FISHERY BULLETIN: VOL. 84, NO. 3 



with increasing latitude along the slope. If this is 

 true, then it is reasonable to assume that growth 

 rates are lower in higher latitudes. Part of the lat- 

 itudinal decrease in mean size, however, is due to 

 the greater relative abundance of small (25-50 mm) 

 crabs in the northern area (Fig. 2). Since we have 

 only two years of data, we do not know if the greater 

 abundance of small crabs in the northern area is a 

 persistent feature of the distribution. But if it is, it 

 may indicate that greater larval settlement occurs 

 in the northern area because of the advection of lar- 

 vae by the northwesterly currents over the continen- 

 tal slope (Kinder and Schumacher 1981). 



The decrease in size with depth may reflect an 

 ontogenetic upslope migration. Another slope dwell- 

 ing crab, Chionoecetes tanneri, also displays a de- 

 crease in size with depth, and this was attributed 

 to an offshore advection of pelagic larvae followed 

 by an onshore migration of juveniles (Pereyra 1968). 

 Although an onshore migration might explain the 

 size variation with depth of golden king crab in the 

 eastern Bering Sea, offshore advection depends on 

 local oceanographic conditions and may not occur 

 everywhere ovigerous golden king crab occur. For 

 example, studies of golden king crab in other areas 

 indicated that adults could be found in shallower 

 water than juveniles (Hiromoto and Sato 1970), or 

 at similar depths as juveniles but in different areas 

 (Rodin 1970) or in deeper water than juveniles (N. 

 Sloan 4 ). 



Size at Maturity 



The change in the relative growth of a male's chela 

 which occurs at maturity is more pronounced for 

 golden king crab than it is for either blue king crab 

 (Somerton and Macintosh 1983) or red king crab 

 (Somerton 1980), and this allows greater precision 

 in the estimates of size at maturity (Fig. 3). Never- 

 theless, the estimates of male size at maturity are 

 less precise than those for females (Fig. 4). For both 

 sexes, however, the estimated sizes at maturity dif- 

 fer significantly between areas and progressively 

 decrease with increasing latitude (Fig. 4). 



The decrease in the size at maturity is consistent 

 with a latitudinal decrease in growth rate; however, 

 the decrease is greater for males than it is for 

 females (Fig. 4). If golden king crab are similar to 

 red king crab (Weber 1967) in that males and 

 females grow identically while they are immature, 



4 N. Sloan, Department of Fisheries and Oceans, Pacific Bio- 

 logical Station, Nanaimo, British Columbia, V9R 5K6, Canada, 

 pers. commun. 1984. 



576 



then the greater latitudinal decrease in male size at 

 maturity implies that female age at maturity in- 

 creases, relative to that of males, with latitude. This 

 could occur if females and males have different life 

 history strategies to maximize their reproductive 

 values (Bell 1980). The reproductive value of a 

 female is largely determined by her lifetime fecun- 

 dity. Since fecundity increases markedly with size 

 and somatic growth decreases abruptly at matur- 

 ity, under conditions of reduced growth, female 

 reproductive value might be increased by delaying 

 maturity until some optimum size is reached. The 

 reproductive value of a male, however, is largely 

 determined by the number of females he is able to 

 mate with over his lifetime. Unless access to females 

 is strictly limited to the largest males, male repro- 

 ductive value is unlikely to be increased by delay- 

 ing maturity. Along a gradient of decreasing growth 

 rate, such strategies would lead to a divergence 

 between male and female sizes and ages at maturity. 



Weight at Size 



Weight-size relationships of males were deter- 

 mined for each of the three subareas by regressing 

 body weight on carapace length after transforming 

 both variables to natural logarithms. Analysis of 

 covariance showed that the slopes of the regression 

 lines were not significantly different (F = 0.49, df 

 = 2, 1,079, P = 0.613), but that the intercepts were 

 significantly different between areas (F = 19.03, df 

 = 2, 1,081, P < 0.001). Pairwise £-tests further 

 showed that the intercept for each area differed 

 significantly from the other two (Bonferroni critical 

 values; maximum P < 0.05) and that the intercepts 

 progressively increased with increasing latitude. 

 Males in higher latitudes are therefore propor- 

 tionately heavier than equal-sized males from lower 

 latitudes. 



This proportionate change in weight with latitude 

 might be due to changes in body shape, such as the 

 relative size of the chelae, that are coincident with 

 the onset of maturity. Since the rate of chela growth 

 increases, relative to carapace growth, at maturity, 

 and since the size at maturity decreases with lat- 

 itude, mature males in northern areas should have 

 larger chelae than equal-sized males in southern 



Figure 3.— For the golden king crab males, chela heights, carapace 

 lengths, and the best fitting two line model are shown for each 

 subarea. For the females, percentage mature, within 5 mm size 

 intervals, and the fitted logistic equation are shown for each sub- 

 area. Estimated sizes (carapace length) at maturity are indicated 

 by dotted lines. 



