A1 Journal article (refereed)
Cormorant (Phalacrocorax carbo) predation on a coastal perch (Perca fluviatilis) population : estimated effects based on PIT tag mark-recapture experiment (2020)

Veneranta, L.; Heikinheimo, O.; Marjomäki, T. J. (2020). Cormorant (Phalacrocorax carbo) predation on a coastal perch (Perca fluviatilis) population : estimated effects based on PIT tag mark-recapture experiment. ICES Journal of Marine Science, 77 (7-8), 2611-2622. DOI: 10.1093/icesjms/fsaa124

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Publication details

All authors or editors: Veneranta, L.; Heikinheimo, O.; Marjomäki, T. J.

Journal or series: ICES Journal of Marine Science

ISSN: 1054-3139

eISSN: 1095-9289

Publication year: 2020

Volume: 77

Issue number: 7-8

Pages range: 2611-2622

Publisher: Oxford University Press (OUP)

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1093/icesjms/fsaa124

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Abstract

The number of cormorants has rapidly increased in the northernmost Baltic Sea. In 2018, 50 km × 50 km ICES catch rectangle 55H1 had 3140 breeding pairs. To estimate the predation effect of cormorants on perch populations, we Passive Integrated Tags tagged 1977 perch and 9.9% of tags were found. The median instantaneous cormorant-induced mortality during the breeding time, with consumption by non-breeding individuals, was estimated at 0.23 and at 0.35 during the whole residing period. We estimated with a yeild-per-recruit model that the long-term maximum loss of perch yield of tagged sub-population would be at 80% probability interval 32–67%, and when extended to the entire 55H1, 10–33%, respectively. The cormorants’ share of the >2-year-old perch biomass and production would be 8%, while that of other natural mortality would be 63% and that of fishing 29% in 55H1. The yield-per-recruit-results should be interpreted as an estimate of maximum cormorant effect because the dependence of predation rate on prey density was not accounted for, and density-dependence of growth, mortality, and reproduction of perch could partly compensate the loss. The results indicate that high density of cormorants can reduce the perch stocks and catches locally.

Keywords: great cormorant; perch; predation; fish populations; fishery

Free keywords: cormorant; fishery; perch; predator–prey interaction; yield

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