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The California drift gillnet fl eet has operated off the U.S. west coast since it developed in the late 1970’s. At its full extent, fi shing effort ranged from the Southern California Bight north to Oregon. The fi shery initially targeted pelagic sharks (family Alopiidae), but shifted targets in the mid-1980’s to swordfi sh, Xiphias gladius, due to the species’ higher value and to the regulatory changes which created an economic advantage for targeting swordfi sh compared to thresher shark, Alopias vulpinas. Consequently the number of participants in the once-small fl eet substantially increased. Conservation concerns over the entanglement of nontarget species, including sharks, sea turtles (family Dermochelyidae and Cheloniidae), and marine mammals, led to the enactment of a series Introduction The Pacifi c Fishery Management Council’s Fishery Management Plan for U.S. West Coast Highly Migratory Species (NMFS, 2007) describes fi ve fi sheries for highly migratory species (HMS), defi ned by the combination of target species and gear type. The largemesh California drift gillnet (DGN) fi shery1 is one of these fi ve federally 1There are two other entangling net fi sheries off the coast of California besides the large-mesh California drift gillnet fi shery, including a set net fi shery and the small-mesh drift gillnet fi shery that targets white seabass, Atractoscion nobilis. Only the large-mesh fi shery targets HMS sharks and swordfi sh. managed HMS fi sheries, along with the albacore, Thunnus alalunga, surface-hook-and-line fi shery, the tuna purse seine fi shery, the deep-set longline tuna fi shery, and the harpoon swordfi sh, Xiphias gladius, fi shery. California’s HMS fi sheries have generally declined from their peak in the 1960’s, when the tuna purse seine fi shery targeting Pacifi c bluefi n tuna, Thunnus orientalis, was one of the largest tuna fi sheries (Calkins, 1982). However, after the closure of the Mexican Exclusive Economic Zone (EEZ) to U.S. commercial vessels in the late 1970’s, the U.S. tuna purse seine fl eet largely disappeared (Hanan, 1983). Although the albacore surface-hookand-line fi shery (Dotson and Center2) appears to be operating near historical capacity, swordfi sh fl eets have experienced a similar decline in recent years 2Dotson, R. C. 1980. Fishing methods and equipment of the U.S. west coast albacore fl eet. U.S. Dep. Commer., NOAA, Natl . Mar. Fish. Serv., Southwest Fish. Sci. Cent., NOAA-TMNMFS-SWFC-8, 126 p. to that of the purse seine fl eet in terms of participation, effort, catch, landings, and revenues. The west coast swordfi sh fi shery has primarily utilized three methods of fi shing in recent decades: harpoon, shallow-set longline, and drift gillnet. A harpoon swordfi sh fi shery has operated off the U.S. west coast since ancient times, with the modern fi shery beginning around the early part of the 20th century. While having little bycatch, the ineffi ciency of this gear type resulted in much of the fl eet switching to the DGN fi shery in the 1980’s (Coan et al., 1998). The DGN fi shery was state-managed before 2004, at which point existing state regulations were incorporated into the Federal HMS FMP, but the permit system continued to operate under California state law. In the 1990’s a pelagic longline swordfi sh fi shery operated off the U.S. west coast; however, shallow-set longline gear was not authorized as a legal gear for targeting swordfi sh off of time and area closures over a period of 19 years to reduce the bycatch of those species. As a result, the fi shery declined dramatically. This paper analyzes catch and effort data for the fi shery to determine the effects of these management measures on targeted pelagic sharks and swordfi sh catch per unit of effort (CPUE). Unlike traditional catch-rate analysis, which seeks to standardize fi shing effort heterogeneity to produce a measure of relative stock abundance, our analysis uses a linear regression of set-level catch counts on time and area combinations where fi shing occurred over the full period for which data is available to estimate the effects of time and area closures on fi shery catch rates while controlling for population abundance trends. Resampling methods are used to quantify uncertainty in the estimates. The analysis documents reduced common thresher and shortfi n mako shark, Isurus oxyrinchus, CPUE resulting from effort shifting out of higher to lower catch rate areas. Before the 2001 establishment of the Pacifi c Leatherback Conservation Area (PLCA) closure which eliminated most effort in the fi shery north of Pt. Conception, the fi shery operated from the Mexican territorial water border northward to Oregon. The cumulative effect of all enacted time and area closures was to concentrate fi shing effort within the Southern California Bight, likely contributing to a decline in vessel participation. The socioeconomic impacts on the operation of the fi shery and on the usefulness of drift gillnet CPUE data for stock assessments are discussed.

marine fisheries review

From Sunrise to Sunset in the California Drift Gillnet Fishery: An Examination of the Effects of Time and Area Closures on the Catch and Catch Rates of Pelagic Species