Grunion season is here! Thousands of grunion fish could potentially come ashore on Coronado beaches late at night this Friday,, May 1 through Monday May 4. If you plan on going, remember this is still closed season meaning any contact with grunion is prohibited.
Grunion Fish
The silver colored grunion fish is native to Southern California and northern Baja California, Mexico. Measuring between five and six inches long, grunion revolve their lives around the phases of the moon and tidal patterns as they are one of the few fish species that spawn on land.
The Run
High tides carry the fish ashore where they squirm and wriggle onto the beach propelled by their tails. The females dig until they are half buried with just their head sticking out and deposit their eggs into the sand. The males swiftly wrap themselves around the females to fertilize the eggs. The process is quick — as fast as 30 seconds — as the fish must return to the ocean before the tide recedes.
Grunion hatch about 10 days later, two or three minutes after eggs are freed from the sand by a high tide. The babies are then washed out to sea where they can live between two and three years.
Schedule
Between March and August, grunion runs occur over four nights during the highest tides synchronized with the lunar cycle. Grunion runs follow a full or new moon and last for two hours with the best viewing during the second hour of the second and third night, often around midnight.
The California Department of Fish and Wildlife posts schedules of expected grunion runs before each season although the schedule varies for different San Diego beaches and some nights the grunion are a no-show.
Protection
Grunion runs are vital to the coastal ecosystem. Fish eggs laid during these runs provide a significant food source for shorebirds and wildlife. California regulation prohibits disturbing the fish or their eggs during prime spawning season (April through June). During open fishing season (July through March), a fishing license is required to capture a maximum of 30 grunion and they can only be taken by hand.
Threatened
Grunion populations have been declining for decades. Warming temperatures endanger the health of grunion and their eggs. Beach erosion, water pollution, and raking the sand below the high tide line also threaten grunion spawning habitats. Protecting our beaches and waters ensures the long term survival of the grunion and grunion run.
Coronado Viewing
Coronado’s expansive shoreline makes it an excellent spot for grunion watching but each run is unpredictable. Optimal viewing is typically around 45 minutes after the high tide. Avoid noise and flashlights that scare the fish. Watch where you step as the vibrations from your feet can deter fish. Check with the local lifeguards for up to date information on optimal viewing.
Protect our beaches and the grunion to keep Coronado Emerald Green, Ocean Blue.
