Fish in the Bay – 2 December 2017 UC Davis Trawl – Part 1: King Tide Weekend; The Fish

Hi Folks.  UC Davis fish researchers returned to trawl the first weekend of December.  I joined them on the Saturday Alviso-side run.

The Hobbs team has begun blogging.  My November email is now posted on the Hobbslab website here:    Possibly with time, we can archive some of my previous emails there as well.

On Saturday, I experienced “King Tide” with the Hobbs crew.  At 9.4 ft NAVD, we were riding on close to second highest-high tide of the year. The marsh got a little soggy, but otherwise, no loss of life or property.  (BTW: Earth’s orbit takes us closest to Sun (perihelion) in early January.  So highest high tides of the year happen on, or close to, January 2nd.

Spring tides in late June to early July are also extreme, but not quite as intense.  In January, Earth swings three million miles closer to the Sun and that difference gives January tides a small extra day-time gravitational punch. )   I plan to discuss King Tide in another installment, but for now I want to give a quick update on fish seen this past weekend.

Saturday – Bay Side:

Sunday – Upstream Side:   

Freshwater effects still being seen.  Some estuarine species like freshwater more than others.  December 2017 data continues to show:

  • Anchovies and Halibut hate freshwater! Anchovy numbers are a very small fraction of the totals we saw during the drought years.  California Halibut catch was roughly half the number for this time of year.
  • Prickly Sculpin and young Starry Flounder like it fresh, but they have largely moved on by now. We saw lots of both species through summer and fall but numbers tapered off as the young got bigger.
  • American Shad and Longfin Smelt love freshwater for spawning and recruitment. We see roughly double the Longfins this year as a result successful spawning last spring.  American Shad baby boom generation:  252 American Shad were counted this weekend compared to 22 max for any comparable weekend last winter.
  • Crangon Shrimp also like it fresh. Populations continue to outstrip non-native Palaemons and Exopalaemons.

Good News – American Shad continue to do very well.  Above is a small sample of the 252 young American Shad seen this weekend compared to, maybe 10 to 15 in a late season weekend in any previous several years of trawls.  These are young that hatched in fresh flowing local creeks the past spring. It would seem that 2017 is the year of “Peak American Shad.”

Anchovies not looking so good.  During dry years, late summer and fall weekend trawls collect a few to several thousand Anchovies.  This year, the wet year we saw several hundred.  The December tally was 17.  Some Anchovies may hang out through January, but the peak of Anchovy season is now behind us.  Dr. Hobbs’ field notes mention that anchovies were looking skinny.  By this time last year, Hobbs was evaluating spawning readiness of this fish that textbooks say does not tend to spawn in the Bay.

We know from Hubbs (1925) and Hobbs’ work, a slightly smaller, “brown race” of anchovies appear to be year-round residents.  These are believed to be a Bay-spawning sub-population, and Jim Hobbs confirmed anchovy spawning in Lower South Bay in recent years.

This year, the brown race seems to be gone. Only a few sickly specimens of ocean-going “green race” are showing up.  (This is some conjecture on my part: These fish have not been genetically tested.  They all look like “spent” green-backs to my naked eye.)

I noticed in past years that “green race” or “green-back” anchovies lose their color. By end of season they have a light or dark gray back with just a trace of green or blue iridescence. (Editor’s Note, June 2018:  In retrospect after later observations, I think this one is a Blue-Back!)  

Green or brown top-shading provides camouflage.  But, why should an anchovy lose its color in fall and winter?  These fish live for 4 to 7 years.  Faded ocean-going green-backs, looking like worn out dish rags should be heading back out to sea now.  How does loss of color help or hinder them?  Anchovies are an environmentally important fish.  This is an interesting mystery.

Green-Back Anchovy.  I should caution that not all Anchovies were looking so gray and sad.  At least one robust and very green-backed Anchovy was found in Pond A21.  Was this fish a recent arrival from the Pacific? Or, is bright color indicating spawning readiness?  What does this color mean?

California Halibut.  The only three “CalHals” seen this weekend were all caught far out in the Bay at LSB2 station.  The young are not as numerous here during a wet year and we are now past their peak season.

Halibut eye.  Halibut are bottom-dwelling ambush predators – small fish beware!  The CalHal may have his eye on you.

Prickly Sculpin continue to be caught.  Adults should now be migrating back upstream for spawning.  This year, for the first time, some pricklys, including one this weekend, were recorded in “Dump Slough” (Coyote Creek bypass channel).  Also, note that UC Davis caught Longfins in Dump Slough this year as well.  This is a good indication that Dump Slough functions as diverse estuarine habitat when Coyote Creek’s winter overflows divert through it.

Best news of all – more than 2x more Longfin Smelt!  The 18 longfins caught this weekend are thought to be first-year adults from spawning that Hobbs documented last spring.  Eighteen may not sound like much, but it is in fact at least double the number caught in previous year winter weekends.  Longfins seek fresh estuarine water for spawning, and there is no doubt that the past wet year was beneficial for this local population.

Jim Hobbs visually examing longfins for signs of spawning readiness.  Longfins are evaluated for spawning readiness in the field then taken back to “Hobbs Labs” at UC Davis to record size, health, diet, and examine otoliths (ear stones).

Do not try this at home!  Longfin Smelt has been listed as threatened under the California Endangered Species Act (CESA) since 2009 … Jim Hobbs is allowed to “take” up to 60 Longfins per year for research purposes under his “Incidental Take Permit” with California Department of Fish and Wildlife (CDFW).  Longfins are doing so well this year in Lower South Bay salt ponds that Jim came close maxing out on his permit.

SIDE NOTE: We have salmon too!  Steve Holmes at South Bay Clean Creeks Coalition (aka: Friends of Los Gatos Creek) reports that his group sees a good late-fall Chinook salmon run this year.  Steve organized 30 volunteers into teams to monitor Gualdalupe River and its tributaries for spawning salmon.  Thus far, they have seen 15 Chinook in Los Gatos Creek and many more in Guadalupe River.  Steve’s video of a female Chinook guarding her REDD (nest) on November 27th is linked here:  South Bay Clean Creeks Coalition

Other bigger fish … Strong swimming fish like Salmon, larger Striped bass and Striped mullet easily outrun our otter trawl nets, so they are rarely, or never, recorded in these UC Davis fish surveys.  To find the latest on populations of top tier big fish, you have to ask someone like Steve Holmes or the people at CDFW who run the California Recreational Fish Survey (CRFS)

When we returned to Alviso Marina in the afternoon, one of the CRFS fish census agents was at the dock, counting and weighing fish caught by Saturday’s recreational anglers. She told me that she had seen two sturgeon and several striped bass that day.  CRFS conducts a count at Alviso Marina on several random days per month.

Chameleon Goby.  I was pleased to see this single Chameleon Goby on Saturday.  He is not rare or particularly desirable (yet another non-native goby!)  But, this was a missing species when I made Fish Poster a few months ago.  Now I have another poster-fish for my collection.

Staghorn Sculpin.  We caught a beautiful collection of Staghorns. These fish also have good years and bad years.  Judging from the size and condition, it looks like a good year for them.

These plump bruiser Staghorns were not happy about being handled – horns pointed way up.

Several Staghorns had a white patch pattern over their eyes and on their heads.  This was not a fungus.  It was a color pattern in the skin.

Crangon continue to outnumber non-native shrimp.  We had a few dry years when it was looking grim for crangons, but they appear to be back in large numbers.

Emily Trites found one “Black-spotted” Crangon amongst all the regular Crangons and Palaemons.  You can see the difference below:  Crangon nigromaculata (Black-spotted) on top and Crangon franciscorum below.  Crangon franciscorum is always the most numerous type.

I have more to say about shrimp and other bugs that I will save for next week.



Leave a Reply