12/24/2011: Merry Christmas, Delta Smelt
DEC. 24, 2011 — This year’s holiday season brought a welcome Christmas present for the Bay-Delta estuary’s most endangered fish species, the delta smelt. The 2011 fall midwater trawl index for delta smelt was the highest in a decade—343, compared to 29 last year—and index values were up for a number of other species as well. (These indices do not directly measure population numbers, but they accurately track abundance trends over time).
While good news for these species on the brink of extinction, the numbers do not by any means represent recovery to viable population size. The delta smelt index number is still considerably less than the median value of 444 observed in the 1967-1987 period when populations were healthy and stable, and the 2011 index number for the highly imperiled longfin, 477, while a big improvement over last year’s 191, is dwarfed by the median value of 6,338 recorded during the 1967-1987 period.
What’s responsible for these encouraging numbers? The primary reason is the higher amount of outflow to San Francisco Bay that occurred in 2010 and 2011, creating greatly improved habitat conditions in the Delta and Suisun Bay. These higher outflows were the combined result of greater natural runoff during two wetter years and stronger controls on Delta export pumping imposed on the state and federal water projects after the Bay Institute and other groups successfully sued to overturn previous inadequate protections for smelt and salmon. Despite these restrictions, the projects managed to export a record 6.5 million acre-feet of water from the Delta in 2011.
Unfortunately, some of the most important new protections for delta smelt were set aside a few months ago in one of the last decisions made by the federal district court judge on the case before retiring. (He later briefly represented the biggest federal exporter of Delta water, Westlands Water District, in a different lawsuit before withdrawing when he received a barrage of criticism on the editorial pages of the state’s leading newspapers for doing so). What this means is that the gains for the species from the recent wetter years and the improved protections could be lost if drier conditions return and higher pumping levels are allowed, crashing the still historically low delta smelt and longfin populations back to the abysmally low numbers of the last decade. Let’s hope for more rain and snow in 2012—and the restoration of critical fish-saving controls in pumping and flow requirements by the powers that be.