SOMERTON and OTTO: DISTRIBUTION AND REPRODUCTION OF GOLDEN KING CRAB 



that the observed difference in fecundity is an arti- 

 fact due to a difference in mean embryo age. We 

 attempted to eliminate the effect of embryo age by 

 considering only clutches with uneyed embryos, but 

 this may not have been a sufficiently sensitive 

 criterion of age and northern females could have had 

 more embryos simply because they had younger em- 

 bryos. Considering that for equal-sized females the 

 percent difference in clutch size between eyed and 

 uneyed stages was greater than the percent differ- 

 ence in clutch size between areas, it is possible that 

 the loss of embryos within the uneyed stage is suf- 

 ficient to account for between-area differences. 

 More precise embryo aging techniques are needed 

 to clarify this. 



Egg Size 



To estimate the size of golden king crab eggs, we 

 considered 1) whether egg size varied with stage 

 of embryo development and 2) whether egg size 

 varied between areas. When mean lengths of uneyed 

 eggs (N = 42) and eyed eggs (N = 26) from the cen- 

 tral area were compared, eyed eggs were found to 

 be significantly larger than uneyed eggs (two sam- 

 ple £-test, P < 0.001). Golden king crab eggs 

 therefore appear to increase in size, as has been 

 reported for other crab species (Wear 1974), dur- 

 ing embryonic development. When mean length of 

 uneyed eggs from the southern (N = 25) and cen- 

 tral (N = 42) areas (no egg length data was collected 

 from the northern area) were compared, no signifi- 

 cant difference was found (two sample £-test, P = 

 0.25). Mean length of uneyed eggs, based on the 

 pooled central and southern data, is 2.2 mm (SD = 

 0.1). 



Our estimate of egg length is similar to those 

 reported for Asian populations of golden king crab 

 (2.38 mm, Hiramoto and Sato 1970; 2.30 mm, Suzuki 

 and Sawada 1978), and it is also similar to egg 

 lengths reported for other Lithodes species (L. ant- 

 arctica, 2.2 mm, Guzman and Campodonico 1972; 

 L. couesi, 2.3 mm, Somerton 1981b). However, this 

 size is more than twice as large as the egg lengths 

 reported for Paralithodes species (P. camtschatica, 

 1.0 mm, Haynes 1968; P. platypus, 1.2 mm, Sasa- 

 kawa 1975). The larger eggs of golden king crab are, 

 in turn, reflected in the relatively large size of their 

 first stage zoea (L. aequispina, 7.3 mm TL, Haynes 

 1981; P. camtschatica, 4.6 mm TL, Sato and Tanaka 

 1949; P. platypus, 4.9 mm TL, Hoffman 1968). The 

 larger size of L. aequispina larvae may allow them 

 to withstand starvation for a longer period or may 

 allow them to capture a wider size range of prey 



than Paralithodes larvae. If this is true, golden king 

 crab larvae may not need to ascend to the photic 

 zone but instead stay at greater depths. Evidence 

 supporting this hypothesis is provided by a study 

 on crab larvae that sampled the upper 50 m near 

 the edge of the eastern Bering sea continental shelf 

 (Fig. 1). Although both P. platypus and P. cam- 

 tschatica larvae were found, L. aequispina larvae 

 were not (D. Armstrong 5 ). 



Seasonality of Reproduction 



King crabs either can be synchronous and seasonal 

 in their egg extrusion and embryo hatching, as 

 reported for P. camtschatica (Powell et al. 1973), 

 or they can be asynchronous and lack seasonal 

 periodicity, as reported for L. couesi (Somerton 

 1981b). To determine which pattern better charac- 

 terizes golden king crab, we tabulated the percent- 

 age of mature females in each of the three reproduc- 

 tive conditions by area and by quarter (Table 3). If 

 the reproductive cycle were synchronous and 

 seasonal, then each of the three categories of repro- 

 ductive condition should predominate sequentially 

 over the course of a year, but such a pattern is not 

 evident. Regardless of the area or the season in 

 which a sample was collected, all three reproduc- 

 tive categories were always obtained. This sug- 

 gests that golden king crab have an asynchronous 

 reproductive cycle lacking distinct seasonal vari- 

 ation. 



Table 3.— Percentage of adult females in each of three categories 

 of reproductive condition: 1) uneyed embryos, 2) eyed embryos, 

 and 3) empty egg cases, and total sample size (W) by subarea and 

 quarter. 



The apparent lack of seasonality conflicts with 

 previous studies of golden king crab reproduction. 

 Hiramoto and Sato (1970) reported that egg extru- 

 sion occurs from July to October and embryo hatch- 

 ing occurs from February to July along central 

 Japan. However, Hiramoto and Sato found embryos 

 in late stages of development throughout the year, 



6 D. Armstrong, College of Fisheries, University of Washington, 

 Seattle, WA 98195, pers. commun. 1984. 



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