Fish in the Bay – August 2021: Red Ceramium, Boogers, a Nudibranch, and other Summertime Oddities.

Trawl map.

We are continuing to experience a very good Anchovy year.  The 2021 total is on track to possibly match 2020 which was the second-best year in the record.  However, 2016 will likely continue to stand as the record Anchovy year barring any surprises. 

Ceramium – red algae explosion.  We collected net-clogging quantities of this fine hair-like red algae at LSB1, LSB2, Coy3, Coy4, Alv3, Pond A21 and even up to the first bend in Guadalupe Slough!  We even saw loose clumps of the stuff floating at LSB2.  Why here?  Why now?  Is this a good thing?  … or a bad thing?

There were two non-native fish population explosions in August:  646 Shimofuri Gobies at Alv1, and 649 Inland Silversides at Art1 & Art2

And, we discovered a few new critters …


Bay-side stations trawling results.

Low Tides on August 14th prevented trawls of Pond A21.  The Pond was trawled four days later on August 18th instead.

Anchovy spawn.  We again found egg-bearing females or milting males at every station where we checked.  Unfortunately, because of the Pond A21 schedule change, Anchovies were not checked on that date.  The fish were likely in the same state of reproductive readiness, but we simply didn’t check.

Boogers!  All jellyfish-like fragments caught in August were, in fact, “Boogers.”  We now know what “Boogers” are.  They are NOT jellyfish; see story farther below.


Upstream of Railroad Bridge.

Summertime low Dissolved Oxygen (DO). New records were set for low DO in the upstream marshes.  The slightly larger red font above indicates that all four DO readings (start and finish, top and bottom) were below 3 mg/l at stations A19-4, UCoy2, UCoy1, and DMP-2.

With only the small exception of the SJ-SC RWF discharge at Art1 and Art2, there was no oxygenated refuge for aquatic organisms within the entire upstream area!  Nonetheless, we encountered six species of fishes plus various shrimp, clams, snails, and crabs in numbers roughly typical for that location at this time of year.


1. Red Ceramium Mess.

Ceramium Red Algae. The photos shown above depict the Ceramium bloom at station LSB1, but identical scenes played out at LSB2, Coy3, Coy4, Alv3, and Pond A21 on August 14th. We were up to our elbows picking out handfuls of rotting red algae.

During subsequent trawls the following week we spotted loose clumps of the stuff floating at LSB2 and collected more big net-filling blooms at LSB stations and up the first bend in Guadalupe Slough!  At all downstream locations, the net pulled up roughly 70 to 90 pounds of slimy red algal mass. It was a slightly revolting experience!

This alga is comprised of tough filaments close to the consistency of human hair.  One hopes that some animal(s) may consume this stuff, but frankly, it does not look or feel edible at all.


Ceramium history.  We first observed tiny innocuous sprigs of Ceramium in warm seasons of 2018 or 2019.  The first big bloom was observed last year: in July 2020 it clogged nets at stations LSB1 and LSB2.  It then disappeared by August.  Now, it has returned with a vengeance. Why here?  Why now?  Is Ceramium a good thing?  … or a bad thing?

Bad News:  Literature mentions hundreds of Ceramium species originating from every part of the world.  At least several species spread very readily via modern shipping.  Are we witnessing a new invasion???

And, the list goes on …


2. Boogers are bad things!

A Decorator Crab pokes at a Booger at LSB1 on 14 August 2021.

We caught another 32 Boogers in August.  For some years we counted these jelly-objects as fragments of medusa-type jellies, aka jellyfish.  Against the fingers in a tray full of fish and bugs, they look and feel like conventional “jellies.  But, we only rarely see complete jellies.  Why so many fragments (aka “Boogers”)???


3 Boogers at LSB1, 14 Aug 2021.

Boogers always have a consistent size, 2 to 3 inches long by 1 inch wide, and cylindrical shape.  They have no organs or internal structure. Inside each blob are tiny golden filaments that wind round and round.  Each filament consists of a string of nearly microscopic dots.


Boogers are egg sacs!  The tiny dots are the key.

Bad news:  These egg-sacs are almost certainly made by non-native “Philine auriformes” snails we commonly catch in this area.


Note: Three calcareous gizzard plates are visible inside the larger Philine at top.  The “Snot-ball” snail uses these to crush the shells of their bivalve prey.

Philine auriformis is a bad mollusk!  This non-native “bubble snail” or “head shield slug” is also known as the “New Zealand Sea Slug.”  Philine are voracious predators of bivalve clams, oysters, and other small marine bugs.  It was first identified in San Francisco Bay in 1993.

We call it the “Snot-ball Snail” others call it “Tortellini Snail” because the shell is on the inside; it looks like a snail turned inside-out.

The only good news is that we have not seen any increase in catches of Philine snails over the last several years.  I like to hope that Bat Rays, Leopard Sharks, crabs, or other critters eat both the Snot-ball Snails and their boogery egg sacs.  However, other naked marine snails and sea slugs like these are famous for using either bad taste or poison as an alternate defense.

Now we know: “Boogers” are egg-sacs from “Snot-ball Snails!”


3. Other Marine organisms.

Decorator Crabs at LSB1 on 14 Aug 2021.


Fifteen scaled worms.  Two more scale worms were collected in August:  one at LSB1 and at Alv3.  (The worm at Alv3 was recorded as generic “polychaete.”)  Scale worms are tiny predators: about ¾ inches (1.5 cm) in length.  Seeing one in Alviso Slough is unprecedented.  High salinity must have drawn it in.


Pile Worm.  Our more common Polychaete is known by several names: Rag Worm, Blood Worm, Sand Worm, and so on.  This one is non-native and most likely arrived as bait used for fishing.  Nonetheless, Pile Worms seem to be as beneficial to the creeks and sloughs as earthworms are in the garden.

I am always impressed by the sophistication and intelligence that these worms display despite having no more than a ganglion of nerve cells as a brain.  When confined in the Photarium, it takes a Pile Worm only minutes to orient itself and develop an escape plan or initiate attack/defense against any other Pile Worm in the box.  This worm can solve problems!


Caprella (aka Skeleton Shrimp) profile view at left, looking down at the dorsal side on right.

Caprellidae amphipod.  Caprellids are also known as “Skeleton shrimp.”  They look like very tiny praying mantises. The two shown above were around 1.5 cm or ¾ inch in length.  If they had not twitched, we would not have noticed them.  Caprellids are very common on the coast, but this is the first time we have seen them here.

Like our terrestrial praying mantises, caprellids tend to perch on stalks of seagrass, hydroids, and bryozoans.  They sit motionless waiting to ambush passing diatoms and larval crustaceans.  In turn, they are excellent food for Surf Perch, shrimp, and nudibranchs.  See Wikipedia:


Nudibranch! presumably Enosima Aeloid.  We caught this ¾-inch long nudibranch (a sea slug) just inside the mouth of Guadalupe Slough during supplemental trawls on 22 August.  I believe this is only the second nudibranch we have ever seen.  They tend to be very small and fragile, so most probably slip through or get mangled beyond recognition. This one appears to be the same species as another damaged specimen we picked up at LSB1 a few months ago.

(One advantage of the current Red Ceramium blooming mess is that soft mats of Ceramium are effectively making our Otter trawling net finer and softer.  Some fragile things like Boogers, Nudibranchs, and Caprellids are being better preserved.)


Enosima Aeloid (Sakuraeolis enosimensis) is probably native to East Asia since it was first reported in Japan and Hong Kong.

  • Enosima is very similar in size and appearance to the native and slightly prettier “Hilton’s Aeolid (Phidiana hiltoni). But, this Enosima lacks the distinctive red markings of the Hilton’s.
  • Alas, we have found yet another non-native species. All else equal, this one is rather charming to look at.
  • BTW: “Aeloid” is one of several superfamilies within the nudibranch group. Nudibranchs are typically described as being either Aeloid or Dorid types depending on the arrangement of soft horn-like structures (cerata) on the dorsal side.  However, there are more than two types, and classification can be much more complicated.


Orange-striped Anemone at LSB1 on 22 Aug.

Orange-striped Anemone. (Diadumene franciscana).  We continue to see slightly more of these tiny orange anemones dotting shells and debris this salty year.  We found a few others far upstream at Coy1 and Coy2 later in the month!

  • It just occurred to me: Aeloid nudibranchs eat anemones and incorporate the anemone’s stinging cells into their fluffy cerata.
  • Later in August, we collected some new anemones at both upstream and downstream stations. They were the same size but more greenish and completely detached and round-bottomed. They may or may not be a different species.  They appear to propagate by rolling around on the Bay bottom?  More to follow …


4.  Baby Leopard Sharks.

Boy and girl Leopard Sharks at Coy4 on 14 Aug 2021.

Leopard Sharks.  Baby Leopard Sharks are growing bigger with each passing month. These two were over a foot long.


5. Shrimp Wars.

Palaemon shrimp at Coy4

Palaemon shrimp.  Of our three primary shrimp species, only non-native Palaemon are doing well this year.  In fact, the 2021 count has now reached 20,302.  This is the best Palaemon year ever, and we still have four months left in the year.  As usual, at least half the Palaemon during this warm season are females bearing eggs.

All shrimp are protein-producing factories that feed the larger organisms.  Some shrimp are better than others, but all are good in our opinion.


Crangon shrimp with a Philine (aka “snotball”) snail at LSB1

Crangon shrimp.  We caught only 14 native Crangon in August!!!  This is a disaster!  Usually, August is one of our better Crangon months.  This is the lowest monthly count we have seen since flooding early in 2017 (aka the “February Freshwater Flush of 2017”) temporarily wiped out the Crangon population.

The Crangon life cycles on the opposite side of the seasonal clock from Palaemon.  Summer is Crangon recruitment season: small winter hatchlings grow big through the summer.  In a good year, we should see at least a hundred or so young Crangon at each station during warm month trawls.  Then, around December we hope to catch and release at least a few thousand of the egg-bearing females that arrive to release their broods in upstream marshes.   That’s what we should be seeing!

  • Where did the young Crangon go so suddenly?  And Why?   Did we just lose a generation of Crangon?


Exopalaemon shrimp at Dmp1. Note the blue antennae!

Exopalaemon shrimp continue to struggle this dry year.  The Exo count is just over 2,200 for the year, and it is almost certain that the 2021 total will fall below 2018, 2019, and 2020.  These are our non-native freshwater shrimp from Korea, so low counts are not necessarily detrimental.

Despite the name, Exopalaemon are members of the Palaemon genus.  Like all Palaemon we know of, females brood eggs throughout the warm season.  Around half of all Exos we caught seemed to be females with egg broods.


6. Anchovies!

Top: schools of Anchovies on sonar at Coy3.  Bottom: Golden-green & Green Anchovies side-by-side at the same location.

Northern Anchovies in heightened state of spawning readiness continued to be caught at all LSB stations.  We only perform a few egg and milt checks in the interest of time and rapid release.

Good News:  Random checks of any 4 or 5 fish at any station invariably detect either egg-bearers or milt-emitters, and that may be sufficient knowledge for this spawning season!


Big Dark Anchovies plus a few Yellowfin Gobies at Alv3 on 14 August 2021.

New Anecdotal observations and some deep thoughts: 

  • Anchovies caught at the creek mouths of Guadalupe, Alviso, and Coyote sloughs tend to be bigger, darker, and possibly more often female.
  • Those caught at LSB stations in the deep Bay tend to be smaller, more silvery and seem to be more often male.
  • But is this a true distribution, or an artifact of bias in our trawling methods? The big mamas are strong swimmers, and may evade our net in a big Bay.  They have less room to maneuver in the creek mouths.
  • Food is the key! Continuous egg production requires a huge amount of protein. It makes some sense that the big mamas would crowd into the creek mouths where food production is highest.
  • Herbold et al. (1992), “Status and Trends Report on Aquatic Resources in the SF Estuary” reported that “Adult females consume 4.5% of their body weight in zooplankton each day.” (No link available.)
  • Peebles et al (1996) found that Anchovy spawning in Tampa Bay, FL was highly dependent on food availability as opposed to temperature or photoperiod. Anchovies would congregate and drift within copepod dense tidal waters during their summer-long spawning season.
  • Hunter and Leong (1981) discuss Anchovy spawning in relation to food availability, e.g: “Before the Pacific sardine decline, most northern anchovy spawning occurred in the winter quarter, whereas now larval production in both quarters [winter and spring] is about equal. This increase in the duration of the peak period of spawning indicates that the annual number of spawning batches produced by northern anchovy has changed significantly since the demise of the Pacific sardine population. Food made available by the collapse of the Pacific sardine population may have been used by the northern anchovy population to increase the number of spawning batches produced annually. 
  • Anchovies spawn in response to food availability! Zooplankton alone may explain why the same Northern Anchovies (Engraulis mordax) generally spawn from Feb to May off the coast in the Pacific but from June to Sept here in Lower South Bay.  IT’S THE FOOD!!!


A typical big Mama Anchovy > 100mm at Coy2.  Did she arrive from the ocean?

Good News:  Big Mamas.  We caught several more big mama Anchovies in supplemental trawls later in August.  A few of these fish were at or over 120 mm.  Anchovies that size should be at least 4 years old or older.   

  • Bigger mamas produce more eggs. We are increasingly recognizing the importance of these big dark mama Anchovies.  They are released promptly after measurement.  The success of our spawning season depends on them.
  • Hunter and Leong (1981) studied spawning Northern Anchovies off the Southern California Bight. They determined that females spawn about 20 times per year and can deliver batches of eggs at weekly intervals.  “The spawning batch fecundity (number of hydrated eggs) of northern anchovy varies exponentially with female weight …” 
  • Dorval et al (2018) estimated daily egg production and the spawning biomass of Northern Anchovies off the California coast. The complicated metrics require some degree of fish sacrifice that we do not envision attempting at the moment.  However, this report, and abundant Anchovy literature, indicates that both egg production and spawning success are highly dependent on the proportion of large mature females in the population. 

As noted before, the majority of Anchovies are golden-green, golden, and/or absent of chromatophores altogether at fresher water stations far upstream in Coyote Creek.  This observation is NOT random or anecdotal: it is confirmed again, and again, in every mid-summer trawl.


7. Non-native Fish Explosions

Shimofuri Gobies. We caught 688 Shimofuri/Chameleon Gobies in August.  This is the highest number we had ever seen!  646 Shimofuris were collected at station Alv1 alone!  Many more were caught in supplemental trawls later in the month, so this was not a single trawl event.  Something very wild happened in Shimo world this month.

Shimos versus Chameleons:  All numbers shown here and above represent a combination of Shimofuri and Chameleon Gobies.  Until a few years ago, we always counted both species as Shimofuris.  Beginning in 2020, we started distinguishing Chameleons from Shimofuris, but the identification is often subject to error.  For August 2021, the three fish caught at LSB1 and LSB2 were definitely Chameleons.  All of the remaining bunch were very likely Shimofuris, and all of those caught in Alviso Slough were definitely Shimofuri.


Two Shimofuri Gobies from Alv2 on 14 August.

Shimos are taking over!  They have just displaced the Yellowfin as our most common goby.  All else being equal, Shimos are a much prettier goby.


Inland Silversides.  We detected a similar explosion of Silversides in Artesian Slough on Sunday.  649 out of 684 were caught at Art1 and Art2.

  • Non-native Silversides are an extreme hazard to our ecosystem. They devour larval fish and fish eggs.
  • Silversides quickly replaced native species in many of California’s inland waters since their first introduction in 1967.
  • We should not allow this invasive scourge to disrupt our Anchovy and Longfin Smelt spawning grounds! That said, I do not know how Silversides can be realistically controlled.
  • This is a very bad fish!


8. Mud Chunks

Chunks of mud falling into the Bay.  Until now, we assumed that rain and hydraulic flushing during wet years increased the rate of marsh erosion into Coyote Creek and Alviso Slough. However, this dry year has not appeared to slow the process at all, from our rough naked-eye point of view

Mud Chunks = Blue Carbon.  As we all know, densely packed marsh plants, like Alkali Bulrush, Spartina, and Pickleweed pull carbon from the sky.  The plants create new soil as they die and rot.  Soil builds up to mean higher high tide elevation then spreads like a mud glacier. Marsh topsoil spreads horizontally and eventually tumbles into creeks and sloughs.  Each mud chunk represents at least several pounds of carbon that was once atmospheric.

Mud Chunks = erosion but no loss of marsh.  Maps of this area show that the marsh has dramatically expanded over the last several decades.  Yet, the mud chunks keep rolling in!  If atmospheric carbon is a problem, this is one solution.


9. Gumplants bloom in August.

San Francisco Bay Gumplant, Alviso Slough, August 2021.

San Francisco Bay Gumplant (Grindelia stricta var. angustifolia).  This dry season stimulated a very conspicuous Gumplant bloom. In late summer, bright yellow flowers on this evergreen shrub serve as beacons indicating points of high ground in the mash.  It is a member of the Asteraceae (Aster) family.  The Gumplant is named for its sticky white gummy resin.

Good News:  The Gumplant is a San Francisco Bay native:

We never pay enough attention to the plants.

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