Harbor seal predation on migrating steelhead smolts entering marine waters
Advanced Search
Select up to three search categories and corresponding keywords using the fields to the right. Refer to the Help section for more detailed instructions.

Search our Collections & Repository

For very narrow results

When looking for a specific result

Best used for discovery & interchangable words

Recommended to be used in conjunction with other fields

Dates
...

to

...
Document Data
Library
People
Clear All
...
Clear All

For additional assistance using the Custom Query please check out our Help Page

The NOAA IR serves as an archival repository of NOAA-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by NOAA or funded partners. As a repository, the NOAA IR retains documents in their original published format to ensure public access to scientific information.
i

Harbor seal predation on migrating steelhead smolts entering marine waters




Details:

  • Journal Title:
    Marine Ecology Progress Series
  • Personal Author:
  • NOAA Program & Office:
  • Description:
    After decades of historic exploitation, harbor seal Phoca vitulina populations in many marine ecosystems are increasing, and in some cases causing alarm over predation impacts on prey species of conservation concern. To gauge the magnitude of harbor seal predation impact on juvenile Puget Sound steelhead Oncorhynchus mykiss , a threatened population under the US Endangered Species Act, we quantified harbor seal predation rates in the Nisqually River estuary and nearshore marine environment of south Puget Sound in Washington State, USA, using 2 independent assessments. First, we developed a prey consumption model for the years 2016-2018 using the proportion of steelhead in seal scat (assessed using DNA metabarcoding, bioinformatics, and hard parts), seal daily energetic requirements, steelhead smolt size and abundance information, and seal abundance estimates. Second, we used acoustic telemetry data from individually tagged steelhead smolts (2014-2019 and 2021) to quantify predation events in the Nisqually River estuary based on spatial and temporal behavioral patterns of both predator and prey. The consumption model estimated that 9.0% (2017) to 32.8% (2018) of steelhead outmigrants (i.e. ‘smolts’) were eaten by harbor seals, accounting for most of the total mortality incurred in the Nisqually estuary and South Puget Sound (23 km) in 2 out of 3 years. Predation mortality rates through the estuary (5 km), assessed using acoustic telemetry analysis, ranged from 11.0% (2014) to 24.8% (2016). Our results demonstrate that a large proportion of a threatened salmonid population can be lost to harbor seal predation over a small segment of their migration route, even in a relatively natural delta estuary.
  • Source:
    Marine Ecology Progress Series, 743, 139-157
  • DOI:
  • ISSN:
    0171-8630;1616-1599;
  • Format:
  • Publisher:
  • Document Type:
  • License:
  • Rights Information:
    CC BY
  • Compliance:
    Submitted
  • Main Document Checksum:
  • Download URL:
  • File Type:
    Filetype[PDF-3.90 MB]

You May Also Like

Checkout today's featured content at repository.library.noaa.gov

Version 3.27.1