ICES Journal of Marine Science: Journal du Conseil Advance Access published online on November 4, 2009
ICES Journal of Marine Science: Journal du Conseil, doi:10.1093/icesjms/fsp244
Fishing simulation experiments for predicting the effects of purse-seine capture on sardine (Sardina pilchardus)
1 Instituto Nacional de Recursos Biológicos (INRB/IPIMAR), Estação Piloto de Piscicultura de Olhão/IPIMAR-Olhão, Avenida 5 de Outubro, s/n, 8700-305 Olhão, Portugal
2 Centre for Research into Ecological and Environmental Modelling, The Observatory, Buchanan Gardens, St Andrews, Fife KY16 9LZ, Scotland, UK, and Centro de Estatística e Aplicações da Universidade de Lisboa, Faculdade de Ciências da Universidade de Lisboa, Bloco C6 – Piso 4, Campo Grande, 1749-016 Lisbon, Portugal
3 CCMAR, Universidade do Algarve, 8005-139 Faro, Portugal
4 Instituto Nacional de Recursos Biológicos (INRB/IPIMAR), Avenida de Brasília, 1449-006 Lisbon, Portugal
Correspondence to A. Marçalo: tel: +351 289 715346; fax: +351 289 715579; e-mail: amarcalo{at}cripsul.ipimar.pt.
Marçalo, A., Marques, T. A., Araújo, J., Pousão-Ferreira, P., Erzini, K., and Stratoudakis, Y. 2010. Fishing simulation experiments for predicting the effects of purse-seine capture on sardine (Sardina pilchardus). – ICES Journal of Marine Science, 67: 000–000.To study the impact of purse-seine fishing on deliberately released sardine, two laboratory experiments were performed to explore the effect of net confinement for 10, 20, 40, and 60 min at 18 and 23°C. A third experiment considered two levels of fish density while confined for 20 and 40 min at 16°C. Analysis of cortisol and haematocrit demonstrated that stress immediately after simulated fishing was milder than in commercial fishing and did not correlate with observed delayed mortality. Scale loss was related to the probability of dying (mean values of 16.3 and 2% for dead fish and survivors, respectively), and fin erosion was a long-term stress response observed in both dead and surviving fish. Time of confinement was an important stressor, with survival rates decreasing significantly with increasing periods in the net, and temperature having an additional negative effect. Density effects were less conclusive, but there was some indication that survival correlated with biological condition (heavier fish were more likely to survive). It seems that delayed mortality after release can be substantial, although death is not certain and appropriately modified fishing operations and favourable environmental conditions may enhance the probability of sardine survival.
Keywords: delayed mortality, physical condition, purse-seine fishing, Sardina pilchardus, stress reactions, stressors
Received 11 March 2009; accepted 20 August 2009.