riding with bottom water temperatures of 14°-16°C. Subsequently, 

 molting continued at a low level (1-4%) from July to October and 

 ceased in January. The variability of incidence of molting among 

 stations and years made it difficult to discern a distinct peak occur- 

 ring in autumn, as indicated by Lund et al. (footnote 3) for LIS, 

 and by Russell et al. (1978) 9 for Narragansett Bay. A single molting 

 peak per year has been described in Maine and in offshore waters 

 (Dow 1966; Skud and Perkins 1969; Krouse 1973). 



Gear Effectiveness 



An important objective of this study was to gather information 

 on as large a segment of the local lobster population as possible. 

 Through the use of wire pots (2.5 cm 2 mesh) we anticipated in- 

 creased catch of smaller sized lobsters capable of escaping through 

 the 3-5 cm gap between the laths of the commercial wood pots. A 

 Kolmogorov-Smirnov test on the size distribution of lobsters 

 caught in the two pot types indicated that wire pots caught 

 significantly (P < 0.05) more of the < 75 mm CL size class than 

 did the wood pots. These results are similar to those of Krouse 

 (1973) who found that CL of the catch from wire pots averaged 

 between 67.9 and 70.5 mm. He considered the modal size of his 

 catch (70 mm CL) to be the size at which lobsters are less apt to 

 escape the traps; using the same reasoning, lobsters in our study are 

 vulnerable to the wire pots at 70 mm CL and to the wood pots at 

 about 76 mm CL. Lobsters of 70-76 mm CL are important, since 

 these individuals constitute a large proportion of the prerecruits 

 (i.e., those individuals within one molt of legal size). The lobster 

 population of the Millstone Point region is subjected to a high ex- 

 ploitation rate. The size of the legal catch is therefore largely deter- 

 mined by these prerecruit size classes. 



Some factors to consider in the selection of lobster pots include 

 the cost, the catch efficiency, the ease of handling, the expected life 

 of the trap, and its susceptibility to storm loss. Wire pots caught 

 more lobsters, were more easily hauled, required less maintenance, 

 and were capable of fishing effectively up to 3 yr. Wood pots 

 allowed escapement of smaller lobsters, required more ballast, 

 travelled through the water slowly thus requiring more effort to 

 haul, and could only be fished for one season (< 1 yr) because of 

 wood borer attack. There was no significant difference (ANOVA 

 P < 0.05) between the CPUE of legal-sized lobsters caught in 

 wood and wire pots. However, wood pots caught more legal-sized 

 lobsters in 3 of 4 yr (Table 3). 



In conclusion, the lobster population of the Millstone Point 

 region has remained stable since 1976. The values for size struc- 

 ture, sex ratios, growth rates, number of berried females, incidence 

 of culled lobsters, and molting patterns of our catch, are within 

 ranges reported throughout northeastern North America. Results 

 indicated that the local population was highly exploited with the 

 commercial and recreational catch (> 81 mm CL) being highly- 

 dependent on the prerecruit size class. The seasonal variation in 

 catch was shown to be a function of molting patterns and changes 

 in catchability, induced by the seasonal change in water 

 temperature. No power plant induced change in water temperature 

 was observed at any station, and any power plant induced effect (if 

 any) on lobster population parameters cannot be distinguished 

 from naturally occurring variability. 



"Russell, H. J., D. V. D. Borden, and M. J. Fogarty. 1978. Management 

 studies of inshore lobster resources completion report. R.I. Fish Game 

 L074-1-Rl(l):l,75p. 



ACKNOWLEDGMENTS 



This research was supported by Northeast Utilities Service Com- 

 pany. Data collection from 1974 to 1977 was done by Battelle 

 (William F. Clapp Lab., Duxbury, Mass.) and from 1978 to pre- 

 sent by Northeast Utilities Service Company personnel. Apprecia- 

 tion goes to the many biologists who contributed to this program 

 and are too numerous to be named. We also owe thanks to B. R. 

 Johnson, W. C. Renfro, S. B. Saila, L. L. Stewart, J. C. Thomas, 

 R. Larsen, J. Foertch, P. Jacobson, and two journal reviewers for 

 critically reading earlier versions of this manuscript . Thanks also to 

 M. Solomon for help in initial stages of this manuscript prepara- 

 tion. 



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