Comparing marine survival among Chinook and coho salmon and steelhead trout in the Salish Sea

Recent work on marine survival in Chinook and coho salmon and steelhead trout has shown a decline in marine survival in the Salish Sea that was not evident in other regions. For Chinook, the decline was not explained well by oceanographic patterns, and for coho, regional-scale patterns were suggested as important in understanding survival. Recent work on the development of indicators of Puget Sound steelhead survival has shown that predator abundance and patterns in hatchery releases, as well as oceanographic conditions are informative in predicting marine survival. While the three species of focus for the Salish Sea Marine Survival Project have different life-histories, and are therefore subjected to variable pressures at multiple scales, this current analysis aims to answer three questions: 1.) Are there similarities in survival trends among the three species? 2.) Do regional patterns in survival emerge when survival trends are evaluated concurrently across the three species? 3.) Does release strategy (yearling or subyearling) confer a survival advantage, and if so, is this consistent across all species? To evaluate survival time series, we used multivariate time series analysis with multiple groupings (species, spatial, and release strategy) to identify commonalities among species. Observed commonalities will aid in the development of indicators of marine survival for coho and Chinook by focusing efforts on appropriate spatial or temporal attributes. A hypothesis-driven approach similar to that employed for the development of indicators for steelhead survival will be used to relate coho and Chinook to environmental, biological, and anthropogenic factors influencing survival

Trophic structure of pelagic fish and jellyfish across spatial and seasonal gradients in the greater Puget Sound

Recent analysis of community structure in the pelagic ecosystem of the greater Puget Sound has revealed a shift in species composition and abundance in some areas from those dominated by fish to those dominated gelatinous mesozooplankton (“jellyfish”). Unfortunately, the mechanisms behind these shifts are unclear due to a deficit of ecological understanding of this system. The analysis of foodweb structure, which reflects the flow of carbon and nutrients, is useful to complement composition and abundance information in order to understand the energetic processes underlying pelagic communities and why they may be changing. In this talk, we examine foodweb structure and trophic ecology of middle trophic level pelagic fish and jellyfish in six oceanographic sub-basins in Puget Sound from April to October 2011. Specifically, we assessed spatial and seasonal variation in 1) the isotopic composition of abundant species of salmonids, forage fish and jellyfish, 2) the trophic overlap between fish and jellyfish and 3) foodweb attributes of whole pelagic communities including niche width, trophic length and basal resource diversity. At the species level, there were strong spatial differences in isotopic composition among sub-basins. Seasonal patterns, possibly suggesting ontogenetic diet shifts or changes in basal carbon sources, were also evident but were more pronounced in fish than jellyfish. The degree of trophic overlap between fish and jellyfish varied among sub-basins and generally decreased seasonally. At the community level, overall community niche width was higher in Whidbey basin in spring and summer months then switched to a north-south gradient in fall months with the highest value in South Sound. Both the trophic length and basal resource diversity exhibited contrasting seasonal patterns among basins with values decreasing seasonally in northern basins (Whidbey and Rosario) and increasing in southern basins (Central and South Sound). Taken as a whole, our observations suggest that the trophic ecology and overall structure of pelagic fish and jellyfish are heavily influenced by local processes at the sub-basin scale as well as temporally dynamic biotic processes such as changes in body size. Our analysis provides an important groundwork to understand how Puget Sound’s pelagic ecosystem is structured and why it may be changing

Potential for ecological nonlinearities and thresholds to inform Pacific salmon management

AbstractEcology is often governed by nonlinear dynamics. Nonlinear ecological relationships can include thresholds—incremental changes in drivers that provoke disproportionately large ecological responses. Among the species that experience nonlinear and threshold dynamics are Pacific salmon (Oncorhynchus spp.). These culturally, ecologically, and economically significant fishes are in many places declining and management focal points. Often, managers can influence or react to ecological conditions that salmon experience, suggesting that nonlinearities, especially thresholds, may provide opportunities to inform decisions. However, nonlinear dynamics are not always invoked in management decisions involving salmon. Here, we review reported nonlinearities and thresholds in salmon ecology, describe potential applications that scientists and managers could develop to leverage nonlinear dynamics, and offer a path toward decisions that account for ecological nonlinearities and thresholds to improve salmon outcomes. It appears that nonlinear dynamics are not uncommon in salmon ecology and that many management arenas may potentially leverage them to enable more effective or efficient decisions. Indeed, decisions guided by nonlinearities and thresholds may be particularly desirable considering salmon management arenas are often characterized by limited resources and mounting ecological stressors, practical constraints, and conservation challenges. More broadly, many salmon systems are data‐rich and there are an extensive range of ecological contexts in which salmon are sensitive to anthropogenic decisions. Approaches developed to leverage nonlinearities in salmon ecology may serve as examples that may inform analogous approaches in other systems and taxa

Landmark geometry and identity controls spatial navigation in rats

In three experiments, a new reference memory procedure was used to examine how male rats search for consistently located food in a cue-controlled spatial environment. The animals searched the tops of 24 poles for six hidden baits in an enclosed circular arena containing a fixed configuration of six object landmarks. In Experiment 1, acquisition was faster and overall performance better for the consistent group (lO rats), in which the six baited poles were fixed relative to the landmarks for each session, than for the random group (4 rats), in which baited poles were randomly configured, Cue-control tests and computer simulations suggested that the consistent group relied on the landmarks to directly go to the baited poles, whereas the random group used them to employ a response strategy for searching the arena. Experiments 2 and 3 revealed that the number, identity, and geometric configuration of the landmarks were important to the consistent group's search performance, Overall, these results are most consistent with the use of a geometric representation by male rats which includes information about both the identity and the relative geometry of discrete landmarks in the surrounding spatial environment. In searching for food, many animals demonstrate an accurate working knowledge oftheir surrounding environment. Two general questions have been of interest in the investigation of this spatial behavior: What stimuli in the environment govern this behavior, and how are these stimuli encoded and used by animals for navigation? Although research addressing these basic questions has in

Juvenile Chinook salmon monitoring in the Skagit estuary: application of results at various scales

We show how monitoring the response of juvenile Chinook salmon to estuary restoration in the Skagit tidal delta occurs at multiple nested scales; each scale having potentially different end users of results. All scales and end users are necessary for successful salmon recovery plan implementation. Monitoring at the restoration project scale identifies how well an individual project is performing compared to its objectives. Local stakeholders use project level monitoring results for adaptively managing a project over its life. However, monitoring of individual projects within the context of a larger plan can also play a role in filling data gaps for a watershed or region. We provide an example for a regional learning objective related to self regulated tidegate structures. Monitoring at the watershed scale follows a plan for salmon recovery. In the case of the Skagit, the guidebook is the Skagit Chinook Recovery Plan. An individual restoration project is only one of many in the Skagit estuary; all are necessary to achieve the plan’s goals. We show Skagit estuary restoration progress to date and the benefit these projects are having on Skagit Chinook salmon populations. The stakeholders using watershed level monitoring results operate at the watershed and regional level and are interested in the success of watershed salmon recovery plan implementation. Monitoring at the watershed scale also needs to fit within a regional framework for monitoring and salmon recovery plan implementation. We show how the Skagit’s monitoring indicators fit within the framework for development of monitoring and adaptive management plans for Puget Sound Chinook Recovery for two ecosystem components (Chinook salmon, estuaries)

A multispecies assessment of climate change threats to salmonids across their life cycle

During their life cycle, salmonids experience conditions in freshwater, estuarine, and marine habitats, exposing them to numerous climate change threats. The extent to which different species utilize different habitat types and habitat-specific climate change risks should result in differential overall vulnerability of these species to climate change, but most previous vulnerability assessments have focused only on particular life stages for particular species, hampering our ability to protect, restore stocks and their habitats to maximize species portfolios in river systems. We performed a life cycle-based risk assessment of climate change threats for nine species of salmonids (species within Oncorhynchus, Salvelinus, and Prosopium genera) inhabiting the Skagit River system, which is vulnerable to the panoply of climate impacts forecasted for the Pacific Northwest. The risk assessment integrated both species-specific intensity and exposure and incorporated uncertainty. We found that while climate change threats existed across all habitats inhabited by these species, the greatest threats to all species were associated with projected changes in the extremes of freshwater flow (high incubation flows, low summer flows). These results suggest that restoration strategies targeting restoration of floodplain function will be most effective for reducing the most serious threats for a broad portfolio of salmonids inhabiting the Skagit River, although other climate adaptation strategies may provide additional benefits to other suites of species