Parasites alter likelihood of fish being caught by anglers
Published:29 Mar.2023 Source:Hokkaido University
Parasites are very common in nature, found everywhere that their hosts are found. Parasites are known to alter the susceptibility of fish to predators. Angling can be considered predation of fish; however, there has been almost no in-depth research on how parasites affect the susceptibility of fish to angling.
Associate Professor Itsuro Koizumi at the Faculty of Environmental Earth Science, Hokkaido University, and graduate student Ryota Hasegawa have investigated how a mouth and gill parasite of the whitespotted char, a salmonid fish, affects its vulnerability to angling. Their findings were published in the journal The Science of Nature.
The study considered two parameters: the body condition of the fish (a relationship between their body mass and body length) and their parasite infection status (whether the fish was infected with parasites or not). Fish were caught by angling and by electrofishing, and the numbers of fish under each category were compared.Two specific groups of char were most vulnerable to angling: those that had a high body condition and also had parasites, and those that had a low body condition but no parasites. Larger fish were more vulnerable to angling.
A survey of tweets curated from Twitter covering a three-year period was also conducted. Both anglers and customers at fish markets reacted negatively to parasites. The negative reaction to parasites by anglers is important, as they are more likely to release infected fish back into the wild. This increases the likelihood that parasitized fish are more common in areas that experience high amounts of angling.Additionally, the reaction to parasites in fish angling might result in the increase of both host and parasite survival."