FISHERY BULLETIN: VOL. 85. NO. 3 



females extrude eggs in October and November 

 while muciparous females extrude eggs from 

 March to May (Fig. 3) (Sakurai et al. 1972). This 

 indicates a 4-10 mo interval between copulation 

 and extrusion. Yoshida (1940) suggested that 

 spawning occurs only in alternate years. 



Oocytes are yellowish white and immature at 

 the time of copulation in both primiparous and 

 multiparous females. During the interval be- 

 tween copulation and extrusion, the oocytes ma- 

 ture into dark orange ova 0.6 mm in diameter 

 (Sakurai et al. 1972). After extrusion, the em- 

 bryos are carried for at least a year during which 

 time they become dark brown; hatching occurs 

 from about March to May. Sakurai et al. reported 

 that an average of 40,000-50,000 eggs and a max- 

 imum of 160,000 eggs were produced and that 

 external embryos were 0.8-0.9 mm in diameter. 



The distribution and timing of the occurrence of 

 hair crab larvae near Hokkaido, the Kamchatka 

 Peninsula, and in the eastern Bering Sea have 

 been the focus of several studies. Near Hokkaido, 

 Takeuchi ( 1969) and Abe ( 1977) found stages I-III 

 in May and June; stages IV and V in June and 

 July; and megalops from June to August. 

 Takeuchi determined that stages were roughly 2 

 weeks apart. Stages I and II were only found in 

 the surface layer (0-19 m), whereas stages III-V 

 occurred in the surface and middle (20-50 m) lay- 

 ers. Temperatures ranged from 6^^ to 11°C at the 

 surface and from 2° to 10°C in the middle layer. 

 Along the West Kamchatka Shelf, stage I larvae 

 were found late- April to May and stages II- V in 

 June and July (Makarov 1967). In the BBS, 

 stages I and II were found late-April to June; 

 stage III, May and June; and stages IV and V and 

 megalops in June (Armstrong et al. 1983"*). Hair 

 crab larvae in all three geographical areas were 

 concentrated over bottom depths of 20-200 m, al- 

 though some have been found in waters outside 

 that range. 



Abe (1977) reported that settlement of hair 

 crab larvae near Hokkaido occurred in July, in 

 waters 20-50 m deep, 5''-7''C, on sandy mud or fine 

 sand. Juvenile crabs remained in that same gen- 

 eral area for the next 1.5 years as they grew from 

 5.1 mm to about 44.5 mm RL""' (40.2 mm CL) in 



eight successive molts. Ovigerous females were 

 found in that habitat during the spring. Adult 

 hair crabs moved offshore during July through 

 September, as nearshore water temperatures 

 gradually increased from 6^ to 15°C (Abe 1977). 

 Matui (1970) found adults at depths of 20 m in 

 April to 130 m in autumn, offshore of eastern 

 Hokkaido, but hair crab have been found at 

 depths of 5-364 m in other areas around Hok- 

 kaido, the Kamchatka Peninsula, and Korea 

 (Kawakami 1934; Sakai 1939). Hair crab were 

 found on a variety of substrates, including sand, 

 mud, gravel, rock, and broken shells, but sandy 

 mud seemed to be most common (Kawakami 

 1934; Sakai 1939; Matui 1970; Abe 1977). 



After settlement in July, hair crab metamor- 

 phose to first postlarval crab instars (CD with a 

 mean size of 5.2 mm RL (Abe 1977, 1982) (Fig. 3, 

 top). External sex characteristics are evident at 

 stage C2 and a mean size of 7.0 mm RL. By the 

 following April, 12 months after hatching, the 

 crab reach stage C7 at a mean length of 27.4 mm 

 RL. Approximately 33 months after hatching, the 

 crab reach maturity at CIO with a length of 55-60 

 mm RL (50-54 mm CL) (Abe 1977, 1982); how- 

 ever, hair crab males do not mate until 4 years of 

 age and 70 mm RL (64 mm CL) (Sakurai et al. 

 1972). The smallest recorded male with mature 

 spermatozoa was 41 mm RL (37 mm CL) (Hirano 

 1935). Molting frequency and mean carapace 

 length are the same for both sexes through stage 

 C9 (Abe 1977, 1982), however, after maturity 

 males molt more frequently (Sakurai et al. 1972) 

 and show greater growth per molt (Abe 1982) 

 than females. Males begin to molt annually at 

 about 55 mm RL (51 mm CL), once every 1-2 

 years (tending toward 2) in the size range 89-95 

 mm RL (81-87 mm CL), and biennially at sizes 

 >100 mm RL (91 mm CL) and growth rate de- 

 creases with age ( Yamamoto 1971 ). Males 65-105 

 mm RL (59-96 mm CL) experience a 10-25% 



^Armstrong, U. A., L. S., Incze, D. L. Wencker. and 

 J. L. Arm.strong. 1983. Di.stribution and abundance of deca- 

 pod cru.stacean larvae in the .southeastern Bering Sea with em- 

 phasis on commercial specie.s. Final Rep. to Natl. Oceanic 

 Atmos. Admin., OCSEAP contract no. NA81-RAC- 

 00059. Office of Marine Pollution Assessment, Alaska Office 

 RD'MPF24. P.O. Box 1808, Juneau. AK 99802. 



•Japanese scientists have traditionally measured crab 

 lengths from the notch between the rostral spines ("rostral- 

 length", RL), whereas NMFS scientists measure from the right 

 orbit ("carapace length", CL). We converted rostral lengths to 

 orbit lengths with the following equations, determined for crab 

 in the size range of 40-100 mm CL: 



Males: CL = -0.81 + 0.921 RL /?2 = 0.982 N = 122 

 Females: CL= -2.10 + 0.943 RL ft^ = 0.998 N=8 



These equations have similar slopes but significantly different 

 intercepts (P < 0.05). All NMP^S crab measurements in this re- 

 port are carapace lengths (CL). Japanese data are reported in 

 original units (RL) and corresponding carapace lengths are also 

 given for crabs '40 mm CL. 



526 



