North County Times File Photo
North County Times File Photo
Grunion run here, and nowhere else
Schools of small, silvery fish live unseen, just beyond the surf zone. If it weren't for their unusual method of reproduction, we wouldn't even know they exist.
Yet each year, from February to September, multitudes of grunion wash up on North County beaches in the churning surf on nights following the highest tides. Eggs are deposited in the semiliquid sand, fertilized, and the adults quickly return to sea with the receding waves. No other fish reproduce in this manner. It's a phenomenon worth seeing.
"I've been out on nights when there were thousands of fish ---- a swarming mass of silver," said Nigella Hillgarth, executive director of the Birch Aquarium at Scripps Institution of Oceanography. "The fish are so intent on what they're doing, they don't pay attention to you."
Washed up by the surf, female grunion literally drill themselves (tail first) into the sand, where they each lay thousands of eggs. Males then wrap themselves around the females and release sperm. Fertilized eggs incubate a few inches below the sand surface, and away from water, for up to two weeks, when the next high tide cycle uncovers and returns them to the ocean where they instantly hatch.
Grunion constitute a unique recreational fishery. During the open season for grunion, a fishing license (with an ocean enhancement stamp) is required for people 16 years and older. Fishing licenses must be displayed on clothing while taking fish.
Grunion, about 5 to 6 inches long, may be gathered only by hand; it's illegal to dig sand holes to trap them. California Department of Fish and Game wardens do patrol during spawning season and will issue citations to those taking grunion without a license, using mechanical means to take fish, or poaching during the closed season of April and May ---- a safeguard to protect grunion during the peak spawning period.
Grunion are found only along the coast of Southern California and northern Baja, Mexico. While their populations appear to be stable, they are by no means abundant, according to Karen Martin, a professor of biology at Pepperdine University who is engaged in long-term studies of grunion. Because of their restricted range, a critical problem facing grunion is the loss of spawning habitat caused by beach erosion, harbor construction and pollution.
"It's really a challenge to assess their populations," Martin said. "The only way to really see them is during the spawning run."
Providing scientists and fisheries managers with important data on grunion is a small army of "citizen scientists" known as Grunion Greeters. Last year, nearly 500 trained volunteers observed designated stretches of beach ---- from the U.S.-Mexico border to the Bay Area ---- on nights of grunion runs during the peak spawning season.
Greeters submit their observations via an interactive Web site and through a toll-free hotline. The data is critical, not only in studying the grunion, but in helping with their management. The timely reporting of the exact locations where grunion have spawned permits local authorities to be notified immediately and take action.
"This allows managers to modify beach grooming so equipment stays above the high-tide mark," said Melissa Studer, senior program officer of The Grunion Greeter Project. "If they didn't know and groomed over the eggs, the eggs are lost."
While scientists can pinpoint with certainty to the days when spawning will occur, no one can say exactly where the grunion will show up.
"Remember, they're fish," Studer said. "There's no predicting where they'll run."
With no guarantees about spotting grunion the night of a run, it's possible that you'll have more luck participating in naturalist-led outings or becoming involved with The Grunion Greeter Project.
First-time grunion watchers are advised to bring a flashlight, expect to get wet, and prepare to be awed.
"This is an experience unique to Southern California," Hillgarth said. "It's as exciting as whale-watching; just the magnitude of it."
Lynne Friedmann is a freelance science writer who lives in Solana Beach.
Grunion activities galore
This year, the grunion will run:
April 13-16 and 27-30 (closed season)
May 12-15 and 26-29 (closed season)
June 11-14 and 25-28
July 10-13 and 24-27
Aug 9-12 and 23-26
For estimated run hours and more grunion facts, visit www.dfg.ca.gov/Mrd/gruschd.html.
The Grunion Greeter Project (www.grunion.org) offers free training workshop for volunteers (18 years and older) to assist in an ongoing study of grunion and their habitat.
Birch Aquarium naturalist-guided Grunion Runs (aquarium.ucsd.edu/).
A fun and educational way to explore grunion behavior through a preview film, hands-on activities and a grunion hunt on a nearby beach. Ages 6-13 with a paid adult. Cost: $12 adults; $9 children.
Sunday, April 30, 10:30 p.m. to 12:30 a.m.
Monday, May 15, 9:45 to 11:45 p.m.
Sunday, May 28, 9:30 to 11:30 p.m.
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