Tuesday, August 28, 2012

Bull Trout Redd Surveys in Northern Puget Sound

Bull trout
Bull trout (Salvelinus confluentus) are a member of the salmonid family, which includes salmon, trout, whitefish, char, and grayling. Bull trout love cold, clean, complex, and connected streams and other aquatic habitat. Habitat degradation and fragmentation, blockage of migratory corridors, poor water quality, the effects of climate change and past fisheries management practices, including the introduction of non-native species such as brown, lake, and brook trout, have resulted in local extinctions and population declines of bull trout. This has led to the listing of bull trout as threatened under the Endangered Species Act in 1999. Within the Puget Sound Bull Trout Management Unit, there are eight core areas with a total of 57 identified local populations. Bull trout are found in the Chilliwack, Nooksack, lower and upper Skagit, Snohomish-Skykomish, Stillaguamish, upper Cedar (Chester Morse Lake system), and Puyallup River basins. With the exception of the Chilliwack and upper Cedar River systems, these basins all support anadromous bull trout that use Puget Sound marine waters for foraging and migration.

A high priority goal of our agency is to acquire more complete information on the current distribution and abundance of bull trout within each core area of the Puget Sound Management Unit. Annual spawning nest (redd) counts provide a non-invasive way to monitor relative population strength of bull trout. Each fall, experienced fisheries personnel count the number of redds in predetermined stream sections. Not all known bull trout spawning areas are monitored, since weather and remoteness limit the ability to conduct the fall surveys in some areas. Comparison of the count numbers over time can provide insight into long- and short-term population trends and alert fishery and land managers to potential problems within aquatic systems.

Since State funds for surveying bull trout redds was no longer available, we provided money to the Washington Department of Fish and Wildlife (WDFW) to continue collecting this valuable data through return year 2011 and to expand the number of survey sites. Staff from WDFW surveyed for bull trout redds within the Skagit, Snohomish, and Stillaguamish River basins from 2009 to 2011. Their findings include:
  • Fewer bull trout redds were observed in the past 3 years than were observed from 2006 to 2008.
  • The total bull trout redd count was very similar in 2011 to what was observed in 2010. However, some areas had more redds than in 2010 and some had less.
  • The total redd count of all sites (637) was 25% below the average count from the years 2006 through 2010 (850).

You can learn more about bull trout biology, critical habitat, and conservation measures at http://www.fws.gov/pacific/bulltrout/


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