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Research article - Peer-reviewed, 2021

Warmer water increases early body growth of northern pike (Esox lucius), but mortality has larger impact on decreasing body sizes

Berggren, Terese; Bergstrom, Ulf; Sundblad, Goran; Ostman, Orjan;

Abstract

Large fish species often display truncated size distributions related to harvest. In addition, temperature, food availability and density dependence affect body growth and together with natural mortality influence population size structure. Here we study changes in body growth, size distributions and mortality in both harvested and nonharvested populations of northern pike (Esox Lucius) over 50 years along the Baltic Sea coast and in Lake Malaren, Sweden. For coastal pike, body growth has increased coincidentally with increasing water temperatures, yet in the last two decades there has been a decrease of larger individuals. In Lake Malaren, in contrast, size distributions and body growth were stationary despite similar increases in water temperature. A dominance of slow-growing individuals in older age classes was evident in all studied populations, also in the no-take zone, suggesting other factors than fishing contribute to the mortality pattern. We propose that increasing temperatures have favoured body growth in coastal areas, but this has been counteracted by increased mortality, causing pike sizes to decline. To regain larger coastal pike, managers need to consider multiple measures that reduce mortality.

Published in

Canadian Journal of Fisheries and Aquatic Sciences

2021, volume: 79, number: 5, pages: 771-781
Publisher: CANADIAN SCIENCE PUBLISHING

Authors' information

Berggren, Terese
Swedish University of Agricultural Sciences, Department of Aquatic Resources
Swedish University of Agricultural Sciences, Department of Aquatic Resources
Swedish University of Agricultural Sciences, Department of Aquatic Resources
Swedish University of Agricultural Sciences, Department of Aquatic Resources

Associated SLU-program

Coastal and sea areas
Lakes and watercourses

Sustainable Development Goals

SDG14 Life below water
SDG13 Climate action

UKÄ Subject classification

Fish and Aquacultural Science
Oceanography, Hydrology, Water Resources

Publication Identifiers

DOI: https://doi.org/10.1139/cjfas-2020-0386

URI (permanent link to this page)

https://res.slu.se/id/publ/117106