Migrations, abundance, and origins of salmonids in offshore waters of the North Pacific, 1997-99 (original) (raw)

as seminars, workshops, and exchanges of scientific personnel for high seas research cruises. At the 1993 annual meeting of NPAFC, the Committee on Scientific Research and Statistics (CSRS) identified "the impact of change in the productivity of the North Pacific Ocean on Pacific salmon" as a critical research issue. CSRS scientists agreed that research on this issue should focus on: "(1) the factors affecting current trends in the productivity of the North Pacific Ocean and their impacts on salmonid carrying capacity, and (2) the factors affecting changes in biological characteristics of Pacific salmon. These characteristics include growth, size at maturity, age at maturity, oceanic distribution, survival, and abundance." Since 1995, the CSRS has developed annual Science Plans to address this research. A new and substantially revised NPAFC Science Plan will be developed in FY00. In 1995, the U.S. National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center, Auke Bay Laboratory (ABL), developed an Ocean Carrying Capacity (0CC) research plan to address the research issues identified by NPAFC. The two principal goals of the plan are "to describe the role and spatial distribution of salmonids in the marine ecosystem, and to test for density dependence in the growth rate of salmonids during various periods of ocean residency." As part of the NPAFC Science Plan, the 1999-2000 U.S. plan incorporates 0CC research on (1) coastal juvenile salmon studies, (2) Gulf of Alaska (GOA) ocean ecology, (3) retrospective analyses, (4) stock identification, and (5) high seas salmon studies. High seas salmon research at FRI is frilly integrated with the 0CC Program at ABL, the research, management, and enforcement activities of NPAFC, and, as needed, other relevant international organizations and bilateral agreements. FRI has a long-term commitment to conservation and management of Pacific salmon and steelhead trout, and is continuing a program of research on migrations, abundance, and origins of salmonids in the North Pacific Ocean and adjacent seas. Our principal research goal is to address research issues and associated questions raised in the NPAFC Science Plan through an integrated program of field, laboratory, and computer modeling research. New lines of research may be developed in response to the changing situation of salmonids and fisheries in the North Pacific. The work involves use of FRI's large archive of historical high seas salmon research samples and data (1954-present), as well as new samples and data acquired through our well-established cooperative high seas salmon research programs with Canada, Japan, and Russia (1983-present). This annual report summarizes our international cooperative high seas salmon research results in FY99 (1 October 1998-30 September 1999) under NOAA Contract No. 5OABNF700003, as well as some pertinent results from previous years. The research was conducted in two major areas: (1) salmon stock origin studies for research, management, and enforcement, including high seas tagging (data storage tags, high seas disk tags, coded-wire tags), scale pattern analysis, and other methods (genetic stock identification and thermal otolith marks), and (2) ocean ecology, carrying capacity, and 9 GOA in July) show fish spent most of the time in the top 40 meters, with infrequent excursions to 60-100 m. Although estimated times of sunrise and sunset have not been calculated and fitted to the data, temperature and depth data seem to indicate a diurnal behavior cycle similar to that seen in 1998. 3.1.1.2 High seas disk tags 3.1.1.2.1 Releases With the goal to maximize return of disk tags from coastal areas in North America and Asia, FRI developed a new high seas disk tag in 1997. These tags display in English, Japanese, and Russian the addresses of high seas salmon tag collection centers in Hokkaido, Japan (National Salmon Resources Center), Petropavlovsk, Russia (KamchatNlRO) and the United States (FRI). Salmonids released during cooperative Japanese cruises have been double-tagged with these new tags and FAJ disk tags. Scientists aboard the Great Pac~flc in the GOA and eastern North Pacific conducted tagging operations on viable salmonids caught by trawl in 1998 and 1999 (Fig. 12; Carlson et al. 1998, 1999b). In 1998, seven salmonids were released with disk tags and DSTs. In 1999, tagging experiments were expanded resulting in 62 salmon releases, including 41 sockeye, 18 chum, 1 coho and 2 chinook salmon. Among these tagged fish, 34 also carried DSTs (Table 1, Carison et al. 1 999b). Recoveries of six salmon prove the feasibility of tagging trawl-caught salmon in good condition. Tagging operations on viable salmonids caught by longline were conducted by scientists aboard the Wakatake maru in the central North Pacific and Bering Sea in summer 1998-1999 (Fig. 12; Ueno et al. 1998, Fukuwaka et al. 1999). In 1998, 884 salmonids were disk tagged and released, including 35 salmonids tagged with DSTs. In 1999, tagging experiments resulted in the release of a total of 398 salmonids, including 16 sockeye, 241 chum, 134 pink, 5 coho, and 2 chinook salmon. Among these releases, 36 fish were tagged with DSTs (Fig. 12, Table 1). In 1999 aboard the Oshoro maru, 26 salmonids (41 in 1998) in the central North Pacific Ocean along the 165°W transect, and 63 salmon (28 salmonids in 1998) in the GOA along the 145°W transect were double disk-tagged and released including 45 salmon also tagged with DSTs (Fig. 12; Table 1; Yamaguchi et al. 1999). Along 180°, 10 fish were disk-tagged in 1998. 3.1.1.2.2 Recoveries From 1 September 1997 to 15 September 1998, seventeen Japan-U.S. disk tags were recovered, including five fish that also carried DSTs. Data storage tags were recovered from one each of steelhead, pink and coho salmon that returned to Alaska and from two 10 chum salmon that returned to Hokkaido, Japan. The remaining disk tag recoveries included 12 chum salmon that were recovered in Japan (Myers et al. 1998b). High seas tag recoveries have increased dramatically to a total of 75 Japan-U.S. tags