Fish in the Bay – May 2022: Big Baby Fish Month!

As reported last month, the early April trawls captured “Traditional Baby Fish Month.”  But with only 721 babies, it was not as bountiful as we had hoped. The situation changed when we trawled again the following month on April 30^th and May 1^st. 

May was Big Baby Fish Month!  This time we caught 1422 babies, plus over 2300 juvenile Yellowfin Gobies.  This was the biggest baby fish month we have seen in several years of trawling! 

• To be clear, “Baby Fish” are larval fish that are too small to be identified to species. The vast majority are larval gobies, and of those, the vast majority are Yellowfin Gobies with Arrow, Cheekspot, and possibly Bay Gobies making up most of the remainder. 
• In addition, most of the 2363 Yellowfin Gobies caught this month were also small juveniles but just large enough to be positively identified as Yellowfins.
• The worrisome ongoing population explosion of (adult) Shimofuri Gobies also shows up in red near the right side of the chart.

We caught Fifty (50) baby Leopard Sharks! (to be discussed later …)

A total of six Sturgeons were seen on sonar, and the baby Crangon count exceeded 10,000 in May.

1. Baby fishes.

The results from the first trawl on Saturday.

We knew by the end of the first trawl in Artesian Slough that this was going to be a big baby fish weekend.  We caught almost 1,100 baby Yellowfins at Art1.

Apparently, the baby fish bloom in early April was just a teaser.  Or perhaps, these Lower South Bay marshes experienced an enormous month-long Goby hatch and recruitment event?

Young Yellowfin Gobies caught at Art1 are shown here.

Yellowfin Gobies.  We counted a total of 2,363 Yellowfin Gobies over both days. Nearly all these Yellowfins were tiny babies.

Unidentified baby gobies, larval fishes, and mysids at Pond A19-1.

Unidentified larval fishes. In addition to tiny Yellowfins, another 1,422 “Unidentified” larval gobies/fishes were counted.  Most of the baby fishes were too young and small to identify at far upstream stations.  Here again, the majority of these “Unidentified Gobies” were likely also Yellowfins, but many were not. 

Mysids were present at all upstream locations.  It was encouraging to see them.  These tiny shrimp-like creatures have been rare to absent over much of the past year, and they are very important food for growing fishes.

Arrow/Cheekspot Gobies.  A total of 80 Arrow/Cheekspots were counted.  No doubt many baby Arrow Gobies were also members of the “unidentified” club: too young and too small to be identified. 

Not all babies were Yellowfins …  A newborn Shiner Surfperch at Dmp1.

2. Shrimp

1,345 Crangon at Art3

Crangon Shrimp – Explosion of Young Crangon!  10,293 young Crangon were counted in May.  How did this happen? 

Crangon all but disappeared after May last year.  We saw very few brooding mamas from December thru March.  Then, over 2,000 showed up in April.  Now, this explosion.  How did all these babies slip past us???

• Adult Crangon don’t tolerate fresher water.  But soon after hatch, the young swim or surf the tide upstream to places where tiny food is most abundant. They slowly migrate downstream as they grow. 
• Crangon populations increase after freshwater rain years. Crangon tend to decline when it’s dry. 
• Will this latest recruitment survive?

Exopalaemon Shrimp at Art2.

Palaemon and Exopalaemon Shrimp.  5,112 Palaemon and 556 Exopalaemon were caught.  For better or worse, populations of non-native Palaemon and Exopalaemon Shrimp are flourishing as well. 

3. Pipefish

Bay Pipefish. Twenty-eight (28) Pipefish were counted in May.  Last month was the record-breaking month (42) and 2022 has become our record-breaking year for Pipefish. 

We caught many adults in various states of sexual readiness as well as juveniles and babies.  2022 is a very good year for Pipefish.

A baby Pipefish, three baby Yellowfins, and an unidentified larval fish flanked by two Exopalaemon Shrimp in Dump Slough.

4. Anchovies

Northern Anchovies.  52 Anchovies were seen in May.  The summertime surge in Anchovies has not yet arrived.  However, we again observed Anchovies with either eggs or milt at six out of eight stations where they were caught.

• Both literature and our experience suggest that food availability triggers Anchovies to begin producing eggs and milt. What food is blooming here?

5. Critters that eat shrimp and other small fishes.

Staghorn Sculpin at UCoy2 with a belly full of shrimp.

Staghorn Sculpin.  We saw 150 Staghorns. That is roughly typical for a May.

Sculpin eat a lot of shrimp: The sculpin shown here has a fat belly full of shrimp.  A shrimp antenna is sticking out of its mouth.  Shrimp carapaces could be felt in the belly.  We see this ‘Shrimp Belly’ condition often in Sculpin.

Snowy Egret at UCoy2

Snowy Egret.  Snowy Egrets are common sights here.  We spotted this one on Coyote Creek actively snatching and eating some of the many tiny baby-boom fishes. 

Two Sturgeon? on sonar at UCoy2 on 30 May 2022.

White Sturgeon.  Six (6) Sturgeon were seen on sonar this month (one could have been a seal).  Sturgeon crawling along the bottom are probably feeding.  Crangon and baby gobies are a big part of their diet.  

6. Bonus Mollusks.

Corbula clams (left) and Ribbed Horse Mussels (right) from UCoy1.

Corbula Clams.  Good News!  Only 19 Corbula were collected during May trawls.

Ribbed Horse Mussel (or “Ribbed Mussel”).  These mussels are numerous amongst spartina stems near the tideline in brackish water marshes, but we rarely catch them in trawls.  Ribbed Mussels latch themselves tightly to marsh roots and rhizomes.  The only ones we ever see have somehow broken loose and fallen into the channel.

• Ribbed Mussels are not native. Like many critters here, they were introduced with East Coast oysters in the late 1800s. 
• But, these mussels are relatively beneficial.  They filter water, consolidate the Spartina marsh, and Clapper Rails (aka Ridgeway Rails) eat them.  https://animaldiversity.org/accounts/Geukensia_demissa/ 

Joy to the world
All the boys and girls
Joy to the fishes in the deep blue sea
Joy to you and me.

Three Dog Night, 1971.  https://www.youtube.com/watch?v=as8K3H7Rros