Author: James Hobbs

Little Fish in Big Trouble: The Bay Delta’s Longfin Smelt

Longfin Smelt, is a small pelagic forage “baitfish” that was once one of the most abundant fishes in the San Francisco Estuary.  Our work on Longfin Smelt was recently featured by KCET’s Alistair Bland.  Here is the link to the news piece.

The extreme wet weather we’ve had during winter 16-17 turned the Lower South Bay Fresh for several months. This has resulted in the first successful reproductive event for Longfin Smelt in Lower South Bay since the 1982-1983 El Nino. Longfin Smelt have been encountered in our fish surveys of the Alviso Marsh during the winter months since we began our surveys in 2010.

Longfin Smelt typically arrive in late fall when temperatures begin to cool.  We see them every month during the winter through early spring.  This is typically the spawning season for Longfin Smelt.  We’ve been seeing them in large numbers inside the tidally restored salt ponds along Coyote Creek. They specialize on feeding on mysid shrimp, “estuarine krill”, which also typically increase in abundance in the winter and spring when Longfin Smelt are in the marsh.

Longfin Smelt seek out low-salinity or tidal freshwater habitats to spawn in the winter months. However, the Alviso Marsh in winter is typically too salty for Longfin to successfully reproduce.  In March of 2017 we found our first larval (baby) Longfin Smelt in the marsh. In our April Survey we captured over 200 of this little Longfin Smelt up to about 35mm about an inch and a half in length.  Our largest single catch of 59 fish occurred inside Pond A21, a tidally restored salt pond that was breached in summer of 2006.


Longfin Smelt were listed as threatened under the California Endangered Species Act in 2010 and as a result 8,000 acres of tidal wetland restoration was prescribed by the state to help mitigate the losses of fish in the giant pumps located in the South Delta.  These pumps are the key to California’s agricultural success.  Our work is demonstrating tidal restoration may provide additional habitat for the Longfin Smelt, however, it is unclear whether additional rearing habitat will bring Longfin Smelt abundance back to where it was before it was listed.  We will continue to monitor the abundance and growth of these fish in the coming months. Stay Tuned.



Monitoring Restoration in South San Francisco Bay Oct 1. 2016

Post by Dr. James Ervin, Compliance Manager for the San Jose-Santa Clara Regional Wastewater Facility

I joined UC Davis / Dr. Jim Hobbs fish monitoring survey on October 1st. I was on the Saturday run this time. As explained last month, monthly trawls are performed in Alviso Slough and Bay-side stations on Saturdays. On Sundays of the same weekend, the crew trawls the upstream half of Lower Coyote Creek. Saturday runs are always good for variety. The fish are fewer, but get bigger and weirder as you venture deeper into the Bay.

On this day, we launched from the public boat ramp at Alviso. This is what Alviso Slough looked like early in the morning. Can you see the gobs of white foam? Many people assume foam like this must be from detergent or some other form of pollution. Foam like this is quite common in sloughs of Lower South Bay. This is a result of billions of microbes cycling carbon. The microbes synthesize and lyse triglycerides, amino acids, proteins, etc. as they grow and die. This material becomes dissolved organic carbon (DOC) in the water column. The least bit of turbulence as Bay tide rushes in and out builds up globs of waxy foam that can persist for hours.

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A New Haven for the Leopard Shark

by Alessandra Bergamin on April 17, 2014

It is early morning at Eden Landing Ecological Reserve and in a pond designated as E9 by the managers of the South Bay Salt Pond Restoration Project, the water is cold and still. A leopard shark, around three feet long with distinct black and brown bands and spots mottled across a steel-gray body, rests on the pond’s silty floor. There is no real agenda for the day except, of course, to eat, but for one of the largest predators in the San Francisco Bay that shouldn’t be too much of a challenge. So the shark can afford to wait for the water to warm and the tide to come in before it starts its day.

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