
The population of Delta smelt, an indicator species that demonstrates the health of the Sacramento-San Joaquin River Delta, has declined to a new record low population level, according to the spring 2016 surveys conducted by the California Department of Fish and Wildlife.
The January Kodiak Trawl survey produced only seven fish, while the February survey yielded just six smelt. The Delta smelt once numbered in the millions, but have plummeted after decades of Delta water exports, combined with the impacts of declining water quality and invasive species.
The delta smelt is a small endangered fish, about 2.0 to 2.8 inches long, found only in the Sacramento-San Joaquin River Delta. It is nearly translucent, with a steely-blue sheen on the sides.
Carl Wilcox, CDFW policy advisor on the Delta, attributed the record low numbers of Delta smelt found in the January and February surveys to the effects of the drought and low outflow conditions and the need to balance water project operations between different species.
Exports from the Delta were very low, maintained for health and safety reasons, most of the time during the drought, Wilcox noted. The real issue was very low inflow, along with contingency plans to support the release of water from Shasta Dam for winter-run Chinook salmon. The water quality standards came at the cost of managing the cold water pool.
Carl Wilcox is still optimistic about the potential survival of the Delta smelt, even though their numbers have reached record lows this year.
Delta smelt are resilient and have the capacity to rebound even when at low levels, he emphasized. We have evidence that they're in the system, are finding each other and they're spawning. We've seen Delta smelt rebound whenever we've had good water conditions. The fish were on a downward spiral until 2011 until we saw an increase in abundance. The fish have experienced bad flow conditions ever since 2000.
The numbers are extremely low and we have a high level of concern, added Wilcox. We look at the Delta smelt from the perspective that they're still out there and we're still working to protect them.