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Browsing by Author "Soriguer, Milagrosa C."

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  • Effects of environmental conditions and fishing operations on the performance of a bottom trawl
    Publication . Queirolo, Dante; Hurtado, Carlos F.; Gaete, Erick; Soriguer, Milagrosa C.; Erzini, Karim; Gutierrez-Estrada, Juan Carlos
    Trawl performance was studied based on net spread and variability in the contact of the footrope with the seabed and their relationship with vessel operations, catch weight, and environmental conditions. Artificial neural networks (ANNs) and generalized additive models (GAMs) were used to model the response of each variable. For the variables net spread and variability in footrope contact (VFC), the ANN models were more accurate than the GAMs, with greater generalization capacity in the validation phase. In the best ANN model for net spread, all variables were significant. The relationship between tow direction and wind direction (tactic) was most important in the sensitivity analysis. Net spread increased with increasing towing speed and windspeed, and decreased with increasing wave height. In the ANN model for VFC, there were differences among vessels, and both scope ratio and catch size were not significant. VFC increased with increasing depth and decreased with increasing towing speed and windspeed. The results demonstrate that both operational variables and environmental conditions affect trawl performance, and suggest that survey protocols designed based on this information might help to improve the precision of biomass estimates.
    2012-03Journal article Restricted access Show more
  • Site fidelity of fish on a rocky intertidal in the south of Portugal
    Publication . Compaire, Jesus C.; Montes, Juan; Gonçalves, Jorge Manuel Santos; Soriguer, Milagrosa C.; Erzini, Karim
    The short-term site fidelity of intertidal fish species was studied in a rocky intertidal zone in southern Portugal using visible implant elastomer tagging. Eleven fish species were caught, tagged and released, seven of which were recaptured. The larger tide pool with the highest complexity level and located at a lower position in the shore level did not have recaptures, while in others the individual fish species recaptured rate ranged from 11.1 to 38.9%, suggesting that the shore height is a dominant factor influencing site fidelity. Although the breeding season seems not to be the only explanation for the recapture rate, the higher mean recapture rates of Parablennius sanguinolentus, Lipophrys pholis and Gobius cobitis may be related to the parental behaviour of these species during that period. Site fidelity of juveniles of Scorpaena porcus in tidepools is reported for the first time, showing the importance of this habitat as a nursery ground.
    2022Journal article Open access Show more