9. A History of the Distribution and Abundance of Spiny Dogfish in Alaska Waters
Christina L. Conrath and Robert J. Foy
Abstract.—Data from research surveys conducted by the National Marine Fisheries Service’s (NMFS) Alaska Fisheries Science Center and the International Pacific Halibut Commission (IPHC) were examined along with catch data from NMFS’s North Pacific Groundfish Observer Program to determine the distribution, abundance, and status of spiny dogfish Squalus acanthias in Alaska. Dogfish are present in the Gulf of Alaska, Bering Sea, and Aleutian Islands but survey and observer data indicate they are most abundant in the central and eastern Gulf of Alaska in waters less than 200 m deep. All data sources indicate that dogfish have increased in abundance in the Gulf of Alaska in recent years. Log-transformed catch per unit effort (CPUE) of dogfish calculated from the NMFS trawl survey data ranged from 0.47 sharks/km2 in 1984 to 0.91 sharks/km2 in 2007, with a peak of 1.17 sharks/km2 in 2003. Log-transformed CPUE of spiny dogfish calculated from the NMFS longline survey data ranged from 0.041 sharks/100 hooks in 1979 to 0.16 sharks/100 hooks in 2007, with peaks in abundance of 0.23 sharks/100 hooks in 1983 and 1998. Log-transformed CPUE of dogfish calculated from the IPHC annual longline survey data showed a similar trend and ranged from 0.84 sharks/100 hooks in 1997 to 1.18 sharks/100 hooks in 2006, with a peak value of 1.38 sharks/100 hooks in 2003. Estimates of the incidental catch of dogfish by Alaska fisheries in the Gulf of Alaska calculated from NMFS observer data from 1990 to 2007 were variable and ranged from 140 to 865 metric tons (mt), with peak values of over 650 mt in years 1998, 1999, 2006, and 2007. Dogfish are currently managed as a member of the “other species” complex by the North Pacific Fishery Management Council in Alaska waters. The increasing abundance of this species in the Gulf of Alaska in recent years and the increasing probability of a fishery developing may necessitate a species-specific management strategy for dogfish in Alaska waters.