Estimating Daily Egg Production of European Anchovy in the Adriatic Sea: A Critical Appraisal |
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| Authors: | Paco Melià Nicola Casavola Marino Gatto |
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| Institution: | Dipartimento di Elettronica e Informazione, Politecnico di Milano, via Ponzio 34/5, 1-20133 Milano, Italy.;Servizio Ittico Ambientale, Provincia di Bari, via Amendola 189,1-70126 Bari, Italy. |
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| Abstract: | Abstract. We discuss the critical problem of estimating daily egg production in the Daily Egg Production Method (DEPM), a widely used technique for the stock assessment of multiple spawning pelagic fishes. Data collected in 1999 for the stock of European anchovy ( Engraulis encrasicolus ) in the Southern Adriatic Sea are used to study the effects of different calibration techniques. We analyze the performances of the mortality model from which daily egg production is estimated. All these calibrations are based on the Bootstrap method. Nonlinear fitting (vs. linear regression on log-transformed data) is shown to guarantee more reliable parameter estimation. We show that specifying the function assigning age to staged eggs is crucial. |
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| Keywords: | Stock assessment pelagic stocks multiple spawning fishes daily egg production DEPM biomass estimation stage-age relationship European anchovy |
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