Abstract: Coastal ecosystems are among the most human-impacted habitats globally, and their management is often critically linked to recovery of declining native species. In the San Francisco Estuary, the Delta Smelt (Hypomesus transpacificus) is an endemic, endangered fish strongly tied to Californian conservation planning. The complex life history of Delta Smelt combined with dynamic seasonal and spatial abiotic conditions result in dissimilar environments experienced among ontogenetic stages, which may yield stage-specific susceptibility to abiotic stressors. Climate change is forecasted to increase San Francisco Estuary water temperature and salinity; therefore, understanding the influences of ontogeny and phenotypic plasticity on tolerance to these critical environmental parameters is particularly important for Delta Smelt and other San Francisco Estuary fishes. We assessed thermal and salinity limits in several ontogenetic stages and acclimation states of Delta Smelt, and paired these data with environmental data to evaluate sensitivity to climate-change stressors. Thermal tolerance decreased among successive stages, with larval fish exhibiting the highest tolerance and post-spawning adults having the lowest. Delta Smelt had limited capacity to increase tolerance through thermal acclimation, and comparisons with field temperature data revealed that juvenile tolerance limits are the closest to current environmental conditions, which may make this stage especially susceptible to future climate warming. Maximal water temperatures observed in situ exceeded tolerance limits of juveniles and adults. Although these temperature events are currently rare, if they increase in frequency as predicted, it could result in habitat loss at these locations despite other favourable conditions for Delta Smelt. In contrast, Delta Smelt tolerated salinities spanning the range of expected environmental conditions for each ontogenetic stage, but salinity did impact survival in juvenile and adult stages in exposures over acute time scales. Our results underscore the importance of considering ontogeny and phenotypic plasticity in assessing the impacts of climate change, particularly for species adapted to spatially and temporally heterogeneous environments.

Komoroske et al., 2014
Abstract: In 2004 the grant and contract work of the High Seas Salmon Research Program, Fisheries Research Institute (FRI), School of Aquatic and Fishery Sciences (SAFS), University of Washington, included five projects: (1) “North Pacific Anadromous Fish Commission (NPAFC) Research Coordination,” (2) “Migration Studies of Salmon in the Bering Sea,” (3) “Diet Overlap and Potential Feeding Competition Between Yukon River Chum Salmon and Hatchery Salmon in the Gulf of Alaska in Summer,” (4) “Estimates of the Bycatch of Yukon River Chinook Salmon in U.S. Groundfish Fisheries in the Eastern Berng Sea, 1997-1999,” and (5) “Global Ocean Ecosystems Dynamics (GLOBEC) 2000: Feeding, Growth, Condition, and Energetics of Juvenile Pink Salmon in the Northern Gulf of Alaska.” This final report for 2004 includes reports on specific tasks as described in the Statement of Work for “NPAFC Research Coordination” (National Oceanic and Atmospheric Administration (NOAA) Contract No. 50ABNF-1-0002), as well as related tasks funded by the other grants and contracts.

Strange, 2004
Abstract: This collaborative project uses temperature sensitive radio transmitters to track the movements and monitor the internal body temperatures of adult spring chinook during upriver migration in the Klamath River Basin, California. Salmon are tagged throughout the run in or near the Klamath River estuary and tracked to their respective holding areas or natal tributaries. Combined with data from automated listening stations, external archival temperature tags, river temperature monitoring, and snorkel surveys of thermal refugia the results of this study will provide valuable information on thermal refugia use, thermal experience, migration behavior, and stock specific run timing for adult spring chinook. This project is a critical step towards understanding the role of thermal refugia in mitigating stress and mortality from elevated temperatures during upriver migration.