Susceptibility of five species of rockfish (Sebastes spp.) to different survey gears inferred from high resolution behavioral data, Science Bulletin 2021-05

Identification Information

Citation

Originator: Rasmuson, L. K.

Publish Date: May 2021

Online Link: https://www.dfw.state.or.us/MRP/publications/docs/Rockfish%20Height%20off%20Bottom.pdf

BPA Project #:

Contact Information

Agency: Oregon Department of Fish and Wildlife

Name: Leif Rasmuson

Job Position: Marine Fisheries Research Project Leader

Telephone: 541-270-5561

E-Mail Address: leif.k.rasmuson@odfw.oregon.gov

Description

Abstract: Fisheries independent surveys are an important data input for stock assessments. However, these surveys are expensive to conduct and require precise, well thought out planning to be effective. Although the amount of money allocated to a survey is often dictated by factors beyond the control of the survey development team, surveys must incorporate their understanding of the biology of the focal species or species group into the survey design. Acoustic telemetry data can provide a high-resolution dataset to answer some of these questions. In this study, we reanalyze past acoustic telemetry studies on Black Rockfish (Sebastes melanops), Copper Rockfish (Sebastes caurinus), Deacon Rockfish (Sebastes diaconus), Quillback Rockfish (Sebastes maliger) and Yelloweye Rockfish (Sebastes ruberrimus) in order to apply these data to future survey development. We combined the telemetry data with multibeam bathymetry data to 1) understand how the height off bottom of each species changed throughout a day and 2) simply define the habitat utilized by each species. We found, on average, Black, Deacon and Yelloweye Rockfish were all more than 1 m off bottom, whereas Copper and Quillback remained on, or near the bottom throughout the day. Deacon Rockfish were associated with the most rugose bottom, followed by Yelloweye Rockfish. Black, Copper and Quillback Rockfish all utilized low relief habitats. In general, we hypothesize that Black and Deacon Rockfish are good candidates for survey by hydroacoustics, whereas, Copper and Quillback Rockfish appear to be good candidates for survey by bottom trawl. However, our study was only conducted at a single nearshore reef and as such the results should be considered experimental and need validation. Surprisingly, due to the habitat they reside in, Yelloweye Rockfish were available to hydroacoustics, and likely not available to bottom trawl. However, Yelloweye Rockfish have variable behaviors, as reported by the original work, and as such, we are wary to suggest that hydroacoustics are an appropriate survey tool. We do, however, propose that Yelloweye Rockfish potentially contribute to backscattering values of acoustic surveys conducted for midwater rockfish, and that bottom trawls are likely not an effective survey tool for Yelloweye Rockfish.

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Geographic Extent: Cape Perpetua to Seal Rock and out to Stonewall Bank

Status: Final

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Format: pdf

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