Fish in the Bay – May/June 2025, WRMP San Pablo Bay Trawls, Part 4 – Wildcat & San Pablo Marshes.

June 10, 2025 Jim Ervin
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Fieldwork, Fish in Lower South Bay, News

Part 4 of the San Pablo Bay Trawls. 

This is the fourth and final installment of our first round of San Pablo Bay fish and bug monitoring.  This installment ends the full circle, from Napa River in the northeast corner – to Petaluma in the west – to Gallinas in the southwest, and now to the Wildcat / San Pablo Creek shores just north of Richmond CA.   

This portion is arguably the most historically industrialized, urbanized, and disturbed segment of our journey. like the previously reported segments, or “Operational Landscape Units” (OLUs in WRMP terminology), it is a place where extensive restoration projects have been undertaken.  

Some random context and background information here:  

Two months of fish and bug counts are reported here: May and June. 

  • From our practical experience in South SF Bay, May fish counts should be dominated by baby gobies.  Here in May however, more than half the fish count was comprised of baby Herring. 
  • Bug (invertebrate) abundance and diversity was also low compared to most other places we visit. 

Bad news: The European Green Crab has established a firm beachhead in this OLU!

June counts were more encouraging.

  • More baby gobies were counted at several stations – especially at station Wil6.  Was this an “extra” or “additional” baby fish month??
  • More adult and baby Anchovies were also seen.
  • A small explosion of Mysids and baby Topsmelt may have been detected at station Wil6.

Good News: Only one European Green Crab was found at Wil1 in June.  Meanwhile, three baby native Dungeness Crabs were observed at stations Wil5 and Wil6.

1. Wildcat Creek.

Five stations are trawled near the mouth of Wildcat Creek.  They range from Wil1 and Wil2 in the lower creek itself, to Wil3, 4, & 5 progressively downstream in Castro Cove.

  • The west-side view is dominated by the Chevron Richmond Refinery.  It is a shockingly industrialized landscape softened by a shoreline of green marsh against the cove. 
  • Wildcat Creek Landscape (2001) https://www.sfei.org/projects/wildcat-creek-landscape-history  “Within five years of MacDonald’s entrepreneurial insight [1895], Point Richmond had become the Western continental terminus of the massive Santa Fe railroad system, catalyzing the subsequent industrial and urban development of Wildcat Creek’s alluvial fan. The proximity of undeveloped flatlands to both the deepwater port and the urban Central Bay almost instantly transformed Richmond into an industrial center of international significance, celebrated as “The Wonder City” and “The Pittsburgh of the West” (Cutting 1917).

    In 1901, Standard Oil selected the Potrero and the marshes along Wildcat Creek (apparently ideal because of their immunity to fire) as the site of their West Coast refinery and a number of other major corporations followed within the next 15 years …”

Wildcat Creek Results.

  • Striped Bass were present in both May and June: 7 at stations Wil1 through Wil4 in May, and 3 more in June.  All but one Bass were caught in the Wildcat segment over May and June. But always keep in mind, Bass are very fast swimmers compared to our slow trawl nets.  Results only suggest more Bass here at this point.
  • Mysids were present both months.  These midget-sized shrimp-like creatures are essential food for young fishes.
  • Corbula Clams were also present. Thankfully the numbers of these invasive clams were small. The majority were collected in the Wildcat Creek segment.

Shocking discovery! (for us) – Mama deer with baby.  Mama deer was photographed near this location in both May and June.  Baby was sighted in June.

The downstream stations of Wildcat Creek (Wil4 & Wil5) open into the Castro Cove embayment.  This portion lies between Chevron Refinery to the west and West Contra Costa Landfill to the east. 

Surfperches.  Three young Surfperches were caught at lower Wildcat stations in June: two Shiners and one Walleye. 
 

Flatfishes at stations Wil4 & Wil5.  Young Halibut and Starry Flounder were found at the offshore Wildcat stations in both May and June.

2. San Pablo Creek.

San Pablo Creek results (Stations Wil6 & Wil7).

  • Counts of small bugs (Mysids and Amphipods), baby Gobies, and Topsmelt were particularly high at these stations in June.
  • The West County Wastewater Treatment Plant (https://www.wcwd.org/) discharges perhaps 2000 feet upstream from station Wil6.  In our experience, it is not uncommon to find high tiny bug counts just downstream from highly treated wastewater.
  • San Pablo Creek per Wikipedia.  https://en.wikipedia.org/wiki/San_Pablo_Creek
    “San Pablo Creek’s delta, located within the city limits of Richmond, is known as San Pablo Creek Marsh, and its 300 acres (1.2 km2) are filled with an abundance of wildlife, including endangered species such as the California clapper rail, the salt marsh harvest mouse, the threatened black rail, the salt marsh wandering shrew, and the San Pablo vole. Other animals present are the shy salt marsh harvest sparrows which live in sloughs, while salt marsh yellow throats live among the willows that grow along the transition between fresh creek water and salty bay water.”

Mouth of San Pablo Creek. Looking northward toward the creek mouth, Station Wil6 on 22 May.

3. Dotson Family Marsh & Giant Marsh.

The Dotson Family Marsh lies along the western shore of Point Pinole.  Giant Marsh is nestled in the inner corner.

  • Dotson Family Marsh per Wikipedia.  https://en.wikipedia.org/wiki/Dotson_Family
    “The Dotson Family Marsh, formerly Breuner Marsh, is a 238-acre (96 ha) … In 2009 the East Bay Regional Parks District acquired the Breuner Marsh site, adding it to Point Pinole Regional Shoreline.  A habitat restoration plan for 60 acres (24 ha) of wetlands and 90 acres (36 ha) of California coastal prarie was subsequently approved.”
  • Giant Marsh Living Shoreline, ESA.  https://esassoc.com/projects/giant-marsh-living-shoreline/  “The project restored approximately 100 acres of subtidal to upland transition habitat and is the first large-scale oyster reef and eelgrass restoration in San Francisco Bay.”
  • Giant Marsh Living Shoreline, SFEI – 2025.  https://www.youtube.com/watch?v=rj-fUF-CEr
  • A Living Shoreline, Built One Oyster at a Time – 2025. https://www.kneedeeptimes.org/a-living-shoreline-built-one-oyster-at-a-time/  “At Giant Marsh, in the San Francisco Bay Area’s Contra Costa County, the oysters don’t have to tough it out on their own. They get castles.  About 200 of them, in fact —  low, chunky structures made of “baycrete,” a mix of concrete, native sand and gravel, and crushed oyster shell to attract, or “recruit,” oyster larvae …” 

Interesting Fishes at stations Wil8 through Wil9 in May and June. 

4. Other Notable Creatures & Plants.

We encountered these non-native “Black Sea Jellyfish” a.k.a “Maeotias marginata” hydrozoans at Gallinas OLU in April and May. They were first identified in SF Bay in the early 1990s.

European Green Crab.  A total of 15 Green Crabs were found: 14 in May and one in June.  They appear to be present in all segments of the Wildcat/San Pablo OLU.

Carcinus maenas per Wikipedia. https://en.wikipedia.org/wiki/Carcinus_maenas “C. maenas is a widespread invasive species, listed among the 100 of the World’s Worst Invasive Alien Species. It is native to the north-east Atlantic Ocean and Baltic Sea, but has colonized similar habitats in Australia, South Africa, South America, and both Atlantic and Pacific Coasts of North America.”

Look Out for Invasive Crab! https://www.fisheries.noaa.gov/alaska/habitat-conservation/look-out-invasive-crab  “The green crab is considered one of the most invasive species in the marine environment. It has few predators, aggressively hunts and eats its prey, destroys seagrass, and outcompetes local species for food and habitat. It has been documented that green crab devour juvenile king crab as well as juvenile salmon. They also destroy eelgrass habitat that larval fish use to hide from predators, and out compete Dungeness crabs for food and habitat.”

Other bugs.  It is still too early to deduce much from initial bug counts.

  • Corbula Clams were present in all three segments. 
  • Native Dungeness Crabs and Mysids were more prevalent in the San Pablo Creek segment.

Colorful algae and eelgrass were collected in the Wildcat/San Pablo OLU at several stations. 

  • Fragments only!  Eelgrass and other seaweeds are critical habitat for marsh restoration. We steer clear of Eelgrass beds and other places where Submerged Aquatic Vegetation (SAV) may be rooted.   
  • We feel reasonably confident identifying Ulva, Cryptopleura, and Eelgrass (Zostera marina).  Unfortunately, our knowledge of aquatic plants is limited. Other species remain unknown and unnamed.
  • Dear readers, if you can identify any of these new seaweeds, please comment!

5. Beggar Birds.

We returned to our launch site at Loch Lomond in June reeking of fish, bugs, and marine debris.  Some local birds took notice. Apparently, they are accustomed to receiving by-catch and discarded bait here.  Alas, we had none to give them.  (Our research permits do not allow reckless feeding of wildlife in any case!).

  • A note to readers.  Most of you are no doubt aware – this is for everyone else: Do not feed bread, crackers, or any other salty or sugary processed foods to wildlife, no matter how hard they may beg for it.
  • Processed foods are bad for your health.  They are deadly for water birds.  DON’T DO IT!!!

San Pablo Bay remains a giant puzzle at this point.

The Rolling Stones – Jigsaw Puzzle.  https://www.youtube.com/watch?v=E8cJ1Wa6U3o&list=RDE8cJ1Wa6U3o&start_radio=1

Fieldwork, Fish in Lower South Bay, News
Fieldwork, Fish in Lower South Bay, News