FN Archimer Export Format PT J TI Estimating stock parameters from trawl cpue-at-age series using year-class curves BT AF COTTER, A MESNIL, Benoit PIET, G AS 1:1;2:2;3:3; FF 1:;2:PDG-DOP-DCN-EMH;3:; C1 Cefas Lab, Lowestoft NR33 0HT, Suffolk, England. IFREMER, Dept EMH, F-44311 Nantes, France. Inst Marine Resources & Ecosyst Studies, NL-1970 AB Ijmuiden, Netherlands. C2 CEFAS, UK IFREMER, FRANCE INST MAR RES, NETHERLANDS SI NANTES SE PDG-DOP-DCN-EMH IN WOS Ifremer jusqu'en 2018 copubli-europe IF 1.934 TC 13 UR https://archimer.ifremer.fr/doc/2007/publication-2776.pdf LA English DT Article DE ;Year class curve;Plaice;North Sea;Iteratively weighted least squares;Forward validation;Fish stock assessment;Cpue;Analysis of relative residual variance AB A year-class curve is a plot of log cpue (catch per unit effort) over age for a single year class of a species (in contrast to the better known catch curve, fitted to multiple year classes at one time). When linear, the intercept and slope estimate the log cpue at age 0 and the average rate of total mortality, Z, respectively. Here, we suggest methodological refinements within a linear least squares framework. Candidate models may include a selectivity term, fleet-specific parameters, and polynomials in year to allow for gradual variations of Z. An iterative weighting method allows for differing precisions among the different fleets, and a forward (one-step ahead) validation procedure tests predicted cpue against observed values. Choice of the best approximating model(s) is made by ranking the biological credibility of each candidate model, then by comparing graphic plots, precision of prediction, and the Akaike Information Criterion. Two example analyses are (i) a comparison of estimated and true results for five stock simulations carried out by the US National Research Council, and (ii) modelling three beam trawl surveys for plaice (Pleuronectes platessa) in the North Sea. Results were consistent with known, age-related, offshore migrations by plaice. Year-class curves are commended as a widely applicable, statistically based, visual, and robust method. PY 2007 PD MAR SO ICES Journal of Marine Science SN 1054-3139 PU Oxford university press VL 64 IS 2 UT 000247795200003 BP 234 EP 247 DI 10.1093/icesjms/fsl025 ID 2776 ER EF