Limits on Gear and Seasons. Catches of halibut and sablefish have historically been controlled through a combination of area, season, and gear restrictions. Most vessels that are engaged in these fisheries are catcher vessels that do little processing of the catch at sea. However, there are a few catcher-processor vessels (freezer-longliners) in the halibut fishery and a larger number in the sablefish fishery. The directed fishery for halibut uses longline gear. The directed fishery for sablefish uses longline, pot, and trawl gear. In the eastern Gulf of Alaska, 95% of the sablefish TAC is reserved for longline operations. Elsewhere in the Gulf of Alaska, longline fishermen are allocated 80% of the TAC. The use of pot gear for sablefish is prohibited in the Gulf of Alaska, but permitted in the Aleutian Islands and the Bering Sea. The Bering Sea TAC is split 50:50 between fixed gear (longline and pots) and trawls. Seventy-five percent of the Aleutian Islands TAC is reserved for fixed gear.
Reporting Requirements. Halibut buyers in Alaska are required to record landings on fish tickets (official landing receipts) from the Alaska Department of Fish and Game (ADF&G), which are either mailed directly to the IPHC or delivered to ADF&G offices and forwarded to the IPHC. Washington and Oregon fishery departments and the Canadian Department of Fisheries and Oceans also forward halibut landings data to the IPHC. The IPHC has also collected logbook data on an occasional basis to supplement information on the CPUE, productive fishing locations, gear configuration, and the mortality of undersized fish that are discarded.
Prior to 1986, ADF&G fish tickets were the sole source of landings data for the sablefish fishery off Alaska. Because at-sea processors were not subject to ADF&G reporting requirements, beginning in 1986, they were required to file "hail weight" reports with NMFS. These reports eventually evolved into the current Weekly Processor Reports. With expansion of the observer program in 1990, observer estimates of landings became available for some larger vessels (30% of vessels greater than 60 feet in overall length). In addition, logbook reporting requirements were strengthened to facilitate on-site verification of catches.
Pacific halibut and sablefish are both long-lived bottom-dwelling species. Halibut are the largest commercial species of the North Pacific, averaging 18 kg each, but occasionally exceeding 180 kg. Halibut are primarily found at 15-200 m depths on sand, gravel, or cobble substrates. Sablefish are considerably smaller (<5 kg) and occur at somewhat greater depths (100-1,500 m). Halibut are distributed from California to the Sea of Japan and into the Bering Sea (IPHC, 1987; Trumble et al., 1993). Sablefish extend this range to include waters off Baja California. Each species is considered a single stock throughout its range. Note, however, that whereas halibut are jointly managed by the United States and