Delta fish populations plummet

Midwinter trawl survey reveals record-low number of fish

After a temporary rebound in 2011, Delta fish populations plummeted once again last year, a midwinter trawl survey conducted by the California Department of Fish and Wildlife revealed.

The survey found a record-low number of threadfin shad, a previously abundant forage fish used as striped-bass bait on the Sacramento-San Joaquin Delta, according to The index level—a relative measure of abundance—of the threadfin shad was 41, compared to 228 last year. Other species experiencing a slip in index level were the Delta smelt (listed as endangered), striped bass, longfin smelt, Sacramento splittail and American shad.

The decrease in fish populations was predicted last year by Thomas Cannon, a fishery biologist who testified about the issue during state Water Resources Control Board meetings.