Report of workshop on the Determination of Acoustic Target Strength of Redfish (WKTAR).
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Original versionThis report is not to be quoted without prior consultation with the General Secretary.
The Workshop on the Determination of Acoustic Target Strength of Redfish (WKTAR) met in Tromsø, Norway on 1–3 June 2010. The workshop was chaired by Mike Jech and Benjamin Planque and was attended by eight participants from five countries. The objective of the workshop was to propose a target strength equation for redfish (Sebastes mentella) in the North Atlantic based on the best available scientific knowledge. This was achieved through an extensive review of published and ongoing studies. Data from these studies were evaluated, ranked, and served as input to a meta‑analysis. The meta‑analysis results indicated that the best candidate for a general model of S. mentella TS‑length equation at 38 kHz is the free slope model: TS = 10.6 log(L) ‑ 55.4. However, the meta‑analysis revealed important departures from this equation in individual studies and the reasons for such discrepancies are generally undetermined or at best very poorly documented. To address this problem the following three actions were recommended: 1) ensure that high quality acoustic/ biological data for TS determination are collected during redfish surveys, 2) perform simultaneous comparative easurements between EK500 & EK60 echosounders for Target Strength determination and 3) pursue TS analysis during a new workshop WKTAR‑II.
Contributors: Benjamin Planque, Alf Harbitz, Gavin Macaulay, Geir Pedersen