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Understanding Stock-Recruitment Relationship of Perch in the Archipelago Sea, Finland

Explore the stock-recruitment relationship of perch in the Archipelago Sea, Finland, focusing on water temperature, pikeperch effects, stock assessment, and environmental variables. The study covers perch catches, population analysis, and recruitment patterns from 1980 to 2016.

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Understanding Stock-Recruitment Relationship of Perch in the Archipelago Sea, Finland

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  1. Stock-recruitment relationship of perch (Percafluviatilis) in the Archipelago Sea, Finland Outi Heikinheimo Fish Pro II, Göteborg 14–16 February 2018

  2. Manuscript in prep.:Stock-recruitment relationship in perch (Perca fluviatilis): effects of water temperature and pikeperch (Sander lucioperca) in the Archipelago Sea, southwestern Finland.Eevi Kokkonen*, Outi Heikinheimo, Anssi Vainikka, Zeynep Pekcan-Hekim • Perch catches and CPUEs • Stock assessment • Stock-recruitment models • Environmental variables

  3. Perch catches 1980 – 2016

  4. Commercial perch catch 1980 - 2016

  5. Stock assessment (Virtual Population Analysis VPA) 1980 1981…………………………………………2009 2 3 4 5 6 7 8 9 10 RECRUITS Age F POPULATION SIZE BY AGE Data: Catch statistics, annual samples from commercial catches. Age structure, mean weights at age =>Annual catches in numbers of perch VPA calculates the population size and fishing mortality

  6. Year-class strength of perch vs. pikeperch population size (ages ≥ 1) June –Julytemp

  7. Perch stock was on a high level from 1993 to 2002

  8. Catches per unit of effort in gillnet fishing

  9. Spawning stock – recruitment (without environmental variables)

  10. Testing models with different variables

  11. Predictions with different models, June-July temperature and pikeperch stock included

  12. Conclusions • Recruitment of perch is determinedby summer temperature, spawningstocksize and the abundance of pikeperch • The assumedeffect of pikeperch is supportedbyliteraturefromFinnishlakes and relativespecies in North America (yellowperch and walleye) • Mostprobablypredation, butcompetitionmightbeinvolved, too • However, thereareotherrathersimultaneouschanges in the environment • Increasedareassufferingfromoxygendeficiency • Increasedabundance of Cyprinidfish, no monitoring data

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