The Trinity River juvenile salmonid outmigrant assessment is conducted to assess juvenile Chinook salmon production from the upper 40 miles and the Trinity Basin to estimate salmon and steelhead emigration timing from the Trinity River basin.
Assessments utilize rotary screw traps at two trapping locations, typically monitored from January through August. The upper trap location – at Pear Tree Gulch, just above the North Fork – provides an estimate of the upper Trinity salmonid production. Meanwhile the lower trap location – just below the town of Willow Creek – provides an estimate for production across the entire Trinity River basin.
Outmigrant monitoring also tracks fish growth, health, and timing of outmigration relative to river temperature and flow rate.
Suggested further reading:
Pinnix, W D and Quinn S (2009) Juvenile salmonid monitoring on the mainstem Trinity River at Willow Creek, California, 2006-2007.
Schwarz, C J; Pickard, D; Marine, K R; and Bonner, S J (2010) Trinity River Restoration Program’s juvenile salmonid outmigrant monitoring evaluation: phase II – analytic framework and statistical approaches. Oral presentation provided at the 2010 Trinity River Science Symposium.
Schwarz, C J; Pickard, D; Marine, K; and Bonner, S J (2009) Juvenile salmonid outmigrant monitoring evaluation, phase II – December 2009.