Weather Watch

Here’s what those big schools of fish gathering in San Luis Obispo Creek are

Striped Mullet seen from the bridge that crosses the estuary of San Luis Obispo Creek by the Avila Beach Golf Resort.
Striped Mullet seen from the bridge that crosses the estuary of San Luis Obispo Creek by the Avila Beach Golf Resort. Special to The Tribune

Last Sunday, Melissa Jenna Godsey along with her husband Michael and their two beautiful children Ellie and Graham walked the Bob Jones trail and noticed hundreds of fish by the bridge that crosses the estuary of San Luis Obispo Creek by the Avila Beach Golf Resort.

“They were all schooled together and didn’t look like any fish we’d seen in the creek before. Do you have any idea what they might be?” she asked on Twitter.

Not only has Melissa inquired about this, but others also have also. Since I didn’t know, I sent an email to San Luis Obispo City Biologist Freddy Otte.

He wrote: “I too have received many calls about the big schools of fish found in the estuary of San Luis Obispo Creek. The people are concerned about them being steelhead and worried about the water quality or that they may be trapped. Upon investigation, they turned out to be striped mullet (Mugil cephalus). It is great that so many members of the public were concerned since steelhead are protected under the Endangered Species Act.”

Otte also told me that Pacific lamprey were found in the watershed in 2017 after a 10-year absence.

“These are indicator species that need to be highlighted and celebrated as they document the holistic ecological restoration the City of San Luis Obispo and many other stakeholders, like PG&E, have undertaken over the past number of years,” Otte said.

Striped mullet are found worldwide in coastal tropical, subtropical and temperate zones waters like Central California and go by numerous names like flathead, common, black, bully, grey or sea mullet.

Adult fish can reach about 20 inches in length and weigh around 3 pounds. They are bluish-gray/olive-green on top and become silver along their sides with six to seven black horizontal bars but with no apparent lateral line. Like salmon and steelhead, they are euryhaline, which means they can acclimate to different levels of salinity.

They primarily feed on different types of algae, zooplankton, bottom-dwelling organisms and small invertebrates. They don’t have the mouthparts to cut up larger prey.

They are also an important food in many parts of the world. They are usually caught by nets or farmed. The fillets of these fish are typically fried, but can also be smoked, baked or canned. Their roe (eggs) are salted, dried and often compressed by hand.

Around this time of year, big schools of mullet gather in estuaries and near the mouths of creeks and rivers waiting and preparing for their migration to the deep waters of their spawning grounds many miles away from the coastline. The females can spread up to seven million eggs on the ocean’s bottom.

After hatching, the young mullet return to their coastal locations to grow into adulthood. Their average lifespan is about five years; however, mullet over 10 years old have been found.

It’s believed, that the passage of storms, rains and storm runoff, cooler seawater temperatures and lower atmospheric pressure trigger gatherings and soon after migration to the deep waters from late October through January.

To single the possible start of the migration to their spawning grounds, I will be on the Dave Congalton Show on KVEC Radio from 4 to 5 p.m. on Friday for the “Guess the First Day of Rain Contest.”

Call 805-543-8830 during the show and predict the first day the Central Coast will receive at least 1 inch of rain over a 24-hour period at any calibrated rain gauge in the region, such as Cal Poly, Santa Maria or San Luis Obispo Airports or even Rocky Butte. The winner will receive a PG&E umbrella and flashlight that can be used during storms. This year’s contest is sponsored by the Farm Supply Company.

John Lindsey’s column is special to The Tribune. He is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at pgeweather@pge.com or follow him on Twitter: @PGE_John.
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