544 



Fishery Bulletin 88(3). 1990 



-"^^T 



BERING SEA 



Arc tosc opus 

 laponicus 



Trichodon 

 trie hodon 





EA of/ ::*C-5;i*H: 



NORTH PACIFIC OCEAN 



80 N 



T I I I I I I I I I I I I I I I I I I I I I I I T 



130 E 150 E 170 E 170 W 150 W 130 W 110 W 



Figure I 



Geographical distribution of two species of sandflshes, family Trichodontidae. (A) Pohang, (B) Akita, (C) Wakkanai, (D) Kholnisk, (E) Nemuro, 

 (F) Attu, (G) Dutch harbor, (H) Kndiak, (I) Sitka, (J) Vancouver. For references, see text. 



temperature ranges of 2-5°C (Nishimura 1969). This 

 zone is shifted to a shallower depth of 100-200 m on 

 the Pacific side off Hokkaido (Ochiai and Tanaka 1986). 

 During the spawning season, the adults move into 

 water shallower than about 15 m. In contrast, T. 

 trichodon is most frequent on the middle shelf at less 

 than 150 m (Allen and Smith 1988) and spawning is 

 restricted to the intertidal area. 



Reproductive ecology 



Both species spawn large demersal eggs in rocky, 

 shallow waters during winter months, but interesting 

 ecological differences are found between them, sum- 

 marized in Table 1. Typically, A.japonicus deposits a 

 spherical egg mass tightly on Sargassum spp. in such 

 a way that supporting stems pass through the axis of 

 the mass. Successful deposition of secure substrata is 

 of prime importance for survival of eggs, because 

 egg capsules that detach from the substrata become 

 stranded ashore and perish. Onset of spawning at fixed 

 times and locations is characteristic of A. japonicus. 

 In the Akita district, for instance, the onset of spawn- 

 ing at major spawning sites rarely fluctuates beyond 

 1 or 2 weeks from the end of November (Kato 1980). 

 In contrast, Eschmeyer and Herald (1983) reported 

 that the eggs of T. trichodon are laid in a gelatinous 

 mass attached to rocks. One report of a natural spawn- 

 ing was on the wall of a fully exposed surge channel 



