Loading...
Please wait, while we are loading the content...
Similar Documents
Juvenile Coho Salmon ( Oncorhynchus kisutch ) Track a Shifting Mosaic of Habitat Conditions over the Early Summer Feeding Period
| Content Provider | Semantic Scholar |
|---|---|
| Author | Raymond, Jeffrey |
| Copyright Year | 2020 |
| Abstract | Variation in river flow results in the expansion and contraction of the main channel, off-channel habitat, and the physical connections between these components. Hence, rivers are characterized by a mosaic of habitat conditions that shift across space and time. Here, we explore how a stream-dwelling fish integrates across spatial and temporal shifts in the availability of thermal and trophic resources. Across multiple years of variable flow, juvenile coho salmon (Oncorhynchus kisutch) have been observed feeding on an ephemeral food source in the cold main channel at night; returning to warm off-channel habitat during the day where their ability to metabolize large meals is greater. We hypothesize that an analogous tracking strategy is used to take advantage of in-situ prey and a shifting distribution of thermally optimal habitat within a single season. During the early summer in southwest Alaska, high lake levels flood the lower reaches of a third-order stream. As summer progresses, lake levels subside and the spatial distribution of thermal resources and connectivity of habitats within the stream is reduced. Preliminary analysis shows that juvenile coho prey heavily on stoneflies, which are concentrated in the cold main channel. Using snorkel surveys, PIT tagging, and gastric lavage, we will monitor changes in the spatial distribution and diet composition of fish over the course of a day and a season. We will compare these observations with changes in the distribution of warm habitat – recorded by i-button temperature loggers – to assess the ability of coho to integrate across shifts in resource availability. We aim to document the frequency of resource tracking in juvenile coho during this early summer period. The results have implications for understanding the importance of environmental complexity to endangered salmon populations and associated species in systems where humans have homogenized floodplains. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://expo.uw.edu/expo/apply/312/proceedings/offering_session/585.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
