Juvenile Chinook Beach Seine Collection for South Fork Nooksack River Captive Brood Program, 2007 - 2010

Abstract

In September of 2007, the Lummi Natural Resources Department began an effort to collect juvenile salmon for a South Fork Chinook Salmon Captive Brood Recovery Program. This work includes also the collection of DNA tissue samples used to identify individuals belonging to the ESA-listed South Fork Nooksack River Chinook Population. Our objectives are to: 1) to collect juvenile Chinook Salmon for a captive brood recovery program and 2) to collect data to describe life-history patterns of juvenile Chinook found in the South Fork Nooksack River.

We use beach seines to capture juvenile salmon. From September 2007 to December 2010 we completed 2,852 seine sets and captured 11, 846 juvenile Chinook. Initially all the juvenile Chinook were taken to the tribe’s Skookum Creek Hatchery. DNA tissues were sampled from individuals held at the hatchery. When DNA results became available, juveniles belonging to the South Fork (SF) stock collected and those belonging to other stocks were returned to the river. The Washington Department of Fish and Wildlife Genetics Laboratory provided the DNA analysis.

During this period 2,254 SF Chinook were identified for the captive brood program. Stock composition for DNA samples examined was: 19.0% SF "Early" Chinook, 22.1% North Fork "Early" Chinook, and 58.9% Fall Chinook.

Individuals belonging to the SF stock were transported to the WDFW Kendall Creek Hatchery where they were reared to maturity. To guard against losses should there be a problem with one hatchery, approximately half of the juveniles were transferred to the National Marine Fisheries Service Hatchery in Manchester, Washington. The Manchester Hatchery is a saltwater facility which offers protection from some diseases and provides for a greater growth rate.

Capture data and DNA results collected during this period has advanced our objective to better understand life-histories of juvenile Chinook. Spatial and temporal patterns of abundance are shown for individual brood years. Catch successes comparisons to seasons and river conditions are also displayed.

In the winter when river temperatures are very cold (below 3C) and the river is clear our catch success is near zero indicating a movement to deeper areas and/or under cover beyond the reach of our beach seine. As the river discharge increases and becomes more turbid, water temperatures and our catch increases, indicating a movement into the shallow margins where we operate the beach seine. These observations offer insight into the function and importance of holding refugia during the over-winter period.