In my experiences hatchery fish raised without predators are pretty naive individuals regarding predation; similar to pheasants and quail introductions. Predatory behavior is not all that different between fish and wildlife game. Predators key on this weakness. 1. New stocker fish also behave somewhat different compared to resident fish. Odd behavior makes the new fish an easier target-prey. 2. New fish are not familar with what habitat is available in the new surroundings. Instinct often causes them to move into a shallow water refuge where larger fish have difficulty swimming. 3. New stockers are usually stressed, sometimes very stressed, and weak for various reasons; due often to mishandling, reduced water quality from crowding, and/or temperature stressors. 4. If the fish is a completely new species to that body of water predators will be attracted to the new behavior pattern. 5. Also new stockers usually have color patterns - hues that are different lighter or darker than resident, similar sized fish of the same species. All these features reduces the chances of survival depending on several things. An important one is amount of dense nearby cover. Predators often 'hang' in wait in these cover areas (habitat) which are designed to be fish attractors! Generally the larger the stocker the better chances of survival during the early acclimation period.
Last edited by Bill Cody; 10/07/11 08:01 PM.
