Scientists recommend ‘reconciliation ecology’ for wild fish

Paul Mann
Mad River Union

CALIFORNIA - A new California science study endorses a management technique for wild fish called “reconciliation ecology.”

The study cites as an example a Central Valley initiative, the Yolo Bypass experiment, which manages rice fields to mimic natural floodplains.

The approach “creates substantial growth benefits for juvenile salmon,” according to a new analysis by UC Davis and California Trout, S.O.S. II, Fish in Hot Water.

Reconciliation ecology takes into account that most ecosystems, such as salmonids, are altered extensively by human work and activity.

“Working landscapes” should fuse human-dominated ecosystems with efforts to support salmonid growth and diversity, according to the S.O.S. II report.

The 41-day rice field/floodplain experiment was summarized in a separate report four years ago by UC Davis. Chinook salmon were introduced to the rice fields of the Yolo Bypass flood plain, where they fed abundantly on insects on their way to the sea.

The marriage of fish and farming joined a food-rich habitat for fish with human ecological management, enabling both salmon and agriculture to thrive. Juvenile chinook growth rates in fresh water set records in the reclamation exercise.

S.O.S. II warns it is essential to protect the best of what riparian habitats are left. “Few fully functioning river ecosystems, with relatively intact watersheds and high-quality habitat, exist today in California, such as the Smith River, Blue Creek, the Eel River and Butte Creek, among others. This is reason enough to make managing systems like these in perpetuity the highest priority, to protect salmonid diversity and production.”

The study notes that many of the historically productive and diverse habitats used by salmonids are either blocked behind dams and levees or are “significantly altered and no longer function properly. Restoring such habitats and access to them is of paramount importance.”

Illustrative of the human-caused damage is the severe depletion – an estimated 95 percent – of historical Coho salmon populations on the Southern Oregon/Northern California Coast.

As ever, recommended conservation measures include removing the four lowermost Klamath dams, scheduled for 2020, to restore access to historical cold water habitat, and halting all production hatchery programs for Coho salmon to allow wild stocks to recover.

Other recommendations are stopping illegal water diversions and expanding the deployment of water storage tanks to maintain cold stream flows during all seasons.

“The relatively recent reduction in salmonid life history and behavioral diversity means that salmonids are less able to adapt to a rapidly changing California,” the U.C. Davis/CalTrout analysis says. “Access to diverse and productive habitats, and reductions in interactions between hatchery and wild salmonids, are fundamental to restoring salmonid resilience.”

Absent relief, the state will lose most of its salmonid diversity, with a few groups maintained as low-diversity “boutique” populations.


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