We summarized existing knowledge on behavioural and physiological responses of Okanagan sockeye salmon (O. nerka) adults to annual and seasonal variations in aquatic thermal regimes during migration. This enabled us to identify an underlying set of 'decision rules' as a biophysical model of how temperature mediates en-route delays as a specific element of annual migrations by sockeye salmon. Several sets of results indicate that adult sockeye migrations stop as seasonal water temperatures increase and exceed 21 o C and then restart when temperatures decrease and fall below 21 o C. Model predictions of annual variations in the duration of migratory delay exhibited close agreement with independent estimates of observed delays available from a subset of years (predicted delay = 1.23 observed delay + 2.08, r 2 = 0.92, p < 0.001, n = 10). We applied the model in a retrospective analysis of the likely impacts of climate variation and change events on adult sockeye migrations in freshwater over the 70 plus year interval between 1924 and 1998. Results indicate that migration delays for a significant portion of the sockeye population averaged 29 days per year (range 0-55). Average annual migration delays roughly equal the 33 day estimate of time required, given continuous migration, to traverse the 986 km distance from the Columbia River mouth to terminal spawning grounds near Osoyoos Lake, BC. Alternating intervals of above-average and below-average migration delays corresponded closely with 'warm-phase' and then 'cold-phase' periods of the Pacific Interdecadal Oscillation. Circumstantial evidence suggests alternating periods of sub-average and above-average productivity for salmon on the southern end of their range are linked to climate variation and change events in both freshwater and marine environments. Climate impact and adaptation responses that register first at the level of salmon, propagate rapidly through both salmon resource users and fisheries managers. Consequently, future climate warming episodes will complicate the manageability and threaten the sustainability of many salmon populations in the southern end of their range (Georgia Basin and the Pacific Northwest). This requires strategies that minimize the impact of uncertain climate variability and change scenarios on the resilience of the salmon resource, and maximize our adaptive capacity for both short-and long-term fisheries planning and management decisions.
RÉSUMÉNous avons résumé les connaissances actuelles au sujet des réactions comportementales et physiologiques du saumon sockeye adulte (O. nerka) dans l'Okanagan face aux variations annuelles et saisonnières dans les régimes thermiques aquatiques pendant la migration. Cela nous a permis de cerner et de déterminer un ensemble de règles de décision comme modèle biophysique de la façon dont la température modifie légèrement les délais de parcours en tant qu'élément spécifique des migrations annuelles du saumon sockeye. Plusieurs séries de résultats indiquent que les migrations du saumon soc...
Watershed stewardship activities throughout North America have evolved into a process that requires more involvement in planning and decision making by community stakeholders. Active involvement of all stakeholders in the process of watershed stewardship is dependent on effective exchange of information among participants, and active involvement of a wide range of stakeholders from “communities of place” as well as those from “communities of interest.” We developed a map‐based stream narrative tool as a means to: (a) assemble a wealth of incompletely documented, “traditional” ecological or natural history observations for rivers or streams; and (b) promote a higher level of active involvement by community stakeholders in contributing to information‐based, watershed management. Creation of stream narratives is intended for use as a tool to actively engage local stakeholders in the development of a more comprehensive information system to improve management for multiple stewardship objectives in watersheds. Completion of map‐based stream narrative atlases provides a valuable supplement to other independent efforts to assemble observations and knowledge about land‐based natural resources covering entire watersheds. We are confident that completion of stream narrative projects will make a valuable addition to the information and decision making tools that are currently available to the public and resource agencies interested in advancing the cause of community‐based approaches to watershed and ecosystem management.
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