Predation of hatchery-cultured juvenile red king crabs (Paralithodes camtschaticus) in the wild

Abstract

The ecologically and commercially important red king crab (Paralithodes camtschaticus) is depleted throughout much of the North Pacific and thought to be recruitment-limited, making it an appropriate candidate for stock enhancement efforts. Information on predation of newly settled red king crabs in nearshore habitats is needed to assess the feasibility of large-scale releases. We tethered hatchery-cultured red king crabs of two sizes (range: 1.75–4.08 mm carapace width) in the field for 24 h trials in July and September 2011 and used underwater video cameras to identify predators and predation susceptibility. We identified hermit crabs (Pagurus spp.), Alaskan ronquil (Bathymaster caeruleofasciatus), Arctic shanny (Sticheus punctatus), northern rock sole (Lepidopsetta polyxystra), and kelp greenling (Hexagrammos decagrammus) as predators. Survival did not vary by body size or deployment month; however, small crabs were consumed sooner than large crabs. Most predation events occurred in daylight hours, with the exception of Alaskan ronquil. Our results suggest stock enhancement efforts should consider predator assemblages when developing release strategies. Future studies should investigate spatial variation in predation pressure at multiple locations on broad temporal scales to optimize release strategies and understand population-level effects.