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Please use this identifier to cite or link to this item: http://hdl.handle.net/10793/1159

Title: Estimating biomass, fishing mortality, and “total allowable discards” for surveyed non-target fish
Authors: Shephard, S.
Reid, D.G.
Gerritsen, H.D.
Farnsworth, K.D.
Keywords: bycatch
catchability
data-poor stocks
elasmobranchs
Pope's postulate
stock assessment
Issue Date: 2014
Publisher: Oxford University Press
Citation: Shephard, S., Reid, D. G., Gerritsen, H. D., & Farnsworth, K. D. (2014). Estimating biomass, fishing mortality, and “total allowable discards” for surveyed non-target fish. ICES Journal of Marine Science: Journal du Conseil, fsu146.
Series/Report no.: 72;2
Abstract: Demersal fisheries targeting a few high-value species often catch and discard other “non-target” species. It is difficult to quantify the impact of this incidental mortality when population biomass of a non-target species is unknown. We calculate biomass for 14 demersal fish species in ICES Area VIIg (Celtic Sea) by applying species- and length-based catchability corrections to catch records from the Irish Groundfish Survey (IGFS). We then combine these biomass estimates with records of commercial discards (and landings for marketable non-target species) to calculate annual harvesting rates (HR) for each study species. Uncertainty is incorporated into estimates of both biomass and HR. Our survey-based HR estimates for cod and whiting compared well with HR-converted fishing mortality (F) estimates from analytical assessments for these two stocks. Of the non-target species tested, red gurnard (Chelidonichthys cuculus) recorded some annual HRs greater than those for cod or whiting; challenging “Pope's postulate” that F on non-target stocks in an assemblage will not exceed that on target stocks. We relate HR for each species to two corresponding maximum sustainable yield (MSY) reference levels; six non-target species (including three ray species) show annual HRs ≥ HRMSY. This result suggests that it may not be possible to conserve vulnerable non-target species when F is coupled to that of target species. Based on biomass, HR, and HRMSY, we estimate “total allowable catch” for each non-target species.
Description: This is a pre-copy-editing, author-produced PDF of an article accepted for publication in ICES Journal of Marine Science following peer review. The definitive publisher-authenticated version “Shephard, S., Reid, D. G., Gerritsen, H. D., & Farnsworth, K. D. (2014). Estimating biomass, fishing mortality, and “total allowable discards” for surveyed non-target fish. ICES Journal of Marine Science: Journal du Conseil, fsu146.” is available online at: doi:10.1093/icesjms/fsu146 peer-reviewed
URI: http://hdl.handle.net/10793/1159
Appears in Collections:Peer Reviewed Scientific Papers

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