Factors Affecting Historical Red King Crab Recruitment Around Kodiak Island, Alaska

Factors Affecting Historical Red King Crab Recruitment Around Kodiak Island, Alaska

W.R. Bechtol and G.H. Kruse

Factors Affecting Historical Red King Crab Recruitment Around Kodiak Island, AlaskaThis is part of Biology and Management of Exploited Crab Populations under Climate Change
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Description

Waters around Kodiak Island in the Gulf of Alaska once supported the world’s largest fishery for red king crab Paralithodes camtschaticus. Commercial fisheries occurred at low levels beginning in 1937, but increased rapidly in the 1960s to a peak harvest of 42,800 t in 1965. Stock abundance declined in the late 1960s, moderated in the 1970s, and collapsed in the early 1980s, but a commercial fishery closure since 1983 has not resulted in stock recovery. We used a modified autocorrelated Ricker spawner-recruit model to examine crab recruitment patterns for the 1964-1999 brood years (n = 36 observations) in relationship to biotic and abiotic variables hypothesized to affect survival of early life stages of Kodiak red king crab. Our hierarchical approach for model selection used AICc, the Akaike Information Criterion corrected for small sample size. Results revealed a strong negative association between biomass of age 3+ Pacific cod Gadus macrocephalus and crab recruitment. The Kodiak stock of red king crab declined following a period of high harvest rates in the late 1960s that skewed sex ratios and compromised reproductive potential. Then in the late 1970s, it appears that predation on crab may have increased, possibly due to increased Pacific cod biomass combined with a nearshore shift in cod spatial distribution that resulted from warmer temperatures associated with a climate regime shift. Inclusion of percent cloud cover at Kodiak, Alaska, as a second ecological variable slightly improved model fit, but the associated mechanism is unclear.

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