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Butterfish 2014 stock assessment
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2015
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Description:A butterfish (Peprilus triacanthus) stock assessment was completed in January 2014. This document provides a summary of the data and results of the final model accepted by the Stock Assessment Review Committee panel. Commercial data used in the assessment consisted of US landings and discard estimates, and commercial mean weights at age, from 1989-2012. Survey data used in the assessment consisted of swept area abundances, and abundance indices (number/tow) by age from 1989-2012 Northeast Fisheries Science Center (NEFSC) fall surveys (inshore and offshore); and swept area abundances from the Northeast Area Monitoring and Assessment Program (NEAMAP) fall (2007-2012) survey. An augmented version of the age-structured assessment program (ASAP) catch at age model of Legault and Restrepo (1999) was used in the assessment. ASAP augmentations included: 1) reparameterization of catchability as the product of availability and efficiency; 2) estimation of natural mortality (M) made possible by fixing catchability, and 3) a length-based calibration of bottom trawl survey data in 2009-2012 was performed internal to the model. Catchability for the NEFSC fall offshore survey was reparameterized by using an average measure of availability based on bottom temperature, while efficiency was based on the relative efficiency of the FRV Albatross IV to the FSV Henry B. Bigelow, given the assumption that the Bigelow was 100% efficient for daytime tows. Results of the model include an estimate of M= 1.22 (CV = 0.05). The current fishing mortality (F2012= 0.02, CV = 0.33) is well below the accepted overfishing reference point (FMSY proxy = 2M/3 = 2 x 1.22/3 = 0.81). The accepted spawning stock biomass reference point SSBMSY proxy (median SSB based on a 50 year projection at the FMSY) proxy is 45,616 mt (CV = 0.25). SSB2012 is estimated to be 79,451 mt, which is well above the accepted SSBMSY proxy. The accepted maximum sustainable yield (MSY) proxy is 36,199 mt (CV = 0.20). SSBthreshold is one half the SSBMSY proxy, or 22,808 mt. Overfishing is not occurring, and the stock is not overfished. [doi:10.7289/V5WM1BCT (http://dx.doi.org/10.7289/V5WM1BCT)]
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Content Notes:by Charles F. Adams, Timothy J. Miller, John P. Manderson, Dave E. Richardson, and Brian E. Smith.
"Web version posted August 28, 2015"--Document's home page: http://www.nefsc.noaa.gov/publications/crd/crd1506/
"August 2015."
doi:10.7289/V5WM1BCT (http://dx.doi.org/10.7289/V5WM1BCT)
System requirements: Adobe Acrobat Reader.
Includes bibliographical references (page 21-22).
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