Age, Growth, and Reproductive Biology of Alaskan Skates

The susceptibility of skates to fishing pressure has been well documented. In the North Atlantic, populations of two once-abundant species, the barndoor skate, Dipturus laevis, and the common skate, D. batis, may have been fished to small fractions of their historical population levels. Fishing mortality has also dramatically altered the relative abundance and population structure of North Sea rajids. In the U.S. Pacific, Alaskan skate landings greatly exceed those of all other states combined. During 2005, approximately 23,000 metric tons of skates were caught as bycatch in Alaskan groundfish fisheries in the Bering and Aleutian Islands, most of which were discarded. Recently, directed fisheries for big (Raja binoculata) and longnose (R. rhina) skates have emerged in the Gulf of Alaska. The deleterious effects of fishing on North Atlantic skate populations emphasize the need for detailed biological information and effective management strategies for this potentially vulnerable group. However, life history information for skates from Alaskan waters is extremely limited. To address this knowledge gap, the age, growth, and reproductive biology of seven bathyrajid species (Bathyraja aleutica, B. interrupta, B. lindbergi, B. maculata, B. minispinosa, B. taranetzi and B. trachura) is currently being determined. Successful completion of this project will provide fishery scientists and resource managers with critical biological information necessary for effective management of several Alaskan skate species at the inception of emerging fisheries. Establishing species-specific regulations and quotas as fisheries are being developed is necessary to ensure sustainability in these historically susceptible fisheries.