Nigiri Project 2013

The experiments to test how well salmon fry will thrive on “surrogate wetlands” (a.k.a. rice fields) is in middle of year two.  The test pods were expanded from 5 acres to 10 2-acre ponds at Knaggs Ranch.  Each of the fields, now ponds, has one of three treatments: fallow with weeds, rice stubble and stomped rice (stubble rolled into soil, twice).  In addition, there are cages within the first pond with all three treatments and the telemetry to track fish behavior using technology like that in Fastrak.

Equipment in pond tracks what type of land treatment the fish prefer: rice stubble, weeds or stomped rice.

Equipment in pond tracks what type of land treatment the fish prefer: rice stubble, weeds or stomped rice.

Another experiment is comparing the success rate of fish that spend time on the floodplain getting fat for 4-6 weeks before swimming to sea, versus going directly into the Toe Drain or into the Sacramento River.  These experiments are coordinated by a Science Team led by Jacob Katz with California Trout.  Scientists from Department of Water Resources, UC Davis Watershed Science Center, National Marine Fisheries Service, CA Department of Fish and Wildlife and US Bureau of Reclamation all collaborate to design the experiments and manage the projects in the field.

The farm manager, John Brennan, is an active partner– especially in solving problems such water supply and field designs. At the beginning of February there was a concern about possible breaks in the field checks.  The good weather relieved those pressures but created other concerns.

The warm weather raised concerns about salmon tolerance for temperature. The sunshine also provided the conditions for the algae bloom that feeds the bugs that feed the fish.  The food is so abundant that the fish are growing at twice the rate of last year, reaching sizes at 3 weeks that were measured after 6 weeks in 2012.

Pilot 2 – Growth 22 days (1)

The floodplains also give the fish space to hang out with few predators while the ocean conditions change to be more salmon friendly.  In another few weeks the Science Team will measure, count and release the fish in to the Toe Drain to swim out to sea. Their report will be available sometime this summer.

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