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Fishery Bulletin 113(3) 
have a distinct competitive advantage in securing 
mates (Sainte-Marie et al., 1997). 
Seasonal inshore migrations of post-terminal-molt 
MM male snow crabs, at least in waters of eastern 
Canada, have been attributed to mating behavior. 
These migrations are either targeted toward pubescent- 
primiparous females, those that will soon terminally 
molt and then brood their first clutch after mating, or 
toward multiparous females, those carrying clutches in 
subsequent years (Lovrich et al., 1995; Sainte-Marie 
et al., 2008). In the eastern Bering Sea, pubescent-pri- 
miparous females reside in shallower water and mate 
1-3 months (February to March) earlier than multipa- 
rous females (Somerton, 1982; Ernst et ah, 2005; Kruse 
et ah, 2007). Peak spawning and subsequent mating 
among multiparous females in the eastern Bering Sea 
occur between March and April (Rugolo 2 ), although a 
small percentage may be in a receptive condition until 
July (Somerton, 1981). 
Whether commercial-size MM males in the east- 
ern Bering Sea undergo a seasonal inshore migration 
for the purpose of mating is unknown. If multiparous 
females in the eastern Bering Sea are relatively sed- 
entary, as they are in eastern Canada (Lovrich et ah, 
1995), an inshore migration by commercial-size MM 
males may be necessary for successful mating. Earlier 
and more extensive inshore migrations would certainly 
be required to mate with pubescent-primiparous fe- 
males (Parada et ah, 2010). Theoretically, there may 
not be a need to migrate toward and mate with multip- 
arous females because these females can store sperm 
over multiple years (Sainte-Marie and Carriere, 1995). 
However, depending on the sex ratios of functionally 
mature crabs, ratios that can affect mate choice (Sainte 
Marie et ah, 2008; e.g., the southern Tanner crab [C. 
bairdi ], Webb and Bednarski, 2010), most multipa- 
rous females are presumed to mate annually if males 
are available. An exception to this assumption occurs 
among some females that reside in colder-water areas 
(<1.5°C) of the eastern Bering Sea and that spawn bi- 
ennially (Rugolo et al. 1 ). 
Compared with the ontogenetic migrations of ju- 
venile snow crabs in the eastern Bering Sea, little is 
known about the seasonal migration patterns of MM 
males because of the paucity of sampling during times 
other than those of the NMFS summer bottom trawl 
survey and the winter commercial fishery. The offshore 
migration of recently terminally molted MM males in 
the eastern Bering Sea was demonstrated by a study 
of the Alaska Department of Fish and Game (ADFG), 
during which MM males were tagged with spaghetti 
tags during summer, on the middle shelf, and many 
were recaptured near the outer shelf during the fol- 
lowing winter snow crab fishery (Gravel et ah, 2006; 
Pengilly 3 ). However, because the fishery and, therefore, 
2 Rugolo, L. 2014. Personal commun. Alaska Fish. Sci. 
Cent., Seattle, WA 98115. 
3 Pengilly, D. 2014. Personal commun. Alaska Dep. Fish 
Game, Kodiak, AK 99615. 
recaptures occur only on the outer shelf, the fraction of 
MM males that migrate to the outer shelf is unknown, 
and nothing is known about the possibility of these 
males migrating back to the middle shelf. Furthermore, 
because of the reliance on the fishery for recaptures, 
ADFG tagged only commercial-size males, and informa- 
tion on migration and distribution for small MM males 
(70-100 mm CW), which are prevalent in the eastern 
Bering Sea (Otto, 1998) and potentially important con- 
tributors to breeding, is lacking. 
For commercial-size MM males, fishery managers 
have recognized a seasonal change in distribution, 
which is centered on the middle shelf of the eastern 
Bering Sea (bottom depth: <100 m) during the summer 
(Foy and Armistead, 2013) but shifts to the outer shelf 
(bottom depth: 100-200 m) from January to March 
when and where the fishery typically occurs (Orensanz 
et al., 2004; Bowers et al., 2011; Turnock and Rugolo 4 ). 
Part of this distributional shift may be explained by 
the post-terminal-molt migration from the middle to 
the outer shelf (Orensanz et al., 2004), but an inshore 
spring migration by outer shelf males may contribute 
to this shift as well. Such a migration was documented 
by Lovrich et al. (1995), who found that MM male snow 
crabs <70 mm CW in the Gulf of St. Lawrence migrat- 
ed to shallow water during early spring to mate with 
pubescent-primiparous females. In that study, however, 
large MM males tended not to migrate as far inshore 
or as early in the year as males <70 mm CW, therefore, 
limiting their mating to multiparous females. 
Determining where and when large (>100 mm CW) 
and small (70-100 mm CW) MM males may migrate, 
and where they are spatially distributed in relation to 
pubescent-primiparous and multiparous females, can 
help elucidate which mating associations occur in the 
eastern Bering Sea. Although at least some large, re- 
cently terminally molted MM males migrate into deep- 
er water after summer, it is not known whether these 
males seasonally migrate back inshore to mate with 
multiparous females or perhaps to shallower waters 
where pubescent-primiparous females reside (Parada 
et ah, 2010). If seasonal inshore migrations do occur, 
it is not known how much they contribute to tempo- 
ral differences in the spatial distribution of large MM 
males. For small MM males in the eastern Bering Sea, 
it is unclear what component of the mature female 
stock they associate with and mate with, because of the 
difficulty in recapturing small, tagged animals in the 
fishery and because the spatial distribution of these 
small MM males has not been examined separately 
from that of adolescents. 
Using data storage tags (DSTs) that were capable 
of timed depth recordings and were deployed on com- 
4 Turnock, B. J. and L. J. Rugolo. 2011. Stock assessment 
of eastern Bering Sea snow crab. In Stock assessment and 
fishery evaluation report for the king and Tanner crab fish- 
eries of the Bering Sea and Aleutian Islands regions. 2011 
crab SAFE, 37-168 p. North Pacific Fishery Management 
Council, Anchorage, AK [Available at website.] 
