferred from size distribution data, presented in Appendix 7.2, a wide variation in shell growth was apparent within each of the estuaries investigated (Table 9).

Average annual growth was highest in Plum Island Sound and lowest in Hampton Harbor and Little Harbor channel.

I 3.3 ADULT STANDING STOCKS IN HAMPTON HARBOR For the first time since the earliest clam population surveys (Table 8) young adult clams (26 to 50 m) completely outnumbered older clams (>50mm).

In Table 10, clams larger than 42 nn were distinguished I

from smaller clams to compare 1978 data with previous results. The 42 mm cut off was chosen because the largest representatives of the 1976 year class appeared to be no more than 42 m long. Clams considerably less than 42 m are probably too small to be of value as human food; thus, the term " marketable" was given to the over 42 mm category.

The former minimum legal size, 51 mm (2 inches) is no longer used in New Hampshire; however, even if the 45 mm size class were added to the 50 mm and up category, biomass estimates would be increased only I

nominally. The influence of individual clams on biomass estimates increases exponentially with increase in body size.; yet, smaller-bodied 1976 year-class clams succeeded in dominating older, larger-bodied clams because of almost two orders of magnitude numerical superiority (Figure 5).

At the end of 1978, biomass estimates of marketable sized clams were about the same as they had been one year earlier (Figure 6).

I I

24 I

I TABLE 8.

SUMMARY

0F NYA ARENARIA POPULATION DENSITIES, ANNUAL NOVEMBER l

SURVEY. SEABROOK MYA ARENARIA STUDY,1978.

POPULATION DENSITY (#/SQ. FT.)

NUMBER OF SAMPLES YOUNG COLLECTED SPAT ADULTS ADULTS LOCATION YEAR ADULTS SPAT

(>l TO 25 mm)

(26 TO 50 mm)

(>50 mm)

Flat 1 1971 18 18 48 6.8 2.1 1972 18 18 110 8.1 3.3 1973 36 18 44 2.5 1.3 1974 40 18 2.6 2.8 3.0 1975 35 18 56 0.4 1.2 1976 63 18 1084 0.12 0.53 1977 66 14 819 0.04 0.15 1978 66 14 372 0.62 0.15 Flat 2 1971 9

9 91 4.8 3.8 1972 9

9 152 2.2 1.4 1973 9

9 136 3.8 1.1 1974 21 9

0.0 2.1 1.9 1975 21 9

9.1 0.0 0.5 1976 24 9

351 0.0 0.21 1977 33 7

86 0.0 0.08 1978 33 7

15 2.1 0.16 Flat 3 1971 6

6 74 4.7 4.6 1972 6

6 39 1.6 0.4 1973 12 6

8 3.6 2.2 1974 12 6

0.6 0.7 1.7 1975 12 6

1.1 0.0 0.6 1976 24 5

560 0.07 0.23 1977 24 6

75 0.12 0.04 1978 24 0

50 1.2 0.14 Flat 4 1971 12 12 106 17.6 2.8 1972 12 12 138 10.6 2.3 1973 24 12 18 3.8 0.6 1974 29 12 1.1 2.8 1.8 1975 29 12 68 0.3 0.7 1976 81 18 843 0.04 0.16 1977 51 11 436 0.09 0.01 1978 51 11 309 12.4 0.05 (Continued)

25 TABLE 8.

(Continued)

I POPULATION DENSITY (#/SQ. FT.)

NUMBER OF iI SAMPLES YOUNG COLLECTED SPAT ADULTS ADULTS LOCATION YEAR l ADULTSSPAT

(>l TO 25 mm) (26 TO 50 m)

(>50 m) l Flat 5 1971 9

9 176 1.3 1.6 1972 9

9 196 3.8 2.3 j

1973 21 11 23 1.0 0.4 3

1974 17 11 2.4 0.0 0.1 1975 9

11 7.5 0.0 0.01 1976 24 12 549 0.0 0.14

'I 1977 33 9

114 0.08 0.03 1978 38 7

56 4.1 0.07 I

All Flats 1971 54 54 92 7.7 2.7 1972 54 54 130 6.2 2.2 1973 111 56 47

?. 8 1.0 1974 119

~6 2.1 2.1 2.0 I

1975 106 26 37 0.2 0.8 19'6 216 62 762 n,06 0.20 1977 212 47 388 0.05 0.07 1978 212 45 208 4.4 0.09 I

I I

I I

I I

I I

26 I

TABLE 9.

COMPARISON OF l1. ARE?/ ARIA SHELL GROWTH (MM) IN SIX NORTHERN NEW ENGLAND ESTUARIES. SEABROOK lHA AREllARIA STUDY,1978.

I I

1976 YEAR CLASS 1977 YEAR CLASS lst YEAR 2nd YEAR lst YEAR LOCATION RANGE MEAN RANGE MEAN RANGE MEAN Plum Island Sound Middle Ground 14-33 20 31-59 40 9-31 1/

Lufkin's Flat 18-35 26 31-56 42 16-28 22 Nut Shoal 13-32 21 32-60 42 14-28 19 I

Merrimack River Salisbury Flat 3 16-26 18 Ball's Flat 1 11-30 la Hampton Harbor Flat 2 9-16 12 16-39 22 8-18 14 Flat 4

+

14-36 19 8-15 12 Little Harbor Channel 9-16 11 12-21 16 I

York River 27-41 33 12-23 17 I

Ogunquit Beach 10-27 18 29-46 38 13-26 19 I

I I

I Insuf ficient date due to heavy preciation

+ Not sampled in summer 1977 I

I I

M'M M

M M

M M

M M

M M

M M

M M

M M

M M

TABLE 10.

RESULTS OF SOFT-SitELL CLAM STANDit!G STOCK ESTIMATES, HAMPTON-SEABROOK ESTUARY. SEABROOK HYA ARENARIA STUDY,1978.

TOTAL NUMBER NUMBER MEAN BIOMASS STANDING CROP NUMBER OF UNITS BURROWLESS (BUSitELS PER ACRE)

(BUSitELS)

SURFACE SAMPLING WITil UNITS NO.

COMBINED AREA UNITS BURROWS SUBSAMPLED BURROWS BURROWS ESTIMATE LOCATION DATE (ACRES)

(n)

(n )

(nj)

(s )

(ij) i STD DEV i STD DEV.

j j

Plat 1 6 Nov 54.91 66 10 27 29.4 7.3 16.3 1 3.4 895 i 185 Plat 2 7 Nov 24.96 33 4

14 65.5 0.0 27.8 i 8.1 694 1 203 12 Apr 33 6

7 57.3 8.5 18.8 1 7.5 470 1 186 Flat 3 6 Nov 10.54 24 3

12 36.0 0.0 18.0 1 5.6 190 1 60 Plat 4 10 Nov 51.05 51 9

22 218.2 13.4 101.8 1 15.5 5195 1 790 Plat 5 7 Nov 23.69 38 4

16 74.3 4.0 33.6 1 16.6 796 1 392 All Plats 6-10 Nov 165.15 212 30 91 All adult clams 89.4 7.0 42.4 1 5.9 7000 1 970

" marketable" size clams (>42 mm) 10.2 2.4 5.7 1 1.3 940 1 215

28

.I i

3.0 -

1 I

2.5 -

i 1978 01977 i

2.0 -

I u

6 o-1.5 -

1 m

U 1

!I 4

1 1.0 -

!I 1

i O.5 -

l m

._i _. _..., _ __..__-

I I

I I

I I

I 3O 35'40 45 50'55'60 65'70 75 80 85 i I

90 i

SIZE CLAS_S_(mm) l Figure 5 Length density distribution of adult clams collected in November surveys from five flats in Hampton Harbor. Seabrook Ada crenars:

i l

Study, 1978.

1 II

29 100 -

"ItARKETABLE SIZE" CLA':S 90 -

(SEE TABLE 10)

(>

T h

ALL ADULT CLA!!S 80 -

8 I

70 -

E 60 -

l x

m i

"e T

a 5

50 -

1 5

T E

l 40 -

l i

I l

l 1

1 30-l l

I r-20 -

sum ot>

I l.

+

1 O

i a

e i

i i

I l

1971 1972 1973 1974 1975 1976 1977 1978 YEARS 1I Figure 6.

Es timate of !.!ya' arer. aria biomass for five tidal flats in Hampton l

Harbor, with approximately 95% confidence intervals. Seabrook Mya aver: aria Study,1978.

I l

30 Flat 1, with one third of the total flat acreage, held approximately 41%

^

of the total marketable crop; but, Flat 4, with approximately 74% of the total standing crop, appeared to hold the greatest potential for future yields (Tables 10 and 11). Due to the successful establishment of the 1976 year class, estimates of percent productive f'at area took a sharp upward turn in 1978, halting the progressive decline that had character-ized previous years (Table 12).

I 3.4 CARCINUS MAENAS For comparison, data from the preliminary, summer 1977, effort has been presented in Figure 7, Table 13 and Appendix 7.5 along with the later, twice monthly, trapping data.

It is unlikely that size frequency distribution (Figure 7), or sex ratio and fecundity (Table 13) has been appreciably affected by the difference in catch method. On the other I

hand, summer 1977 catch per effort values are probably not equivalent to similar values computed from subsequent trapping results.

The smallest crab taken during the study was 1.5 cm at the widest part of the carapace while the largest was 7.2 cm wide. From July 1977 through December 1978, approximately 99% of the crabs caught had carapaces between 3 and 7 cm wide. Although the majority of the captures were female (Table 13), males predominated at carapace widths greater than 6 cm (Appendix 7.5). In 1977, fecundity appeared to be I

highest from the third week in July through mid August (Appendix 7.5).

In contrast, fecundity peaked in mid-May, 1978.

In both years the egg bearing season virtually ended in mid September, although a single gravid female was caught in December in 1977 and 1973 (Appendix 7.5).

I lI I

I 9

31 I

TABLE 11. COMPARISON OF " MARKETABLE" AND TOTAL STANDIfiG CR0P ESTIMATES, HAMPTON-SEABROOK ESTUARY, NOVEMBER SURVEY. SEABROOK l17A ARE:iARIA STUDY,1978.

I

" MARKETABLE"

"!MRKETABLE" TOTAL PERCENT I

BIOMASS STANDING CR0P STANDING CROP

" MARKETABLE" LOCATION (BUSHELS PER ACRE)

(BUSHELS)

(BUSHELS)

SIZE

• Flat 1 7.0 383 895 43 i

Flat 2 7.4 185 694 27 Flat 3 10.7 113 190 60 Flat 4 2.5 126 5195 2

I Flat 5 3.1 74 796 9

All Flats 5.7 940 7000 13 1

of total standing crop on flat in question

I lI iil lI l

!I

!I lI lI i

32 I

TABLE 12.

ESTIMATES OF CLAM FLAT PRODUCTIVE AREA (%) IN HAMPTON-SEABROOK ESTUARY. SEABROOK MYA ARF;/ ARIA STUDY,1978.

I YEAR OF SURVEY LOCATION 1978 1977 1976 1975 1974 Flat 1 60 17 35 53 80 Flat 2 36 15 17 41 63 Flat 3 42 32 48 39 67 Flat 4 62 20 19 57 98 Flet 5 43 22 27 4

20 All Flats 52 19 26 45 66 I

I I

I I

I I

I

l 8 SUMMER 1977 E FALL 1977 5 SPRIl1G 1978 g

M SUMMER 1978 l

, 30 -

M FALL 1978 l

l

'25-E E

G E

l

[

20 -

E f$

(

8

'15 -

i I

j

' 10 -

MM 0-I I

I I

I I

I-

<3 3 -3'a 3!-4 4-453 4 '2-5 5-513 51 - 6 6-612 61-7

>7 2

2 2

MAXIMUM CARAPACE WIDTil (CM) i Figure 7.

Size frequency distrioution of Carcinus macnas from liampton liarbor Flat 2. Seabrook Mja averutria Study,1978.

4 34 i

l TABLE 13. SELECTED C. I61ENAS CATCH STATISTICS 1977-1978.

SEABROOK NYA ARENARIA STUDY,1978.

FECUNDI~Y CATCH PER SEX RATIO

(% GRAVID a

)

SAMPLE PERIOD UNIT EFFORT (M:F)

FEMALES)

Su::mter 197N July 24.6 1:4.9 6.2 August 10.3 1:3.5 9.4 September 21.6 1:2.2 0.9 Fall 1977 17.5 1:0.9 0.3 Spring 1978 7.5 1:3.3 7.0 4

Summer 1978 8.6 1:1.5 3.2 l

Fall 1978" 7.2 1:1.3 0.5 l

l i

4 I

a l

j lI

(

!I i

1. No. of C. maenas per trap per day b

7.,o.' prism" traps, fishing for 2 to 5 days at a time l

Eight " box" traps, fishing for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> twice per month

!I

35 I

3.5 MYA AEVARIA REPRODUCTIVE CYCLE Examination of gonad condition in Hampton-Seabrook M. arenaria populations indicated a single annual spawning cycle in 1978 (Figure 8).

Gametogenesis appeared to begin in females in late winter or early spring; whereas, male gametogenesis apparently did not begin until early I

May.

Once sta2ted, however, male gonad development proceeded rapidly enough that both sexes were rer.dy to spawn by July. Spawning activity peaked during August and September, with some activity probably continuing after the last gonad sample collection in mid September.

I I

I I

I I

I I

i M

M M

i i

I i

i I

j.

N=

6 12 5

10 12 11 9

11 15

1. of Ad11ts j

10 0 -

j

= EiiE = =_

j

= EEE E 1

E EEi! E

=

F

= E E z

w EE E M 50-EEi i!EE 4

w EEE E i

n.

55! E i

E EEE

-:

1 5.

EE =

=:

1 En Es E=

0 i

i i

i i

i

.i 28 11 26 9

22 18 31 ll 12 j

APRIL MAY JUNE JULY AUG SEPT M ALES 4

w

]

N=

19 13 20 14 13 14 16 14 10

1. of Adults I

100 -

=

_g E=_

1

==_

i

!EE @ g h

INDIFFERENT N

i r

EEE 225 iEiE EE EEi l

bbbbb b

DEVELOPING O

=llll l

g 50-

@ E g g= =

E m

j o

E EE E Ei! E M

RIPE

= = =

EEE EE iEEi EiEi iEEi 9 E EEli EE=

N SPAWNING

__=

0-

=

SPENT l

4 I

i I

i I

28 11 26 9

22 18 31 Il 12 APRIL MAY JUNE JULY AUG SEPT FEMALES Figure 8.

Percentages of male and female Mya arenaria in each gonadel development phase during 1978.

37 4.0 DISCUSSION 4.1 ORIGIN, DISTRIBUTION AND RECRUITMENT OF MYA ARENARIA LARVAE In 1978, plankton tows clearly indicated a bimodal temporal distribution of M. arenaria larvae, confirming earlier suspicions based on scant evidence (NAI, 1977) that a late spring, or early summer, abundance peak :nay, in some years at least, precede the well documented late summer peak. Examination of 1978 gonad samples, on the other hand, corroborated earlier NAI (1971) findings of a single, late summer, spawning cycle in Hampton-Seabrook Estuary. presuming that these findings I

are representative of the entire estuary, this discrepancy can have only one logical explanation: larvae which appear in New Hampshire nearshore waters in early summer largely come from source (s) other than Hampton-Seabrook estuary.

I Correlation between water currents flowing northward for several dayr, and peak-in larvae abundance was first noted in 1975 (NAI, I

1976) and led to the supposition that northern Massachusetts was the origin of much of the larvae entering New Hampshire waters. The credi-bility of this hypothesis has now been enhanced by present evidence of bimodal larvae peak abundance combined with Brousseau's (1978) claim that M. arenaria populations in the Jones River, Gloucester, Massachu-l setts spawn in qpring, and again in late summer. Until Brousseau's histological examination of gonad tissue from Jones River M. arenaria bimodal spawning periodicity had been conclusively demonstrated only l

south of Cape Cod (Landers, 1954; pfitzenmeyer,1962; Ropes and Stick-ney, 1965).

In 1978, dense populations of M. arenarla larvae continued to be closely associated with onset of northerly wind drift, usually fol-Icwing a period of indeterminant or southerly current flow (Appendix l

7.4).

The heaviest concentracion of larvae (31 August and 1 September) was associated with ab upt onset of high velocity northward flowing currents (30 and 31 August; Appendix 7.4).

1 1

38 I

Onset of strong northerly flow on 12 August did not produc e an abundance of M. arenaria larvae probably because during this time clams I

were not spawning but recovering (" resting") from earlier (May-June) spawning efforts.

In 1978, the summer larval peak was unusually late; observations during the past several years also indicate that a high larvae concentration in July is unusual (NAI 1975, 1976, 1977, 1978),

suggesting thct. Jelayed timing of a spring peak, until early summer, may have offset the timing of the conventionally accepted summer peak.

I The hypothesis that M. arenaria larvae are more densely distri-buted inshore along the New Hampshire coast reattires no further elabor-ation. As explained in previous reports (NAI, 1977, 1976), the inshore-offshore gradient occurs as a statisticall" rverage condition, and is most fully expressed when the larvae are ab udant.

Umboned veliger abundance off Hampton Beach continued to be poorly correlated with spat settlement density in Hampton Harbor (Table 14).

Although larval abundance increased by a factor of nearly 20, from I

a five year low in 1977, spat settlement declined by a factor of approx-imately four betaeen 1977 and 1978. A similar inderendence of Crassostrea virginica larval abundance and rpatfall density has long been noted by cor:mercial oystermen (pers. comm., Long Island Oyster Co. representatives).

I 4.2 OTHER BIVALVE MOLLUSC LARVAE I

To the species, Modiolus modiolus, Mytilus edulis, Hiatella sp. and Anomia sp. which predominated in 1977 (NAI, 1978), 1978 results added Macoma balthica and Spisula solia ssima. In both years, M. modi-I olus larvae populations peaked during June and exhibited concentrations in excess of 50,000 larvae por m. Also in both years, Anomia sp.

I comprised up to 54% of the total population in August. Generally, Hiatella sp. percent composition was relatively low in the summer of 1978 compared to 1977; there were no spring samplcs in 1977 to ccrepare with 1978 findings.

'I

M M

M M

M M

M M

M M

M M

M M

M M

M TA3LE 14.

COMPARISON OF M. ARENARIA UMB0NED LARVAL ABUNDANCE OFF !!AMPTON BEACil WITil YOUNG-0F-Tile-YEAR SPAT DENSITIES IN HAMPTON !! ARBOR. SEABROOK NYA ARENARIA STUDY,1978.

LARVAL DENSITY DAILY MEAN x DENSITY OF PERIOD OVER WilICil MEAN SEASON LENGTil YOUNG-0F-Tile-YEAR YEAR LARVAE WERE COLLECTED (per m / day)

(per m )

(Spat per ft )

3 3

2 1974 16 Jul to 5 Sep ( 51 days) 69 3,520 2

1975 16 Aug to 14 Oct ( 59 days) 532 31,400 37 1976 28 Jun to 17 Oct (113 days) 158 17,800 762 1977 27 Jun to 6 Oct (102 days) 7 714 179 1978 22 May to 31 Oct (163 days) 83 13,600 46

40 I

Ensis directus occurred in concentrations of up to 2000 larvae I

per m on 19 September 1977, but barely attained peak concentrations of 450 per m on 5 October 1978. This difference may not be definitive since it is the nature of such planktonic populations to fluctuate I

widely even within a few hours. Absence of Placopecten magellanicus larvae from fall 1978 collections through the end of October may have been due to the same seasonal delay which appears to have affected the temporal distribution of other bivalve mollusc larvae as well.

I 4.3 SHELL GROWTH I

Evidence presented in Table 9 and in Appendix 7.2 indicates tiat N. arenaria shell growth has been generally slower in New Hampshire waters than in adjacent areas of northern Massachusetts and southern Maine. Size frequency distribution graphs given by Brousseau (1978) show growth rates in the Jones River, Gloucester, Massachusetts, com-parable to rates reported here for Lufkin's Flat in Flum Island Sound.

Dow and Wallace (1951) reported the average 1 year old clam in the Scarboro River and in Doctor's Creek, Wells, Maine, to be approximately I

20 mm, and the average 2 year old clam to be approximately 33 ca.

These values are reasonably close to average values reported here for the York River and Ogunquit Beach, Maine (Table 9).

In Hampton-Seabrook estuary, Ayer (1968) reported growth rate of clams in " growth boxes" similar to the growth rate reported by Dow and Wallace (1951). Subsequently, NAI (1977) gave slightly higher I

growth rate estimates than those of Ayer (1968) for the 1968 through 1972 Hampton-Seabrook year classes. Thus, Hampton-Seabrook clams, in the 1976 and 1977 year classes, appear to be experiencing less than optimum growth.

Substratum was probably not an important factor in the ooserved shell growth differential although quantitati'fe substrate sampling has been restricted to Hampton Harbor (NAI 1978) visual examination has shown no I

41 I

distinctive differences between flats in the six estuaries studied. Fine sand predominated at all sampling sites, with some slightly more muddy or shelly areas also present.

I Crowding is probably the main reason for the slower than expected growth in Hampton-Seabrook estuary. NAI (1978) presented data suggesting growth to be inversely proportional to population density. Earlier, Stickney (1964) found such a relationship between growth and population I

density in a small cove near Bremen, Maine. Laboratory experiments (Stickney, 1964) indicated the detrimental effects of crowding to be related to competition for food (i.e., unicellular microalgae). Food scarcity may be a particularly critical issue in estuaries like Hampton-Seabrook which have high flushing rates preventing endemic aggregation (build up) of algal populations.

I 4.4 SURVIV0RSHIP AND PREDATION I

Judging from the areas under the size density curves in Figure 5, approximately 25% of young clams in both the 1976 and 1977 year class have survived from one November survey to the next.

It is estimated that approximately 6% of those clams which settled on Hampton Harbor flats in 1976 survived until November 1978. Earlier calculations of first-year survival (NAI, 1977) gave estimates ranging from 0.2% for the 1975 year class to 7% for the 1971 year class; data then available showed 25% survival occurring only in the second and subsequent years following settlement. Present estimates therefore suggest marked recent improvement in first year survival, a finding supported by observation I

of young adalts (25 to 43 mm) in the Merrimack River estuary for the first time in three yeare (Section 3. 2).

The apparent increase in first year survivorship, accompanying an increase in population density, suggests relaxation of predator pressure. If true, relaxation of predation could be due to increased abundance of the prey (i.e., small clams) or be compounded by a decrease I

42 I

in predator (i.e., Carcinus maenas) abundance. Two factors which point to a possible reduction in C. maenas abundance are: 1) recent decline W

in winter water temperature (Figure 9), upon which Welch (1969,1975) has shown C. maenas abundance to be directly dependent, and 2) the decrease in Flat 2 C. maenas catch-per-effort comparing fall 1977 with fall 1978. Pressure of human predators (clam diggers) has also decreased because of: 1) closing the flats in summer (see Section 4.5), and a general decline in interest in digging concurrent with the clam pop-ulation decline (Table 15).

4.5 PRESENT AND FUTURE STATUS OF MARKETABLE AI. ARENARIA STANDING CR0P IN HAMPTON HARBOR I

Between November 1977 and November 1978 the standing crop of marketable clams (shell size: 43 m and up) essentially stabilized at approximately 940 bushels (Table 15).

It appears that recruitment, probably of no more than 350 bushelt, virtually compensated the amount I

harvested.

In the future, however, the policy of closing the flats to digging, from Memorial Day to Labor Day, should help restore standing crop to a condition eventually approaching that which existed earlier in this decade (Table 15).

By November 1979, there could be at least 3000 bushels of

" marketable" clams on the Hampton-Seabrook flats. This estimate has I

been derived primarily by considering the probable rate of recruitment of young adults (30 to 42 mm) to marketable size.

In November 1978, there were approximately three clams per ft in the 30 to 42 mm size range (Appendix 7); at a 25% survival rate and a 13 mm per year growth rate this yields 0.75 clams per ft in the size range: 43 to 55 mm.

Using Belding's (1930) tables this converts to approximately 14 bushels per acre and on 165 acres this gives a standing stock recruitment of approximately 2300 bushels, 74% of which will probably ccme from Flat 4 alone (cf. Table 11). An additional 700 bushels is expected to be com-I posed of older clams overlooked by diggers.

I

43 I

I I

I l

38 I

37 -

I w

l

@ 36 P

I e

e2 35 1

w F-I 34 I

i i

i i

i i

1973 1974 1975 1976 1977 1978 l

YEAR OF RECORD I

I Figure 9.

Means of daily minimum winter (February and March) winter temperature off Hampton Beach, New Hampshire. Seabrook A+ja arenar a Study,1978.

I

44 I

RECEN HISTORY OF THE STANDING CROP 0F " MARKETABLE" SIZE TABLE 15.

ADULT { M!A ARENARIA IN HAMPTON HARB0R.

SEABR00K li!A ARE:iARIA STUDY, 1978.

I ESTIMATED BUSHEL TOTAL ESTIMATED NuttBER DATE PER ACRE OF BUSHELS November 1967 152.0 23,400 July 1969 103.0 15,840 November 1971 84.0 13,020 November 1972 58.0 8,920 November 1973 41.0 6,310 November 1974 56.0 8,690 I

November 1975 29.0 4,945 November 1976 11.0 1,350 November 1977 6.4 1,060 November 1978 5.7 940 I

I I

lI f,

• 1967-1975, shell length = 50 mm and up; 1976-1978, shell length =

I 43 mm and up from Ayer (1968)

I I

45 Between November 1979 and November 1980, four clams per ft should be recruited to the 42 to 55 mm range if survival and growth I

continues at the present rate. This would provide an additional stand-ing crop recruitment of over 6000 bushels. By the end of 1981, the 1976 and 1977 year classes together should have yielded at least 11,000 bushels of harvestabla clams. These are conservative estimates; stand-ing crop recruitment

'ld be much higher if survival turns out to be better than projected, o. if growth rate improves with the inevitable decline in population dennty.

I I

I I

I I

I I

I I

5

46 5.0

SUMMARY

By November 1978, approximately 940 bushels of clams with a shell length greater than 42 mm remained on the five largest flats of Hampton Harbor (approx. 166 acres', representing a negligible net loss from November 1977. Successful establishment of the 1976 year class of I

spat (the strongest in more than 10 years) caused a sharp upturn in total standing crop estimates to approximately 7000 bushels, with a projected yield, after growth to a more " marketable" size, of at least 11,000 bushels.

The largest clams representing the 1976 year class had attained a shell size of 42 mm as of November 1978, although the mean size at Hampton Harbor was only 22 mm.

Slower growth of the Hampton Harbor population, compared to adjacent areas of northern Massachusetts and southern Maine, was attributed to crowding, complicated by limited food I

resources available in a well flushed estuary.

Increased survivorship accompanied the increased abundance of young clams in Hampton Harbor; this was partly attributed to reduction in predation by the green crab, Carcinus maenas. Based on preliminary trapping data, plus a downward trend in winter water temperatures (to which fecundity in this crab is believed to be sensitive) since 1974, I

green crab numbers are suspected to be declining, or at least not keep-ing up with the increased availability of the prey. Summer closure of the Hampton and Seabrook flats to human diggers has also probably had a favorable effect on 1976 year class survival.

lI Over a 163 day monitoring period, Nya arenaria umboned larvae 3

densities at the cooling water intake site averaged 83 per m. Peak i

densities of one to two hundred per m were recorded throughout most of l

June and into early July, followed by a midsummer lull in which there 3

were never more than 5 larvae per m. A second abundance peak began l

abruptly at the end of August, diminished through September, and surged for the final time to several hundred larvae per m in early October.

I

'I

47 I

Examination of gonad samples showed that Hampton Harbor clams first began to spawn in late July and early Auguct. This evidence, together with data on non-tidal (net) current drift, supports a northern Massa-chusetts origin for a substantial proportion of the M. arenaria larvae entering New Hampshire coastal waters.

As in previous surveys, M. arenaria larvae were found more densely distributed along the coast within 0.5 to 1.0 nautical miles of the shore, especially during major spawnings. Larvae of several other I

bivalve mollusc species usually outnumber M. arenaria in the plankton.

In order of decreasing abundance these include: Modiolus modiolus, Mytilus edulis, Hiatella spp., Anomia spp., Macoma balthica, Spisula solidissima and Ensis directus. Fever larve of Placopecten magellanicus were collected than during 1977.

I I

I I

I

I I

lI lI

48 I

6.0 LITERATURE CITED I

I Armed Forces Institute of Pathology. 1949. Manual of histologic and special staining techniques. McGraw Hill.' 2nd edition.

pp.

7-14, 25-30.

I Ayer, W.C.

1968. Soft-shell clam population study in Hampton-Seabrook Harbor, New Hampshire. New Hampshire Fish and Game Dept.

39 pp.

I Belding, D.L.

1930. The soft-shelled clan fishery of Massachusetts.

Commonw. Mass. Dep. Conserv. Div. Fish Game, Mar. Fish. Ser.

1,65 p.

I Coe, W.R., and H.J. Turner, Jr.

1938. Development of the gonads and gametes in the soft-shell clam (Nya arenaria).

J. Morphol.

62:91-111.

Dow, R.L.

1977. Effccts of climatic cycles on the relative abundance and availability of commercial marine and esturaine species.

J.

Cons. Int. Explor. Mer.

37(3):274-280.

and D.E. Wallace, 1951. Soft-stell growth rates in Maine.

Rept. Dept. Sea and Shore Fish, ME.

6 pp.

Guenther, W.

1964. Analysis of variance. Prentice-Hall, Inc., Engle-wood Cliffs, N.J.

199 pp.

Landers, W.S.

1954. Seasonal abundance of clam larvae in Rhode Island waters, 1950-52.

U.S. Fish Wildl. Serv. Spec. Sci, Rep. Fish.

117, 29 p.

Normandeau Associates, Inc.

1971. Seabrook Ecological Study: Phase I 1969-1970, Hampton-Seabrook Estuary, New Hampshire. Prepared for Public Service Company of New Hampshire. 313 pp.

1975. Spatial and temporal distribution of the larvae of the soft-shelled clam, Nya arenaria, in the Hampton-Seabrook Estu-ary and nearby offshore waters. Technical Report VI-l.

1976. Spatial and temporal distribution of the larvae of I

the soft-shelled clam, Nya arenarla, in New Hampshire coastal waters, 1975. Technical Report VI-10.

1977. Seabrook Ecological Studies 1975-1976. Studies on I

the soft-shelled clam, Nya arenarla, in the vicinity of Hampton-Seabrook estuary, New Hampshire. Technical Report VII-3.

73 Isp.

I I

I

49 1978. Seabrook Ecological Studies 1976-1977. Studies on the soft-shelled clam Nya arenaria, in the vicinity of Hampton-Seabrook estuary, New Hampshire. Technical Report VIII-2.

85 pp.

Pfitzenmeyer, H.T.

1962. Periods of spawning and setting of the soft-I shelled clam, Nya arenarla, at Solomons, Maryland. Chesapeake Sci. 3:114-120.

I Porter, R.G.

1974. Reproductive cycle of the soft-shell clam, Nya arenaria at Skagit Bay, Washington. Fish Bull., U.S. 72:648-656.

Ropes, J.W. and A.P. Stickney. 1965. Reproductive cycle of Nya arenaria in New England Biol. Bull. 128:315-327.

Savage, N.B. and R. Goldberg. 1977. Investigation of practical means of distinguishing Nya arenaria and Niatella sp. larvae in plankton samples.

Proc. Nat. Shellfish. Assoc.

66:42-53.

deSchweinitz, E.H. and R.A. Lutz.

1976. Larval development of the northern horse mussel, Modlolus modiolus (L.), including a com-l parison with the larvae of Nytllus edulis (L.) as an aid in l

planktonic identification. Biol. Bull.

150(3):348-360.

Sokal, R.R. and F.J. Rohlf. 1969. Biometry.

W.H. Freeman Co. San Francisco. 776 pp.

Stickney, A.P.

1964. Feeding and growth of juvenile soft-shell clam, Nya arenarla Fish Bull. 63(3):635-642 Sullivan, Charlotte M.

1948. Bivalve larvae of Malpeque Bay; P.E.I.

Fish Res. Bd. Canada Bull.

77.

36 pp.

I Welch, W.R.

1969. Changes in abundance of the green crab, Carcinus maenas (L.) in relation to recent temperature changes.

U.S. Fish Wildl. Serv. Fish. Bull. 67(337-345).

I 1975. Report on the relative abundance of green crabs along the Maine coast, Fall 1975. Maine Dept. of Marine Recources.

lI 1I lI iI iI 1I

g I

!I I

I

-I

!I I

lI l

APPENDICES i

I lI

'I I

I I

I I

I

M M

M M

M M

M M

M M

M M

M M

APPENDIX TABLE 7.1.

ANALYSIS OF VARIANCE TABLE FOR TWO-WAY TREATMENT MODEL i

PROJECT AND STUDY: seabrook uga study TRANSFORf1ATION: square root DATES OF DATA: June, July, September 1978 ALPHA LEVEL:.05 3

SUBJECT OF ANALYSIS: nya larvae counts NATURE OF DATA:

s's/m Mya FACTOR A: Dates (7) 6/5, 6/12, 6/26, 7/10, 9/1, 9/5, 9/21 l

FACTOR B: stations (4) I2, 14, 16, 18 i

OBS/ CELL:

2 SUM 0F MEAN SOURCE OF VARIATION SQUARES D.F.

SQUARE F-RATIO P

Dates A

1061.91 6

176.985 55.637

<.001 stations B

964.426 3

321.475 101.059

<.001 Dates x Stations AB 1048.812 18 58.267 18.317

<.001 g

i Error E

89.070 28 3.181 l

Total T

3164.220 55 COMMENTS: All main effects and interactions are highly significant I

E APPENDIX TABLE 7.2.

SHELL SIZE DISTRIBUTION.

PLUM ISLAND SOUND Mr.DDLE GROUND 1978 SIZE CLASS 6

4 13 11 12

{

(un)

JAN APR JUN AUG OCT 1

1.5 2

19.9 32.8 10.7 1.5 3

16.0 40.5 4.6 29.0 1

4 18.3 19.1 1.5 1.5 34.4 5

11.5 16.0 4.6 0.8 22.9 6

15.3 8.4 9.2 0.8 19.1 I

7 9.9 8.4 15.3 0.8 6.9 8

6.9 6.1 13.0 0.8 9

3.8 3.1 13.0 3.8 3.1 1

10 6.1 4.6 17.6 7.6 3.1 11 3.1 3.8 15.3 6.1 6.9 12 2.3 2.3 9.9 9.2 15.3 13 2.3 0.8 10.7 17.6 11.5 1

14 1.5 0.8 2.3 22.9 29.8 15 7.6 29.0 20.6 16 1.5 7.6 23.7 22.9 l

17 3.1 3.1 3.8 18.3 9.2 18 4.6 2.3 3.1 11.5 12.2 19 5.3 3.1 0.8 14.5 7.6 20 5.3 5.3 0.8 17.6 2.3 I

21 6.1 6.1 1.5 7.6 2.3 22 13.8 6.1 0.8 9.2 3.8 23 13.8 6.1 1.5 2.3 1

24 8.4 5.3 0.8 3.1 3.1 25 6.9 9.2 0.8 3.8 1.5 26 4.6 9.2 2.3 3.8 2.3 27 6.9 3.1 2.3 0.8 2.3 1

28 5.3 8.4 0.8 2.3 3.1 29 5.3 6.1 0.8 2.3 0.8 30 6.9 3.1 3.8 2.3 2.3 1

31 4.6 3.8 4.6 6.1 4.6 32 1.5 4.6 3.1 2.3 0.8 33 2.3 3.8 0.8 1.5 34 0.8 1.5 1.5 0.8 3.1 1

35 1.5 1.5 0.8 5.3 3.1 36 1.5 3.1 3.1 37 1.5 3.8 3.1 1

38 0.8 1.5 0.8 3.1 1.5 39 0.8 0.8 2.3 2.3 40 1.5 2.3 I

i 1

d t

I 53 APPENDIX TABLE 7.1 (Continued)

SIZE ig CLASS 6

4 13 11 12 j

(m)

JAN APR JUN AUG OCT i

41 0.8 1.5 0.8 0.8 0.8 42 1.5 3.1 4

4 43 0.8 0.8 1.5 l

44 3.1 3.8 ig 45 1.5 0.8 jg 46 1.5 1.5 j

47 0.8 1.5 48 0.8 4.6 l

49 3.1 2.3 50 1.5 51 0.8 1.5 52 0.8 1.5 53 0.8 l

54 l

55 56 0.8 0.8 l

57 58 lg 59 0.8 I3 60 i

l I

l ll J

I i

!I

!I i

1 i

i i

i i

. -. ~...

-e o-4 54 i

APPENDIX TABLE 7.2 (Continued)

Ij

I PLUM ISLAND SOUND

3 LUFKIN'S FLAT 1978

5 I

SIZE CLASS 6

4 13 11 12 l

(mm)

JAN APR JUN AUG OCT 1

i 2

8.9 14.0 3.8 l

3 11.5 25.5 8.9 l

4 17.8 16.6 1.3 3.8 2.5 5

8.9 14.0 2.5 6

6.4 10.2 1.3 1.3 7

6.4 6.4 2.5 1.3 I

8 3.8 2.5 2.5 9

6.4 5.1 6.4 2.5 10 2.5 6.4 1.3 1.3 11 2.5 1.3 14.0 1.3 1.3 12 6.4 1.3 1.3 13 5.1 14 1.3 1.3 1.3 I

15 1.3 2.5 16 9.6 3.8 17 2.5 6.4 18 1.3 1.3 2.5 19 1.3 2.5 6.4 20 1.3 1.3 1.3 5.1 21 2.5 2.5 22 1.3 3.8 8.9 23 1.3 5.1 24 5.1 6.4 25 7.6 1.3 26 1.3 1.3 1.3 3.8 27 1.3 3.8 28 1.3 1.3 3.8 3.8 29 1.3 3.8 30 1.3 2.5 1.3 31 2.5 3.8 1.3 32 3.8 33 1.3 2.5 1.3 34 2.5 1.3 1.3 3.8 I

35 1.3 1.3 36 2.5 1.3 37 1.3 38 2.5 39 1.3 1.3 40 1.3 1.3 1.3 (Continued)

I

l l

55 i

f APPENDIX TABLE 7.2 (Continued)

!I 1

SIZE

}

CLASS 6

4 13 11 12 (mm)

JAN APR JUN AUG OCT

I l

}

41 1.3 1.3 1.3 i

42 1.3 1.3 i

43 1.3 ja 44 i

45

)

46 1.3 47 1.3 1.3 l

j 48 1.3 1.3 49 1.3 1.3 1.3 50 51 1.3 1

52 1.3 1.3 Ig 53 g

54 55 1.3 56 1.3 57

=

58 59 a

4 1

I l

'I I

I 56 APPENDIX TABLE 7.2 (Continued) i i

i PLUM ISLAND SOUND EAGLE HILL RIVER AT NUT SH0AL 1978 I

SIZE CLASS 6

4 13 11 12 (mm)

JAN APR JUN AUG OCT l

7.6 2

40.1 72.6 59.2 3.8 3

43.9 49.7 1.9 32.5 30.6 l

4 51.6 22.9 1.9 3.8 17.2 5

26.7 11.5 19.1 13.4 l

6 19.1 11.5 9.6 1.9 5.7

{

7 17.2 5.7 17.2 9.6 8

19.1 5.7 21.0 5.7 9

5.7 9.6 28.6 3.8 10 5.7 5.7 36.3 3.8 11 1.9 3.8 26.7 12 3.8 1.9 30.6 13 1.9 1.9 15.3 7.6 14 1.9 13.4 5.7 21.0 15 9.6 7.6 11.5 16 17.2 21.0 ll 17 24.8 13.4 18 13.4 21.0 19 3.8 17.2 13.4 20 1.9 5.7 5.7 7.6 3

i 21 1.9 1.9 5.7 11.5 7.6

)

22 1.9 3.8 11.5 13.4 23 3.8 1.9 3.8 11.5 24 3.8 1.9 1.9 9.6 7.6 2

25 3.8 7.6 11.5 3.8 26 3.8 7.6 1.9 3.8 9.6 27 3.8 3.8 3.8 5.7 28 3.8 3.8 1.9 3.8 ll 29 5.7 1.9 i 3 30 7.6 3.8 1.9 I

31 1.9 1.9 32 7.6 3.8 1.9 3.8 I

33 3.8 1.9 1.9 j

34 5.7 1.9 1.9 3

35 7.6 1.9 1.9 1.9 I

36 3.8 3.8 3.8 1

37 3.8 9.6 7.6 38 1.9 3.8 3.8 1.9 1.9 39 1.9 3.8 1.9 1.9 40 1.9 1.9 1.9 1.9 3.8 i

i (Continued) f

l 57 APPENDIX TABLE 7.2 (Continued) 3 il i

SIZE i

CLASS 6

4 13 11 12 (nn)

JAN APR JUN AUG OCT

I 41 1.9 1.9 l

42 1.9 1.9 5.7 5.7 43 1.9 3.8

!=

44 5.7 1.9

}

45 1.9 1.9 1.9 46 47 1.9 1.9 l

48 1.9 1.9 1

49 l

50 1.9 1.9 51 3.8 1.9 i

52 1.9 ig 53 1.9 l3 54 l

55 i

56 1.9 i

57 l

58 1.9 l

59 60 1.9 il i

1 il 1

i il 1

)

i

.----..-___J__--____.___.__..____,._._.-_._-_

APPE'7IX TABLE 7.2 (Continued)

I MERRIMACK RIVER ESTUARY I

BALL'S FLAT #1 1978 i

SIZE CLASS 4

5 19 9

13 (nm)

JAN APR JUN AUG OCT I

1 0.8 2

283.4 59.6 j

3 51.2 45.8 8.4 l

4 16.0 17.6 19.9 l

5 8.4 5.3 28.3 l

6 2.3 1.5 24.4 j

7 2.3 35.1 8

0.8 29.8 9

0.8 20.6 l

10 15.3 11 9.9 1.5 l

12 0.8 8.4 1.5 i

13 1.5 3.1

{

14 1.5 4.6 i

15 0.8 6.1 i

16 6.1 1.5 l;

17 4.6 1.5 j

18 14.5 0.8

{

19 6.1 4.6 l

20 6.1 6.1 j

21 3.8 6.1 22 6.9 9.2 l

j 23 3.1 10.7 j

24 0.8 8.4 1

25 0.8 6.9 l

26 3.8 27 6.1 28 1.5 3.8 29 0.8 30 0.8 31 0.8 32 1

33

!g 34 j g 35 j

36 j

37 0.8

!I 1

I!I 4

!I

I 59 APPENDIX TACLE 7.2 (Continued)

R MERRIMACK RIVER ESTUARY SALISBURY FLAT #3 t

l SIZE CLASS 5

6 19 9

13 (mm)

JAN APR JUN AUG OCT 1

2 3.8 3.8 6.9 0.8 3

6.9 9.9 14.5 4.6 4

3.8 3.8 0.8 5.3 3.8 5

0.8 3.8 3.1 3.8 I

6 4.6 0.8 1.5 7

0.8 0.8 8

3.1 0.8 9

0.8 10 0.8 0.8 0.8 0.8 11 12 1.5 I

13 0.8 0.8 14 15 i

16 0.8

I 17 0.8 l

18 0.8 I

19 l

20 21 0.8 22 0.8 0.8 I

23 24 I

25 O.8 26 0.8 lI 27 28 29 0.8

'g 30 13 31 32 33 34 35 36 37 I

I I

I 60 APPENDIX TABLE 7.2 ' Continued)

HAMPTON HARBOR FLAT #2 SIZE CLASS 4

5 9

14 9

(mm)

JAN APR JUN AUG OCT 1

0.6 2.3 1.5 3.8 I

2 37.6 52.0 5.3 9.9 24.4 3

17.2 48.9 3.1 0.8 35.9 4

7.0 24.4 5.3 2.3 21.4 5

5.7 13.0 10.7 3.1 11.5 I

6 8.3 9.9 9.2 2.3 6.1 7

1.9 6.1 8.4 4.6 3.1 8

5.7 5.3 6.9 6.9 0.8 I

9 5.7 3.8 6.9 5.3 10 10.2 3.0 9.2 7.6 0.8 11 14.6 8.4 11.5 9.2 2.3 I

12 22.3 8.4 3.1 13.8 1.5 13 19.7 13.8 4.6 13.0 4.6 14 27.4 13.8 1.5 15.3 1.5 15 15.3 18.3 2.3 19.9 6.9 I

16 16.6 15.3 15.3 6.1 17 8.3 7.6 13.8 9.9 18 7.0 7.6 0.8 14.5 10.7 I

19 5.1 4.6 2.3 17.6 13.8 20 2.5 3.1 11.5 18.3 21 3.1 11.5 9.2 22 0.6 2.3 8.4 9.2 23 9.9 16.0 24 12.2 12.2 25 0.8 10.7 8.4 I

26 0.8 5.3 8.4 27 7.6 6.1 28 6.1 5.3 29 3.1 5.3 I

30 5.3 4.6 31 2.3 1.5 32 1.5 3.8 I

33 0.8 3.1 34 0.8 35 0.8 0.8 36 0.8 I

37 0.8 38 39 0.8 I

40 41 42 0.8 I

I

I 61 APPENDIX TABLE 7.2 (Continued)

I I

HAMPTON HARBOR FLAT #4 SIZE CLASS 5

9 14 9

(nm)

APR JUN AUG OCT 1

3.1 2.3 2

57.3 2.3 11.5 25.2 I

3 60.4 13.8 48.9 77.2 4

48.1 21.4 55.8 105.4 5

32.9 14.5 27.5 119.9 I

6 39.7 8.4 14.5 104.7 7

40.5 9.1 11.5 94.7 8

45.8 14.5 4.6 67.2 9

47.4 9.9 9.2 32.8 I

10 63.4 22.2 9.2 16.0 11 67.2 18.3 9.9 8.4 12 82.5 19.9 14.5 13.0 I

13 74.9 19.1 9.2 16.0 14 94.7 22.2 8.4 16.8 15 104.7 16.0 9.9 35.9 16 74.1 17.6 10.7 36.7 I

17 45.1 20.6 17.6 39.7 18 28.3 13.0 13.0 32.1 19 19.1 14.5 19.9 26.0 I

20 11.5 13.0 13.8 36.7 21 6.1 10,7 16.8 26.7 22 3.1 5.3 11.5 19.1 23 1.5 1.5 6.1 17.6 24 3.1 3.8 7.6 j

25 1.5 3.8 14.5 26 0.8 7.6 10.7

'I 27 0.8 5.3 9.9 28 0.8 5.3 3.8 l

29 4.6 4.6 30 3.1 5.3 31 3.1 3.9 32 3.8 i

33 1.5 2.3

.l 34 0.8 0.8 5

35 1.5 36 0.8 37 0.8 5

38 i

39 40 43 44 0.8 45 I

. ~. -.

l lll 62 APPENDIX TABLE 7.2 (Continued)

!I 1

I l

LITTLE HARBOR CHANNEL i

FLATS l

i SIZE l

CLASS 13 10 16 8

6 (mm)

JAN APR JUN AUG OCT

'I 1

2 0.6 0.6 7.0 I

3 1.9 2.5 1.3 9.6 4

3.2 2.5 5.7 3.8 5

2.5 2.5 1.3 1.3 6

0.6 2.5 2.5 0.6 tI 7

0.6

(

8 1.9 1.9 l

9 0.6 0.6 l

10 0.6 1.3 l

11 0.6 l

12 0.6 0.6 13 14 15

(

16 0.6 l

17 i

18 0.6 l

19 lg 20 lE 21 0.6 il I

lI I

I I

I I

l

I 63 APPENDIX TABLE 7.2 (Continued)

I YORK RIVER FLAT AT ROUTE 103 BRIDGE 1978 I

SIZE CLASS 17 3

14 10 1,1 I

(nn)

JAN APR JUN AUG OCT 1

1.5-^

I 2

11.5 1.5 14.5 3

13.0 1.5 6.1 1.5 11.5 4

13.8 6.1 5.3 2.3 5

14.5 8.4 8.4 1.5 lI 6

14.5 6.8 5.3 2.3 l

7 9.2 4.6 6.1 1.5 8

4.6 3.1 3.1 2.3 j

9 2.3 4.6 3.8 3.1 1.5 j

10 0.8 4.6 3.1 2.3 i

11 3.1 3.1 3.8 3.1 Ig 12 0.8 3.8 1.5 0.8 jg 13 0.8 0.8 2.3 4

14 3.1 l

15 0.8 0.8 0.8 j

16 0.8 0.8 j

17 1.5 0.8 1

18 C.8 0.8 jg 19 0.8 0.8 j3 20 i

21 0.8 lg 22 1.5 O.8 15 23 0.8 24 25 I

26 27 0.8 28 29 I

30 31 0.8 32 0.8 I

33 1.5 34 35 O.8 36 5

37 38 39 40 I

I 4.

,g -

4 64 APPENDIX TABLE 7.2 (Continued) i

\\\\

SIZE

!E CLASS 17 3

14 10 11

'5 (mm)

JAN APR JUN AUG OCT i

j 41 08 I

42 43 44

]

45 f

46

!l 47 48 im 49 i

50 13 51 Ig 52 08 t

lI lI 4

?

!I i

II 1I il

!I iil l

I

I 65 APPENDIX TABLE 7.2 (Continued)

OGUNQUIT BEACH 1978 I

SIZE CLASS 17 3

14 10 11 (cm)

JAN APR JUN AUG OCT 1

0.6 1.3 1.3 I

2 7.0 0.6 12.1 9.6 3

3.8 1.9 3.8 17.8 4

3.8 2.5 2.5 1.3 9.6 i

5 0.6 1.3 10.8 0.6 I

f 0.6 0.6 1.9 0.6 7

1.3 1.9 5.1 8

0.6 0.6 1.9 l

9 0.6 0.6 7.6 0.6 l3 10 1.3 0.6 l

11 0.6 1.3 12 1.3 1.3 13 1.3 3.2

]

14 1.3 1.9 15 1.3 1.3

l 16 0.6 2.5

!E 17 0.6 0.6 3.2 0.6 18 0.6 1.3 0.6 0.6 1.3 19 1.3 1.9 0.6

'I 20 2.5 1.3 3.2 0.6 21 3.2 2.5 1.3 22 3.8 1.9 23 3.2 4.5 0.6 0.6 24 1.9 3.8 1.3 1.3 25 2.5 3.8 0.6 1.3 0.6 26 1.9 2.5 1.3 2.5 0.6 27 1.9 1.9 1.9 0.6 28 3.S 2.5 0.6 i

29 1.9 2.5 4.5 0.6 I

30 1.9 1.9 0.6 1.3 0.6 31 1.9 1.3 0.6 1.3 l

32 1.9 0.6 2.5 0.6

' g-33 0.6 0.6 1.9

)g 34 0.6 0.6 i

35 1.9 36 0.6 1.3 2.5 37 1.3 0.6 i

38 3.2 1.3 39 0.6 40 0.6 0.6 2.5 1.9

~1 (Continued)

I

66 APPENDIX TABLE 7.2 (Continued)

I I

SIZE CLASS 17 3

14 10 11 (m)

JAN APR JUN AUG OCT 41 1.9 1.3 I

42 1.3 43 0.6 1.3 44 1.3 1.3 45 1.3 1.3 I

46 0.6 47 48 I

49 1.3 l

]

50 0.6 51 52 I

53 l

54 55 56 0.6 I

I I

I I

I I

I I

I

67 APPENDIX 7.3.

I TABLE A.

SHELL SIZE DISTRIBUTION OF SOFT-SHELL CLAMS ON FLAT 1 FOR THE NOVEMBER SURVEYS, 1971-1978. SEABROOK NYA ARENARIA STUDY,1978.

I SIZE CLASS (m) 1971 1972 1973 1974 1975 1976 1977 1978 il

!E 5

19.00 74.00 30.00 2.50 55.00 1031.00 283.00 38.00 10 11.00 9.00 6.00 1.14 52.00 413.00 100.00 15 11.00 15.00 3.00 0.75 117.00 148.00 lI 20 7.00 11.00 5.00 0.02 5.82 76.00 25 0.47 2.50 0.16 0.11 0.48 9.20 30 1.30 2.30 0.51 0.17 0.02 0.02 0.56 I

35 1.50 1.20 0.60 0.48 0.04 0.03 40 1.80 1.40 0.67 0.89 0.23 0.01 0.03 45 1.80 0.61 0.49 1.10 0.14 0.10 0.01 50 1.00 0.83 0.42 1.20 0.36 0.03 0.02 0.03 55 0.64 1.60 0.30 0.82 0.25 0.04 0.03 0.03 60 0.36 0.33 0.29 0.42 0.28 0.23 0.02 0.03 65 0.08 0.19 0.18 0.31 0.1, 0.1.3 0. 0 '.

0.04 I

70 0.03 0.19 0.11 0.10 0.11 0.00 0.04 75 0.03 0.08 0.05 0.10 0.03 0.03 0.02 0.02 80 0.02 0.07 0.02 85 0.01 0.01 0.01 I

90 0.01 I

I I

I I

I I

I I

0 41 8954 623 3 2 2 V8 0

96521 00000 00 O7 8

N9 1

12 10000000 00 7

1 1

9 1

5 R8

- - - - 4 82 3 223 2 2

7 P7 0

00 00000 0

9 A9 1

0 00 00000 0

1 S

00 6

2 Y

V7 09 0

0 E

O7 V

N9 3 2 0

0 R

1 8

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Y G7 2

2 2494 9

L U7 0

0 0000 0

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1 0

0 0000 0

T R

AU Y7 2

4 26 2

2 Q

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0 00 0

0 M9 R

1 0

0 00 0

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t 2

B7 l

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T F9 s

A 1

e r

L F

0 2

2 2 2 2

no N

V6 0

0 0

00 0

O O7 i

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0 0

00 0

t S

1 5

a M

3 t

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L C

G6 4

de U1 0

x L

A9 i

r L

1 0

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S Y6 l 22 4121 o

l 01 01 f

T A7 r,. 0 0 F

M9 00 0000 2

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000 i

d N

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1 00 0

000 ne I

T p

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2729472 464 A

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0000000000 I

e R

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1 9

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)

S s

d I

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01 0000000 0

0 e

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t I

1 3

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o a

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68822481 242 2 2 4 2

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y 3 i M9 l

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1 9

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od X

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B B5 0

3 277248046622 a

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1 33 672 1 200000 r

N E F9 E L 1

5 0000000000000 t

P B o

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ES)

=

ZAn 5050505 05 0505 0505 0505 0 I L u 1 1 22 3 344556677 8899001 SC(

1 1 1 1

!!lll ll

69 APPENDIX 7.3 (Continued)

TABLE C.

SHELL SIZE DISTRIBUTION OF SOFT-SHELL CLAMS ON FLAT 3 FOR NOVEMBER SURVEYS, 1971-1973.

SEABROOK MYA AREJARIA STUDY, 1978.

SIZE CLASS (m) 1971 1972 1973 1974 1975 1976 1977 1978 5

35.00 28.00 6.00 0.64 1.14 556.00 67.00 38.00 10 29.00 4.70 1.00 4.10 3.40 1.10 I

15 5.20 4.00 3.40 3.00 20 4.80 2.00 1.13 3.71 25 0.17 0.42 1.00 0.05 3.74 30 0.92 0.25 1.00 0.14 0.85 I

35 0.67 0.17 0.38 0.12 0.02 0.10 0.27 40 1.50 0.33 0.62 0.11 0.02 45 1.4C 0.42 0.50 0.30 0.02 0.04 I

50 1.30 0.17 0.29 0.11 0.03 0.02 0.02 55 1.1 0.17 0.79 0.08 0.03 0.02 0.04 60 0.83 0.08 0.54 0.18 0.08 0.02 65 0.58 0.46 0.38 0.08 0.04 0.02 70 0.33 0.08 0.42 0.14 0.02 0.04 75 0.25 0.08 0.22 0.03 0.06 0.02 0.02 80 0.08 0.08 0.14 0.03 0.06 85 0.04 0.03 0.08 90 0.08 0.06 0.08 lI l

i lI l

lI l

I I

I

I 70 APPENDIX 7.3 (Continued)

.I TABLE D.

SHELL SIZE DISTRIBUTION OF SOFT-SHELL CLAMS ON FLAT 4 FOR NOVEMBER SURVEYS, 1971-1978. SEABROOK NYA AREllARIA STUDY, 1978.

SIZE CLASS (m) 1971 1972 1973 1974 1975 1976 1977 1978 I

5 38.00 116.00 12.00 2.50 66.00 830.00 117.00 113.00 10 11.00 31.00 1.00 1.80 13.20 183.00 91.00 I

15.

7.00 20.00 3.00 115.00 48.00 20 4.00 18.00 2.00 0.64 20.40 45.10 25 2.80 1.10 0.52 0.05 0.01 0.62 12.38 30 3.50 3.00 1.40 0.26 0.01 0.02 8.29 I

35 4.60 2.80 0.62 0.58 0.01 0.01 3.19 40 4.00 1.70 0.46 0.96 0.16 0.85 45 2.60 2.00 0.35 0.92 0.16 0.09 0.02 I

50 1.30 1.00 0.38 0.80 0.18 0.03 55 1.10 0.79 0.14 C.50 0.21 0.13 0.01 60 0.25 0.21 0.08 0.29 0.12 65 0.17 0.04 0.14 0.21 0.14 0.01 0.01 I

70 0.12 0.08 0.06 0.03 0.04 l

75 0.02 0.01 0.01 1

80 0.04 0.01 0.01 85 0.01 0.01 0.01 l

I l

,I lI 1

I 1I 1I l

I

)

i3

E 71 APPEtiDIX 7.3 (Continued) l TABLE E.

SHELL SIZE DISTRIBUTION OF SOFT-SHELL CLAMS Oft FLAT 5 FOR NOVEMBER SURVEYS, 1971-1978.

SEABROOK MYA AREHARIA STUDY, 1978.

I SIZE CLASS lI (mm) 1971 1972 1973 1974 1975 1976 1977 1978

)

5 67.00 136.00 22.00 2.40 7.50 546.00 92.00 44.00 10 38.00 94.00 1.00 2.80 8.30 4.80 ll j

15 12.00 16.00 7.50

'E 20 3.00 6.00 5.30 4.80

}

25 0.06 0.55 0.10 0.75 2.28 IE 30 0.11 0.89 0.31 2.17

g 35 0.33 0.61 0.14 0.01 0.01 1.41 j

40 0.44 1.00 0.28 0.07 0.41 45 0.44 0.77 0.12 0.10 l

l 50 0.94 0.94 0.10 0.02 0.04

'E 55 0.39 0.61 0.12 0.01 60 0.28 0.50 0.12 I g 65 0.11 0.05 0.08 0.01 g

70 0.11 0.05 0.04 75 0.05 0.01 0.01 0.01 i

80 0.06 0.01 j

85 l

90 IlI

'I il I

I I

I I

72 I

I s:.e s en -- :rmor cuee e: mec my w.n w ma:ar :2.

.3 ar usy 17 1979

.1Wi uAy 31 1979 i 7 i 2 s i m i ea i a i a a i s i aimiaiaisi i al i i

6.

T-7 y

g gy ypr e.

tw gy j

srf

/

,[' i

\\

/

s; i e i e] : a i a i a i da i e. m i e7 i a i a i 30 i a i i

I m=l9 tr cA tt.Md ok -

4 %LYM6 kW/

k en:

^'\\

~ ~ Tyt&%& 1%

'Mhp \\

i 17 i is i is i ao a i a i a i ea i a, a i e7 i a i a i 30 i z i i

!l

/r w.

.b m?G.:'

s TN%?sW 1,7 y l ( " n7 W N 9 7 7jPr.' N P f i 17 i is i is i eo i a i a i a i aa i a i a i e7 i a i a i m i x i

A\\

arc

% R7

/

~7 s w :a.

I 13 1

13 I

13i 3g

10 l

l. I t

l i.

r l

lj,.j

!,l l

l l 2

-3

-3

>I I

Appendix Figure 7.4.

Hourly average sequential vector plots of water current meter data and wind data (both representing I

direction toward ) as well as high and low tide heights for May 17 to Sept 30, 1978.

I

73 I

wm sww - wm ~.uee. an: s me.swa acm w w M 1 1979

..YS

,.1.N 16 1979 3 1 1 2 6 3 1 4 i s1 6 1 7 i 9 i 9 1 10 1 11 1 12 i 13 1 14 1 15 i 16 1

/

s

/..

2~ ~a u30 57 A /(/

1 i

m i

l{g My//

e I

./

u%

6 1 1 2 1 3 i 4 1 ' 6 G i/*9 8 9 i J.) I 11 1 21 13 1 14 t a i 16 I I

Tj%6 W div he v h A l,/5 h MLW.

@A Y/ k ' /7;ff/f my x Ts /s,Tj i< m 4:

cuee.-

t 3 I

j

, 1 i 2 i 3 i 4 s

a6 i ei9

.0, u a i la i 14 i a i 16 i

.,. 4

-.. 1In i.r1

'.?i-?t, r.,9 7 y f/fj'pv,Fi y n # r t w

>L tx m s:

W

. x i

w l

l 4 1 i 2 i 3 i 4 isia i

s.e to u 12 13 14 : a i sc i

.nc kWW

!b ll}kw _t,$klk)hk'Pb M 4u sca

~p W gN

• w mm lE l

l I

13 t

1'3 tc 1

'ill l

l1lll i l !v i

j i

j iE o

3

-3 3

I Appendix Figure 7.4.

(Continued) 1 1

lI

i 74 I

=r e s s: s = c_m corc u#u m a c asic m:n w e J.N 17 1979 mys a m mygcr i 17 I 19 i o i 20 t 21 i e i a i 24 i d5 i dG 1 2/4 S I a i m I i

i t

I e

-S 'NPc

-7 4I

? FT IbE'ER 1.'

./

~// '

I m

"mTH i a i la i a i e2 i a, ea a. aa, e.

a er i a a m i

Te% i'

'sk!d% W

_ X %w 4

~

knas fof N /WM MittKk,%*WLfl\\ W W W W I

a_e-

+ 3 I

igilsimieuiaimiaiaana.mieriaiaimi j

e i

+ 0. <4 ss ec r a_

2l*:"

'twer-"

prJogr -nry 1-f-fy@y[y u,i 17 i la i a_ i ao i a i a. a i e4 m m i e7 i a i a i ao i i

t I

• DC tO s ra Irv

,,r/F-.

&L Yu:u!511 $YT l

Qf $h x

I e e ym

.I20

@S Gt 1 23 101 l

x s 13 ctt-r

'lf

~

I l

l lI lt l

r l

ot

-3 $

.: o

$ -2

(

i l

Appendix Figure 7.4.

(Continued) i 4

i

75 I

I

- cr.ro -

-- e. xc

.ca.v - sc -em we 41.17 LT9 CAf5 J.L. 31 1579 i 17 i G i L9 1 2o i a i e a a 1 ad 6 5iEI U i a i B i 30 i 31 &

I a

I I*7 wou M

i g i ta i ts i ao i m i m i a i a. i e i m i c i n i m i m m i i

n,,

8a

% n+

y :-- / <

v,g 3 v e n v 3

woa l[

m i e i is i is i ao i a i e i o i a. i a i a i e i a i e i m i a i i

o.4 mw, mit s b N/ t!s t, o a A I/

'E Wcpq'l,\\.\\ Abwc Y rmw~y~y"vnWr eve si i o i is i :s i ao i a i e i a i e4 i a i m i e i a i a i 30 e n i i

oc emm

r --

A e MxNiilb/sx1 A

ec ALesJ su.

c 3-s 7-4" 13

+ 13 to

• k to 31

!-3 I

Appendix Figure 7.4.

(Continued)

I

76 maux s 4T=>. - smx --.o.r:=ro

,an.vaee cuser:>.o c

%.G 1 1.579 lMS

'di is 15?E 4 1 1 2 1 3 1 4 i ! I E I 7 i eiS 1104114 121131144 15 I is I aCI7tPG T-7

,\\

$ h/..

I

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?JJ,7,

py 39 ugw mn -

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1

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,af.

I1 12 13 14 15 1 S I7 iB i5 113 111 1 12 l13 814 515 118 I Y$lNk

.I.

&L

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ww

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.-4,

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I o

i1 1 2 1 3 1 4 1 5 iG I 7 iB l 5 1 10 8 ja i la i 131 14 115015i Q.4 R,co%. 51

_ i: _. _ _ i 1. n a v.

a >> I? )i>

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ejguyw si='r1 t r V - v pn v.xppn 1 1 2 1 3 1 4 8 5 i E I 7 I e1 9 1134111 12613114 e 15 i is i WBC kg fdff g,, _

cf, _ _ $,Jt))

wSc g

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,, r=,,

4r --

r y/cr

-r-13 t.

a l} *

+=r,e f\\

fff f

V o

,: o

-2 k-3 l

i l

Appendix Figure 7.4.

(Continued)

ll 1

1 E*AD + N NT O7N MV AVOEA7. NM EO.C"">4 TDedeG I

I

/2 i p+ F,,,,f e /f st i a

icsix T-7

=,

~

i a 8+\\i A'Y

.ni,-

l u,

y gxp,y,ygya w <

/f

M i

i gi...

....i......i.i.i....

i e

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1,

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11

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whhth[A&.

.x

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w

'Tj77

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Appendix Figure 7.4.

(Continued) i i

1

, - _. _ -o

78 zg sg - -

e,g

.ua.<

eu c :me:.,c-2

. 1

...,. _2.u.a.u,1.

m.m.

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cu.n i 1, 2, 3 e. 1. I E I 7 8 9 l 9 4 13 8 11 s 12 1 13 1 1. I 15 e is,

t

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Appendix Figure 7.4.

(Continued)

Jw

-fsEO3 N. O C Ws vWv't3 W cts"

C mm

. o, TE ' _ ' 2C

• 2T E PE a F>

• E *. r O ! es ee 2*

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mn

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4,'LJ a

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, x.

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Appendix Figure 7.4.

(Continued) i

!I

a APPENDIX 7.5.

C,1RC1NUS MAENAS CATCH RECORD, SUMMER 1977, TWO "PRIS!!" TRAPS,

MAXIMUM CARAPACE WIDTils (cm)

TRAPPING DATES

>3 3-31/2 3 1/2-4 4-4 1/2 4 1/?-5 5-5 1/2 5 1/2-6 6-6 1/2 6 1/2-7 >7 8-11 Jul 4M 7M 12M SM IM 2F(g) 84F;6F(g) 78F;2F(g) 6F 11-13 Jul 1M 1F; 2F (g) 4M 9M 12M IM 49F;1F(g) 34F;4F(g) 3F l

l 13-15 Jul lP(g)

SF; 1F (g)

IM 4M IM IM IM 2M l

9F;4F(g) 26F;2F(g) 18F; 3F (g) 10F IF j

l 15-18 Jul 1F 1H 1M 2M 2M IM 5F 4M 2M 2F llF; 2F (g) 30F;1F(g) 9F 3F 18-20 Jul 2M 7M 6M 2M 8M 4M GM co l

3F;1F(g) 17F;6F (g) 48F;1F(g) 32F 14 F;1F (g)

IF 1F l

20-23 Jul 2F IM 6M 4M SM SM 4M IM 12F 26F;1F(g) 41F; 3F (g) 35F;4F(g) 14F 2F 23-27 Jul 8F 3M 7M 4M 6M 6M 3M 29F;3F(g) 68F; 2F (g) 4 3F; 2F (g)

ISP 5F 27-29 Jul 1F 1M 4M 2M 2M 4M 7M IM IM 9F 20F;1F(g) 28F;lF(g) 23F;1F(g) 4F 1F 29 Jul-3 Aug 1F 1M IM 3M 3M 2M 7M SM 2M 3F;lF (g) 22F; 5F (g) 34F;6F(g) 32F;3F(g) 15F;1F (g) 2F 1F 3-7 Aug IF 2F IM 2M 2M 4M 6M 2M 12F 18F;1F (g) 22F;2F(g) 10F 2F (Continued) l l

l l

M M

M M

M M

M M

M M

i APPENDIX 7.5.

(Continued)

MAXIMUM CARAPACE WIDTHS (cm)

TRAPPING DATES

>3 3-3 1/2 3 1/2-4 4-4 1/2 4 1/2-5 5-5 1/2 5 1/2-6 6-61/2 6 1/2-7 >7 7-12 Aug SF IM 6M 2M BM 4M 3M 16F; 3F (g) 34F;1F(g) 23F 11F;3F(g) 6F IF 12-17 Aug 1M IM 3M 4M 6M SM SM 2M 2F; 2F (g)

SP; 4F (g) 26F;3F(g) 19F; 3P (g) 8F;1F(g) 1F 1F 17-25 Aug IF 3M 2M 3M 4M 2M 15P;1F (g) 15F;2F (g) 3F 2F;1F(g) 13-16 Sep 1F 1F 2M IM 4M 7M 3M IM 10F 22F;1F(g)

ISP 12F 3F 16-20 Sep 1F BP 2M IM 4M 2M 3M 12F 19P;1P(g) 13F 2F g

20-23 Sep 2F 1M 2M 8M 13M 2M IM 6F 22P 44F 23F 6F M = Male F = Female P(g) = Egg bearing female 1 trap only on loan from Maine Dept. Marine Resources s

AF'EllDIX 7.5.

CARCINUS MAE'NAS CATCl1 RECORD FALL 1977 Ti!R00Gil FALL 1978, 8 RECTAtlGULAR TRAPS.

MAXIf10M CARAPACE WIDTilS (cm)

TRAPPING DATES

>3 3-3 1/2 3 1/2-4 4-4 1/2 4 1/2-5 5-5 1/2 51/2-6 6-6 1/2 6 1/2-7

>7 27-2d Oct IM 6F 2M 7M 17M 9M 4M SF 16F 14F 19F 2F 1F 9-10 Nov 3F 3M IM SM llM 13M 4M 3M SF 10F 18F 26F 19F 3F l

21-22 riov IF 3M 3M 7M 18M llM 9M 4M 2F 7F 16F 27F 23F 1F IF 2M l

7-8 Dec IM 1F 2M llM 21M 78M 66M 37M llM 2M 5F 22F 18F;1F(g) 28F 18F 3F 19-20 Dec 2F IM IM IF IM m

3F 3F 4-5 Jan IF 2F IP l

17-18 Jan No catch l

l l-2 Feb fio catch l

l 16-17 Feb No catch l

l 6-7 Mar No catch 20-21 Mar tio catch 3-4 Apr No catch I

L

M M

M M

M M

APPENDIX 7.5.

(Continued)

MAXIftUM CARAPACE WIDTHS (CM)

TRAPPING DATES

<3 3-31/2 3 1/2-4 4-4 1/2 4 1/2-5 5-51/2 51/2-6 6-61/2 6 1/2-7

>7 17-18 Apr 2F 3F 2M 1F 2M 1F 1-2 May IF 2t 4ft 10M 7M 5!!

IM 1F;lF(g) 7F SF SF IF 18-19 May IF 2F 12F;lF(g)

IM 2M 2M 3M 43F;2F(g) SlF;5F(g) 17F 3F 8-9 Jun 1M IM 1F 2M 2M 10M 4M IM IM IF 2F (g) 5F 3F 22-23 Jun 1M IM 3F;2F(g)

IM lt!

6F;1F(g) 2M 1F;1F(g) m 3F;1F(g) 13F 19F 3F 10-11 Jul 3M 4F 1M 4M 10M 8M llM 8M 3M 1F 6F;1F (g) 14F;1F (g) 25F 23F 2F I

25-26 Jul 1F 3M 2M 3F IM IM IM IM 3F;lF(g) 4F;1F(g) 1F 8-9 Aug IM 3M SM 13F llM 9M 3M 2M SF 12F 18F; 2F (g) 25F 17F 3F 22-23 Aug IF;1F(g) 6F 3M SM 9 21 7M 4M lli 7F 8F SP 8-9 Sep 2M IM 4M 2M SM 2M IM 1F 1F(g) 10F 4F 3F 20-21 Sep 1F 1F 3F 1M 3M SM SM 6F 8F 8F 3F l

(Continued)

M M

M M

M M

M M

M M

M M

i t

i j

APPENDIX 7.5.

(Continued)

[

MAXIMUf-i CARAPACE WIDTHS (CH)

TRAPPING

}

DATES

<3 3-3 1/2 3 1/2-4 4-4 1/2 4 1/2-5 5-5 1/2 5 1/2-6 6-61/2 6 1/2-7

>7 5-6 Oct 2M 3F 1M IM 4M 2M 2M IM IM 1F SF 4F 9F 9F 3F 19-20 Oct 3M 4M 7M 8M 15M 10M 15M SM 3M l

4F 4F 9F 17F 21F 12F 2F l

l 3-4 tiov 1M 3M 3M IM 7M SM 2M 2M 4

7F 6F 9F 7F 10F 2F 1F IF 16-17 tiov 1M 2M 6M 7M 4M 6M 3M 3F 7F 9F SF SF 4F 4

11-12 Dec 1F 1F 2M IM 2M 2M IM j

4F 3F' 2F 1F l

20-21 Dec 1F 1M IM 3F 2M IM 2M 1F(g) 1 I

I i.

M = male F = Female P(g) = Egg bearing female r

a

.