Juvenile Chinook Salmon Rearing in Small Non-natal Streams Draining into the Whidbey Basin
Presentation Abstract
We electrofished for juvenile Chinook presence in 63 small coastal streams draining into Whidbey basin. The streams sampled range in watershed size from 3 to 1,862 hectares with channel slopes ranging from less than 1% to 38% for electrofished reaches. Bankfull channel width of electrofished stream reaches range from 0.8 to 6.9 meters. In 32 of the 63 streams we found juvenile Chinook salmon present on at least one of the sampling days over the six year study period (2008 – 2013. Most juvenile Chinook salmon were caught in the months of January through May each year. Juvenile Chinook body size found in the small streams was similar to or larger than juvenile Chinook body size found in adjacent nearshore habitat from January through April. After April, juvenile Chinook salmon were larger in nearshore areas than in small streams. While in small streams, individual juvenile Chinook reared an average of 38.5 days and grew 0.23 mm/day. Statistical analysis suggests four factors influence whether juvenile Chinook salmon are present within Whidbey Basin small streams: 1) distance to nearest Chinook salmon bearing river, 2) stream channel slope, 3) watershed area, and 4) presence and condition of culverts at the mouth of stream. Streams further from Chinook salmon bearing rivers and with steeper channel slopes had lower juvenile Chinook salmon presence rates. A minimum watershed size of 45 hectares with channel slopes less than 6.5% may be necessary for juvenile Chinook salmon potential. Culverts at stream mouths likely cause upstream migration problems for small fish such as Chinook salmon fry. Streams of this size are often not considered salmon habitat because many flow seasonally and do not provide habitat for spawning salmon. However, we found that numerous small streams entering the Whidbey Basin do provide rearing habitat for fry migrant Chinook salmon originating from the three nearby rivers (Skagit, Snohomish, and Stillaguamish). These small streams are not well mapped and may be subject to inadequate protection as fish habitat. Better mapping of small streams and a predictive model for juvenile Chinook salmon potential would help managers better protect this unique habitat type.
Session Title
Session S-04C: Importance of Puget Sound Lowland Streams
Conference Track
Freshwater
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
1-5-2014 8:30 AM
End Date
1-5-2014 10:00 AM
Location
Room 606
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Chinook salmon--Habitat--Washington (State)--Puget Sound; Chinook salmon--Monitoring--Washington (State)--Puget Sound; Streamflow--Washington (State)--Puget Sound
Geographic Coverage
Salish Sea (B.C. and Wash.); Puget Sound (Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Juvenile Chinook Salmon Rearing in Small Non-natal Streams Draining into the Whidbey Basin
Room 606
We electrofished for juvenile Chinook presence in 63 small coastal streams draining into Whidbey basin. The streams sampled range in watershed size from 3 to 1,862 hectares with channel slopes ranging from less than 1% to 38% for electrofished reaches. Bankfull channel width of electrofished stream reaches range from 0.8 to 6.9 meters. In 32 of the 63 streams we found juvenile Chinook salmon present on at least one of the sampling days over the six year study period (2008 – 2013. Most juvenile Chinook salmon were caught in the months of January through May each year. Juvenile Chinook body size found in the small streams was similar to or larger than juvenile Chinook body size found in adjacent nearshore habitat from January through April. After April, juvenile Chinook salmon were larger in nearshore areas than in small streams. While in small streams, individual juvenile Chinook reared an average of 38.5 days and grew 0.23 mm/day. Statistical analysis suggests four factors influence whether juvenile Chinook salmon are present within Whidbey Basin small streams: 1) distance to nearest Chinook salmon bearing river, 2) stream channel slope, 3) watershed area, and 4) presence and condition of culverts at the mouth of stream. Streams further from Chinook salmon bearing rivers and with steeper channel slopes had lower juvenile Chinook salmon presence rates. A minimum watershed size of 45 hectares with channel slopes less than 6.5% may be necessary for juvenile Chinook salmon potential. Culverts at stream mouths likely cause upstream migration problems for small fish such as Chinook salmon fry. Streams of this size are often not considered salmon habitat because many flow seasonally and do not provide habitat for spawning salmon. However, we found that numerous small streams entering the Whidbey Basin do provide rearing habitat for fry migrant Chinook salmon originating from the three nearby rivers (Skagit, Snohomish, and Stillaguamish). These small streams are not well mapped and may be subject to inadequate protection as fish habitat. Better mapping of small streams and a predictive model for juvenile Chinook salmon potential would help managers better protect this unique habitat type.
