Fish in the Bay – February 2025, Part 2. Bottom Fishes & Bugs in the Valley of the Heart’s Delight.

This is the rest of the February report – Fishes, bugs, plus a few other items that didn’t fit into part 1.

1. Flatfishes.

We tend to overlook the importance of delicious flatfishes.

California Halibut count = 45.  Post-El Nino recruitment of young Halibut continues!

Starry Flounder count = 4.  For reasons we don’t understand, the Starry Flounder hatch of 2023 was off the charts (for modern times) – 1,577 total catch for the year, almost all were tiny babies.  But, numbers declined quickly: only 261 were netted in 2024.  Now, we are catching a few pan-sized adults per month.  These are probably adult survivors of the 2023 baby boom. 

English Sole count = 15.  Baby Sole reliably show up in Lower South Bay from January thru May.  We seem to see up to hundreds per month following La Nina years and very few after El Ninos.   

Speckled Sanddab count = 2.  Sanddabs also arrive during the cold months. 

Baby Flatfishes!  San Francisco Bay is a nursery for many different sea critters. 

Baby Halibut hatch in San Francisco Bay.  Adults spawn in the Bay.  Soon after hatch, baby Halibut migrate upstream into brackish sloughs where risk of predation is low and food abundance is high. The young move downstream after their first year or two.

Baby English Sole recruit but do NOT hatch in the Bay.  Adult Sole spawn along the coast.  Tiny, thumbnail-sized hatchlings swim and surf the tides up into the Bay.  Sole also grow fast in Lower South Bay but only for a few months.  By May, or June at latest, they migrate back out to sea. 

Far Right: Niko Floros with adult Halibut caught during Broodstock trawls.

Halibut are extremely important game fish in San Francisco Bay.  – Nature is the best fish farmer!   

Starry Flounder – the other important game fish. 

• The Starry Flounder baby boom of 2023 is described here: https://www.ogfishlab.com/2023/08/14/fish-in-the-bay-august-2023-starry-starry-summer/   
• No one knows why Starry populations in SF Bay declined since the 1980s.

2. Staghorn Sculpins.

It’s Staghorn spawning time!

Staghorn Sculpin count = 5.  Staghorns are another “La Nina fish.”  We caught thousands per month in early spring following the strong La Nina of 2010/11 and again after the moderate La Ninas of 2020-22.  We saw drastically fewer Sculpins after El Ninos in 2015/16 and 2023/24.  https://ggweather.com/enso/oni.htm

• Currently, we are in a Staghorn deficit: catches dropped to just a few individuals per month after April 2024.
• Why do El Ninos hit Staghorns so hard?

3. Gobies

Yellowfin Goby count = 19.  Yellowfins are the largest of the gobies in LSB.  We catch big adults during the coldest months. – And then …

• April is “Baby Fish Month” as defined by all the baby gobies we catch – e.g. baby Yellowfins (plus a few Arrow Gobies.)  

Digging and defending burrows defines the male gobiid lifestyle.  Male gobies generally display broader jaws or flared cheeks as part of their sexual display.  In many species, males become darker during spawning season. 

Unfortunately, Yellowfin Gobies display very little of these sexually dimorphic characteristics most of the time.  On occasion we catch one or two Yellowfins that are clearly male.  More often, it’s still just a guess.

Shimofuri Gobies.  Sex determination is much easier in Shimofuri Gobies. 

• Darker males: Shimofuri males display exaggerated puffy cheeks and darker body color when actively attracting mates and defending burrows during spawning season. The “epaulets” at the base of each pectoral fin also lighten up to almost white.   
• Lighter Juveniles: Juvenile Shimos universally show a lighter tan body color with dark longitudinal stripes.
• Mixed up Females and subdominant males? Body color in adults, other than dominant males, seems to vary from lighter (with stripes) to darker depending on mood. Shimos sometimes change body color as we watch!

More about Gobies in February.

Arrow/Cheekspot Goby count = 8.  Arrows and Cheekspots are the two native gobies here.  They are both tiny: Adults are less than 2 inches in length.  Their numbers remain steady.

Shimofuri Goby count = 24. Shimos rebounded a bit in February.  Earlier in 2024, their numbers declined sharply after June and remained low until now.

Shokihaze Goby count = 5.  Shokihaze numbers dropped a bit.  We continue to see an inverse relationship between Shokihazes and Shimos: When we catch more of one, we immediately see fewer of the other. – Shokihazes and Shimofuris are members of the “Tridentiger genus.” They evidently compete with each other. https://en.wikipedia.org/wiki/Tripletooth_goby

4. Bugs.

Amphipods are good bugs.  They are significant vectors in the food chain for moving organic carbon up into larger fishes and birds.  Shore birds pecking at mud near the tideline tell us that amphipods are abundant. 

Amphipods burrow under soil along the shorelines. They are analogous to terrestrial crickets, grasshoppers, ants, and/or bees.  Some amphipods even pollinate underwater plants.  Their importance in this ecosystem cannot be overstated.

• See: Ritter and Bourne (2024) Marine amphipods as integral members of global ocean ecosystems. “These crustaceans are also recognized as bioengineers (Howard and Dörjes, 1972), benthic-pelagic coupling facilitators (Limia and Raffaelli, 1997; Dauby et al., 2003), and widespread mesograzers (Howard, 1982; Buschmann and Santelices, 1987; Berthelsen and Taylor, 2014). Amphipods live everywhere between the coastal shallows and the deep sea (Ahyong and Hughes, 2016), and thus, more comprehensive knowledge of their biology and ecology would provide a better understanding of the inner workings of ecosystems throughout the ocean.”
  
• Our trawls catch only small samplings of Amphipods from mid-channel bottoms. We usually pull up more of these bugs midway upstream in Alviso, Artesian, and Upper Coyote (“UCoy”) sloughs.  Those are the places where detritus drops to the bottom as freshwater meets higher salinity Bay water. 

Bad Bugs.

Devil Bugs: Wintertime Cymothoid Isopod infestation continues.  Gill parasites hitch rides in the gills of migrating Shad, Herring, Longfin Smelt and other pelagic fishes.  Their host fishes carry them in from cooler, deeper Bay waters or the ocean.  We see them every winter. 

• Devil Bugs are very intelligent! Cymothoids readily jump from host-to-host.  They appear to track and chase a new host as if it were prey. 
• We invariably find small “Devil Bugs” in smaller fishes and large “Devil Bugs” in the gills of big fishes. This could indicate they abandon small hosts and seek bigger ones as they grow – kind of like Hermit Crabs???  Don’t underestimate these clever bugs!

Corbula clam count = 2,176.  The 2024 Corbula count was 14,615 – nearly double the number we have seen in any year after 2012.  January and February results show no letup in this trend.  This is unfortunate! – We were hoping Corbula populations would again decline a bit during the cold months as they usually do. 

Good News? – We did NOT see certain Bad Bugs in February.

• Atlantic Oyster Drill count = ZERO!
• Philine Snail count = ZERO!
• Both of these bad bugs are non-native predators of bivalve mollusks … (like Corbula clams?).   Oyster Drills and Philines have been rare or absent for months now.  (Don’t be fooled; they will return eventually!) 
• Questions: Where did they go? What makes their populations boom and bust like this?

Crangon shrimp count = 3,857.  This year’s Crangon brooding event continues.  Adult females are releasing countless young.  We will soon see thousands of baby Crangon in upstream sloughs. 

• Crangon are delicious!  They are important food for all bigger fishes.

Sphaeromatids.  Brackish water “pill bugs” burrow into the banks and bottoms of upstream sloughs here. They come in at least two varieties: big dark ones, and smaller brownish ones.  They are ancient cousins of “rolly-polies” found in terrestrial gardens.  They are shown and described here – See Item #5:  https://www.ogfishlab.com/2022/03/02/fish-in-the-bay-february-2022-supplemental-report-gobies-shrimp-etc/ 

• The big dark one shown above is likely Sphaeroma quoianum (I think).  S. quoianum comes from Australia and New Zealand. The species was first identified in SF Bay in 1898.   https://invasions.si.edu/nemesis/species_summary/92340  
  • See: Cohen and Carlton (1995) https://nas.er.usgs.gov/Publications/SFBay/sfinvade.html  “- The Australian-New Zealand boring isopod Sphaeroma quoyanum creates characteristic “Sphaeroma topography” on many Bay shores, with many linear meters of fringing mud banks riddled with its half-centimeter diameter holes. This isopod may arguably play a major, if not the chief, role in erosion of intertidal soft rock terraces along the shore of San Pablo Bay, due to their boring activity that weakens the rock and facilitates its removal by wave action. Sphaeroma has been burrowing into Bay shores for over a century, and it thus may be that in certain regions the land/water margin has retreated by a distance of at least several meters due to this isopod’s boring activities.”
• Little brown ones might be natives of the West Coast, if not the Bay: Gnorimosphaeroma lutea (Oregon Pill Bug) or closely related varieties.  https://zookeys.pensoft.net/article/63017/
• We still only guess about their identities. There are probably more than two “pill bug” species here. 

5. Climate vs. Weather.

It wasn’t our imagination.  The weather is better here.  This really happens!

During winter wet months, atmospheric rivers from the Pacific Ocean slam against the California Coast.  Ocean storms drop abundant rain against the lee side of the outer coastal mountains.  Less rain falls directly over Silicon Valley (San Jose, Santa Clara, Sunnyvale, Mountain View, and surrounding cities in the valley). 

• We noticed this “San Jose Bowl” or bubble a few years ago.   First described here in 2020:  https://www.ogfishlab.com/2020/12/13/fish-in-the-bay-december-2020-anchovy-rebound-blue-fish/
• It’s really an atmospheric dome: a combination of rain shadow, along with – maybe – some urban heat island effect?
• Rain shadow from the coastal mountains is the bigger factor. During both days of the February trawling weekend, we watched near constant rain against the lee-side of the mountains … and an equally constant “rip” in cloud cover downwind, and over us, as the latest “Pineapple Express” blew in.   https://abcnews.go.com/US/atmospheric-river-slams-california-heavy-rain-latest-forecast/story?id=118431845 
• History: Long before people named it “Silicon Valley,” this place was called “The Valley of the Heart’s Delight.”  Mild weather, fertile soil, and abundant fresh water via constantly replenished underground aquifers made it an agricultural paradise.   
  • Until the 1960s, Santa Clara Valley was the largest fruit-producing and packing region in the world, … https://en.wikipedia.org/wiki/Santa_Clara_Valley
  • Fruit trees were everywhere! https://fortheloveofapricots.com/2016/07/valley-of-hearts-delight/
  • Even after massive suburban buildout, mild climate still makes Santa Clara Valley a very desirable place to live. We see and experience this pleasant climatic wonderfulness every trawling weekend.

Jim Hobbs and Sami Araya showing off “Marsh Merch” collected on 2 Feb 2025.

It gets even better …

The marsh rewards hard work.  We collected some high value junk that was littering the marsh on Sunday.  Some items will sell like hotcakes at a yard sale.

• The “Pelican-brand double rifle case” alone is worth a fifty-dollar bill even before cleanup!
• Is this a great country or what?!?!?!

Halibut Song  https://www.youtube.com/watch?v=YSHulx38r6U