Rapport nr 126: Basinventering av potentiella lekplatser för abborre ( Perca fluviatilis) och gädda (Esox lucius) i grunda vikar på västra och södra Åland
KIVILUOTO, S (2010)
KIVILUOTO, S
Åbo Akademi, Husö biologiska station
2010
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This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-12-2401-0
https://urn.fi/URN:ISBN:978-952-12-2401-0
Tiivistelmä
During the summer 2009 a basic survey of potential spawning places and nursery areas for perch (Perca fluviatilis) and pike (Esox lucius) was conducted under the assignment by the Government of Åland. The study was conducted in 25 shallow bays in mainly western and southern parts of the Åland Islands. The main goal of the study was to determine the suitability of these shallow bays as reproduction areas for pike and perch. Composition of the fish species in the bays was measured by beach seining and visual observation. Vegetation was surveyed and the quality of bottom was estimated in the bays. Water samples were taken in each bay at the depth of 0,5 m for measurement of temperature, salinity and pH. All fish caught were defined to species level, as well as most of the underwater vegetation. The most abundant fish species were perch, roach (Rutilus rutilus), bleak (Alburnus alburnus), sticklebacks (Gasterosteus aculeatus, Pungitius pungitius) and gobies (Pomatoschistus microps, P. minutus). Even some flatfish (Psetta maxima) were caught. Most of the bays in the study proved to be suitable reproduction areas for both perch and pike, allthough both species were not caught at all sites. At all sites vegetation was dominated by either Chara- or Potamogeton species. One endangered species, Chara horrida, was found at two different locations. Effects of boat traffic and eutrophication were seen at several sites, with decreased quality of under water vegetation and increased number of cyprinids as indicators. To maintain perch and pike stocks at the level they are today, conservation of these shallow bays is recommended.