Laserfiche WebLink
in captivity for a while. Rapid growth, high survivorship, and ease of culture were chosen to <br />maximize production, as were other enhancements of the product's desirability to a consumer <br />(e.g., body size, "fighting" qualities, beauty [color], and even palatability). Programs were <br />designed to meet quotas that satisfied demands in cost-effective ways, with little regard for <br />other than health of broodstock or progeny to insure consistent production. <br />Thus, the institutional goals of such hatcheries now handling endangered taxa were <br />abruptly charged from efficient production of large quantities of fish to custodians of a <br />resource temporarily removed from nature, perpetuated for a while in captivity, and destined <br />to resume its natural course at some future time. We view data from the razorback sucker as <br />a vehicle to address some problems arising from mixing the production philosophy applied to <br />fishes destined for harvest with the conservation philosophy essential for managing <br />endangered species. <br />Razorback suckers have been cultured at Dexter National Fish Hatchery and Technology <br />Center (DNFH) since 1981 (Johnson, 1985; Johnson and Jensen, 1991.). Contrasts of <br />mitochondrial DNA (mtDNA) diversity in hatchery produced stocks with those of their <br />ultimate source, Lake Mohave, allow evaluation of success in maintaining genetic variability <br />and development of recommendations regarding hatchery versus alternate forms of <br />management toward perpetuation of this species. Reduction in mtDNA diversity of a <br />hatchery stock relative to its source would indicate a change in genetic composition with <br />potentially deleterious effects, especially in a species already subject to other environmental <br />stresses. <br />Materials and methods <br />Description of the source population and habitat.- The original broodstock fo~,razorback <br />16 <br />