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

Berggren, TereseSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för akvatiska resurser,Department of Aquatic Resources (författare)

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.

Bergström, UlfSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för akvatiska resurser,Department of Aquatic Resources(Swepub:slu)50486 (författare)
Sundblad, GöranSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för akvatiska resurser,Department of Aquatic Resources (författare)
Östman, ÖrjanSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för akvatiska resurser,Department of Aquatic Resources(Swepub:slu)51897 (författare)
Sveriges lantbruksuniversitetInstitutionen för akvatiska resurser (creator_code:org_t)
Sveriges lantbruksuniversitet

Ingår i:Canadian Journal of Fisheries and Aquatic Sciences: Canadian Science Publishing79, s. 771-7810706-652X1205-7533

Av författaren/redakt...: Berggren, Terese; Bergström, Ulf; Sundblad, Göran; Östman, Örjan

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