had stabilized and lobsters had returned to 

 the affected area. 



2. The mean size of lobsters caught during 1986 

 (70.1 mm) and 1987 (70.2 mm) was smaller 

 than values reported in previous years (range 

 70.7-71.8 mm) due to the lower CPUE of 

 legal-sized lobsters during 1986-87. 



3. Male to female sex ratios during 1986 and 

 1987 were 1.0:0.87 and 1.0:0.88, respectively, 

 within the range of values in previous years. 

 The Twotree station continued to yield a 

 higher proportion of females than the other 

 two nearshore stations, a trend consistent 

 since the study began. 



4. Female size at sexual maturity was similar 

 during 2- and 3-unit operations; females be- 

 gan to mature between 50 and 55 mm CL 

 and aU females were mature at sizes greater 

 than 95 mm CL. The mean CL of berried 

 females during 1986 (78.0 mm) and 1987 

 (76.5 mm) and the proportions of sublegal 

 size berried females caught in 1986 (75%) 

 and 1987 (90%) confirmed the small size at 

 first sexual maturity of females in the Mill- 

 stone area. 



5. Lobsters that were near molting comprised 

 3.2% and 3.0% of the 1986 and 1987 total 

 catches., respectively, which were within the 

 range of values reported during 2-unit oper- 

 ations. Growth per molt averaged 13.3% in 

 1986-87 compared to 13.9% from 1978-85. 



6. The percentage of culls in 1986 (10.6%) and 

 1987 (10.3%) was lower than the average 

 percentage culled in previous years (range 

 10.6%- 15.5%) and due to the implementa- 

 tion of the escape vent regulation in 1 984. 



7. The number of lobsters tagged in 1986(5,698) 

 and 1987 (5,680) was witliin thi- range of 

 annual values for lobsters tagged in pre- 

 operational studies. Recapture rates for 1986 

 (21.0%) and 1987 (23.9%) were also similar 

 to pre-operational values (range 



15.9%-23.9%). Lobstermen recaptured 

 20.2% of our tagged lobsters in 1986 and 

 17.8% in 1987. 



8. Lobster movements were localized, since 

 94% and 97% of all commercial recaptures 

 were made within 8 km of Millstone Point 

 during 1986 and 1987, respectively. Sev'eral 

 lobsters moved outside LIS and were caught 

 in waters off R.I. and MA.; 3 lobsters moved 

 offshore during 1986-87, where they were 

 caught in deep water canyons on the edge of 

 the continental shelf. 



9. Lobster larvae densities (number per 1000 

 m ) in entrainment samples were higher in 



1986 (0.88) and 1987 (0.63) when compared 

 to 1984-85(0.42-0.43). The estimate of total 

 lobster larvae entrainment, based on sample 

 density and total MNPS cooling water de- 

 mand, was also higher in 1986 (548,635) and 



1987 (304,694) when compared to 1984-85 

 (79,511-138,820). Lobster larvae survival 

 was 6.5% and 3.8% in 1986 and 1987, re- 

 spectively. More stage IV larvae were col- 

 lected in 1986 compared to 1984, 1985, and 

 1987 when greater numbers of stage I larvae 

 were collected. 



10. The estimated numbers of lobster impinged 

 at Unit 2 during 1986 and 1987 were 676 and 

 825, respectively, these values were within 

 the range of values reported in previous years 

 (261-1220). Fish return systems at Units 1 

 and 3 improved overall survival of impinged 

 lobsters. Based on impingement of all or- 

 ganisms at Unit 2 since 1 972, a request made 

 by NUSCO to discontinue impingement 

 monitoring at Unit 2 was accepted by the 

 CT DEP in December 1987. 



Conclusion 



Our studies indicate that the local lobster pop- 

 ulation is heavily exploited; more than 90% of 

 legal sized lobsters are removed by fishing. The 

 commercial and recreational catches are highly 

 dependent on the number of lobsters in the 



Lobster Population Dynamics 



141 



