On Thursday 23 August Steve Railsback from Humboldt State University, California USA, will give a seminar at Karlstad University titled: “Can Big Complex Models be Useful? Lessons from 20 Years of Salmonid Modeling for River Management”.

The seminar will start at 10:00 in room 5F416, everyone is welcome to attend the seminar.

Steve will give a brief overview and history of individual-based trout and salmon models, and provide examples of how the modeling experience produced general knowledge about ecology and fish.

Read more about Steve’s work on individual-based modeling and ecology here.

 

 

anders

Anders Andersson will defend his licentiate thesis on June 9, at 10:15 in Room 9C203 at Karlstad University.

For over two years Anders Andersson, PhD-student at Karlstad University, has been researching the catch and effort from the recreational fishery in Lake Vänern  the largest lake in the European Union. His research has focused on landlocked Atlantic Salmon and migratory brown trout. In accordance with tradition, Anders two weeks ago nailed his licentiate thesis on a wall at the university. On June 9, he will defend his thesis “Catch and effort from a recreational trolling fishery in a large lake” . Opponent will be Ian Cowx from the University of Hull, United Kingdom and the defence will take place at 10:15 in Room 9C203 at Karlstad University. 

In the abstract of the thesis, Anders writes:

Over recent decades recreational fisheries have grown substantially throughout the world. Despite this increase, catches from recreational fisheries have often been ignored in fisheries management, although this is now being remedied. Monitoring recreational fisheries can be expensive, and the primary means used for monitoring is angler (creel) surveys, typically funded from sales of fishing licences. The studies presented in this thesis examine different approaches to monitoring recreational trolling fisheries’ catch and effort, where fishing licenses are not required and there are no reporting requirements. I present results from a complemented roving/mail-in survey undertaken during 2013-2014 to estimate recreational effort and catch of Atlantic salmon (Salmo salar) and brown trout (S. trutta) in the largest lake in the European Union, Lake Vänern, Sweden. I also evaluate different angler catch reporting methods (mail-in, tournament reports and face-to-face interviews) and compare catch rates within and among spring and fall fishing periods. In addition, mail-in survey data are examined for recall bias.

I estimate that 28.7 tonnes of salmon and trout combined were harvested by the recreational trolling fishery in 2014, more than the commercial and subsistence fisheries combined. Seasonal differences in both recreational effort and catch were observed. Effort, in boat hours, was significantly higher in spring than in fall. Catch rates of trout were higher in fall than in spring, but there were no seasonal differences in catches of salmon. Harvest per boat day did not differ significantly among catch reporting methods, indicating that all three methods could be useful for managers interested in harvest rates. In contrast, total and released catch per boat day differed among reporting methods, with tournament anglers catching more fish in total. Finally, there was little evidence for recall bias in mail-in surveys, indicating that mail-in surveys are useful for collecting unbiased catch data. My study is the most comprehensive angler survey to date for Lake Vänern, and my results should be of immediate use to local fisheries managers and should also be of interest to researchers and managers interested in estimating catch and effort for fisheries at large spatial scales.”

Download the full licentiate thesis here.

Boktips: King of Fish

Posted by Daniel Nyqvist | Nyheter

King_of_FishKing of Fish  – The Thousend Year Run of Salmon” är en välskriven bok av David. R. Montgomery som sätter den vilda laxen i ett socialt, historiskt och ekonomiskt sammanhang. Annektoter, historiska källor, vetenskapligt dokumenterad kunskap och entusiasm blandas för att ge en bild av fisken och människans relation till den. Författaren beskriver hur laxens historia (delvis) upprepar sig med kraftigt försvagade eller utplånade laxbestånd som ett resultat av överfiske, dammar och föroreningar i Europa på 1700-talet, på den amerikanska östkusten under slutet av 1800-talet och på den amerikanska Stillahavskusten under 1900-talet fram till idag. På de flesta platser och under de flesta tider har kunskap om varför laxen minskat inte varit det huvudsakliga problemet. I minst tvåhundra år har det pratats om upp- och nedströmspassage, begränsningar av fiske och habitatskydd men starkare ekonomiska och sociala intressen (industri, fiske, vattenkraft) har övertrumfat laxen. Och det är kanske dags att vi lär oss läxan, boken avslutas med en varning och sensemoral: ”In the end, the resurrection or destruction of salmon will come down to moral and ethical issues – to value choices that society can make explicitly or continue to make implicitly. Do we want salmon in our rivers? Are we willing to drive species knowingly to extinction, even if only by looking the other way? The solution is not really all that mysterious. We simply cannot keep on doing things the way we’ve been doing them, or we risk losing the salmon. The choice is ours; the future is not. The sixth H in the salmon story also is ours to choose. Will it be hubris or humility?” 

Boken innehåller bland mycket annat även personliga beskrivningar av laxälvar, intressanta skildringar av laxens betydelse för den amerikanska ursprungsbefolkningen (med effekter på förvaltningen också idag), redogörelser för bevarandeåtgärder och diskussioner runt dem och en hel del fascinerande kuriosa. En viktig och intressant sommarläsning för den som är intresserad av lax i synnerhet och människans relation till naturen i allmänhet.

Boken lånas med fördel på ett välsorterat bibliotek men kan också läsas som e-bok.

Imorgon, tisdagen den 14:e April, kommer Ian Fleming att ge ett seminarium med titeln ””Influence of environmental enrichment and transgenerational effects on salmon recovery”. Ian Flemming är till vardags verksam vid Memorial University, Kanada men är förnärvarande gästprofessor tid vid Göteborgs Universitet.

Seminariet ges klockan 13:15 i sal 5F416 på Karlstads Universitet. Alla är välkomna!