Browsing by Author "Silva, Cristina"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- REPORT OF THE WORKSHOP ON MODELLING CATCH-PER-UNIT-EFFORT (WKCPUE)Publication . Coelho, Rui; Fernandes, Ana Cláudia; Mendes, Hugo; Moura, Teresa; Serra-Pereira, Bárbara; Silva, Andreia V.; Silva, Cristina; Azevedo, Manuela; Instituto Português do Mar e da Atmosfera, I.P.Standardized Catch-Per-Unit-Effort (CPUE), i.e., data from commercial fisheries that have been statistically modelled to remove fishery dependant effect, are often used in stock assessments as indicators of abundance and biomass. Here we report the outcomes of the workshop on modeling CPUEs that took place virtually on the 3-5 November 2020 and 6-7 January 2021 organized by IPMA and integrated in PNAB/DCF (National Program of Biological Sampling). We provide a summary of the methods used, focusing particularly on Generalized Linear Models (GLM) with Tweedie distributions for treatment of zero captures. We provide examples of case-studies developed and discussed, namely Norway lobster (Nephrops norvegicus) caught by crustacean trawlers, black-bellied anglerfish (Lophius budegassa) caught by the polyvalent fleet, chub mackerel (Scomber colias) discards and hake (Merluccius merluccius) caught by the Portuguese trawl fleet. The discussions on the exploration of input data and model fitting resulted in some recommendation for future work, summarized at the end of the report.
- Workshop on Sampling Effort for Biological Parameters - WKSEBPPublication . Silva, Cristina; Azevedo, Manuela; Chaves, Corina; Coelho, Rui; Costa, Ana Maria; Dinis, David; Dores, Sandra; Fernandes, Ana Cláudia; Gonçalves, Patrícia; Lino, Pedro G.; Mendes, Hugo; Moura, Teresa; Nunes, Cristina; Oroszlányová, Melinda; Silva, Daniel Pinto Maria do Carmo; Instituto Português do Mar e da Atmosfera, I.P.The Workshop on Sampling Effort for Biological Parameters (WKSEBP), chaired by Manuela Azevedo and Cristina Silva (IPMA) met in Lisbon, 18 – 20 November 2017, to focus on the analysis of the current Portuguese sampling designs under PNAB/DCF (Programa Nacional de Amostragem Biológica/Data Collection Framework) with the aim to optimize the sampling effort and improve precision on the estimation of biological parameters. Several approaches and methodologies were discussed and guidelines for future work were recommended. Four case-studies were analyzed focusing on: 1) survey sampling for length, 2) atmarket sampling for length, 3) estimation of age-length key and 4) maturity ogive. The number of samples, the effective sample size and the precision in parameters estimation were discussed in each case-study.