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

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 an...

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Bibliographic Details
Published in:Canadian journal of fisheries and aquatic sciences 2022-05, Vol.79 (5), p.771-781
Main Authors: Berggren, Terese, Bergström, Ulf, Sundblad, Göran, Östman, Örjan
Format: Article
Language:English
Subjects:
Body size
brochets
Coastal management
Coastal zone
Density dependence
Environmental aspects
Esox lucius
Fish
Fish and Aquacultural Science
Fisk- och akvakulturforskning
Food availability
Lakes
Mortality
Mortality patterns
Oceanografi, hydrologi, vattenresurser
Oceanography, Hydrology, Water Resources
Population number
Population studies
Populations
Size
Water temperature
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Summary: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 Mälaren, 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 Mälaren, 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.
ISSN:0706-652X
1205-7533
1205-7533
DOI:10.1139/cjfas-2020-0386