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Biological Sampling

RTA has the expertise and equipment to conduct a variety of fisheries sampling, including: 


  • Population estimates of stream-dwelling fish.  Mark-recapture and/or depletion methods with electro-fishing equipment.  Modified Hankin-Reeves methodology (direct observation calibrated with electo-fishing).


  • Presence/absence verification surveys with electro-fishing and/or snorkeling.


  • Fish relocation in conjunction with stream crossing replacement projects. RTA has worked with private contractors, city, county, and state entities in providing this service.

  • Out-migrant trapping of juvenile salmonids in small streams.

  • Spawning surveys for Chinook salmon, Coho salmon, steelhead, and all species of trout.

  • Seine netting and minnow trapping to determine presence/absence and distribution.

  • Underwater videography to determine presence/absence in water conditions unsuitable for snorkeling or electrofishing.

  • Radio-telemetry studies. RTA co-lead a three-year radio telemetry-movement study of brown trout in Rush Creek using both fixed antenna arrays and mobile receivers. Radio tags were surgically implanted in 90 trout. Study results included movement behavior and focal-point habitat measurements. 

  • PIT tagging. Over a 10-year period, RTA has implanted approximately 9,800 PIT tags in brown and rainbow trout in Rush and Lee Vining Creeks to determine movement, survival and specific growth rates. RTA has also used PIT tags to evaluate the growth of non-natal coho salmon rearing in off-channel habitats in Martin Slough and Freshwater Creek.

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