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Stock-recruitment relationship of perch ( Perca fluviatilis ) in the Archipelago Sea, Finland

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

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Stock-recruitment relationship of perch ( Perca fluviatilis ) 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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