|
The Problem
As salmonid populations continue to decline in the western US, it is imperative to develop a better understanding of ecological, genetic, and biological aspects of these species. Over the last 10 years, molecular tools have been used to nonlethally characterize salmonid populations. While this has provided invaluable information to resource managers, there is still a need to develop nonlethal genetic diagnostic systems to discriminate life histories, hybridization, and gender in salmonids. This will allow for the design of management strategies involving water allocation, supplementation, harvesting, and habitat usage that will ensure their continued survival. Objectives Within the broad context of the Fisheries and Aquatic Resources Program the 5-year research goals address: development of non-lethal genetic procedures for identification of gender, populations, phylogeographic, and taxonomic relationships for western fish; and conservation genetics of rare and endangered species. The genetic systems generated from this research address broad goals to characterize salmonid genetic diversity and more specific objectives to: (1) help ensure that hatchery practices do not contribute to the decline of salmonids due to the generation of inferior genetic products; (2) allow for the monitoring of the movement of juveniles from endangered runs for better management of water allocations and to obtain more complete life history information; (3) ensure equal sex ratios are collected when take limits are imposed for listed species; and (4) determine if temporal and/or spatial aspects of salmonid genetics within and between river systems require modifications in management strategies. Methodology To aid in the understanding of both returning adults and outmigrating juveniles, four aspects of salmonid genetics are being pursed: (1) assessment of temporal and spatial aspects of genetic diversity in wild and hatchery populations; (2) development of genetic markers to discriminate runs
Highlights and Key Findings Three non-lethal genetic diagnostic systems have been developed that discriminate spring and fall chinook in the Columbia/Snake river system, gender of chinook salmon, and hybridization between cutthroat and rainbow trout. In addition, we have identified genetic markers that discriminate populations of steelhead trout and char from several rivers of the Kamchatka peninsula in Russia. All of these systems are currently being used in field studies and have resulted in manuscripts that are currently being reviewed for publication in scientific journals. These diagnostic systems are based on the Polymerase Chain Reaction (PCR) so non-lethal samples can be collected and
Where Are We Headed In 2003 We will pursue three aspects of this system over the next year: complete the development of species-specific molecular markers; complete the third year of hybridization analysis on populations of introduced non-native rainbow and native cutthroat trout that have overlapping habitat; and identify streams that have native rainbow and native cutthroat trout to determine levels of hybridization in populations that have not experienced any introductions. To complete the molecular genetic system, mitochondrial markers will be developed that are species-specific. This will involve generating consensus DNA sequence from regions of the mitochondria and developing species-specific PCR primers to amplify those regions. All of the species-specific markers will be applied to trout populations in select streams on the Olympic peninsula and North Cascades National Park, both locations have rainbow and cutthroat trout occupying overlapping habitat (all of these streams have had hatchery raised non-native rainbow trout planted on top of native cutthroat trout). This will be the third year of a study to determine how hybridization frequencies change over time and space. This year we will analyze juveniles as well as adults to determine where hybrids are reproducing and how genomic content is reflected in animal behavior. These data will be compiled for publication in a peer-reviewed scientific manuscript and used to determine if management strategies can be generated to recover the pure cutthroat populations. In order to determine the full impacts of hybridization on cutthroat populations it is necessary to determine if hybridization occurs between native populations of these species that have overlapping habitat. There are a limited number of river/stream systems in the contiguous western U.S. that may have these populations. Each year of this project we will analyze populations in one or two new systems. The proposed systems for 2003 are the John Day river in Oregon and the Chilliwack river in North Cascades National Park. Project Contact Rusty Rodriguez Email: rusty_rodriguez@usgs.gov Publications |
