(Quebec) A new study by researchers at Laval University suggests that Atlantic salmon caught and then released reproduce less than those who have not taken the bait.
Posted at 10:29
These new conclusions contradict those of another study conducted ten years ago and open the door to a reflection on better supervision of the practice of release, believes the main author of the research.
The study published in the journal Fisheries Management and Ecology became interested in salmon from the Rimouski River. They found in the summer of 2018 that the reproductive success of salmon caught and then released was 27% lower than that of salmon that did not cross paths with a fisherman.
“A fight between a salmon and a fisherman can last up to 30 minutes. It’s stressful and exhausting for these fish,” notes Raphaël Bouchard, doctoral student in biology at the Faculty of Science and Engineering at Laval University in Professor Louis Bernatchez’s team.
“In addition, as they have not eaten for several weeks, they have to draw on their reserves to survive,” he adds. Their reproductive success may suffer. »
To reach this conclusion, the researchers took the genetic fingerprint of 475 adults captured as they entered the river. Then, a year later, they captured some 2,500 fry to examine their DNA and trace them back to their parents.
After these laborious maneuvers, the researchers were able to calculate the reproductive success of 33 adults caught and released in 2018. In the end, the released salmon had proportionally fewer offspring (-27%).
This is not the first study to look into this important subject for the community of fishermen who practice catch-and-release, a way of doing things that aims to be more ethical and sustainable. Ten years ago, Professor Bernatchez’s team had not noted any impact of catch-and-release on the reproduction of salmon in the Escoumins River.
“The temperature of the water could be in question, speculates Raphaël Bouchard. The water in the Escoumins River is colder, so it is better oxygenated. The capture could be less trying in these conditions. »
Work by other teams suggests that the mortality rate of released salmon is around 5% when the water temperature is below 12 degrees Celsius, but can climb to 20% at temperatures of 18 to 20 degrees Celsius, says the researcher.
Research by Raphaël Bouchard, Laurie Lecomte and Louis Bernatchez of Laval University, Kyle Wellband of Fisheries and Oceans Canada, and Julien April of the Quebec Ministry of Forests, Wildlife and Parks indicates a correlation and not causality.
Despite everything, Mr. Bouchard wonders if the practice of catch-and-release should not be better regulated in view of its potential impact on the health of salmon populations.
“You have to ask yourself if there is a need to limit the daily number of salmon that a fisherman can catch and release,” he says. We must also question the relevance of allowing fishing during a heat wave or in the colder zones of a river where the salmon take refuge when it is very hot. »