Hårt fisketryck kan förändra fiskars evolution

En grupp brittiska forskare menar sig ha hittat tecken på att hårt fisketryck och trålning påverkar fiskars evolution. Snabbare simmare fångas i mindre utsträckning än de som är långsammare vilket driver på en förändring mot att fiskarter som helhet lär sig att simma snabbare:

The results of the simulation revealed that some fish were indeed more susceptible to capture than others and this was strongly related to anaerobic capacity – the ability to engage in short periods of intense physical activity which demands more oxygen than is available from breathing alone.

Maximum aerobic swim speed was also negatively correlated with vulnerability to trawling. Metabolic rate – an indicator of how much energy an animal needs to live – was highest among fish that were least vulnerable to trawling but this relationship probably arose through correlations with anaerobic capacity.

Dr Killen said: “Humans are effective predators, and selective harvest of animals by humans probably represents one of the strongest drivers of evolutionary change for wild animal populations. “Hunting and fishing are selective processes which often remove individuals that, under normal circumstances, may have the highest reproductive potential. Available evidence suggests selective harvest can lead to genetic change within wild populations for specific traits.

“Using simulated trawling, our study provides the first evidence better swimming fish, and those with higher metabolic rates, are more likely to escape capture. “Over time, the selective removal of poor-swimming fish could alter the fundamental physiological makeup of descendant populations that avoid fisheries capture.”

Om intensivt fiske påverkar fiskars simhastighet kan naturligtvis det också påverka storleken på fisken. Om små fiskar aldrig fångas, men alla stora fångas kommer sannolikt storleken hos fiskarten ifråga minska på sikt. Kanske något att tänka på när det gäller Östersjötorsken och storleksselektivt fiske rent allmänt.

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