title: Pikeperch (Sander lucioperca (L.)) in decline: high mortality of three populations in the northern Baltic Sea.
abstract: The development of three pikeperch (Sander lucioperca (L.)) populations in the northern Baltic Sea was monitored using standardized multimesh gillnets in 1995-2009. Declining trends in the abundances of pikeperch over 40 cm total length, low numbers of individuals older than 6 years, and high mortality rates were observed in all three populations. In the site with the largest commercial catches per unit area and a rapidly increased colony of great cormorants (Phalacrocorax carbo sinensis Blumenbach 1798), also the abundance of pikeperch below 40 cm total length and year-class strength showed declining trends. The adverse population level changes did not correlate with changes in water quality or eutrophication status. Together, the results suggest that in all study sites fisheries are harvesting a large proportion of the pikeperch soon after or even before reaching the maturity, and that predation from great cormorants may increase mortality of juveniles. Pikeperch is important not only for fisheries but also for ecosystem functioning, and our results point at the need for further management measures to ensure viable populations in the areas studied.
authors.affiliation: Environmental and Marine Biology & Husö Biological Station, Åbo Akademi University, Tykistökatu 6, 20520, Turku, Finland, noora.mustamaki@abo.fi.
authors.forename: Noora
authors.initials: N
authors.lastname: Mustamäki
authors.forename: Ulf
authors.initials: U
authors.lastname: Bergström
authors.forename: Kaj
authors.initials: K
authors.lastname: Adjers
authors.forename: Alf
authors.initials: A
authors.lastname: Sevastik
authors.forename: Johanna
authors.initials: J
authors.lastname: Mattila
mesh_terms: D000375:Aging; D000818:Animals; D001717:Birds / Q000502:physiology; D017753:Ecosystem; D005398:Fisheries; D009792:Oceans and Seas; D010473:Perciformes / Q000502:physiology*; D011157:Population Dynamics; D011235:Predatory Behavior; D013696:Temperature; D013997:Time Factors
references.citation: Trends Ecol Evol. 2005 Jul;20(7):356-8
references.pmid: 16701393
references.citation: Ambio. 2011 Jul;40(5):447-56
references.pmid: 21848134
references.citation: Ambio. 2011 Nov;40(7):786-97
references.pmid: 22338716
references.citation: Oecologia. 1993 Mar;95(1):38-46
references.pmid: 28313309