Dive Dry with Dr. Bill

#144: Run, Grunion, Run

When I was a teenager living in the Chicago suburbs, one of our favorite activities was to organize a snipe hunt. Now there were two strategies. Either you gathered up nets, flashlights and other paraphernalia and conned some unsuspecting newcomer into going out with you (only to "lose" them); or you got together with a few friends and your girlfriends and went off into the darkness... often without the required "hunting" paraphernalia.

Then, when I moved to Catalina in the late 1960's, I discovered the island had no snipe. However, the ingenuity and innovation long noted for Californians had created an acceptable substitute... grunion hunting. Many think that grunion don't exist either, but they do. This activity takes place on the sandy beaches which offer opportunities for bonfires, beer and skinny dipping at night... at least in the days before "Jaws" came out! I think it is a lot more fun than hiding in the deep woods with bears and other scarey critters. Well, my readers... prepare yourselves because it is grunion hunting season. Just remember that you need a valid fishing license if you are 16 or older, and can only take them by hand.

Grunion are predicted to invade our beaches during the month of June, specifically between the 8th to 12th and the 23rd to 27th. These represent the periods of the highest (and lowest) tides a few days after the new and full moon respectively. At this time, hundreds to thousands of grunion may congregate offshore, then "body surf" onto the upper beach with a good wave. They do this for pleasure... the 30 seconds that their mating takes in the sand. Kind of like Burt Lancaster and Debra Kerr in the 1953 movie "From Here to Eternity" (or , if you prefer, William deVane and Barbara Hershey in the 1980 version). The next time you go to the bar and order "Sex on the Beach," think of these little fishies. After all, they originated the concept!

After riding the wave onto the beach, the female grunion twists her body and digs it tailfirst into the sand. She deposits anywhere from 1,600 to 3,600 eggs in the "nest," while the male wraps his body around hers and releases his milt (sperm) which runs down the female's body to fertilize the eggs. Males outnumber females, and several may fertilize the same female's eggs. Afterwards both return to the sea on the next high wave. Spawning may occur at anytime from February until September, but usually peaks from late March to early June. Females may spawn as often as six times during the season, producing a new batch of eggs every two weeks. They are the only marine fish I'm aware of that breeds on land.

The eggs remain safe in the nest rather than drifting with the plankton where they may be preyed upon by fish. However, birds, insects and worms can eat the eggs while in the sand "nest." They hatch during the next high tide, about 10 days later. Grunion reach lengths of 5-6" with the females slightly larger than the males. They are sexually mature after one year, but rarely live longer than three years.

Grunion's food habits are not well known, but they probably feed on plankton like other baitfish. In turn, adults are eaten by humans (remember the "hunt"), larger fish and marine mammals. Apparently they were eaten by southern California's native American tribes. They were also the target of a significant modern fishery which showed signs of decline by the 1920's. At that time a closure was instituted during the peak breeding months and is still in effect today. Environmental issues which affect them include beach erosion, harbor construction, and pollution. Years ago on Catalina I observed feral pigs rooting in the sand during a grunion run, so they probably also fed on them.

Grunion are members of the silversides family which includes the topsmelt and jacksmelt. This species is normally found from Pt. Conception to Punta Abreojos in Baja, but occasionally may be seen as far north as Monterey or south to San Juanico Bay in Baja. There is a closely related species in the northern Gulf of California (Mexico) from which our species may have evolved. The Cabrillo Aquarium reports that the name "grunion" came from the early Spaniards and was applied because of the grunting noises they heard from the fish while they were mating (the grunion, not the Conquistadors).

I must admit that the last grunion hunt I attended was back in the mid-1970's when these pictures were taken. A certain local figure and I, along with our girlfriends, went down to the beach at Toyon Bay. We parked both of our jeeps with the headlights pointing out to sea. In our hands was the requisite beer... I think it was Brown Derby, about all we could afford then (or now come to think of it). And then there was the time about thirty of us were out on my old dory partying. The Blanche W. passed by looking for flying fish. They sure picked the optimum time, for as the search light flashed across my boat's gunnel that night, the passengers were greeted by dozens of "full moons."

© 2005 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

(Top) Grunion on sandy beach at Toyon Bay in the 1970's; (bottom) female grunion
partially buried in the sand laying eggs in her "nest."

This document maintained by Dr. Bill Bushing.
Material and images © 2005 Star Thrower Educational Multimedia