Pacific Cod Predation on Tanner Crab in Marmot Bay, Alaska

Pacific Cod Predation on Tanner Crab in Marmot Bay, Alaska

J.D. Urban

Pacific Cod Predation on Tanner Crab in Marmot Bay, AlaskaThis is part of Biology and Management of Exploited Crab Populations under Climate Change
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Description

Pacific cod (Gadus macrocephalus) have long been recognized as an important predator of Tanner crab (Chionoecetes bairdi). This study reports on Pacific cod predation on Tanner crab populations as determined from the stomach contents of Pacific cod sampled seasonally for a year in Marmot Bay off Kodiak Island, Alaska. This predator/prey relationship is of particular interest since both the predator and prey are commercially important species. Extrapolations from this 14 month study suggest that cod consumed over 365 million immature Tanner crab, mostly 10-45 mm carapace width, from four different cohorts. The cod per capita predation rate suggests moderate density-dependence on prey numbers, but cod were also confirmed to be opportunistic predators that rapidly switched from Tanner crab to alternative prey species. Without more extensive temporal and spatial data, the role cod predation plays in regulating crab populations is difficult to determine.

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