7384 - Laserfiche WebLink

Home Browse Search

r cannot be restored simply by stocking them in areas from which they have previously been extirpated, or are decining. Without habitat improvement hatcheries are ony temporary refuges for genetic material, and provide research facilities for laboratory studies. hQV'L .ltre. S'~=~S arL Colorado squawfish 11`h`a--s a complex life cycle in +spatial~S C't'ICI~ ~w tLS -tK~vL 1~ V~o ~SuCr,-~.y ~v~. Q.~!'L~.S Vl~~.d. 17 ~ .~ i~~~`1Vlwl~zlf YO~~ separat s, the incorporation of an energetically-costly migratory behavior, and no doubt other, as yet unknown components. Management for recovery must embrace stocking programs cautiously. There are too many examples of dumping fish into a river with too little knowledge, and too little thoughts for future evaluation. Our work in the Green River Basin has demonstrated a homing response of Colorado squawfish, in which long spawning migrations are made to special areas. Some stocks of Colorado squawfish migrate downstream to reach spawning grounds, and some migrate upstream to reach the same spawning grounds (Tyus 1985). This phenomenon could be an environmentally induced response (e.g. olfaction), or under pure genetic control (Bowler 1975). Annual downstream movements of larvae of 100 km and more, to reach nursery habitat have also been documented. The preceeding suggests mechanisms for which we only have hypotheses, but are potentially critical to ,judge the potential success of stockings. If management for recovery is to be successful, these, and other attributes of this fish must be understood. Non-native Species and Sportfishing 31