Fish in the Bay – June 2024, El Nino Watch.

El Nino officially ended in May, but effects on fishes linger. 

Overall fish totals remain low – with one exception.  

Good News: 

• Anchovies arrived for their summertime spawning season, albeit in numbers not quite as high as we would like.
• Young and baby Halibut continue to recruit in response to the latest El Nino. More about that below.

1. Summer Greening.

Summertime Greenness.  The difference between cold wet season and sunny dry season is stark: dead-brown versus living-green.  

• These last two wet years were very good for fresh-to-brackish marsh. Both Cattails and California Bulrush stands have expanded well downstream from their drought-year ranges.   
• Triple La Nina drought years, 2020 to 2022, were tough on marsh plants.

New faces:  Our trawling Sunday was augmented by two UC Davis undergrad trainees: Rachel Lowe and Nathan Pompeani. 

Interesting early catches:

• Two Striped Bass. These were the only Striped Bass caught during the weekend – both at Art2, just a bit downstream from the SJ-SC RWF.
• One Green Sunfish. This was the first Green Sunfish we had seen since February 2019.  Sunfish are very beautiful freshwater fishes. (An extremely stunning fish for any freshwater aquarium.)  But, Sunfish are also well-known noxious invasives. Fortunately for us, they are still rare here.     https://en.wikipedia.org/wiki/Green_sunfish  

Nathan and Rachel learn the ‘Art of the Trawl’ at Station Art3 under Sami’s supervision.

2. California Halibut – the El Nino Fish.

California Halibut count = 65.  Halibut were again almost as numerous as they were in 2015 and 2016 following the last El Nino.

• Literature consistently points out that baby California Halibut recruit best during El Nino years. – we see it here as well!  

More young and baby Halibut, 1 June 2024.

California Tonguefish count = 1.  Tonguefish is the weirdest fish in the Bay.  It consists of no more than a tiny mouth, two beady little eyes, and a tongue-like body.

Tonguefish is another El Nino fish.  We caught dozens of Tonguefish each month during El Nino 2014-2015.  In contrast, we saw only a couple of them during La Nina years after 2020.

3. Starry Flounder & Prickly Sculpin.

Starry Flounder count = 3.  Only three Flounder!  This was the lowest count since April 2023.  Our hopes that the Starry Flounder surge would continue were utterly crushed in June.

Prickly Sculpin count = 4.  The year-to-date Prickly count is 14.  This is not many considering the extended rainy season. 

• For comparison, the highest Prickly year (entire year) was over 400 in 2017, a wet year. The lowest count was 1 (one) in 2022, a drought year. 

4. Spawning Anchovies & other pelagics.

Northern Anchovy count = 367.  Anchovy counts in June can range from 50 to a few thousand.  This June’s catch was roughly a median value. 

Pond A21 was this month’s  Anchovy winner:  145 Anchovies. 

• Station Coy3, about a mile downstream of Pond A21 had 47 Anchovies.
• Dump Slough, far upstream, was number two with 58.

Overall Anchovy assessment:  The was June catch was average at best. It was a little disappointing compared to record catches of recent La Nina years. 

Anchovy color studies continue:  

Background:  At both Pond A21 stations on Saturday, salinity was slightly higher at the start of each trawl and very close to the Clupeiform green-to-brown salinity threshold of roughly 10 ppt. 

Methods:

• Upon completion of each trawl net contents were emptied into a holding tub which was filled with water at the start point (slightly saltier water in these instances.)
• Fishes were hand transferred from the tub to counting trays. Counting trays are filled with water after the end of trawling (slightly fresher water).   

Results: As expected, both Anchovies and American Shad  dorsal sides “browned down” in the counting trays.  They exhibited a greenish-gold hue at the higher salinity (above 11 ppt in both cases).  The greenness quickly faded to golden (for Anchovies) or brownish (for Shad) when the fish were exposed to lower salinity (roughly 9 ppt).

• Always be mindful of salinity! Salinity-induced color changes within minutes amongst Clupeiform fishes.

Results at the second Pond A21 station (A21-4) were even more dramatic:  Green Anchovies browned down to golden as we watched! 

Note: Fish color changes were observed using only ambient salinity.  Anchovies were released as quickly as possible. – We strive to minimize harm to our spawning population. (Otherwise, what’s the point?)

Pacific Herring count = 1.  We usually see “few” to “zero” young Herring this late in the season.

• This oddball Herring had a strange brownish / mauve color on the dorsal side that made it easy to spot amongst the green and golden Anchovies.
• All Clupeiforms “blue up” in high salinity and “brown down” in fresher water. But, each species exhibits a slightly different color response.  Herring salinity-induced dorsal color is usually just a tad browner than Anchovies or Shad at any given salinity.   

5. Elasmobranch Nursery at LSB stations.

Leopard Shark count = 2. Two baby Leopard Sharks were caught in June.  These were our first Leopard arrivals for 2024. 

Lower South San Francisco Bay (south of the Dumbarton Bridge) is a safe zone for baby elasmobranchs in summer.

• At around 9 inches long, the Leopard Shark pups shown here were around a month old.
• Pregnant mama Leopard Sharks, Bat Rays, and Guitarfish swim into this corner of the Bay to give live birth to several to a few dozen pups each summer.  

Bat Ray count = 34.  30 of the Rays were newborns not more than a few weeks old. — At least a few mama Rays delivered new pups here recently!

Jane’s Addiction – Summertime Rolls: https://www.youtube.com/watch?v=VG_sjkYw9kM
–  Halloween concert – Costumes & hair styles were a little crazy.