TABLE 13. Annual impingement estimates for lobster collected at Units I and 2 from 1978 to 1987. 



Unit 1 



Unit 2 



Both Units 



1978 

 1979 

 1980 

 1981 

 1982 

 1983 

 1984 

 1985 

 1986 

 1987 



245 

 323 

 368 

 665 

 938 

 999 



a 



a 



261 

 426 

 405 

 1009 

 1041 

 497 

 1220 

 480 

 676 

 825 



506 

 749 

 773 

 1674 

 1979 

 1496 

 1220 

 480 

 676 

 825 



Total 



3538 



6840 



10378 



Unit 1 sluiceway began operating December 1983. 



smaller than the trap catch values (NUSCO 

 1987a). Smaller lobsters enter the intake through 

 the course bar racks (bar spacing 6.4 cm) more 

 readily than larger lobsters which are seldom im- 

 pinged. Male to female sex ratios of impinged 

 lobsters during 1986 and 1987 were 1.0:0.46 and 

 1.0:0.38, respectively. These values were slightly 

 lower than the range of pre-operational sex ratios 

 reported from 1982 to 1985 (1.0:0.47 to 1.0:0.58) 

 and reflected the higher abundance of male lobsters 

 nearshore at the Jordan Cove and Intake stations 

 (1.0:0.6-1.0:0.7, NUSCO 1987a). The percentage 

 of impinged lobsters missing one or both claws 

 (culls) during 1986-87 (27%) was lower than pre- 

 operational values (30-50%). Impinged lobsters 

 suffered greater claw loss when compared to trap 

 catch values (wire pots, 10-16%) due to the high 

 pressure (80 psi) wash used to remove debris from 

 the traveling screens (NUSCO 1987a). 



Survival of lobsters impinged at Unit 2 during 

 1986 (97%) was higher than the ten year range 

 of survival values reported from 1975-85 

 (64-80%). During 1987 survival was slightly 

 lower (62%), due to higher impingement of lob- 

 sters during the summer; more than half of all 

 lobsters were impinged from May through Sep- 



tember in 1987. Historically, mortality of im- 

 pinged lobsters was highest during the peak molt- 

 ing period (May-June) when lobsters were soft 

 and easily injured, and during the later summer 

 months when water temperatures were highest 

 (August-September; NUSCO 1987a). 



Summary 



1. Total CPUE during 1986 and 1987 was 1.70 

 and 1.72, respectively, within the range of 

 values reported during 2-unit operations 

 (0.85-2.10). Legal CPUE was lower during 

 1986 and 1987 (0.097, 0.089) when compared 

 to previous years' results and may be related 

 to increased fishing pressure. A 50%> decline 

 in catch at Jordan Cove occurred from August 

 to September 1986 and was related to 3-unit 

 operations. Sediments in the discharge area 

 were scoured and subsequently deposited in 

 Jordan Cove, where lobster habitats were 

 buried by sediments. This decline in catch 

 was only temporary, since catches in October 

 1986 and througliout 1987 at Jordan Cove 

 were normal and indicated that sediments 



140 



