Fish in the Bay – October 2024, Hot October – Invasions Continue.

October was a hot weekend.  Air temperature was beastly.  Water temperatures in October were close to 2 degrees C warmer compared to this time in 2023. Warm is not good for many of our native La Nina-loving fishes, like Staghorn Sculpin, Anchovies, and Herring.  Hopefully, a break in the weather is coming soon. 

• Once again, overall fish totals increased. But once again, the increase was entirely due to a whopping eruption of over 4800 non-native Silversides in Artesian Slough!

Silverside explosion in Artesian Slough … 

Ironically, this is yet another demonstration of the enormous power of Artesian Slough as a biogeochemical fish-producing machine.  For better, and sometimes for worse, the healing waters of Artesian Slough produce a lot of fish – seemingly out of nothing but the magical influence of highly-treated wastewater! 

• If only we could tune this power to raise only the native fishes we like.

Bat Rays and Halibut continue to do well in this seemingly perpetual warm-season regime.  All other critter numbers remain relatively low.

The Captain: Dr Hobbs has returned to volunteer his help to LSB trawling.  In 2010, Jim Hobbs created the local trawl monitoring stations and trawling protocol that we continue to this day. 

• Our trawling boat was designed to his specifications.
• The tradition of donut sacrifice was inspired by Hobbs and his partner Emily (“M”). We continue to practice this tradition as well.
• Hobbs was absent in recent years, but he was never lost to us as we continued the trawling mission in Lower South San Francisco Bay.

GRAND FUNK RAILROAD – I’m Your Captain   https://www.youtube.com/watch?v=mA-CBXuTaeo 

• Fun fact: This song has a strong Vietnam War protest vibe. – Or maybe, it’s just about a captain and his ship.

1. Invasions.

Some of the 4,405 Silversides at Art2 on 5 October 2024.

Silverside count = 4,914 !!!  Over 4,850 Silversides were caught in Artesian Slough alone.

In both their native ranges in the east and here in California, Silversides bloom and bust with the seasons:  Their numbers explode in late summer, then diminish as temperatures drop in winter. Hopefully, this pattern prevents them from decimating the Longfin Smelt winter spawn.  Nonetheless, Silversides must impose a tremendous tax on summer-spawning Anchovies. 

• Silversides are the non-native egg-eating demons mentioned many times in the past. According to history and genetics, these are “Mississippi Silversides” (Menidia audens).  However, I continue to wrongly refer to them as “Inland Silversides” (Menidia beryllina) because their slightly higher salinity tolerance here seems to closer match that variety.  There is no practical difference between them.
• By either name, Silversides are a horribly bad fish for California! We can safely assume that Anchovy eggs and young in Artesian Slough after September were consumed into Silverside biomass.  If this Silverside bloom persists into the cool season, they will eat Longfin Smelt eggs and young as well. – We must stop this fish!  

Exopalaemon shrimp count = 239. This was a sharp drop from the September count of 1025.  Most Exopals in October were caught in Dump Slough.  Like Silversides, Exopalaemon shrimp bloom during the warm season and die back when it gets cold.

Striped Bass count = 2.  The year-to-date count is 51. Which is a little below average.  Stripers don’t like warm water.  They start dying of heat-stress above 25 degrees C.

2. El Nino Fishes.

California Halibut at Coy1

California Halibut count = 21.  Year-to-date count = 327.  We continue to experience a good but brief El Nino/Halibut year.  Nonetheless, Halibut numbers remain well below totals we saw following strong El Nino in 2015 (1168 halibut) and 2016 (721 Halibut). 

• This too shall pass: After we flip to La Nina sometime soon as expected, Halibut numbers will eventually decline once again. (Literature says that Halibut recruitment improves up to a year following El Nino events.)

Bat Ray count = 58.  The year-to-date Bat Ray count is now tied with 2022 for second place at 177.  All of the October Rays were babies. 

I included Bat Rays in this section only because they, and Halibut, alone are doing better than average this year.  In truth, Rays are NOT known to be affected by the ENSO cycle.  Studies show that Rays tend to move away from the shallows when waters get too warm.  This may partially explain why we are seeing only baby Rays this season.  The adults remain in deeper cooler waters farther out in the Bay.

• Is late-season warm water healthy for Baby Rays?  Time will tell.

3. Little Fishes.

Anchovy count = 332.  Anchovy numbers are still low compared to recent years.  El Nino suppresses Anchovy numbers.  Pray for La Nina!

Only a few individuals expressed either eggs or milt in October.  Anchovy spawning usually tapers off around October, but this year it seems to have ended abruptly.  We assumed that cooler temperatures might be the trigger that terminates the local Anchovy spawn.  Apparently, that is not so. 

Good news!  The 2024 spawning season must have been at least somewhat successful.  Baby Anchovies continue to show up in trawls at downstream LSB stations.  Judging from the tiny size, these babies must have hatched only a few weeks earlier.

Correction to the record:  Data sheet field notes indicate that most Anchovies at LSB1 were “fairly golden brown.”  Photos reveal that the characterization was mistaken. 

• These were mostly young-of-year Anchovies that had not yet accumulated sufficient guanine in chromatophores to express dorsal color. The ‘golden brown’ was actually flesh tone under the clear/translucent colorless dorsum. (Chromatophore Score = 0 / No Color.)
• This distinction makes a difference. Salinity was fairly high at 23.5 ppt. Mature Anchovies with guanine in the same group were expressing deep blue or blue green dorsal color – near the “Bosphorus” hue as expected. 
• Always check for sparkles of guanine crystals in the dorsum. With careful observation, we will learn to visually assess salinity, fish age, life-stage, and perhaps even recent migrations of each fish!  How cool will that be?
• Also note: accurate Anchovy color reading requires HIGH illumination. Full Sun works best.      

Late Fall Baby Fish Month.  Baby/Unidentified goby count = 414.  Shimofuri Gobies, and perhaps Chameleons as well, spawn late in the year. 

• We first documented this “second” or “late season” Baby Fish Month in December 2018: 229 baby Shimo/Chameleon gobies were caught that month. Since then, we detected similar baby Shimo explosions in either Octobers or Novembers of 2019, 2020, 2021, 2023, and now this year.
• Non-native Shimofuri Gobies are thought to have first arrived in Lower South Bay around 2010. They were rare catches in our trawls prior to 2017. 
• Baby Shimofuri and Chameleon gobies are easily distinguished from other gobiids only weeks after hatch.  They have distinctive longitudinal stripes from eyes to tail –  and pink color just behind the head. 
• A few other baby gobies, likely Cheekspot and/or Yellowfin, were also seen in October, but the overwhelming majority were Shimos.

Adult Shokihaze Goby at Coy1

Shokihaze Goby count = 16.  Year-to-date count = 44.  We caught several hundred Shokihaze Gobies each year from 2015 thru 2021.  Then Shokihazes became scarce as the Shimofuri population exploded. 

• Shimo numbers declined for most of 2024, and Shokihazes rebounded a bit.
• Evidently, Shimo and Shokihazes compete for much of the same mid-salinity real estate in Lower South Bay.

Staghorn Sculpin count = 3.  Year-to-date = 182.  2024 is on track to be our worst Staghorn year on record.  We normally have counted hundreds to thousands of them by October.  

• Staghorns are a documented “La Nina” fish in literature, and we already knew they don’t do so well in warm El Nino years. But, even the strong El Nino of 2015 didn’t hit them this hard.  Something else, perhaps the PDO?, somehow modified El Nino’s effect here.    

4. Big Fishes – October Surprises.

Salmon carcass collected at Alv1.  A dead Chinook Salmon was floating near station Alv1.  This was the downstream end of Guadalupe River.  No doubt, he expired along his way to spawning grounds farther upstream. Late season high temperatures could have added to his stress, or he could have died of completely natural causes.    

• Brian removed the Salmon’s otoliths (ear stones) so they can be added to the South Bay Clean Creeks Coalition database. Otolith growth rings can tell us when and possibly where this Salmon hatched.
• SBCCC is a 501c3 non-profit group that organizes creek cleanups and monitors Salmon spawning and migration in the Guadalupe River and Coyote Creek watersheds. https://sbcleancreeks.com/
• Salmon make way to South Bay creek, draws in crowds. https://www.nbcbayarea.com/news/local/south-bay/salmon-make-way-to-south-bay-creek-draws-in-crowds/3718617/ 
  “According to experts, the number of salmon in the area is larger than usual. Volunteers with the South Bay Clean Creeks Coalition said that in areas where there are usually three to six salmon, there are now close to 30.  “In the last 11 years I have been doing this, I have never seen this many fish,” said Steve Holmes, founder of the coalition.” 

Rejoice!  Salmon are returning to the Bay Area thanks to a combination of habitat restoration, hatchery fish releases, and abundant winter rain over the last few years: 

• Jan 2022. Nearly extinct salmon spawn in the Bay Area for the first time in 18 years  https://www.sfgate.com/local/article/Nearly-extinct-coho-salmon-spawns-in-Bay-Area-16761425.php 
• Jan 2022. Big Rain Leads to a Big Year for Salmon  https://baynature.org/2022/01/10/big-rain-leads-to-a-big-year-for-salmon/?fbclid=IwY2xjawGl0AtleHRuA2FlbQIxMQABHQZ1byFQZLrFUNICSc9u0d8iKK6HZq-YCfYLlZ8dIGf397UoF04Td682QQ_aem_U-t9Q4p34iujhh9moffkXg 
• Feb 2024.  Endangered coho salmon make a major comeback in Bay Area creek  https://www.sfgate.com/bayarea/article/endangered-coho-salmon-bay-area-comeback-18682993.php?fbclid=IwY2xjawGwdrZleHRuA2FlbQIxMAABHZ1f7enEjuMhtDZqUHzC5Nr9F_AQiPLsTGvhf7mTUrGYahtFp3NHiNeHrw_aem_9gqJ_SO9PjPk_mtxQhJ4ew 
• Nov 2024. ‘Moment of awe’: Native California species washes up dead in downtown Oakland  https://www.sfgate.com/local/article/chinook-salmon-wash-up-dead-bay-area-lake-19929203.php?fbclid=IwY2xjawGwd1hleHRuA2FlbQIxMAABHfSW6jDq_OYeczwKE4q1CZIOjU1kG5QoK7-dibpBKZLoBTX9_u1DcU_IlQ_aem_iIXfXcr-1RMwf8kDtArrVg

Sturgeon count = 2 (from sonar only).  Sonar sensors imaged two Sturgeon loitering at upstream stations.  Both appeared to be feeding near channel bottoms at UCoy stations.

• Sturgeon generally avoid warm water. Water temperatures were warm – near 25 degrees C at both stations.  And yet, they were here.
• Sturgeon eat shrimp, gobies, anchovies, lampreys, and many other small fishes and invertebrates. Coyote Creek and Alviso Slough are winter feeding grounds. More Sturgeon will arrive as the weather cools.

5. Longfin Smelt.

Dr Hobbs points to a palm tree near Longfin Smelt spawning ground at station UCoy1.

Longfins Smelt count = 0.  Year-to-date count 1190.  On paper, this is our third best Longfin Smelt year in 15 years of trawling record.  In spirit, it doesn’t feel so good. 

• Longfin spawning season ended early last spring, and relatively few new recruits were recovered.
• As of October, returning adults are no-shows. This is worrisome, but not alarming; the first Longfin arrivals usually showed up in either October or November (50:50) according to our records.
• On the other hand, records also show that Longfins did NOT spawn here until 2017. They have spawned here every year since!
• We never give up hope!