First Results of the Tagging of Shortspine Thornyhead in Alaska

April 15, 2017

Shortspine thornyhead (Sebastolobus alascanus) is a commercially valuable deep dwelling rockfish species that has been tagged in Alaska waters since 1992. These tagging results are the primary analyses available for evaluating the movement of this species, which will allow managers to determine the appropriate geographic scale of management. A total of 13,897 tagged fish have been released, with 228 recoveries reported during 1992–2016. Of the returned tags, 19% traveled<2 M (nm) between tagging and recovery location, 36% traveled 2–5 nm, 18% traveled 6–10 nm, 12% traveled 11–50 nm, 4% traveled 51–100 nm, and 11% traveled>
100 nm. While a small percentage of tagged shortspine thornyhead traveled large distances, at times crossing management and international boundaries, the low movement rate indicates that the current scale of management for shortspine thornyhead rockfish in Alaska appears to be appropriate.

Shortspine thornyhead (Sebastolobus alascanus, SST) is a long-lived, commercially valuable, deep dwelling species that inhabits the northeastern Pacific Ocean from Baja Mexico to the Gulf of Alaska (GOA), westward to the Aleutian Islands (AI), Eastern Bering Sea (BS), and into the Seas of Okhotsk and Japan (Love et al., 2002). Adult SST are generally found along the continental slope at depths of 150–450 m. Thornyheads belong to the family Scorpanenidae, which contains the rockfishes. While SST are considered rockfish, they are differentiated from Sebastes in that they lack a swim bladder, making them ideal tagging specimens. The Alaska Fisheries Science Center (AFSC) of the National Marine Fisheries Service (NMFS) has been tagging SST in Alaska waters since 1992. To our knowledge this is the first tagging study on this species. We present here the first summary of the release and recapture data from SST tagging.

Spatially explicit management, that is managing allowable catch by areas, is used for management of several economically important fisheries in Alaska, including the thornyhead stock complex fishery. The thornyhead complex contains three Sebastolobus species, including SST (Echave et al., 2015). To help managers determine the appropriate scale of spatial management, an understanding of the distribution and movement of fishes is necessary. Tagging of SST occurs during stock assessment surveys. Analysis of tag data is used to examine SST movement patterns and can assist with questions regarding stock structure and growth. The objectives of this study are to provide a summary of the information on SST growth and movement based on E-mail address: katy.echave@noaa.gov. http://dx.doi.org/10.1016/j.fishres.2017.06.015 Received 11 April 2017; Received in revised form 20 June 2017; Accepted 22 June 2017 Available online 07 July 20170165-7836/ Published by Elsevier B.V. these tagging data, and to examine how these growth and movement results contribute to the definition of SST stock structure.

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Last updated by Alaska Fisheries Science Center on 11/15/2018

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