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Research article2005Peer reviewed

Relating plaice (Pleuronectes platessa) recruitment to deteriorating habitat quality: effects of macroalgal blooms in coastal nursery grounds

Pihl, L; Modin, J; Wennhage, H


Concentration of juveniles of marine fishes in nurseries may act as a bottleneck during the life cycle, where quantity and quality of nurseries determine population size. Macroalgal blooms have become a common phenomenon in eutrophic shallow waters worldwide, and matforming algae may now cover many essential nursery habitats. In this investigation, the aim was to assess the quantitative effect of algal mats on the recruitment of plaice (Pleuronectes platessa) from nurseries in the Swedish Skagerrak archipelago. A model was constructed using data on nursery size, settling density, and mortality of plaice combined with data on algal distribution. Recruitment of 0-group plaice from nurseries could be reduced by 30%-40% due to algae. The largest negative effect occurred during high settlement, reducing the important influence of strong year classes on stock size. The model predicted a reduction of juveniles due to algae of 45-46 x 10(6) individuals at high settlement. This amounts to 68% of the output at medium settlement and equals the amount of plaice produced during 5 years of low settlement. Up to 75% of the total reduction could occur in one quarter of the study area. With limiting resources, management actions should not be generally applied but rather be concentrated to optimize the cost-benefit of measures taken.

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Canadian Journal of Fisheries and Aquatic Sciences
2005, Volume: 62, number: 5, pages: 1184-1193 Publisher: NATL RESEARCH COUNCIL CANADA

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