Juvenile Salmonid Outmigrants

Rotary Screw Trap 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.

Trinity River Outmigration Studies (linked to ODP)

Petros P, Harris N, Pinnix WD (2013) Juvenile Salmonid Monitoring on the Mainstem Trinity River, California, 2010. Yurok Tribal Fisheries Program, Hoopa Valley Tribal Fisheries Department, U. S. Fish and Wildlife Service, Arcata Fish and Wildlife Office, Arcata Fisheries Data Series Report Number DS 2013-28, Arcata, California.

Pinnix WD, Heacock A, Petros P (2013) Juvenile Salmonid Monitoring on the Mainstem Trinity River, California, 2011. U. S. Fish and Wildlife Service, Arcata Fish and Wildlife Office, Yurok Tribal Fisheries Program, and Hoopa Valley Tribal Fisheries Department. Arcata Fisheries Data Series Report Number DS 2013-29, Arcata, CA.

Harris, N; petros, P; and Pinnix W D (2012) Juvenile Salmonid Emigration Monitoring on the Mainstem Trinity River, California, 2009. Yurok Tribal Fisheries Program, Hoopa Valley Tribal Fisheries Department, U. S. Fish and Wildlife Service, Arcata Fish and Wildlife Office, Arcata Fisheries Data Series Report Number DS 2012-27, Arcata, California.

Pinnix, W.D.; Harris, N.J.; and Quinn, S. (2010) Juvenile Salmonid Monitoring on the Mainstem Trinity River at Willow Creek, California, 2008. U. S. Fish and Wildlife Service, Arcata Fish and Wildlife Office, Arcata Fisheries Data Series Report Number DS 2010-20, Arcata, California.

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.

Pinnix, W D and Quinn S (2009) Juvenile salmonid monitoring on the mainstem Trinity River at Willow Creek, California, 2006-2007.

NSR, ESSA, and Simon Fraser University (2008) Trinity River Restoration Program Juvenile Salmonid Outmigrant Monitoring Evaluation, Final Technical Memorandum.

Pinnix, W; Polos, J; Scheiff, A; Quinn, S; and Hayden, T (2007) Juvenile Salmonid Monitoring On The Mainstem Trinity River At Willow Creek, California, 2001 - 2005. U.S. Fish and Wildlife Service, Arcata Fisheries Data Series Report DS 2007-09.

Green J, Petros P (2004) Emigrant Surveys and Rotary Trapping: Estimation of Abundance of Outmigrating Juvenile Salmonids in the Trinity River Using Rotary Screw Traps in 2004. Hoopa Valley Tribal Fisheries Department, Hoopa, CA.

Green J, Logan E, Zajanc D, Petros P (2002-2003) Emigrant Surveys and Rotary Trapping: Estimation of Abundance of Outmigrating Juvenile Salmonids in the Trinity River Using Rotary Screw Traps in 2002 and 2003. Hoopa Valley Tribal Fisheries Department.

Scheiff, A J; Lang, J S; and Pinnix, W D (2001) Juvenile Salmonid Monitoring on the Mainstem Klamath River at Big Bar and Mainstem Trinity River at Willow Creek 1997-2000. Annual report of the Klamath River Fisheries Assessment Program. U.S. Fish and Wildlife Service, Arcata, CA.

McLeod, R; Craig, J; Prall, M; and Williamson, J (1999) Juvenile salmonid monitoring on the mainstem Klamath River at Big Bar and mainstem Trinity River at Willow Creek, 1996. U.S. Fish and Wildlife Service, Arcata, CA.

Lang, J S; Gray, A E; Jackson, C L; Mcleod, R F; and Phalen, G G (1998) Juvenile salmonid monitoring on the mainstem Klamath River at Big Bar and mainstem Trinity River at Willow Creek, 1992-1995. U.S. Fish and Wildlife Service, Arcata, CA.

Stables, T. B. (1996) Hydroacoustic Monitoring of Out-migrant Salmonids in the Trinity River Basin: June 4-18, 1996 Feasibility Study Final Report. Report by BioSonics Inc. to the Hoopa Valley Tribal Fisheries.

Goldsmith, G H (1994) Juvenile salmonid monitoring on the Trinity and Klamath Rivers. U.S. Fish and Wildlife Service, Arcata, CA.

Craig, J L (1992) Annual report, Klamath River fisheries assessment program juvenile salmonid trapping on the mainstem Trinity River at Willow Creek and on the Klamath River at Big Bar, 1990. Report No. AFF-1-FRO-92-13, U.S. Fish and Wildlife Service, Arcata, CA.

Krakker, J. J. (1991) Progress Report Estimating Numbers of Salmon and Steelhead Juvenile Outmigrants Produced in the Trinity River Basin. Report from the USFWS Trinity River Restoration Program.

USFWS (1989) Annual report, Klamath River fisheries assessment program juvenile salmonid production monitoring, 1988. Report No. AFF-FAO-89-12, U.S. Fish and Wildlife Service, Arcata, CA.

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