Fish in the Bay – July 2024, El Nino Summer Doldrums.

I suppose we could call this the “slow summer” or maybe the “warm summer.”  Fish counts remain low compared to most summers. For want of a better explanation, I blame this on continued El Nino impacts.

Water temperatures at all upstream stations were unusually warm.  This alone could explain low fish numbers.  

• 25 degrees C is iconic upper temperature stress-level for striped bass. Any fish bass-sized or larger would seek refuge in deeper cooler waters far downstream or face possible heat stress.   

Water was at least a few degrees cooler at the extreme downstream LSB stations. 

Interesting sidenote:  Random egg-checks inadvertently revealed that Anchovies in the restored island ponds were overwhelmingly female!  Anchovies at downstream LSB and Coy4 stations were slightly more likely to be males. This will be discussed in part 2 of the July report. 

1. The Catch at Station Art1.

Aquatic life at Art1.  This station is roughly 300 feet downstream from the SJ-SC RWF discharge point. We can never be certain what we will find here.  This time, the net was full of tiny fishes and bugs … along with a very plump and happy-looking Striped Bass.       

Three-spined Stickleback count = 441.  Stickleback populations have boomed and crashed every few years over the last decade of monitoring.  We have yet to discern a reason for the variability.

• The chins and undersides of male Sticklebacks turn cherry red as they get ready for mating. Their eyes become more reflective and blue. This display attracts gravid females and scares away competing males.
• Franco-Belussi et al. (2018) https://pubmed.ncbi.nlm.nih.gov/29577284/
  “Males of Gasterosteus aculeatus develop ornamental blue eyes and a red jaw during the reproductive season, colours that are further enhanced during courtship.”

Rainwater Killifish count = 66.  These non-native pupfishes tend to hide in the weeds.  Their bodies are small enough to slip through all but the cod end of an otter trawl net.  For those reasons, our monthly counts are probably gross underestimates. 

• Catches from beach seine nets give a better estimate of Killifish abundance.

2. Gobies – Summer is ‘Goby Season.’

Teenager Yellowfins at Coy4 on 7 July 2024.

Yellowfin Goby count = 167.  I refer to these young-of-year Yellowfins as “Teenagers.”  They hatched under the watchful eye of their father goby sometime between March and May.  

• Tiny fish lives are short. By the end of this year, these youngsters will be mating-ready adults.
• “The average longevity of A. flavimanus is 3 years, but there have been examples of older specimens (Moyle, 2002).”

Shimofuri Goby count = 10.  Shimo numbers are still very low compared to the last 3+ years.

Shimos during spawning season:

• Territorial males excavate and guard mating burrows this time of year. They develop puffy cheeks as part of their mating display.  Their bodies darken and fin colors and face spots become more pronounced.
• Mating-ready Shimofuris also express white “epaulets” at the base of their pectoral fins. (Is this a male-only characteristic (?))
  • We occasionally catch adult Shimos with no epaulets and bigger face spots during the season. Are these the females???

Shokihaze Goby count = 5.  When Shimos are away, Shokihazes come out to play. 

Cheekspot/Arrow Goby count = 54.  Cheekspot and Arrow Gobies are almost exactly the same size and similar shape. 

• The main distinguishing feature is mouth size: Arrows have big mouths; Cheekspots have small mouths.  This is very difficult to discern in the field.  Macro photography helps but is also often uncertain. For that reason, I continue to lump the two together on excel data tables.
• It is sufficient to know that both species continue to be present at most stations in LSB.   

 3. Pipefish.

Bay Pipefish count = 4.  Literature says that female Pipefish often deposit eggs in more than one receptive male. It is also likely that males accept eggs from more than one female.

• I have long wondered if male Pipefish might organize eggs by slowly moving them downward in the belly pouch: Sometimes the egg clutch looks highly organized at the bottom of the pouch. Sometimes the clutch looks totally random and chaotic.  Investigation continues.

4. Halibut, Flounder, & Bat Ray

California Halibut count = 43. Our catch of young and baby Halibut keeps increasing: 228 so far in 2024.    

Slightly larger Halibut plus a Starry Flounder.

Starry Flounder count = 2.  What a difference a year makes.  In July 2023, we caught 266 baby Starries. This year, the catch was only two, both adults.

Alex releasing the only young Bat Ray at LSB2.

Bat Ray count = 1.  Low salinity and high temperatures are keeping pregnant mama Bat Rays out of LSB for now. 

5. Bugs.

Overall counts of benthic critters have been low with only a few exceptions.  Philine bubble snails have been rare.  Atlantic oyster drills have been all but absent.  The year-to-date Tunicate count is the lowest we have seen since 2019.

Two notable exceptions:

Corbula Clam count = 1475.  This is already the biggest Corbula year since 2020 with numbers still climbing.  Corbula clams have been notably concentrated at station Alv1 this year.     

Musculista count = 87.  We had never seen even 50 Musculista mussels in any month prior to September 2022.  Then, Musculista numbers exploded: hundreds per month in late 2022; thousands per month in late 2023. … 

• We are now heading into the late summer Musculista season and numbers are again climbing.
• Musculista mussels are ecosystem engineers. They are changing our benthic bottom for better or worse.

Polychaete count = 1.  Polychaetes are fascinating creatures.  They are surprisingly intelligent.

• Wikipedia: Nereididae (formerly spelled Nereidae) are a family of polychaete worms. It contains about 500 – mostly marine – species grouped into 42 genera. They may be commonly called ragworms or clam worms [or pile worms].
• Alitta Succinea probably came from the Western Atlantic, but it’s original homeland is uncertain. https://invasions.si.edu/nemesis/calnemo/species_summary/-48 

Survival tip:  In addition to being good bait, similar worms are consumed as food in some parts of the world:

• As food. It is eaten as a local delicacy in the Chinese coastal provinces of Guangdong, Fujian, and Zhejiang and in Northeast Vietnam. The worm has high nutritional value in protein and fats.  In Vietnam, it is mainly used in a dish called chả rươi, which has been known as a delicacy for centuries, especially in the area of Tứ Kỳ district, Hải Dương province.  https://en.wikipedia.org/wiki/Tylorrhynchus_heterochetus 

To be continued.