Fish/Shellfish Research and Management - Fish/Shellfish Research
Date Published: November 2010
Number of Pages: 101
Publication Number: FPT 11-02
Author(s): Farron Wallace, Tien-Shui Tsou, Yuk Wing Cheng, and Lorna Wargo
Black rockfish (Sebastes melanops) is an important natural resource to the coastal recreational fisheries that coastal communities rely upon for a vital economy. The economic value in Washington State in 2006 for saltwater fish other than salmon and steelhead was $11.2 million (TCW Economics, 2008). Black rockfish accounts for 80% of the annual catch from bottomfish targeting angler trips. Due to the importance of this resource, the Washington Department of Fish and Wildlife and the coastal recreational charter boat fleets have been collaborating on tagging projects for the conservation of black rockfish and other coastal groundfish species. Information collected through these projects has been incorporated into stock assessments for evaluating black rockfish stock status and supporting Washington’s and Pacific Fishery Management Council’s (PFMC) management needs. This report compiles nearly 30 years of black rockfish tagging studies, and is intended to serve as a key reference document describing changes in research objectives and methods that evolved over time as research built upon earlier studies.
In Washington, the first black rockfish tagging project began in 1981. Since then, there were several major changes to objectives and scope of the project. These changes were reflected in the distribution of tagging effort over time. The effort distribution and its geographical extent for tag releases were based on salmon management Punch Card Areas (PCA 1-4) or a finer scale division of these areas (Figure E-1). Between 1981 and 1985, black rockfish were tagged and released in selected areas located within the recreational fishing areas off the ports of Ilwaco (PCA 1), Westport (PCA 2) and Neah Bay (PCA 3) aboard both Department and recreational charter vessels. Between 1986 and 1990, an effort was made to allocate tagging effort in a random fashion throughout coastal waters fished by the Washington recreational fleet. PCAs were divided among six tag areas each with three sub-areas (a, b and c) and the amount of time fishing (effort) was equally allocated among each tag sub-area. No effort was expended between the mouth of the Columbia River and Ledbetter Point, Washington, due to the lack of rocky habitat. Beginning in 1998, the study area was constrained to the central Washington coast in areas within the operation range of the Westport charter fleet (tag sub-area 3a, 3b, 3c and 5c). Between 1998 and 2000, distribution of tagging effort was based on the knowledge of the charter vessel captain and tagging crew to distribute tags “proportionally” to the resource in this area. In order to formalize methods and provide greater consistency in effort distribution through time, rocky habitat was identified and geo-referenced. Beginning in 2001, tagging effort was weighted proportionately and distributed relative to the amount of rocky habitat found in each 2-degree latitudinal block.
Tag release and recovery statistics reflected changes in research goals, objectives, and funding, which affected the number of releases and spatial distribution of the release sites (Table E-1). Between 1981 and 1990, a total of 52,042 fish were tagged with three-inch Floy FD-68B T-end spaghetti anchor tag of which 1,962 were recovered. In the early part of the study (1981-1985), tag recoveries were entirely dependent on voluntary returns. A catch sampling program was initiated in 1986 and continued through 1992 in an effort to recover tagged black rockfish from both the recreational and commercial fishery. Tagged black rockfish were also recovered through voluntary returns. Although the catch sampling program ended in 1992, voluntary returns continued through 1997. Beginning in 1998, fish were internally tagged with Code Wire Tags (CWT) or Passive Integrated Transponder (PIT) tags. A catch sampling program was again initiated to sample recreational catch for tags caught from the central Washington coast. Because these tags are not visible, there are no voluntary recoveries. Tagged black rockfish have been part of the recreational catch for nearly three decades with some tagged fish recovered after more than 15 years at large. As a consequence of tag loss, fishing, and natural mortality, and immigration and emigration tags from all release groups show a significant declining recovery rate through time (Table E-2). Although, the largest proportion of tag recoveries occurred near the area of release, data clearly show that tag recoveries could occur at extended distances from the release area. However, there was a declining tag recovery trend with increasing distance from release area.
Although tagging objectives and methods have varied through time, tagging information has provided key information to determine population dynamics for the black rockfish stock located between Cape Falcon, Oregon, and Cape Flattery, Washington. Continuation of a data collection program that measures biomass or population trends such as the current tagging program is essential for monitoring the health of this important coastal resource and for supporting future stock assessments of this species. Much consideration has been taken to ensure proper evaluation of these data. Importantly, changes in spatial and temporal distribution of tag releases and the spatialtemporal changes in the fisheries need to be considered for proper interpretation of tag recovery rates and movement patterns.
The black rockfish tagging program was last reviewed in 2008 based on program costs and its efficacy in providing information needed for sustainable ecosystem management. An overall conclusion was that there was an urgent need to develop a long-term monitoring program with greater spatial extent for multiple fish species to support Washington fisheries management. The review recommended the use of fixed stations for capture and recapture of all fish species along the entire Washington coast using PIT tags. The experiment will be conducted in spring and fall, before and after the main fishing season. The revised tagging program will provide more unbiased biological information on spatial movement and growth for multiple fish species commonly caught in the recreational fishery. It will also improve validity and reliability of estimates on abundance trends. The recommendations and changes will be field tested beginning in fall 2010. Current protocols for tag release and recovery will continue.