ML19259C062
| ML19259C062 | |
| Person / Time | |
|---|---|
| Site: | New England Power |
| Issue date: | 04/30/1979 |
| From: | Davis W, Marcello R NEW ENGLAND POWER CO., YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19259C058 | List: |
| References | |
| YAEC-1175, NUDOCS 7906120287 | |
| Download: ML19259C062 (50) | |
Text
'
POPULATION STATISTICS AND COMMERCIAL CATCH RATE OF AMERICAN LOBSTER (HOf4ARUS AMERICANUS)
IN THE CHARLESTOWN-MATUNUCK, RHODE ISLAND REGION OF BLOCK ISLAND SOUND YANKEE ATOMIC ELECTRIC COMPANY Y
2284 072 7 90612 0 Q 87
YAEC 1175 POPULATION STATISTICS AND COMMERCIAL CATCH RATE OF AMERICAN LOBSTER (HOMARUS AMERICANUS)
IN THE CHARLESTOWN-MATUNUCK, RHODE ISLAND REGION OF BLOCK ISLAND SOUND By ROCCO A. M ARCELLO, JR.
WALLACE DAVIS,111 THOMAS O'HARA JOHN HARTLEY
,Yamuss YANKEE ATOMIC ELECTRIC COMPANY 20 TURNPIKE ROAD WESTBOROUGH, MASSACHUSETTS 01581 2284 073 Submitted to NEW ENGLAND POWER COMPANY 20 TURNPIKE ROAD WESTBORO, MASSACHUSETTS 01585 APRIL 1979
NOTICE This document was prepared by Yankee Atomic Electric Company on behalf of New England Power Company. This dxument is believed to be completely true and accurate to the best of our knowledge and information. It is authorizhd for use specifically by Yankee Atomic Electric Company, New England Power Company, and/or the appropriate subdivisions within the U.S. Environmental Protection Agency or the Nuclear Regulatory Commission only.
With regard to any unauthorized use, Yankee Atomic Electric Company, New England Power Company, and their officers, directors, agents, and employees assume no liability nor make any w..rranty or representation with respect to the contents of this document.
Referencing of trade names or commercial products in this report does not necessarily constitute endorsement or recommendation for use.
228A 074
's
SUMMARY
This report describes the results of a program to determine the population structure and harvest rate of the lobster fishery in the immediate vicinity of the abandoned Charlestown Naval Auxiliary Landing Field (NALF). The study was conducted in the Charlestown-hfatunuck, Rhode Island region of Block Island Sound during the period 28 hfay through 31 August 1978. The objectives of this study were to determine legal /sublegal catch rates, sex ratio, size at sexual maturity of females, frequency of berried females, length-frequency distributions by sex, and total instantaneous mortality rates of post-recruitment lobsters by sex in the study area. After field work commenced,it appeared that the tagging oflobsters was feasible. The use of tags a!! owed some information to be collected on movement and population size of pre-recruit lobsters in the study area.
Approximately twice a week, the daily catch of a commercial lobsterman was recorded. For each lobster caught, the carapace length, sex, tag number, reproductive state of females, evidence of molting, claw complement and mher general comments were re orded. All berried females and sublegallobsters were tagged and released from 18 June to 31 August 1978.
During this study,1,055 pot hauls were made; these resulted in a total catch of 2,974 lobsters. Of these lobsters,25.6% were oflegal size ( > 79 mm). Overall catch per pot averaged 2.8 lobsters. hfcan legal catch per pot per set-over day ranged from 0.13 to 0.23 lobsters. Generally, there was no significant difference in the mean catch rates oflobsters from different areas. The catch rate of sublegal unberried female lobsters, however, was significantly higher at 3 sampling regions (IE,3E and OR).
Of the total catch,1,228 were males and 1,744 were females for an overall sex ratio (hi:F) of 1:1.42; a sex ratio significantly different from 1:1. No apparent trend in sex ratio with date or size class was observed. Expressed as frequencies,41% of the catch were males and 59% were females.
Of the total catch of 1,744 female lobsters, only 90 (5.2%) were egg bearing or berried. The highest frequencies of berried females occurred during early June and in August. Of these egg bearing female lobsters,31.5% were less than the minimum legal size.
Total mortality rates for post-recruitment male and female lobsters were estimated by two methods.
Age frequency distributions were derived from length-frequency distributions by applying the Von Bertalanffy growth equation, probability mode analysis, and constant annual molt increments. Total mortality rates for males and females were estimated to be 67% and 58%, respectively.
To determine alongshore movement,1,202 sublegal or berried female lobsters were tagged with coded bands and released. A total of 140 were recaptured of which it was possible to determine the date and point of release of 44 individuals. Of the 44 traceable returns, only 5 were recaptured outside of their release area. Distances traveled were approximately 1.4-2.7 nautical miles. There were no apparent trends in direction traveled, nor did the distances traveled appear related to sex or time at large. Use of the marking ( banding) technique was found to be unsatisfactory for studies to discern movements oflobsters.
The population of pre-recruit (69-78 mm) lobsters in the area fished by the lobster traps was estimated by three different analytical methods. Final population estimates for the period 29 June-31 August 1978 ranged from 3837-4033 lobsters. Estimated densities of pre-recruit lobsters ranged from 77-100 lobsters per acre of similar (rocky) habitat.
The period of molt onset in 1978 was determined by graphical analysis to be approximately late June.
2284078 iii
o-ACKNOWLEDGEMENTS We would like to express our appreciation to Mr. Michael J. Fogarty (Rhode Island Division of Fish and Wildlife, Marine Fisheries Section) for his cooperation and assistance in locating a local lobsterman
, willing to participate with tis in our study. Special thanks goes to Mr. Richard Jchnston who allowed us to work with him aboard his boat " Jaws 3" to collect the data for this report, and for his many helpful suggestions. Lastly, we wish to acknowledge the helpful advice on field sampling procedures provided by Mr. Robert P. Lawton and Mr. Wendell T. Sides of the Massachusetts Division of Marine Fisheries.
2284 076 0
IV e
TABLE OF CONTENTS Section Py NOTICE-il
SUMMARY
iii A"CKNOWLEDGEMENTS iv
1.0 INTRODUCTION
I 2.0 METHODS AND MATERIALS.
I 2.1 Study Area 1
2.2 Trap Description.
I 2.3 Sampling Methods..
4 2.3.1 General Trapping Survey Methods.
4 2.3.2 Tagging Study Methods -
4 2.4 Populadon Estimates 9
3.0 RESULTS AND DISCUSSION.
10 3.1 Catch per Unit Effort.,
10 3.2 Sex Ratio.,
21 3.3 Maturity 23 3.4 Length-Frequency.
28 3.5 Total Monality Rates.
30 3.6 Movement..
31 3.7 Population Estimates.
34 3.8 Molt Onset.
37 4.0 LITERATURE CITED.
39 2284 077 I
v
s LIST OF FIGURES Figure No.
Page 2.1 1 1978 lobster pot survey sampling regions..
2 2.2-1 Lobster traps used during 1978 lobster pot survey.
3 2.3-1 Carapace length oflobster being measured.
5 2.3-2 Rubber bands used for marking all berried female and sublegal lobsters..
6 2.3-3 Banding tool used for placing rubber bands on lobster cheliped.
7 2.3-4 Position of band on cheliped..
8 3.3-1 Length-frequency distribution of all female lobsters, and berried and unberried females caught during 1978 lot ter pot survey.
27 3.4-1 Length-frequency distribution of alllobsters, and males and females caught during the 1978 lobster pot survey..
29 3.8-I Catch per pot per setover day oflegal unberried females and legal males by date at station IE.
38 22B4 078 O
vi
s LIST OF TABLES Table N_o.
P_ age 3.0-1 Summary of 1978 lobster pot survey results..
i1 m
31-1 Catch per unit of effon (no./ pot /setover day) of all lobsters by sample date and locadon-12 3.1-2 Catch per unit of effon (no./ pot /setover day) by sample date and location of male lobsters ( 279 mm )..
13 3.1-3 Catch per unit of effort (no./ pot /setover day) by sample date and location of male lobsters ( < 79 mm) 14 3.1-4 Catch per unit of effort (no./ pot /setover day) by sample date and location of unberried female lobsters ( 279 mm )..
15 3.1-5 Catch per unit of effon (no./ pot /setover day) by sample date and location of berried female lobsters ( 279 mm) 16 3.1-6 Catch per unit of effort (no./ pot /setover day) by sample date and location of berried female lobsters ( < 79 mm )..
17 3.1-7 Catch per unit of effon (no./ pot /setover day) by sample date and location of unberried female lobsters ( < 79 mm)..
18 3.1-8 Catch per unit of effon (no./ pot /setover day) by sample date and location of male and unberried female lobsters ( 279 mm )
19 3.1-9 Analysis of variance between stations on the average catch per unit of effort of all lobsters,1978 lobster pot survey..
20 3.1-10 Analysis of variance among stations on the average catch per unit of effon of male lobsters ( 279 mm ),1978 lobster por survey..
20
- 3. ! -l 1 Analysis of variance among stations on the average catch per unit of effort of male lobsters ( < 79 mm ),1978 lobster pot survey..
20 3.1-12 Analysis of variance among stations on the average catch per unit of effort of unberried female lobsters ( 279 mm ),1978 lobster pot survey.
20 3.1 -l 'l Analysis of variance among stations on the average catch per unit of effort of berried female lobsters ( 279 mm ),1978 lobster pot survey -
20 3.1-14 Analysis of variance among stations and Duncans Multiple Range Test on the average catch per unit of effon (CPUE) of unberried female lobsters ( <79 mm),1978 lobster pot survey.
21 3.2-1 Number of male and female lobsters and sex ratios by 5 mm size classes,1978 lobster pot survey..
22 3.3-1 Length-frequency and cumulative frequency distributions oflobsters caught from the Charlestown-hfatunuck region of Block Island Sound,28 May-31 August 1978..
. 24 3.4-1 Sample statistics on lobster size,1978 lobster pot survey 28, 3.5-1 Von Bertalanffy growth equation coefficients for Rhode Island Sound derived by
. Russell et al. (1978) 31 2284 079 vii
Table Page No.
3.5-2 Estimated total instantaneous mortality rates (Z) for post-recruitment lobsters in the inshore Charlestown-Matunuck region of Block Island Sound.
31
,3.6-1 Summary oflobster recaptures during 1978 lobster pot survey -
32 3.7-1 Summary of mark-recapture information for 1978 lobster tagging study..
34 3.7-2 Summary of mark-recapture information for pre-recruit lobsters in the size range of 69-78 mm,1978 lobster tagging study..
35 3.7-3 Estimates of population size and density (rocky habitat) cf pre-recruit lobsters (69-78 mm) in the Charlestown-Matunuck region of Block Island Sound, 29 June-31 36 August 1978.
3.8-1 Date and location (station) of capture of recently molted lobsters,1978 lobster pot 37 survey
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1.0 INTRODUCTION
There is a commercial fishery for American lobster ( Homarus americanus ) in the vicinity of the site of New England Power Company's proposed nuclear power facility (NEP 1&2) in Charlestown, Rhode Island. In view of this local fishery and its proximity to the proposed site, considerable effort has been directed toward compilation of data that would help identify and assess the significance of potential plant-induced effects on the lobster population.
Little information was available on the population structure and harvest rate of the lobster fishery in the immediate vicinity of the site. Accordingly, the present study was conducted to obtain estima:-s of these parameters. The study was conducted in the Charlestown-Af atunuck, Rhode Island region of Block Island Sound during the period 28 Afay 1978 through 31 August 1978. The specific objectives of the study were to determine:
e legal /sublegal catch rates, e sex ratio, e size at sexual maturity of females, e percent of gravid females, e length-frequency distributions by sex, and e total instantaneous mortality rates of post-recruitment lobsters by sex of the lobster fishery in the vicinity of the site. Additionally, attempts to determine move at, estimate population size of pre-recruit lobsters, and approximate date of molt onset were made.
2.0 METilODS AND MATERIALS 2.1 Study Area This study was conducted in the Charlestown-hf atunuck, Rhode Island region of Block Island Sound.
The region was divided into 11 sampling areas (Figure 2.1-1) ba:ed on visible shoreline landmarks. Areas 3W and 6E were non-bounded; h1 wever, fishing effort was generally in the immediate vicinity of the adjacent station boundary. The NEP 1&2 proposed intake and discharge locations are within area IW.
The proposed site is an abandoned Naval Auxiliary Landing Field (NALF).
2.2 Trap Description.
The lobster traps used in this study were of two designs. The majority of the traps were rectangular, wooden framed, and lined with I inch (2.5 cm) plastic coated wire mesh (Figure 2.21). The traps were 34 inches (86 cm ) long,20 inches (51 cm) wide, and iI inches (28 cm ) high. The entrance funnels were constructed of I inch (2.5 cm) plastic coated wire mesh, while the single parlor funnel was fabricated of 2.5 inch (6.4 cm) mesh twine. Two to six bricks were secured in each trap for ballast.
A fewer number of rectangular traps, constructed entirely of 1 inch (2.5 cm) hardware cloth, were also fished. These traps were 36 inches (91 cm) long,19 inches (48 cm) wide, and iI inches (28 cm) high. The entrance and parlor funnels were constructed of 1.5 inch (3.8 cm) and 2 inch (5 cm) stretch mesh twine, respectively.
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2.3 Sampling Methods 2.3.1 General Trapping Survey Methods All traps were fished as singles in rocky areas at depths generally ranging from 20 to 35 feet (6.1 to 10.7 meters). Traps were usually baited with six to eight winter flounder racks, although bluefish and hake racks were xasionally used.
Approximately twice a week, the daily catch of the participating lobsterman was recorded. The station, sample number (the sequential number of samples collected to date), replicate number (all pots within a sampling area were considered replicates), and the duration of the set were recorded prior to hauling each trap. Set-over days for traps hauled varied from approximately 2 to 7 days.
For each lobster caught, the carapace length to the nearest millimeter (measured parallel to the midline from the eyesocket to the distal edge of the carapace) (Figure 2.3-1), sex, tag number, reproductive state of females (i.e., berried or non-bcmed and the color of tne eggs), evidence of molting, ciaw wmplement, and other general comments (e.g., presence of oth<r species in the trap, lobster anatomical abnormalities such as broken claws, missing anpendages, etc.) were recorded on cassette tape.
Data collected on cassette tape in the field were transcribed onto data coding forms in the laboratory.
2.3.2 Tagging Study Methods To determine whether repetitive catches of the same lobsters were occurring, all berried female and sublegallobsters caught be;; inning 18 June 1978 were tagged prior to release by placing a 0.5 in (1.3 cm) rubber band (Figure 2.3-2) on the right cheliped (Figt.res 13-3 and 2.3-4) similar to the technique of Pecci et al. (1978). Additionally,nyfing data would be usd to estimate movement, and population size of sublegallobsters. Rubber bandk rece positioned pr%:m'ay ta the dactyl portion c,f the cheliped so as not to interfere with normal claw furstiot.<. Fr.; n 1j Ac to 29 June 1978, uncoded bands were used. In order to evaluate alongshore movement'ef nhigts, !cs rs ve.re tagged witn coded bands from 29 June 1978 through termination of the study. Bars wgre mded with up to four alpha-numeric characters using waterproof ink. Tag codes assigned to inndu d Msters as well as carapace length, sex, area released, and any other pertinent observations vere recorM on cassette tape in the field and subsequently transcribed onto data forms in the laboratory. Tagged 1.aosters were celeased in the same area that they were captured. Alllobsters recaptured with tags were haradled as described above. All sublegal or berried female lobsters recaptured with tags were released after processing. Points of release and recapture were designated only in the alongshore direction by sta. tic,n regions. It was not practical during this s:edy to designate position in the onshore-offshore direction.
Since it was not initially planned to conduct a tagging study, no announcements to the general public cm the nature of th'e pro' gram or rewards for recaptures made by others were offered. Thus, no information on recaptures made by other lobstermen who may have fished the study area is available.
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s 2.4 Population Estimates The practice of marking or tagging fish or other aquatic organisms to estimate population size began in the late 1800's. Among the methods generally employed are the:
o Peterson method, e Schnabel method, and e Schumacher-Eschmeyer method.
The Peterson method is generally a single census procedure. The individuals are marked only once; subsequently a single sample is taken and examined for marked individuals. Mathematically, the Peterson method for estimating the population is expressed as:
9 = An C
Eq. I A
where N = estimate of the population A = number ofindividuals caught during the sampling period B = number of fish marked and returned prior to sampling period C = number of marked individuals recaptured during the sampling period.
The Schnabel and Schumacher-Eschmeyer methods are multiple census methods. Individuals are marked and added to the population over a considerable period, during which time samples are taken and examined for recaptures or marked individuals. These methods assume zero mortality and recruitment (Jones 1976). The Schnabel method for estimatmg population is expressed as:
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IAB N=
Eq.2 C
The Schumacher-Eschmeyer method is expressed as:
^
IB2A N = IIBC')
Eq.3 Further information on the general principles of population estimation by marking methods is given in Ricker ( 1975 ).
All three of the above methods were used to estimate population size of pre-recruit lobsters (69-78 mm) in the vicinity of the lobster traps. A computer program developed by McCann and Cruse (1969) was used to perform the calculations. This program also calculated the variance and error of the Schumacher-Eschmeyer method according to the formulae:
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l\\ I C2 IBC Variance = (-
IJ-Eq.4 Error =
k( N )3(Variance)
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~BC 2284 089 where K = number of sampling periods N =, Schumacher-Eschmeyer population estimate 9
The Petersen method can also be apphed to multiple census techniques simply by using the results for each day (or other short interval) for a Petersen estimate. (With this approach the minimum number of recaptures should preferable be 3 or 4) ( Ricker 1975 ). The mean of these Petersen estimates is then taken as the estimate of population size.
3.0 RESULTS AND DISCUSSION A sunimary of the data collected during this study is given in Table 3.0-1.
3.1 Catch Per Unit Effort A summary of the lobster catch by date from the Charlestown-hfatunuck region of Block Island Sound is presented in Table 3.0-1. During the 28 hiay-31 August 1978 study period,1,055 pot hauls were made; this resulted in a total catch of 2,974 lobsters. Of this catch,753 were legal and 2,214 were sublegal (7 lobsters could not be categorized as legal or sublegal because no length measurements were available) resulting in an overall legal to sublegal ratio of 1:2.9 (legal lobsters were considered to be >_79 mm carapace length). Expressed as percentages, 25.6% of the lobsters were legal and 74.4% were sublegal. Overall catch per pot haul averaged 2.8 lobsters (of which 0.7 were legal) and ranged from 2.0 (15 August 1978) to 3.4 (l1 July 1978) (Table 3.0-1). Russell et al. (1978) reported similar percentages of legal catch (21.1-44.4%) and legal catch per pot haul (0.62-0.76) for their lobster study in Narragansett Bay-Rhode Island Sound. Average legal catch per pot haul off Pilgrim Station in Plymouth, hiassachusetts for the period 1970-1976 ranged from 0.51-0.83 (Lawton et al.1978). Off Hampton Beach, New Hampshire, the average legal lobster catch per pot during 1972-1977 ranged from 0.50-0.66 (Normandeau Associates, Inc.1978).
Catch data per pot per setover day by sample date and location for all lobsters, legal males, sublegal males, legal unberried females, legal berried females, sublegal berried females, sublegal unberried females, and legal male and unberried females is given in Tables 3.1-1 through 3.1-8, respectively. hican legal catch rates per pot per setover day (males and unberried females combined) ranged from 0.13 (Station 6E) to 0.23 (Station 2W) (Table 3.1-8); rates similar to the lower rates for Narragansett Bay and Rhode Island Sound as reported by Russell et al. ( 4978).
To determine if statistical differences existed between mean catch rates (catch / pot /setover day) of the different areas for the lobster categories stated above, one-way analyses of variance ( ANOVA) were conducted (Tables 3.1-9 through 3.1-14); ( ANOVA for sublegal berried females was not conducted due to the paucity of data in this category). With the exception of sublegal unberried females, mean catch rates by area for all other lobster categories were not significantly different at the oc=0.05 levc'.
Differences between the mean catch rates by area for sublegal unberried females were distinguished by Duncans Afultiple Range Test (Table 3.1-14). This analysis demonstrated that catch rates of sublegal unberried female lobsters for Stations SE, NS,4E,2W,2E and IW were similar and significantly lower than catch rates for Stations IE, OR, and 3E. We have no obvious explanation for this segregation of catch rates by area.
2284 090 10
TABl.E 3.0-I. Summary of 1978 lobster por survey results.
Frequency (%)
Number of Legal:
Sex Date Number of Total Numberof Numbesof Berned Numberof Numberof Sublegal Rauo Berned Carth/
(1978)
Pop Catch Males
- Females Females Legals h Sublegal Rauo (M F)
Males Females Females Pot 5/28 42 112 44 68 3
23 89 1:3.9 1:1.55 39 61 4.4 2.7 5/30 41 93 36 57 10 26 67 1:2.6 1:1.58 39 61 17.5 2.3 6/2 47 132 60 72 8
42 90 1:2.1 1:1.20 45 55 11.1 2.8 6/5 52 164 71 94 12 47 117 1:2.5 I:1.34 43 57 12.8 3.2 6/11 55 154 58 95 10 36 118 1:3.3 1:1.64 38 62 10.5 2.8 6/18 64 190 68 122 11 36 154 1:4.3 1:1.79 36 64 9.0 3.0 6/22 15 48 16 32 4
2 46 1:23.0 1:2.0 33 67 0
3.2 6/24 19 58 19 39 3
12 46 1:3.8 1:2.05 33 67 7.7 3.0 6/27 36 104 38 66 1
14 90 1:6.4 1:1.74 37 63 1.5 2.9 6/29 24 77 23 54 1
15 62 1:4.1 1:2.35 30 70 1.9 3.2 7/2 40 1II 35 75 1
30 81 1:2.7 1:2.I4 32 68 1.3 2.8 7/6 49 137 59 78 0
32 104 1:3.2 1:1.32 43 57 0
2.8 7/11 59 198 91 107 0
65 133 1:2.1 1:1.18 46 54 0
3.4 7/15 56 180 76 104 0
56 124 1:2.2 1:1.37 42 58 0
3.2 7/18 56 183 76 107 0
58 124 1:2.1 1:1.41 42 58 0
3.2 7/21 22 53 26 26 0
25 28 1:1.1 1:1 49 51 0
2.4 7/28 61 202 92 110 3
65 137 1:2.1 1:1.20 46 54 2.7 3.3 7/31 65 188 82 106 1
37 149 1:4.0 1:1.29 44 56 0.9 2.9 8/5
$9 136 61 75 6
40 96 1:2.4 1:1.23 45 55 8.0 2.3 8/10 56 123 45 78 4
24 98 1:4.1 1:1.73 37 63 5.1 2.2 8/15 46 94 43 51 5
23 70 1:3.0 1:1.19 46 54 9.8 2.0 8/19 51 143 70 73 4
31 112 1:3.6 1:1.04 49 51 5.5 2.8 8/31 40 94 39 55 7
14 79 1:5.6 1:1.41 42 58 12.7 2.3 Totals 1055 2974 1228 1744 90 753 2214 1:2.9 1:1.42 41 59 5.2 2.8
' Two lobsters caught were not sexed
- Seven lobsters were not measured and therefore could not be categorized as legal or sublegal 2284 091 L
e 11
TAaLE 3.l-l. Catch per unit of efort (no./potIsetover day)'of alllobsters by sample date and location.
Stauons Date 3W 2W IW IE 2E 3E 4E SE 6E NS OR 5/28/78 1.36
.75
.79 1.20 5/30/78
.92
.86 1.34 1.15 1.12
.92 6/02/78 1.00 1.00 1.07
.85
.78
.94 6/05/78 1.69 1.25
.76 1.13 1.07 1.00
.90 6/1I/78
.41
.49
.51
.69
.65
.34
.42 6/18/78
.97 1 33 1.00
.67
.92
.98 6/22/78
.71
.90
.81 6/24/78
.50
.50
.65 6/27/78
.60
.91
.92 6/29/78
.80
.87
.70
.56 7/02/78
.58
.53 1.01
.40 7/06/78
.81
.54
.75
.14
.66
.48
.31
.63 7/11/78
.62
.71
.88
.60
.87
.40
.62
.73 7/15/78
.96
.75 1.00
.85
.64
.52 7/18/78 1.06
.93 1.58
.69 1.21 1.38
.75
.78 7/21/78 1.00 1.00
.86
.67
.33 7/28/78 1.02
.60
.76
.63 1.46
.60
.69
.61 7/31/78 1.13
.89 1.05 1.13 1.22
.60
.33
.72 8/05/78
.29
.40
.59
.30
.53
.48
.40
.47 8/10/78
.25
.45
.44
.43
.64
.54
.40
.33 8/15/78
.20
.50
.30
.41
.40
.53
.40 8/19/78
.81
.56
.35
.87
.25 1.44
.44
.25
.63 8/31/78
.75 0.00
.42
.88
.70
.63
.83 Mean
.51
.76
.72
.82
.72
.91
.68
.61
.63
.57
.67 Std. Dev.
.43
.37
.36
.27
.34
.29
.30
.27
.20
.17
}hh
? -.
12
TraLE 3.1-2.
Catch per unit of efort (no./ pot /setover day) by sample date and location of male lobsters
(> 79 mm).
Statens Date 3W 2W lW IE 2E 3E 4E SE 6E NS OR 5/28/78
.07
.10
.07
.07 5/30/78
.12
.05 0.00 0.00
.13
.12 6/02/78
.22
.I1
.27
.08
.22
.06 6/05/78
.31
.06
.13
.24 0.00 0.00
.06 6/II/78
.02
.02
.I1 0.00 0.00 0.00 0.00 6/18/78
.04 0.00
.06 0.00 0.00
.02 6/22/78 0.00 0.00 0.00 6/24/78 0.00
.10
.04 6/27/78
.03
.06 0.00 6/29/78 0.00 0.00 0.00
.03 7/02/78
.04 0 00
.03
.07 7/06/78
.16
.04
.07
.14
.03
.10
.01 0.00 7/11/78
.11
.07
.12 0.00
.07
.08
.12 0.00 7/15/78
.15
.11
.17
.05
.18
.05 7/18/78
.13 0.00
.17 0.00
.08
.48
.13 0.00 7/21/78
.33
.33
.14
.17
.11 7/28/78
.10
.05
.12
.13
.21
.15
.06
.14 7/31/78
.10 0.00
.08
.04
.11 0.00
.08
.11 8/05/78
.02
.04
.07 0.00
.10 0.00 0.00
.03 8/10/78
.03 0.00
.04
.03
.04
.03 0.00 0.00 8/15/78
.13
.10
.10
.05 0.00
.07
.10 8/19/78
.06 0.00
.15
.05 0.00
.06
.03
.13 0.00 8/31/78
.08 0.00 0.00 0.00
.07
.04
.08 Mean
.10
.09
.06
.08
.07
.06
.10
.06 0.00
.07
.01 Std. Dev.
.05
.08
.06
.08
.Ii
.06
.12
.05
.05
.03 2284 093 13
TABLE 3.1-3. Catch per unit of efort (no./ pot /setover day) by sample date and location of male lobsters ( < 79 mm).
Stauons Date 3W 2W_
IW IE 2E 3E 4E SE 6E NS OR 5/28/78
.43
.29
.21
.36 5/30/78
.46
.28
.31
.51
.13
.29 6/02/78
.11
.33
.20
.31
.33
.39 6/05/78
.56
.48
.18
.30
.22
.36
.48 6/11/78
.18
.11
.11
.26
.24 0.00
.15 6/18/78
.32
.33
.30
.22
.50
.31 6/22/78
.33
.15
.31 6/24/78 0.00
.10
.18 6/27/78
.19
.31
.25 6/29/73
.10
.33
.15
.16 7/02/78
.18
.09
.32 0.00 7/06/78
.25
.21
.29 0.00
.23
.19
.11
.06 7/11/78
.21
.38
.16
.26
.23
.12
.16
.20 7/15/78
.28
.21
.25
.20
.11
.18 7/18/78
.29
.37
.75
.24
.27
.24
.21
.11 7/21/78
.27
.33
.14
.17 0.00 7/28/78 44
.25
.21
.13
.38
.10
.13
.21 7/31/78
.43
.50
.35
.46
.22
.13 0.00
.44 8/05/78
.11
.16
.21
.10
.10
.20
.07
.23 8/10/78
.10
.15
.10
.07
.28
.17
.08
.27 8/15/78
.07
.10 0.00
.13
.20
.27
.07 8/19/78
.44
.25
.05
.39 0.00
.56
.19 0.00
.13 8/31/78
.17 0.00
.19
.25
.25
.21
.25 Mean
.25
.25
.25
.24
.21
.28
.18
.13
.13
.21
.14 Std. Dev.
.26
.13
.16
.15
.12
.13
.10
.16
.11
.12 2284 094 14
TAntE 3.1-4. Catch per unit of efort (no./ pot /setover day) ly sample date andlocation of unberriedfemale lobsters
(> 79 mm).
Stauons Date 3W 2W IW IE 2E 3E 4E SE 6E NS OR 5/28/78 0.00
.07
.14
.20 5/30/78
.12
.14
.26
.14
.07
.23 6/02/78
.33
.19
.27
.10 0.00
.03 6/05/78
.36
.18
.04
.12
.13
.14
.18 6/11/78
.06
.08
.06
.04
.17 0.00
.10 6/18/78
.16
.13
.06
.22
.08
.13 6/22/78 0.00
.10 0.00 6/24/78 0.00 0.00
.06 6/27/78
.08
.03
.04 6/29/78
.10
.13
.10
.II 7/02/78
.14
.07
.10
.20 7/06/78
.22
.13
.07 0.00
.09
.10
.06
.13 7/11/78
.12
.18
.20
.09
.20
.16
.10
.13 7/15/78
.18
.14
.21
.15
.18
.07 7/18/78
.27
.10
.25
.24
.30
.24
.17
.33 7/2I/78
.27
.33
.05
.17
.11 7/28/78
.12
.10
.19
.06
.21
.10
.31
.07 7/31/78
.17
.06
.20
.17
.17
.07
.25
.11 8/05/78
.09 0.00
.12
.05
.17
.08
.13 0.00 8/10/78
.03 0.00
.10
.07
.16
.03
.12 0.00 8/15/78 0.00
.10 0.00
.03 0.00 0.00
.03 8/19/78
.19
.06
.10
.14 0.00
.25
.08 0.00
.13 8/31/78
.08 0.00
.06 0.00
.07
.08 0.00 Mean
.09
.14
.09
.12
.12
.14
.10
.14
.13
.08
.16 Std. Dev.
.13
.09
.08
.07
.11
.07
.07
.11
.05
.12 2284 095 15
TAaLE 3.1-5. Catch per unit of efort (no./ pot /setover day) by sample date and location of berriedfemale lobsters
(> 79 mm).
Stat.ons Date 3W 2W-IW IE 2E 3E 4E SE 6E NS OR 5/28/78 0.00 0.00 0.00
.07 5/30/78
.12
.09 0.00
.09
.13
.06 6/02/78 0.00
.04 0.00
.03 0.00
.09 6/05/78 0.00
.03
.09
.06 0.00
.21 0.00 6/II/78
.03
.0I
.06
.09 0.00 0.00
.05 6/18/78
.01
.07
.06 0.00
.04 0.00 6/22/78 0.00 0.00 6/24/78 0.00 0.00
.04 6/27/78 0.00 0.00 0.00 6/29/78 0.00 0.00 0.00
.01 0.00 7/02/78
.01
.02 0.00 7/06/78 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 7/11/78 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 7/I5/78 0.00 0.00 0.00 0.00 0.00 0.00 7/I8/78 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 7/21/78 0.00 0.00
.05 0.00 0.00 7/28/78 0.00 0.00
.01
.06 0.00 0.00
.06 0.00 7/31/78 0.00 0.00
.02 0.00 0.00 0.00 0.00 0.00 8/05/78 0.00 0.00
.01 0.00 0.00
.12 0.00
.03 8/10/78 0.00 0.00
.01 0.00 0.00 0.00
.04 0.00 8/15/78 0.00
.03
.05
.02 0.00 0.00 0.00 8/19/78 0.00
.06
.05 0.00 0.00 0.00 0.00 0.00 0.00 8/31/78
.08 0.00
.02 0.00
.02
.04
.08 Mean 0.00
.01
.02
.02
.02
.0I
.03
.04 0.00
.01 0.00 Std. Dev.
0.00
.02
.03
.03
.04
.02
.06
.04
.02 0.00 2284 096 16
TABLE 3.l-6. Catch per Unit of e[ Ort (no./ pot /setoyer day) by sample dGle and lOCation &lberriedfem0le (Obsters
(< 79 mm).
Stanons Date 3W 2W IW IE 2E 3E 4E SE 6E NS OR 5/28/78 0.00
.03 0.00 0.00 5/30/78 0.00 0.00 0.00
.05
.07 0.00 6/02/78 0.00 0.00
.07
.03 0.00
.03 6/05/78 0.00
.03
.04
.06
.04
.07 0.00 6/I1/78 0.00 0.00
.06 0.00
.03 0 00 0.00 6/18/78
.0 I
.07
.03 0.00 0.00
.02 6/22/78 0.00 0.00 0.00 6/24/78 0.00 0.00 0.00 6/27/78 0.00
.03 0.00 6/29/78 0.00 0.00 0.00 0.00 7/02/78 0.00 0.00 0.00 0.00 7/06/78 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 7/1I/78 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 7/15/78 0.00 0.00 0.00 0.00 0.00 0.00 7/18/78 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 7/21/78 0.00 0.00 0.00 0.00 0.00 7/28/78 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 7/31/78 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 8/05/78 0.00 0.00
.01 0.00 0.00 0.00 0.00 0.00 8/I0/78 0.00 0.00
.02 0.00 0.00 0.00 0.00 0.00 8/I5/78 0.00 0.00 0.00
.01 0.00 0.00 0.00 8/19/78 0.00 0.00 0.00
.03 0.00 0.00 0.00 0.00 0.00 8/31/78 0.00 0.00 0.00
.I3
.02 0.00 0.00 Mean 0.00
.00
.0 I
.0 I
.0 I
.01
.0 I
.00 0.00
.00 0.00 Std. Dev.
.00
.00
.02
.02
.04
.02
.02
.01
.00
.01
.00 2284 097 17
TABLE 3.1-7. Catch per unit of efort (no./ pot /setover day) by sample date and location of unberriedfemale lobsters
(< 79 mm).
Stations Date 3W 2W IW IE 2E 3E 4E SE 6E NS OR 5/28/78
.86
.26
.36
.52 5/30/78
.12
.31
.77
.37
.59
.23 6/02/78
.33
.33
.27
.31
.22
.33 6/05/78
.46
.48
.27
.36
.67
.21
.18 6/11/78
.13
.26
.11
.30
.21
.34
.12 6/18/78
.42
.73
.48
.11
.33
.46 6/22/78
.38
.65
.50 6/24/78
.50
.20
.34 6/27/78
.30
.47
.63 6/29/78
.60
.40
.45
.25 7/02/78
.20
.35
.57
.13 7/06/78
.19
.17
.32 0.00
.31
.10
.13
.44 7/1I/78
.I9
.09
.40
.26
.37
.04
.24
.40 7/15/78
.36
.29
.38
.45
.18
.23 7/18/78
.38
.47
.42
.21
.56
.43
.25
'3 7/21/78
.13 0.00
.48
.17
.11 7/28/78
.37
'.20
.24
.25
.67
.25
.13
.18 7/3I/78
.43
.33
.40
.46
.72
.40 0.00
.06 8/05/78
.07
.20
.!7 15
.17
.08
.20
.17 8/10/78
.10
.30
.17
.27
.16
.31
.16
.07 8/15/78 0.00
.18
.15
.17
.20
.20
.20 8/19/78
.13
.19 0.00
.25
.25
.56
.14
.13
.38 8/31/78
.33 0.00
.15
.50
.27
.25
.42 Mean
.06
.27
.31
.34
.28
.40
.26
.19
.38
.21
.36 Std. Dev.
.09
.13
.22
.17
.18
.18
.15
.12
.11
.14 2284 098 18
TABLE 3.l-8. Catch per unit of efort (no./ pot /setover day) by sample date and location of male and unberried female lobsters (> 79 mm).
Stanons Date 3W 2W IW IE 2E 3E 4E SE 6E NS OR 5/28/78
.97
.17
.21
.27 5/30/78
.24
.19
.26
.14
.20
.35 6/02/78
.55
.30
.54
.18
.22
.09 6/05/78
.67
.24
.17
.36
.13
.14
.24 6/11/78
.08
.10
.17
.04
.17 0.00
.10 6/18/78
.20
.13
.12
.22
.08
.15 6/22/78 0.00
.10 0.00 6/24/78 0.00
.10
.10 6/27/78
.II
.09
.04 6/29/78
.10
.13
.10
.14 7/02/78
.18
.07
.13
.27 7/06/78
.38
.17
.14
.14
.12
.20
.07
.13 7/11/78
.23
.25
.32
.09
.27
.24
.22
.13 7/15/78
.33
.25
.38
.20
.36
.12 7/18/78
.40
.10
.42
.24
.38
.72
.30
.33 7/21/78
.60
.66
.19
.34
.22 7/28/78
.22
.15
.31
.19
.42
.25
.37
.21 7/31/78
.27
.06
.28
.21
.28
.07
.33
.22 8/05/78
.11
.04
.19
.05
.27
.08
.13
.03 8/10/78
.06 0.00
.14
.10
.20
.06
.12 0.00 8/15/78
.13
.20
.10
.08 0.00
.07
.13 8/19/78
.25
.06
.25
.19 0.00
.31
.11
.13
.13 8/31/78
.16 0.00
.06 0.00
.14
.12
.08 Mean
.19
.23
.14
.20 0.19 0.20 0.20 0.19
.13
.15
.I 7 Std. Dev.
.08
.16
.13
.14 0.18 0.10 0.16 0.12
.09
.13 2284 099 19
TABLE 3.l-9. Anahsis of variance between stations on the average catch per unit of efort of alllobsters, 1978 lobster pot survey.
Source D.F.
SS MS F
P Total 139 13.415 Between 8
1.260 0.157 1.697 0.105 Within 131 12.155 0.093 TABLE 3.l-lo. Anabsis of variance among stations on the average catch per unit of efort of male lobsters (279 mm),1978 lobsterpot survey.
Source D F.
SS MS F
P Total 139 0.867 Between 131 0.052 0.006 1.038 0.411 Within 8
0.816 0.006 TABLE 3.1-11. Analysis of variance among stations on the average catch per unit of efort of male lobsters
(< 79 mm),1978 lobsterpor survey.
Source D F.
SS MS F
P Total 139 2.524 Between 8
0.192 0.024 1.350 0.225 Within 131 2.332 0.018 TABLE 3.l-12. Analysis of variance among stations on the average catch per unit of efort of unberried female lobsters (2 79 mm),1978 lobsterpor survey.
Source D F.
SS MS F
P Total 139 0.999 Between 8
0.071 0.009 1.246 0.278 Within 131 0.928 0.007 TABLE 3.1-l3. Analysis of variance among stations on the average catch per unit of berriedfemale lobsters
(>_79 mm),1978 lobster pot survey.
Source D F.
SS MS F
P Total 138 0.168 Between 8
0.011 0.001 1.144 0.338 Within 130 0.156 0.001
~
2284 100 20
TAnu 3.1-l4. kalysis of variance among stations and Duncans Multiple Range Test on the average catch per unit of efort (CPUE) of unberriedfemale lobsters ( < 79 mm),1978 lobster pot survey.
Source D F.
SS MS F
P Total 139 4.120 Between 8
0.524 0.066 2.387 0.020 Within 131 3.596 0.027 Station SE NS 4E 2W 2E IW IE OR 3E
~Mean CPUE
.19
.21
.26
.27
.28
.31
.34.36.40 3.2 Sex Ratio Dunng the study period,1,228 males and 1,744 females were caught for an overall sex ratio (hi:F) of 1:1.42 (Table 3.0-1); a sex ratio significantly different from 1:1 (X2 = 89.42 > X2m = 3.84). Expressed as frequencies,41% of the total catch were males and 59% were females. Changes in the sex ratio and frequencies of males and females by date are depicted in Table 3.0-1.
With respect to date; sex ratios varied from 1:1 (21 July 1978) to I:2.35 (29 June 1978). The frequency of males ranged from 30% (29 June 1978 ) to 49% (21 July and 19 August 1978) (Table 3.0-1).
Changes in the sex ratio by 5-mm size classes are shown in Table 3.2-I. Ratios varied from 1:1 for the 105-110 mm size class to I:3.50 for the 100-105 mm size class. No apparent trend in sex ratio with size class was observed. In contrast, data presented by Russell and Borden (1975) for inshore Rhode Island waters indicated an apparent decline in the frequency of female lobsters wi@ increasing s2ze.
The observed sex composition of the lobster population in our study was similar to that reported by Smith (1977) for Long Island Sound, and Skud and Perkins (1969) for offshore waters of the North Atlantic. Other investigators, howes er, have reported lobster sex ratios that approach 1:1. Krouse (1973) found that in 1969 and 1970 female lobsters collected in the coastal waters near Boothbay Harbor, hiaine comprised 48.1% and 50.3% of his total catch. In 1968, he found that the proportion of females was 56.4%;
an increase he attributed to a small sample size. Cooper et al. (1975) found that in September 1967 and February 1968, males and females each comprised approximately 50% of the population of two inshore (i.e., less than 24 meters depth) lobster fishing regions in hiaine. In deeper waters (30-60 meters),
however, they reported preliminary findings of a predominance of females. Russell and Borden (1975)
- eported that the overall sex ratio oflobsters caught from the inshore waters of Rhode Island in April 1975 was 1:1.253 (ht:F). In their Piscataqua River, New Hampshire ecological studies, Normandeau Associates (1978) found males to predominate. Sex ratios (ht:F) for their area during 1971-1977 varied from 1.22:1 to 1.92:1.
Significant deviations from a 1:1 sex ratio could be attributed to sampling bias, differential gear vulnerability between sexes, differential molting and growth rates, regulations protecting females during part of their life cycle, or actual differences in sexual composition of the population (e.g., may be survival advantage for increased numbers of females for intensely fished populations that remove substantial numbers ofindividuals before they have an opportunity to reproduce). Skud (1969) has discussed the effect of fishing on size composition and sex ratio of offshore lobster stocks.
2' 2284 101
O TABLE 3.2-1. Number of male andfemale lobsters and sex ratios by 5 mm si:e classes,1978 lobster por survey.
Number Number Sue Class or of
' Sex Rado (mm)
Males Females (M F) 50-55 8
9 1:1.13 55-60 27 54 1:2.0 60-65 90 134 1:1.49 65-70 271 295 I:1.08 70-75 321 376 1:1. I 7 75-80 255 384 1:1.51 80-85 129 245 1:1.90 85-90 67 170 1:2.54 90-95 37 48 1:1.30 95-100 9
10 1:1.11 100-105 2
7 1:3.50 105-110 2
2 1.1 110-115 0
2 l15-120 0
1 22g4 102 22 l~'
3.3 Maturity Sexual maturity of female lobsters was determined by the external presence of eggs similar to Russell and Borden (1975), Russell et al. (1978) and others. Of a total catch of 1744 female lobsters, only 90 or 5.2% were egg bearing. Similar low percentages of egg bearing females were reported by Normandeau Associates, Inc. (1978) for lobsters from the Piscataqua River and off flampton Beach, by Russell and Borden ( 1975) for Rhode Island Sound, by Pecci et al. ( 1978) for the Weepecket Islands (5 miles west of Woods llole, Mass.) and by Lawton et al. (1978) from Cape Cod Bay in the vicinity of Plymouth, Massachusetts. From data of Smith (1977) on the Long Island Sound lobster fishery, we determined that 17% of the total catch of females during his lobster pot survey were egg bearing. For the size range 79 mm
( minimum legal size) to 90 mm (a size rarely exceeded in the inahore fishery),10.4% of the females caught in the vicinity of the proposed NEP I&2 were egg bearing.
As seen in Table 3.0-1, the frequency of berried females varied from 0-17.5%. liighest frequencies occurred during early June and in August. Between these time periods, few,if any, egg bearing females were captured. In their study of the inshore Rhode Island lobster fishery, Russell et al. (1978) reported peak percentages of egg-bearing females in June end October.
The average size of egg bearing females was 83.1 mm (s.d = 7.5 mm) with a size range of 65-11I mm.
The length-frequency distribution of egg bearing females caught during this study is shown in Figure 3.3-1 and Table 3.3-1. Results from the study of the inshore lobster fishery in Rhode Island by Russell and Borden (1975) and Russell et al. (1978) agree with those from our study. These investigators found that the smallest berried female in Rhode Island Sound was 70 mm and that the average size was 85.3 mm.
The mean size of egg bearing females in Long Island Sound has been reported as 79.8-86.2 mm (Smith 1977) and 83.7-86.1 mm ( Lund 1970). Thus, based on the above information,it appears that the onset of sexual maturing for female lobsters in the vicinity of the proposed NEP I&2 site occurs around 70 mm.
The above reports on minimum and average size of female lobsters at maturity from Southern New England waters differ from that reported in Maine by Thomas (1973) and Krouse (1972), and for the offshore waters of the North Atlantic by Skud and Perkins (1969). These authors found that lobsters from their study areas seldom matured until they were between 90-100 mm. Aiken and Waddy (1976) as cited in Lawton et al. (1978) have indicated that there is extensive variability in the size at which female lobsters mature depending on geographical area. Areas where some lobsters are berried at a relatively small size, <70 mm, are characterized by relatively high summer temperatures of approximately 20 C (State-Federal Lobster Scientific Committee Workshop,1975). Conversely in oceanic waters, e.g., in '
areas of the northern Gulf of Maine and the slopes and canyons of the continental shelf, with relatively low summer temperatures (11 C), lobsters mature at a relatively larger size ( > 85 mm). Intermediate areas may show varying characteristics of both extremes (State-Federal Lobster Scientific Committee Work-shop,1975).
Cumulative length-frequency distribution of egg bearing female lobsters from this study revealed that 31.5% were $79 mm (Table 3.3-1). From Rhode Island Sound,21.6% of egg bearing females were < 79 mm (Russell and Borden 1975). Smith (1977) reported percentages ranging from 25.5-63.5% sublegal berried females throughout Long Island Sound.
2284 103 23
TAnu 3.3-1. Length. frequency and cumulative frequency distributions of lobsters caught from the Charlestown.
Matunuck region of Block Island Sound, 28 May-31 August 1978.
Frequency (% )
C umulauve Frequency (%)
Carapace Males Non-Males Non-J ength and All berned Berned and All berned Bemed
-( m m )
Females Males Females Females Females Females Males Females Females Females 21
<.1
<.1 0
0
<.1
<.1 0
0 0
22
<.1
<.1 0
0
<.1
<.1 0
0 0
23
<.1
<.1 0
0
<.1
<.1 0
0 0
24
<.1
<.1 0
0
<.1
<.1 0
0 0
25
<.1
<.1 0
0
<.1
<.1 0
0 0
26
<.1
<.1 0
0
<.1
<.1 0
0 0
27
<.1
<.1 0
0
<.1
<.1 0
0 0
28
<.1
<.1 0
0
<.1
<.1 0
0 0
29
<.1
<.1 0
0
<.1
<.1 0
0 0
30
<.1
<.1 0
0
<.1
<.1 0
0 0
31
<.1
<.1 0
0
<.1
<.1 0
0 0
32
<.1
<.1 0
0
<.1
<.1 0
0 0
33
<.1
<.1 0
0
<.1
<.1 0
0 0
34
<.1
<.1 0
0
<.1
<.1 0
0 0
35
<.1
<.I 0
0
<.1
<.1 0
0 0
36
<.1
<.1 0
0
<.1
<.1 0
0 0
37
<.1
<.1 0
0
<.1
<.1 0
0 0
38
<.1
<.1 0
0
<.1
<.1 0
0 0
39
<.1 0
0.1 0.1 0.1
.I 0.1 0.1 0
40
<.1
<.1 0
0 0.1 0.2 0.1 0.1 0
41
<.1
<.1 0
0 0.2 0.2 0.1 0.1 0
42
<.1 0
<.1
<.1 0.2 0.2 0.2 0.2 0
43
<.1
<.1 0
0 0.2 0.3 0.2 0.2 0
44
<.1 0
<.1
<.1 0.3 0.3 0.2 0.2 0
45 0
0 0
0 0.3 0.3 0.2 0.2 0
46
<.1
<.1 0
0 0.3 0.4 0.2 0.2 0
47
<.1
<.1 0
0 0.3 0.5 0.2 0.2 0
48 0
0 0
0 0.3 0.5 0.2 0.2 0
49
<.1
<.1 0
0 0.4 0.6 0.2 0.2 0
50
<.1
<.1 0
0 0.4 0.6 0.2 0.2 0
51
<.1 0
<.1
<.1 0.4 0.6 0.3 0.3 0
52 0.1
<.1 0.1 0.1 0.5 0.7 0.4 0.4 0
53 0.1
<.1 0.1 0.1 0.6 0.7 0.5 0.6 0
54 0.3 0.4 0.2 0.2 0.9 1.1 0.8 0.8 0
55 0.3 0.2 0.5 0.5 0
1.2 1.3 1.2 1.3 0
56 0.3 0.2 0.4 0.4 0
1.6 1.6 1.6 1.6 0
57 0.4 0.5 0.4 0.4 0
2.0 2.0 2.0 2.1 0
58 0.9 0.7 1.1 1.2 0
2.9 2.8 3.1 3.2 0
2284 104
TABLE 3.3-1. (Continued)
Frequency (%)
Cumulauve Frequency (%)
Carapace Males Non.
Males Non-length and All bemed Bemed and All bemed Bemed (mm)
Females Males Females Females Females Females Malgs Females Females Females
$9 0.7 0.6 0.8 0.8 0
3.7 3.4 3.9 4.1 0
60 0.8 1.0 0.8 0.8 0
4.5 4.3 4.0 4.9 0
61 1.2 0.9 1.4 1.5 0
5.7 5.2 6.0 6.3 0
62 1.0 0.9 1.2 1.3 0
6.7 6.1 7.2 7.6 0
63 i.9 2.2 1.8 1.9 0
8.7 8.3 9.0 9.5 0
64 2.6 2.5 2.6 2.7 0
11.3 10.7 11.6 12.2 0
65 2.9 3.0 2.9 3.1 1.1 14.3 13.7 14.5 15.2 1.1 66 3.0 4.0 2.4 2.5 0
17.3 17.7 16.9 17.7 1.1 67 3.7 4.2 3.4 3.6 0
21.0 21.9 20.2 21.3 1.1 68 4.8 5.9 4.0 4.2 0
25.8 27.8 24.2 25.2 1.1 69 4.6 5.1 4.3 4.4 1.1 30.4 32.8 28.5 29.9 2.2 70 5.6 6.0 5.3 5.5 1.1 36.0 38.8 33.8 35.5 3.4 71 3.9 4.8 3.4 3.5 1.1 40.0 43.6 37.2 38.9 4.5 72 4.6 4.9 4.4 4.7 1.1 44.6 48.6 41.5 43.5 5.6 73 3.8 5.2 2.8 2.8 0
48.4 53.8 44.3 46.4 5.6 74 5.5 5.2 5.8 5.8 4.5 53.9 59.I 50.0 52.2 10.I 75 5.0 5.2 4.8 4.7 7.9 58.9 64.2 55.0 56.8 17.9 76 4.0 4.2 3.9 3.9 2.2 62.9 68.5 58.7 60.8 20.2 77 5.1 4.8 5.4 5.5 3.4 68.0 73.3 64.1 66.4 23.6 78 4.2 3.9 4.5 4.5 4.5 72.2 77.2 68.6 71.0 28.1 79*
3.1 2.7 3.5 3.5 3.4 75.4 79.9 72.1 74.3 31.5 80 2.5 1.8 3.1 3.0 4.5 77.9 81.7 75.2 77.4 35.9 81 2.8 2.9 2.8 2.7 4.5 80.8 84.5 78.0 80.0 40.4 82 2.4 1.8 2.8 2.8 3.4 83.2 86.4 80.8 82.8 43.8 83 2.3 1.7 2.7 2.0 56 85.5 88.1 83.6 85.4 49.4 84 2.5 2.4 2.6 2.4 5.6 88.0 90.4 86.2 87.9 55.1 85 2.3 1.1 3.2 2.8 10.1 90.4 91.6 89.4 90.6 65.2 86 1.9 1.4 2.4 1.9 11.2 92.3 93.0 91.7 92.5 76.4 87 1.4 1.1 1.8 1.8 2.2 93.8 94.0 93.5 94.3 78.6 88 1.2 1.1 1.3 1.2 2.2 94.9 95 2 94.8 95.5 80.9 89 1.0 0.7 1.2 1.2 2.2 95.9 95.9 95.9 96.6 83.2 90 1.0 1.1 0.8 0.7 2.2 96.9 97.1 96.8 97.4 85.4 91 0.7 0.6 0.8 0.6 4.5 97.6 97.6 97.5 97.9 89.9 92 0.5 0.7 0.4 0.4 1.1 98.1 98.3 97.9 98.3 91.0 93 0.4 0.2 0.5 0.3 3.4 98.4 98.5 98.4 98.6 94.4 94 0.4 0.4 0.4 0.2 3.4 98.9 98.9 98.7 98.8 97.7 95 0.2 0.2 0.2 0.2 0
99.0 99.2 99.0 99.0 96 0.1
<.1 0.1 0.1 0
99.2 99.3 99.1 99.2 97.7 97
<.1 0.2 0
0 0
99.2 99.4 99.I 99.2 97.7 25 2284 105
TAntt 3.3-1. (Continued)
Frcquency ("e )
Cumulauve Frequency (Tr)
^
Carapace Males Non-Males Non-Length and All berned Berned and All bemed Berned (mm)
Females Males Females Females Females Females Males Females Females Females 98 0.2 0.2 0.1 0.1 0
99.4 99.7 99.2 99.3 97.7 99
<.1 0
0.1 0.1 0
99.5 99.7 99.3 99.4 100 0.1
<.1 0.1 0.1 0
99.5 99.8 99.4 99.5 97.7 101
<.1 0
0.1 0.1 0
99.6 99.8 99.5 99.6 97.7 102 0
0 0
0 0
99.6 99.8 99.5 99.6 97.7 103 0.1
<.1 0.2 0.2 0
99.7 99.8 99.7 99.6 97.7 104 0
0 0
0 0
99.7 99.8 99.7 99.6 97.7 105 0
0 0
0 0
99.7 99.8 99.7 99.6 97.7 106
<.1 0.2
<.1
<.1 0
99.8 100.0 99.8 99.8 97.7 107 0
0 0
0 0
99.8 99.8 99.8 97.7 108
<.1
<.1 0
1.1 99.8 99.8 99.8 98.9 109 0
0 0
0 99.8 99.8 99.8 98.9 110 0
0 0
0 99.8 99.8 99.8 98.9 111 0
0.1
<.1 1.1 99.8 99.9 99.9 100.0 112 0
0 0
99.8 99.9 99.9 II3 0
0 99.8 99.9 99.9 114 0
0 99.8 99.9 99.9 115 0
0 99.8 99.9 99.9 116
<.I
<.I 100.0 100.0 100.0
- Minimum legal size 2284 106 26
, (t.;
2 e
w
O= FEMALE LOBSTERS X:UNBERRIED LOBSTERS a: BERRIED LDBSTERS 9
8_.
. MINIMUM LEGAL. SIZE (79MM) u OO f_
NO. OF UNBERRIED = 1654 NO. OF BERRIED = 90 8
E O
E 9
=
a p
x f;
m.
y r-u om E
x n
8 w-
,O A
%.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 eo.co 90.00 100 00 110.00 120.00 g
Nm CARAPACE LENGTH (MM) b FIGURE 3.3-1. Length-frequency distribution of allfemale lobsters. and berried and unberriedfemales
~
CD caught during the 1978 lobsterpor survey.
N
3.4 Length-Frequency A total of 2,974 lobsters were collected during the study period. Of this total,1,228 were males,1,744 were females, and 90 were egg bearing females (the sex of 2 lobsters caught was not designated). The mean length, standard deviation, and minimum and maximum length of these lobster categories are
, presented in Table 3.4-1.
Length-frequency distributions of alllobsters, and males and females is shown in Figure 3.4-1, and for all females, and berried and non-berried females in Figure 3.3-1.
Length-frequency and cumulative frequency distributions for these lobster categories are also given in Table 3.3-1. The stepwise increase in number of lobsters with size to approximately 70-75 mm suggests that this is the size range at which lobsters become fully vulnerable to the gear. Krouse (1973) has indicated that the reduced vulnerability oflobsters smaller than 70 mm in his study might best be attributed to the effects of gear selectively and, possibly, the more seclusive behavior of smalllobsters. Sharp reductions in the number oflobsters 79 mm (minimum legal size) or greater reflects the influence of commercial exploitation. Legal size lobsters (males and females combined) comprised only 24.6% of the total catch (Table 3.31); a frequency similar to that reported for the Piscataqua River lobster survey by Normandeau Associates (1978).
TABLE 3.4-l. Sample statistics on lobster si:e,1978 lobsterpor survey.
Lobster Bemed
$tausuc All Male Female Female Mean length (mm )
74 1 73.4 74.6 83.1 Standard deviation ( mm )
8.7 8.4 8.8 7.5 Maximum length ( mm )
I16 106 116 111 Minimum length ( mm) 21 21 39 65 Number 2,974 1,228' 1,744 90
- sex of 2 lobsters not designated 2284 108 v.
28
D= FEMALE LOBSTERS
- = ALL LOBSTERS A= MALE LOBSTERS 9
E.
MINIMUM LEGAL SIZE (79MM) 8 5-NO. OF FEMALES = 1744 I
e NO. OF MALES = 1228 h
oe E-j
~
z l
C i
9 E-S 4
rg g-i e
m M
P 8
d I
8 d.
I N
m
^
N
- A-
%.00 10.00 20.00 30.00 40 00 50.00 60.00 70.00 80.00 90.00 100.00 110.00 120 00 CRRRPRCE LENGTH (MM)
CD Flount 3.4-l. Length-frequency distribution of alllobsters, and males andfemales caught during the 1978 lobster por survey.
3.5 Total Mortality Rates Total instantaneous mortality rates (Z) for postrecruitment male and female lobsters were estimated from Sngth-frequency data given above in Section 3.4 by two methods. The first method was based on the exponential regression of abundance in numbers on age in years. The slopes from these regressions provides an estimate of total mortality. The second method was described by Robson and Chapman (1961) and uses the relation:
I-S = IN + T-1 Eq.6 where S = survival T = N, + 2N, + 3Na +
IN = No + N, + N, +.
and No. N,, N,.
are indices of abundance of fully vulnerable age classes represented in the catch.
Estimates of the instantaneous mortality are then derived from the negative logarithm of survival, S.
Assumed age-class distributions used to estimate mortality rates were developed from the length-frequency data by applying the following methods:
e Von Bertalanffy growth equation (Ricker 1975) rearranged for t, age in years for fully recruited age classes.
1 8
'F$ h Eq.7 t=
K where t = age in years to = age at first egg extrusion
- 1. = length at age t L. = mean asymptotic length K = Brody growth coefficient The coefficients for the above equation for Rhode Island Sound male and female lobsters were developed by Russell et al. (1978) and are presented in Table 3.5-1.
e Probability mode analysis to determine the size range associated with fully recruited age classes as developed for the inshore Rhode Island lobster fishery by Russell et al. (1978), and e Annual 13.25"e molt increments to establish size ranges associated with fully recruited age classes. (Molt increment from Russell et al. (1978) for the inshore Rhode Island lobster fishery.)
The totalinstantaneous mortality rates estimated for male and female lobsters are presented in Table 3.5-2. No major discrepancies between estimates were found; hence mean Z values for male and female lobsters were calculated to be 1.95 and 1.79, respectively. Converted to percentages, total mortality for males and females would be 67"e and 58"+, respectively. These rates are similar to those reported by Russell et al. (1978) for the inshore Rhode Island lobster fishery.
Based on several methods, Russell et al. ( 1978) estimated overall mean Z-values for male and female lobsters from Narragansett Bay and Rhode Island Sound to be 1.99 and 1.70, respectively. For other areas (Cox Ledge and Mid-shelf), estimated mean mortality rates for males ranged froy.M.60,jadd@or females from 0.56-0.93.
30
Afortality rates for the hiaine lobster She., hve been reported bv Thomas (1973) and Krouse (1977). Thomas (1973) estimated the annu;f m reality rate to range from 29.8% to 94.6% depending on the method and yearly data set used. Krouse ( 1977) reported mortality rates for three areas of h1aine to range from 72.5 %-96.6 %
Tant.E 3.5-1. Von Bertalanp> growth equation coeficientsfor Rhode Island Soundderived by Russell et al.
(1978).
Category I,
K to i
Afa!es I89.552 0.094
-0.290
)
Females 184.589 0.097
-0.198 TAntt 3.5-2. Estimated totalinstantaneous mortahty rates (Z) for post-recruitment lobsters in the inshore Charlestown4fatunuck region of Block Island Sound.
Totalinstantaneous mortality ror age distnhuuons from Probabdity Annual Techmque Category Von Bertalantry mode mois incn ents
- l. Exponential regression males 2.09 2.02 2.17 females ( al!)
1.52 1.73 2.04 unberried females 1.54 1.81
- 2. l 3 berried females 1.05 1.43 1.61
- 2. Robson & Chapman (196I) males 1.74 1.83 1.83 females ( all) 1.80 1.66 2.01 unberried females 1.82 1.71 2.18 herried females 1.39 1.36 1.56 3.6 Mo ement During the period 29 June-31 August 1978, 1,202 sublegal or berried female lobsters were tagged with coded bands and released in the study area. Through 31 August, a total of 140 were recaptured. Of these recaptures,it was possible to determine the date and point of release of 44 individuals. The inabihty to determine the date and point of release of the remaining lobsters was attributed to the method of tagging as explained later in this section. A summary of the individually identifiable recaptures is given in Table 3.6-1.
The majority of tagged lobsters were recaptured within their respective release zone (Table 3.6-1).
Of the 44 traceable tag returns, only 9 were recaptured outside of their release area. Of these 9 lobsters, however, four (tag no. 37, 24,.124,.96) were recaptured in areas immediately adjacent to their release Based on measurements from the center of each station area, the above four lobsters may have zone.
moved alongshore for distances up to approximately 0.7-0.8 nautical miles (nm). These recaptures, however, may not represent movement of any magnitude if the lobsters were captured and released in close proximity to station area boundaries. Furthermore, movements of this magnitude are within the range ofintra-station alongshore distances. The remaining five lobsters (tag no. I1,141,.088,749,920) which were caught outside their release area moved further than the adjacent station (approximately 1.4-2.7 nm alongshore).
2284 111 3i
4 s
There were no appars.n: tread. ;n dpmdweu o c.
.astety or westerly) for these lobsters, nor did the distance it.w/cd aPr<ar related to sex. t Ina n, hh 7 4 ?targe fo: all recaptures averaged approximately 14 days with a range el 3-44 (ays (TatA 3 6-i L TAnts: 3.61. Summary oflob.s:er recaptures duton.D n > Or cawmy.
Change From Alongshore ke(apture Relcaw Datante hme at Tag Date Date Length Length saten Statwn Moved Large Number Released Recaptured (mm)
(mm)
Released Recaptured Sea (nauttm l tdays) 37 2 July 78 11 July 78 68
+2 IE IW
'M 0?
9 94 Il july 78 15 July 78 73 0
11 II M
0 4
171 11 July 78 15J.ly78 76 0
2W 2W F
0 4
28 li July 78 15 July 78 75
+2 2W
'W F
0
.i 24 29 June 78 18 July 78 77
+2 2L lE M
0.7 19
.01 15 July 78 18 July 78 65 0
3E IE M
0 3
318 15 July 78 18 Juiy 78 66 0
NS NS F
0 3
221 15 July 78 18 July 78 72 0
2W 2%
F 0
3 32 15 July 78 18 Ju!) 78 72
-1 2W 2W M
0 3
.124 11 July 78 18 July 78 68 0
2W IW F
08 7
11 291unc78 2 t Jul> 78 71
-1 II 3I F
l.4 22 141 29 June 78 2 July 78 76 0
2L 2W M
2.3 3
141 2 July 78 28 July 78 76 0
2W 2W M
0 26 52 2 July 78 31 Ju!) 78 71 0
It it F
0 29
.088 11 July 78 31 July 78 75
-1 3E 11.
F I4 20 689 28 July 78 31 July 78 77 U
2L 21-F 0
3 775 28 Jely 78 31 July 78 71 0
IW IW M
0 3
.066 2 July 78 31 July 78 68 0
2W 2W F
0 29 902 28 July 78 5 Aug 78 70 0
11 ll F
0 8
.027 ll July 78 5 Aug 78 76 0
t i.
lE M
0 25 1011 31 July 78 5 Aug 78 75 0
2f 2E M
0 5
749 28 July 78 31 July 78 68
+ 1 3L NS M
l4 3
749 31 July 78 10 Aug 78 69 0
NS NS M
0 10 77 6 July 78 10 Aug 78 75 0
41 4I F
0 35 611 28 July 78 10 Aug 78 70 0
3E 3E M
0 13 920 28 July 78 10 Aug 78 72
+ 1 Si if F
2.7 13 94A 5 Aug 78 15 Aug 78 77 0
IE 11 F
0 10
.96 11 July 78 15 Aug 78 68 0
IW 10 F
0.7 35 922 28 July 78 15 Aug 78 78 0
IE lE M
0 18
.63 6 July 78 19 Aug 78 68 0
IE IE M
0 44 984 31 July 78 19 Aug 78 70
+4 IE lE F
0 19 14E 10 Aug 78 19 Aug 78 74
-l IE IL F
0 9
6A 5 Aug 78 19 Aug 78 72
+2 3L 31; M
0 14 23A
$ Aug 78 3! Aug 78 66
+ 1 IE lE M
0 26 44E 19 Aug 78 31 Aug 78 70 0
IE 10 M
0 12 42C 19 Aug 78 31 Aug 78 68 0
IE IE M
0 12 47C 10 Aug 78 31 Aug 78 78 0
3L 30 F
0 21 24F 19 Aug 78 31 Aug 78 67 0
3E 3E F
0 12 70F 19 Aug 78 31 Aug 78 77 0
3E 3E M
0 12 25C 15 Aug 78 31 Aug 78 77
-1 3E 3E F
0 16
.80 31 July 78 5 Aug 78 72 0
4E 4E M
0 5
26 28 July 78 5 Aug 78 74 0
IE IE F
0 8
26 S Aug 78 10 Aug 78 74 0
IE lE F
0 5
13 yg fg7 39 15 July 78 28 July 78 64 0
NS NS e t u U - Unk now n i.
32
e Observations from this study on movement agree with those of other authors. In their lobster tagging studies in the Piscataqua River, New Hampshire, Normandeau Associates Inc. (1978) found that the majority of recaptures were taken from within the study area and generally from the same trap location as originally released. From their data, they concluded that Piscataqua River lobsters are either remarkably stationary in their habit or else those that travel always return to the same "home" area or do not return at all.' Studying the migration of American lobster near Afonhegan Island, Maine, Cooper ( 1970) found that approximately 99% of the 1,755 recaptures during the period January 1966 to June 1968 were caught within the 2-mile fishing limit of Monhegan.
Krouse (1977) also studied lobster n ovement along the Maine Coast and found that from 73.6%-
98.0% (depending on area) were recaptured within a 5-mile radius of the release site and only 1% of the recaptures. moved greater than 10 miles. He also found little association between time lobsters were at large with the extent of movement. Similar observations were reported by Russell and Borden ( 1975) in their study on the inshore lobster fishery in Rhode Island. They found that only 2 out of 88 recaptured lobsters moved a distance greater than 3 nm. Average distances travelled ranged from 0-2.6 nm.
Direction of movement was random but with a tendency for lobsters to move into or remain in rocky areas.
g Lawton et al. (1978) studied the lobster fishery in the vicinity of the Pilgrim Nuclear Power Station, Plymouth, Massachusetts and found that 1,533 (71.2% of those tagged) tagged lobsters were recaptured within their respective release zone. Only 16.2% of tagged lobsters were recaptured at distances greater than 3 miles frem release sites, a finding similar to that of Fair (1977), who also studied the Plymouth lobster fishery. Similar to others, Lawton et al.1978 did not find any apparent relationship between time at large and distance travelled.
Based on their own tagging studies and those of a considerable number of other authors, Cooper et al.
(1975) as cited in Normandeau Associates, Inc. ( 1978) stated that lobster populations shoreward of the 30 m isobath are essentially nonmigratory.
The inability to determine the date and point of release of the remaining 96 lobsters recaptured during our study can be attributed to the method of coding. Tag codes, which consisted of up to 4 alpha-numeric characters, were legible prior to placement on the cheliped. However, after placement on the cheliped, the expansion of the band often resulted in illegible codes, or codes easily subject to misinterpretation (e.g.,
the character,0, could appear as 1 or as a decimal point depending on the degree and direction of band stretching ).
Thus, while the data record would indicate the initial date and release point of a lobster tagged with a specific code, the subsequent record of a recapture of that coded tag did not necessarily imply that the originally tagged lobster was reaptured (e.g., there were many cases oflobsters initially tagged and subsequently recaptured being of different sex). Furthermore, the problem of the chaiacters of the codes fading wn:h time was also encountered.
Since it was not originally the objective to mark lobsters for the purpose of determining movement or making population size estimates (see Section 2.3.2), a method of coding and tagging was selected which would not interrupt normal field data acquisition, but which would provide some information on alongshore movement oflobsters and enhance the overall usefulness of the study. While some information on movement was obtained, the use oitubber bands coded by marking with waterproofink was found to be an unsatisfactory method for tracking the movement ofindividual lobsters. Any future attempts at determining lobster movement should use more conventional tagging methods.
2284 113 33
e 3.7 Population Estimates During the tagging period 18 June-31 August 1978, a total of 1,416 lobsters (either sublegalin size or berried) were tagged and released. Of this total,140 or 9.9% were recovered. A summary of the number of all lobsters caught, marked, and recaptured by date is given in Table 3.7-1.' A similar summary
. for lobsters in the pre-recruitment size range of 69-78 mm is presented in Table 3.7-2 (lobsters in this size range were judged fully vulnerable to the gear).
Population estimates cf lobsters in the pre-recruitment size range of 69-78 mm by date in the Charlestown-Matunuck region of Block Island Sound for the period 29 June-31 August 1978 by the Petersen, Schnabel, and Schumacher and Eschmeyer techniques are presented in Table 3.7-3. Although tagging oflobsters began 18 June 1978, population estimates were not calculated until 29 June in order to have at least 2 recaptures. Final population estimates by the Peterson, Schnabel, and Schumacher and Eschmeyer methods were 3832,3837, and 4033 lobsters, respectively.
TABLi 3.7.1. Summary of mark-recapture information for 1978 lobster tagging study.
Date Total Captured Marked Recaptures 1978 May 28 112 0
0 May 30 93 0
0 June 2 132 0
0 June 5 164 0
0 June 11 154 0
0 June 18 190 19 0
June 22 48 47 0
June 24 58 51 1
June 27 104 91 0
June 29 77 61 2
July 2 IIi 75 7
July 6 137 90 7
July ii 198 122 4
July 15 180 107 13 July 18 183 113 9
July 21 53 25 2
July 28 202 135 13 July 31 188 136 18 August 5 136 91 9
August 10 123 91 13 August 15 94 61 14 August 19 143 87 15 August 31 94 14 13 Total 2,974 1,416 140 2284 I14
TABLE 3.7-2. Summary ofmark-recapture informationforpre-recruit lobsters in the si:e range of 69-78 mm, 1978 lobster tagging study.
Date Total captured Marked Recaptures 1978 May 28 50 0
0 May 30 40 0
0 June 2 67 0
0 June 5 78 0
0 June ll 72 0
0 June 18 96 10 0
June 22 26 25 0
June 24 29 29 1
June 27 47 47 0
-"ne 29 41 39 2
July 2 51 40 6
July 6 69 60 6
July II 85 78 3
July 15 79 68 9
July 18 79 70 6
July 21 14 10 2
July 28 92 90 10 July 31 84 77 14 August 5 67 63 8
August 10 62 59 10 August 15 48 42 10 August 19 54 46 12 August 31 49 10 9
Total 1,379 863 108 2284 115 35
e-TABLE 3.7-3. Estimates of population si:e and density (rocky habitat) of pre-recruit lobsters (69-73mm) in the Charlestown-Matunuck region of Block Island Sound, 29 June-31 August 1978.
Estimated density ( No./100m2 )
Population estimate (2 standard error) based on population estimate of Total cEcctive Number area Date of fished a Schumacher &
Schumacher (1978) pots
( 100m2)
Peterson Schnabel Eschmeyer Peterson Schnabel & Exhmeyer 6/29 24 984 2.275 (l1.061) 2,275 (4.02i) 2,275 (0) 2.3 2.3 2.3 7/2 40 1,640 1,275 (1,446) 1,525 (1,123) 1.473 (4x7) 0.8 0.9 0.9 7/6 49 2.009 2,185 (2,479) 1,807 (981)
I,831
( 5 72 )
1.1 0.9
- 0. 9 7/II 59 2,419 7,083 (16,501) 2.738 (l 340) 3.139 (2,20I) 2.9 1.1 1.3 7/15 56 2,296 2.879 t 2,491 )
2,787 (1,092) 3.010 (1,319) 1.2 1.2 1.3 7/18 56 2.296 5,214 (5.916) 3,242
( l.14 I )
3.638 (I,545) 2.3 I.4 1.6 7/21 22 902 3.262 (15,857) 3.243 (1,106) 3.600 (1,338) 36 36 40 7/28 61 2,501 4,379 (3,468) 3,501 (l.046) 3.864 (l,160) 1.8 14 1.5 7/31 65 2.665 3,396 (2,075) 3,476 (902) 3,695 (832) 1.3 1.3 1.4 8/5 59 2.419 5,385 (4.972) 3,707 (901) 4.016 (888) 2.2 1.5 1.7 8/10 56 2.296 4.377 (3.467) 3.795 (859) 4.090 (780) 1.9 1.6 1.8 8/15 46 1.886 3,672 (2,908) 3.781 (803) 4,014 (663) 1.9 20 2.1 8/19 51 2.091 3.631 (2.476) 3,762
( 748) 3.942 (565) 1.7 1.8 1.9 8/31 40 1,640 4,644 (4.002) 3,837' (730) 4.033' (539) 28 2.3
- 2.5
- Mean 48.9 2,003 3.832' 1.9
- S d.
13 2 542.5 1,501
- Final population or density estimate
" Schnabel, and Schumacher and Exhmeyer techniques are.neraging methods; therefore overall mean not appropnate.
A. Based on Miller's (1975) estimate of the cKective area nshed for traps used in the commercial spider crab hshery in Newfoundland.
2284 116 36
The population estimates given in Table 3.7-3, along with information on the effective area fished per trap, can be used to estimate density of pre-recruit lobsters in the 69-78 mm size range. Miller (1975) estimated that the effective area fished for traps used in the commercial spider crab ( Chionoecctes opilio )
fishery in Newfoundland was approximately 4100 m2/ trap. If his estimate is assumed adequate for lobster traps used in our study, then densities of lobsters can be estimated. Estimated densities of pre-recruit lobsters (no./100 m2) by date are given in Table 3.7-3. The final estimated density varied from 1.9-2.5 pre-recruits /100 m2 of similar (rocky) habitat. Expressed as numbers per acre, the densities ranged from g
approximately 77-100 pre-recruit lobsters / acre of similar bottom.
3.8 Molt Onset An approximation of the date of molt onset can be determined by plotting the legal catch per pot versus sampling date. A nadir in the plot would indicate the near depletion oflegal lobsters just prior to the molt, and should be followed by a sharp increase in the catch rate as a result of a new cohort oflobsters reaching legal size with the molt. The catch rate oflegal male and unberried female lobster for Station IE by date is shown in Figure 3.8-1 (Station IE was selected due to the continuous sampling effort). From Figure 3.8-1, as well as examination of catch rates for other stations (Tables 3.1-2 and 3.1-4), it would appear that molt onset occurred in approximately late June. Few soft shell or rewntly molted lobsters were caught during our study (Table 3.8-1 ), thus giving little additional evidence on the approximate date of molting. Lund et al. (1970) observed two distinct periods of massive molting in Fishers Island Sound, June-July and October-November. Russell et al. (1978) also suggested that two molting periods (June and in late September-early October) occur in Narragansett Bay-Rhode Island Sound. Our study terminated prior to when the later molting period could have occurred.
TABLE 3.8-l. Date and location (station) of capture of recently molted lobsters,1978 lobster por survey.
Date Stauon Number Caught 1978 6/18 IW l
6/18 IE 1
6/27 IW l
7/15 NS I
7/18 3E I
8/10 2E 1
8/31 3E I
Total 7
2284 117 37
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2284 118 C
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- 4 4.0 LITERATURE CITED Aiken, E.D. and S. L. Waddy.1976. Controlling growth and reproduction in the American lobster.
Fisheries and Marine Service, Biological Station, St. Andrews, New Brunswick, Canada.
Cooper, R.A.1970. Retention of marks and their effects on growth, behavior and migrations of the American lobster, Romarus americanus. Trans. Amer. Fish. Soc. 99(2):409-417.
\\
Cooper, R.A., R. A. Clifford, and C. D. Newell.1975. Seasonal abundance of the "American lobster, Homarus americanus, in the Boothbay Region of Maine. Trans. Amer. Fish. Soc. 104(4):669-674.
Fair, J.J. Jr.1977. Lobster investigation in management area I: southern Gulf of Maine. NOAA, NMFS i
State-Federal Reglationships Div., Mass. lobster report No. 8, April 21,1975-April 20,1977,8 pp.
and Appendix,14 pp.
3 Jones, R.1976. The use of marking data in fish population analysis. FAO Fisheries Tech. Paper No.153, 42 p.
Krouse, J.S.1973. Maturity, sex ratio, and size composition of the natural population of Araerican lobster, Romarus americanus, along the Maine coast. Fishery Bull. 71( I ):165-173.
l Krouse, J.S. 1977. Lobster tagging project. Completion report #3-228-R, October 1974 through September 1977. Maine Department of Marine Fisheries. 29+p.
Lawton, R.P., W. T. Sides, E. A. Kouloheras, R. B. Fairbanks, M. Borgatti, and W.S. Ccilings. 1978.
Final report on the assessment of possible effects of Pilgrim Nuclear Power Station on the marine environment. Project Rept. No. 24. Mass. Dept. of Fisheries, Boston, MA.
Lund, W. A. Jr., L. L. Stewart, and H. M. Weiss.1970. Investigation on the lobster Comm. Fish. Res. &
Devel. Act Project No. 3-44-R. Univ. Conn. Mar. Res. Lab., Moank, Ct.,105 p.
McCann, J. A. and D. F. Cruse,1969. Computer program for mark and recovery population estimates (CDC 3600 Computer). Trans. Amer. Fish. Soc. 98(2):332-334.
Miller, R. J.1975. Density of the commercial spider crab, Chionoecetes opilio, and calibration of effective area fished per trap using bottom photography. J. Fish. Res. Bd. Can. 32(6): 761-768.
New England Power Company.1978. NEP l&2 Environmental Report, Appendix G. The Environmen-tal Impact of Construction and Operatian of the Cooling Water System for NEP I&2 on selected Representative Important Species.
Normandeau Associates, Inc.,1978. Piscataqua River Environmental Studies Report. Normaadeau Associates, Nashua Rd., Bedford, N.H.
Pecci, K.J., R. A. Cooper, C. D. Newell, R.A. Clifford, and R. J. Smolowitz,1978. Ghost fishing of vented and unvented lobster, Homarus americanus, traps. Marine Fisheries Review 40(5-6): 9-43.
Ricker, W.E.
Computation and interpretation of biological statistics of fisl. populations. Dept. of the Environment, Fisheries and Marine Service Bulletin 191,382 p.
Robson, D.S. and D.G. Chapman.1961. Catch curves and mortality rates. Trans. Ame-F),h. Soc.
90:181-189.
Russell, H.J., and D.V.D. Borden.1975. Management studies ofinshore lobster resources. R.I. Division of Marine Fisheries Lobster Report No. 5, Contract No. 03-4-043-360. 17 + p.
2284 119
=..,,
Russell,11.J., C.V.D. Borden, hi. J. Fogarty,1978. Af anagement Studies of Inshore Lobster Resources.
Completion Report. Identification No. LO74-1-RI (1):1. R.I. Fish & Game,75 p.
Skud, B.E.1969. The etrect of fishing on size composition and sex ratio of offshore lobster stocks.
Fisketidir. Skr. Ser. ItavUnders. 15:295-309.
Skud, B.E. and ll.C. Perkins.1969. Size composition, sex ratio, and size at maturity of ofTshore northern lobsters. U.S. Fish Wildl. Serv. Spec. Sci. Rept. Fish. 598,10 p.
Smith, E.M.1977. Some aspects of catch / effort, biology and the economics of the Long Island Sound lobster fishery during 1976. Conn. Dept. of Environmental Protection, Niarine Region, Project No. 3-253-R-1, 97 p.
State-Federal Lobster Scientific Committee Workshop.1975. Sexual maturity of the American lobster.
New England Center, Durham, New flampshire. 6 p. (as cited by Lawton et al. 1978).
Thomas, J.C.1973. An analysis of the commercial lobster (1/omarus americanus) fishery along the coast of hiaine, August 1966 through December 1970. NOAA Tech. Rept. Nh1FS SSRF-667,57p.
2284 120 40