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Fishery Bulletin 90(1). 1992 



Shelikof Strait is located in the 

 northern Gulf of Alaska between 

 the Alaska Peninsula and the 

 Kodiak Archipelago at about 57°N 

 (Fig. 1). Water depths within 

 Shelikof Strait exceed 300 m in 

 some areas. At the northeast and 

 southwest ends of the strait there 

 are sill depths of about 200 m. 

 Depths of greater than 500 m are 

 reached on the continental slope im- 

 mediately beyond the southwestern 

 sill. The southern part of the strait 

 and waters to the south comprising 

 about 12,450 km^, are the areas oc- 

 cupied by eggs and larvae of wall- 

 eye pollock originating in Shelikof 

 Strait. 



Physical oceanography 



The water of Funka Bay originates 

 from the seasonal influx of two 

 water masses: The Tsugaru Warm 

 Water and the Oyashio Water. 

 Tsugaru Warm Water enters the 

 Bay in late-summer when surface 

 waters exceed 15°C and there is a strong thermocline 

 in the upper 20 m (Nakatani 1988). Autumnal cooling 

 produces isothermal conditions and cooling to about 

 4°C (Winter Funka Bay Water: Ohtani and Kido 1980). 

 In late-winter or early-spring, the cold (<2°C), less 

 saline (<33.0"/oo) Oyashio Water usually intrudes into 

 the Bay above the Winter Funka Bay Water, produc- 

 ing a stratified condition with a temperature inversion. 

 In late-spring and early-summer, seasonal warming of 

 surface waters occurs and a thermocline develops. 

 Throughout the year, bottom temperatures remain at 

 3-6°C. 



Shelikof Strait has an estuarine type circulation, with 

 less seasonal variation than Funka Bay. In its upper 

 layers, the Alaska Coastal Current (ACC) flows to the 

 southwest and is particularly pronounced on the Alaska 

 Peninsula side of the Strait. During runoff seasons 

 Gate-spring to early-fall), substantial amounts of fresh- 

 water enter the strait, primarily from Cook Inlet, and 

 flow along the Peninsula until thoroughly mixed with 

 the ACC. From approximately 150m to the bottom, 

 more saline water flows into the strait over the sill to 

 the southwest (Kim 1987). During April and May (when 

 walleye pollock eggs and larvae are present), near- 

 surface water temperatures in the ACC are generally 

 0-4°C, warming to 7°C by late May, while the deeper 

 waters are generally 4-5. 5°C. Salinity varies from 

 about 31 to 33.5''/oo. 



In Fimka Bay there is considerable interannual varia- 

 tion in the date when the Oyashio Water intrudes and 

 in the length of time that surface temperatures remain 

 cold (<3°C). In Shelikof Strait, interannual variation 

 in the frequency, intensity, and track of storms affects 

 water properties and transport. 



Biological comparisons 



Spawning 



In Funka Bay, adult walleye pollock mature and spawn 

 from November to March, with peak spawning activ- 

 ity occurring in January and February (Maeda et al. 

 1976 and 1981, Yoon 1981). whereas in Shelikof Strait 

 most fish mature in February and March and spawn- 

 ing peaks in early April (Kim 1989, Kendall and Pic- 

 quelle 1990). Pelagic eggs are present in Funka Bay 

 from December until March, and in Shelikof Strait eggs 

 are present mainly in April. There is some interannual 

 variation in time of spawning in Funka Bay, and eggs 

 have even been collected in November and April 

 (Maeda et al. 1980). Thus the spawning season seems 

 to occur earlier in the year and lasts longer in Funka 

 Bay than in Shelikof Strait. Spawning occurs mainly 

 at depths of 100- 120 m near the entrance of Funka Bay 

 (Maeda et al. 1976, Nakatani 1988, Nakatani and 

 Maeda 1989). In Shelikof Strait, spawning is concen- 



