Dont want to put aynone off here but this is a good report
On the grand scale, there is no doubt that catch and release is good for fish. Sport anglers who release portions of their catch keep populations of vulnerable fish species from being quickly depleted.
Catch and release allows ever increasing numbers of anglers to continue chasing fish, in places where the harvest of fish cannot be supported.
But catch and release is not without risk to fish, says Brian Heise, an associate professor of aquatic ecology at the University College of the Cariboo in Kamloops.
There is no guarantee a sport-caught fish will survive, despite the best intentions of those holding the rod. Even in ideal conditions, biologists believe five per cent of released rainbow trout die — out of sight and long after being put back in the water.
The mortality rate increases dramatically if anglers don't handle and release fish properly, Heise says. The rules of catch and release — play the fish fast, use a proper landing net, keep the fish in the water and release it quickly, and use barbless hooks — are important.
To understand why requires a closer look at the physiology of rainbow trout.
Play it fast
Rainbow trout are finely tuned predators designed to find and catch food efficiently. Everything about a trout — from the composition of its muscle fibres to the chemical balances in its body — is designed to accomplish that task.
It's a delicate balance, one that can be easily upset. And once a fish's chemical and physical systems are out of whack, its very survival is threatened.
Rainbow trout muscle is comprised of two different kinds of fibres — red and white, Heise says. The distinctions between the two types of fibre are complex and not visible to the eye.
Red muscle is aerobic and burns oxygen pulled from the water by a fish's gills. Red muscle is used for long-distance cruising, for getting around — the human equivalent of walking, or light jogging.
White muscle fibres are used for “burst movement” — activities like chasing quickly moving prey, or escaping predators like loons, ospreys and bears. White muscle is anaerobic, burning glycogen stored in the muscles instead of oxygen. When the supply of glycogen is used up, white muscle fibres stop working. Glycogen is not replenished quickly.
Heise says the intense fight of a sport-caught rainbow trout is powered mostly by white muscle fibres. When the fish burn up all their white muscle fuel, they are physically exhausted and stop trying to escape.
The byproduct of that intense glycogen burning is lactic acid, Heise says, which builds in great quantities in a fish's muscles and blood.
Humans have similar anaerobic muscle fibres that allow for fast sprinting, or other intense activities like heavy weight lifting. Human muscles also create lactic acid when heavily worked. Lactic acid causes that intense burning that precedes a muscle's complete exhaustion.
But unlike humans, fish cannot clear their muscles of lactic acid quickly. While the legs of a fit human sprinter may be ready to go again in as little as 45 minutes, rainbow trout may not be able to effectively use their white muscle fibres for as long as 12 hours.
The more exhausted the fish, the more lactic acid and the longer the recovery period. In some cases, it can take up to 72 hours for complete recovery to occur. A fish that is recovering from being caught cannot chase down food, or escape easily from predators. Both scenarios can prove dangerous to fish.
Bringing a fish quickly to the net with fight still in it means it will recover faster, increasing its chances of survival. An utterly exhausted fish may not be able to restore proper chemical balances in its body, because its heart cannot move sufficient quantities of oxygenated blood through its body quickly enough.
There is another benefit to releasing fish with some kick still in them, Heise says. Studies have shown that rainbow trout that perform some slow, steady swimming immediately after release will clear lactic acid build-ups in their muscles in as little as two hours. A fish that is not played to complete exhaustion is better able to swim away and cruise for a while.
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Topic: catch and release (Read 2421 times)