Year: 2018
Type: conference-paper
Abstract: Use of tidal marsh surfaces by juvenile salmon in Pacific Northwest estuaries has generally been ignored by ecologists, engineers and planners involved in salmon habitat restoration. In contrast, fish use of marsh plains has been documented in many other parts of the world. Are Pacific Northwest marshes an exception to the pattern of fish use that is so common elsewhere? For three consecutive years, fish were sampled bi-monthly in tidal channels and on tidal marsh plains of the Skagit Delta to answer this question. Juvenile Chinook and chum salmon, as well as sticklebacks were the most consistently caught and abundant fish in channels and on the marsh surface, but eight other fish species were also found on the marsh surface. While fish densities were much higher in tidal channels than on marsh surfaces, marsh surface area was much greater than channel area, so sticklebacks and juvenile chum were potentially 50% more numerous on the marsh surface than in channels. However, due to their high channel densities, juvenile Chinook were nevertheless more abundant in tidal channels than on the marsh surface; those on the marsh surface amounted to 40% of those in tidal channels. The ratio of marsh surface to channel fish density peaks late in the season for all three fish species, which may be a response to increased prey production over the marsh plain. The substantial use of the marsh surface by juvenile salmon that we observed suggests estuarine habitat restoration for salmon recovery should not neglect the direct value of vegetated marsh plains to juvenile salmon. Tidal marsh habitat for juvenile salmon is more than just tidal channels. Partial habitat restoration that only restores tidal flow to channels and not to adjacent marshes, e.g., using self-regulating tide gates (SRTs), has a direct impact on juvenile salmon habitat use.
Authors: W. Gregory Hood, Eric M. Beamer, Rich Henderson
Language: English
Subfield: Aquatic Science
Domain: Life Sciences
SDG: Life below water
Open Access status: green
OpenAlex ID: W2895635184