FISHERY BULLETIN: VOL. 85. NO. 3 



Sampling periods 



111 



MMFS 

 983' 



ILJ. 



NMFSr 

 985! 



I 



I . i . i ,i| i | ' . i . i . i . i | i | 



' NMFS 1979 '.' ' 'iiiVi, 



M!'iTiTi;i 1,1.1,1.1,1,1,1,1, 



1 I I 1 I I I NMFS 1980 1 



I I II I M I I, M 1,1,1 I, 

 ;|||X'1VNMFS 1981 



 rr i' n 'i'i' i ' , ' . 'i' , i , i . i , i | i | i | i | i | i | i | | 



,' Ji'i'iNMFS 1982i|i|'|iiVi'i'i 



OCSEAPII 



','1983:1:1 



I 1 , 1 I 1 , 1 I 1 , 1 1 , 1 , 1 i , i , i , i | i |'i ' | i , i | ' i ' l 

 ' I i'i|''iNMFS1983;i|iJi;i|iXi| 



II I I I I I I I, NMFS 1984 ',',,i,'|i|i,J 

 •'■'•''•'''' I . I I .,1 1, 1. 1,1, 1, i« 



January February March 



April May 



Months of year 



June 



July 



August 



FuiUKK 6. — Seasons and durations of sampling periods in the eastern Bering Sea, from 1979 



through February 1985. 



at as many stations as possible. After the catch 

 was brought aboard, all species including hair 

 crab were removed, counted, and weighed. 



Carapace length of each crab was measured 

 with steel vernier calipers to the nearest 1.0 mm 

 from the rear of the right orbit to the middle of the 

 posterior edge of the carapace (carapace length, 

 CL). Carapace width (CW) was measured to the 

 nearest 1.0 mm across the widest part of the cara- 

 pace, excluding the lateral spines. Crabs were 

 weighed on a triple-beam balance, and weights 

 recorded to the nearest 1.0 g for crabs selected 

 from a stratified size distribution. Shell condition 

 was recorded as follows: molting (Drach's stages 

 D2 through E; Passano 1960), softshell (stages Aj 

 through Bj), new hard shell, old hard shell (prob- 

 ably skipped one annual molt), and very old hard 

 shell (probably skipped several annual molts). 

 Hard-shell conditions were graded subjectively 

 according to the amount of epifauna on the cara- 

 pace, color of carapace, and wear on the spines. A 

 new hard-shelled crab carapace was relatively 

 clean with no epifauna, reddish to yellowish 

 brown, with sharp spines. A very old hard-shelled 

 carapace, however, was usually darker brown in 

 color and almost always had epifauna, and spines 

 that were rounded or worn smooth. An old hard 

 shell was intermediate between these two condi- 

 tions, but in practice it was difficult to distinguish 

 between new and old hard shell. The presence or 

 absence of external embryos was recorded for all 

 female crabs. Six ovigerous females caught by 

 NMFS in the EBS, 1979-85, were preserved in 



10% formalin and returned to the Kodiak NMFS 

 laboratory for determination of fecundity. The en- 

 tire clutch was removed from the crab, and the 

 embryos dried, sieved to remove debris, and 

 weighed to the nearest 0.1 mg. Three subsamples 

 of embryos from each crab were weighed and 

 counted. The total number of embryos was esti- 

 mated by dividing the total clutch weight by the 

 average embryo weight. For each of three crabs 

 caught in 1980, diameters of 30 fixed embryos 

 were measured to the nearest 0.1 mm under a 

 stereomicroscope with an ocular micrometer, and 

 average embryo diameters were calculated. Em- 

 bryos were nearly spherical so no distinction was 

 made between length and width. Other data were 

 analyzed to determine distribution and abun- 

 dance, sex composition, length frequency, molt- 

 ing periods, relative age according to shell condi- 

 tion, distribution by temperature and depth, and 

 reproductive condition of females. 



Population estimates were derived from trawl 

 data using the area-swept technique (Alverson 

 and Pereyra 1969) as described in Otto et al. 

 (1985). The sampling variable was crab density, 

 expressed as crabs caught per unit area swept, 

 the latter equalling the product of net width and 

 distance fished (determined with loran). High- 

 and low-density strata were defined using the cu- 

 mulative square root of frequencies method 

 (Cochran 1963). Mean, total, and variance of crab 

 density was determined within each stratum, and 

 these combined for extrapolation to the survey 

 area. 



530 



