Fish in the Bay – Special Report: Green Water, 6-7 Aug 2022.

This is a Fish in the Bay special report to document observations of water color in Lower South San Francisco Bay over the first weekend in August 2022.

Eye-ball & camera observations of water color from August trawls.
(Microscopic evaluation of Phytoplankton species composition & abundance would be ideal, but this is the best we can do for now.)

Phyto Alert:  Many news outlets are reporting incidents of RED or REDDISH-BROWN water being seen near Oakland, in Richmond Bay and at other places in the northern and central portions of San Francisco Bay.  The first sightings of possible red tide conditions were reported in late July with most reports arriving after August 19th

News Reports:

The phenomenon is associated with a variety of phytoplankton called Heterosigma akashiwo.  H. akashiwo is a microscopic single-celled form of marine or freshwater algae that is known to cause Red Tides and biological upsets. 

  • H. akashiwo is usually present in SF Bay, but only rarely a problem. Red Tide or Brown Tide blooms may arise from a combination of warmth, stratification, and too much nutrient in the water.  The last time this was seen in SF Bay was in 2004.
  • A few more wonky details for both serious and armchair phyto-experts: H. akashiwo belongs to a class of phytoplankton called Raphidophyceae (raphidophytes) which only a few years ago was known as Chloromonadineae.  …  Members of this class have numerous discoid chromatophores that provide a bright green tint due to presence of excess of xanthophyll.  The motile forms of these algae are with two almost equal flagella. 

Harmful algal blooms that cause Red Tides or Brown Tides can result in fish kills and bad smells. We must not allow such conditions to disrupt our fragile and productive spawning grounds!

  • In our monthly trawls, we note abnormal water conditions & take copious photos.
  • We observed NO dead fish during the August trawls.
  • Good News!  H. akashiwo blooms were NOT evident during the weekend of 6-7 August 2022.


This Lower South Bay water color assessment from early August is for historical context only.  Phytoplankton composition can literally change overnight.


1. Saturday Trawls, 6 August 2022.

Alviso Marina at about 0820 near Alv1.  It was a calm and surprisingly pleasant summer morning. The sky was overcast with low cloud cover that burned off by mid-morning.  The cloud cover complicated assessment of water color prior to about 10 AM.  

  • Water in Alviso Slough was more greenish than brownish. There was no redness nor murky brownness.  


Alv2 & Alv3 at 0900 to 0930.  210 out of 1459 spawning-ready Anchovies caught in August were caught and released in Alviso Slough. 

  • Water appeared greenish, but again, cloud cover muddled the color assessment.


Pond A21 at 0940.  The transformation of this former salt pond into a productive marsh is breathtaking.  

  • Water color here was close to green pea soup.


Coy2 at 1040.  I took several photos of this mutant dwarf Yellowfin Goby at Coy2.  We had never seen one like it.  He or she has only half the normal body-length, and yet it survived to near-adulthood. Like many interesting observations, I did not have space to squeeze this one into a regular monthly blog.  Relevant to this discussion … look at the water color! 

  • Water color at Coy2 was intense green!


Coy3 at 1120.  This was the tiniest newborn Bat Ray we had ever seen.  We all took photos before releasing her back to the green water.

  • Water color was more olive green here.  


Coy4 at 1130 to 1150.  Luca trained his telephoto lens on the Harbor Seal Rookery at Calaveras Point.  I focused on a long-bodied, blue-backed, sea-going Anchovy measuring 120 mm! 

  • Water color was very green!


LSB1 at 1220.   The color of water at LSB stations usually muddles out to a bit more brownish.


LSB2 at 1250.  Luca shows off a tiny baby Plainfin Midshipman and some Ceramium red algae on his fingertip. 

  • Water color was muddled greenish-brown.


2. Sunday Trawls, 7 August 2022

Art1 at 0840.  This station is heavily influenced by treated wastewater discharge from the SJ-SC Regional Wastewater Facility.  The actual discharge point from the SJ-SC RWF is seen in the far background just right-of-center in this photo.  The water here is always remarkably clear and slightly greenish from phytoplankton growth. 

  • I took this photo to show off the water’s greenness, but alas, the greenness came out very faint in the picture.   


Artesian Slough – Art2 and Art3.  As the treated and discharged wastewater effluent from 800,000+ people in San Jose and surrounding cities mixes and mingles with Bay water in Artesian Slough, the water gets greener.

  • Water turned into rich pea soup green at these stations.  


Topsmelt, Pond A19

Pond A19 at about 1100.  We trawl two stations in each restored salt pond.  The restored ponds are often, though not always, our most productive spawning places for Longfin Smelt (in winter) and Northern Anchovies (in summer).  On this weekend, we caught a combined total of almost 200 spawning-ready Anchovies along with almost 100 Topsmelt (shown above) and 142 Sticklebacks.  Topsmelt and Sticklebacks are native eaters of eggs and larval fishes so it is not a huge surprise to find them in association with spawning Anchovies.

  • Water was very green here.  


Dmp1 at 1130.  This was one of six Bay Pipefish photographed on Sunday. 

  • Water at the upstream end of Dump Slough was green with just a tinge of brownness.


Dmp2 at 1200.  Luca and I examined a fairly large male Longjaw Mudsucker and several Shimofuri Gobies in the Photarium at this station.

  • Water at the downstream end of Dump Slough was intensely green


Three-spined Sticklebacks at UCoy1

UCoy1 & UCoy2 at 1230 to 1320.  The upper reaches of the main stem of Coyote Creek wrap around the western and northern sides of Newby Island Landfill.  Anchovy, Stickleback, and Palaemon Shrimp catches were still respectable at these upstream stations.  

  • Water was green but with a little more brownness … olive-green?

We rely on healthy Phytos to feed this fishery! 

The Phyto Threat Condition remains high.

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