This article was written by Jamie Madden, who recently earned her Master’s degree from Carleton University in Ottawa, Canada, co-advised by Dr. Steven Cooke and Dr. Andy Danylchuk. Her research focuses on recreational fishing and best practices for freshwater fishes.
This is a great example of how we use science to derive best practices for catch-and-release fishing.
Background
It’s that time of year when thermometer graphics show up on social media alerting anglers to be more cautious when targeting trout as water temperatures increase. Many of the graphics point to 68°F/20°C as a cutoff for when we should stop fishing for trout, but rarely are there details presented as to how that number was derived. Where is this number coming from, anyway? Does it cover all species? How about when a trout is first fought – physiologically stressed – on the end of a line?
Depending on species, fish can have a large or small range of water temperatures that they can generally tolerate. Science is often conducted to determine optimal temperatures for growth and feeding, and the outcomes can provide insights into changes in fish behavior and their reactions to warming global temperatures. One major caveat here is that many of these studies test the effects of water temperature without the additional stresses that are related to angling. So, while the preferred or optimal temperature range of a trout may be appropriate for most of its life, the higher end of that range may present challenges during and in recovery from an angling event.
Fish undergo exhaustive exercise during angling causing their demand for oxygen to increase. In warmer temperatures, dissolved oxygen may be harder to come by, which can be one factor increasing mortality if the fish is released. In addition to exhaustion, air exposure time in warmer temperatures can result in increased lethal and sublethal (i.e. longer recovery times, reflex impairment, higher stress and lactate levels) effects compared to similar times in cool water (see this study and this study).
Continue reading about fishing for trout in warming waters at the Keep Fish Wet website.
The Women's Outdoor News, aka The WON, features news, reviews and stories about women who are shooting, hunting, fishing and actively engaging in outdoor adventure. This publication is for women, by women. View all posts by The WON
