Grunions were important to the diets of California Indians, like the Kumeyaay, who lived in coastal regions. Yes, but you must have a fishing license to catch them. According to California code , it is unlawful to waste fish. Grunion numbers have been declining over the past decade due to several key issues. Many grunions are being illegally taken by those without permits.
Using nets or other gear and fishing out of season or without a license are not uncommon, says Dr. April, May, and June are the peak spawning months, but since , only April and May are closed to fishing. Habitat loss is another major issue. Beaches are disappearing from erosion, real estate development, and harbor construction.
Combing or grooming beaches disturbs grunion eggs in the sand and many are washed out to sea before they are mature enough to hatch. Water pollution from urban runoff and the frequency of harmful algal blooms during summer spawning months is also taxing on these small fish.
Increasing temperatures in the ocean and onland are even more concerning. Air temperature on land is increasing faster than marine temperatures in the ocean. Because grunions breed on land, Dr.
Martin is concerned that grunions will have more and more problems in the southern part of their range. Warmer temperatures are already being seen, even during earlier months like April. Protected beaches with less light pollution and fewer disturbances offer refuge for grunion trying to spawn along a modified coast.
Written by Emily Harwitz Thank you to Dr. During the early part of the season only older fish spawn, but as the season progresses fish hatched the previous year come into spawning condition and join the runs. Fish of all ages will spawn by April and May. The eggs are initially deposited 2 to 3 inches below the surface of the sand by the female.
The outgoing tide deposits sand onto the beach covering the eggs to a depth of 8 to 16 inches. Here the eggs remain in the moist sand. They will be ready to hatch in about 10 days, but remain viable until they are freed from the sand by the next series of high tides to reach them. The baby grunion hatch 2 or 3 minutes after the eggs are freed from the sand and are washed out to sea.
Young grunion grow very rapidly and are about 5 inches long by the time they are 1 year old and ready to spawn. The normal life span is 2 or 3 years, but individuals 4 years old have been found. The maximum size attained is between 6 and 7 inches. The growth rate slows after the first spawning and stops completely during the spawning season, consequently the fish grow only during the fall and winter.
This cessation of growth during spawning causes a mark to form on each scale, and the age of the fish can be determined by counting these marks, much like the age of a tree can be determined by counting its "growth" rings. The life history of grunion while at sea is not well known, but these fish apparently spend most of their life close to shore in water 15 to 40 feet deep.
Tides are caused by forces exerted on the earth by celestial bodies in direct proportion to their mass. Theoretically all celestial bodies affect the tides but realistically only the sun and moon need be considered. Since the sun has 26 million times the mass of the moon, one might expect it to be the dominant tide producing force. However, the force exerted by a celestial body decreases rapidly as its distance from earth increases inversely proportional to the square of the distance.
Consequently, the sun, being almost times farther from earth than the moon, exerts less than half as much force as the moon. Tidal highs and lows vary according to the relative positions of the sun, earth, and moon Figure 2.
Highest and lowest tides occur when the sun, earth, and moon are most in line, such as during full moon sun and moon on opposite sides of the earth and new moon sun and moon on the same side of the earth. These tides are known as "spring" tides.
The tides occurring during the first and last quarters of the moon, when the sun and moon are least in line, are known as "neap" tides and are intermediate in range. Grunion have adapted to tidal cycles in a precise manner See Figure.
Along the Pacific coast of North America the two daily high tides vary in height, and the higher of the two occurs at night during spring and summer months.
Grunion spawn only on these higher tides, and after the tide has started to recede. Since waves tend to erode sand from the beach as the tide rises and deposit sand as the tide falls, it is obvious that if grunion spawn on a rising tide the succeeding waves would wash the eggs out.
This danger is eliminated since spawning usually is confined to the falling tide. In addition, grunion nearly always spawn on a descending series of tides when succeeding tides are lower than tides of the previous night.
The eggs would be washed out prematurely by succeeding tides if spawned during the ascending tidal series. The eggs mature and are ready to hatch in about 10 days or about the time of the next series of high tides. Thus, spawning must take place soon after the highest tide in a series if the eggs are to have adequate time to develop before the next series of high tides.
Looking at the tidal cycle, it becomes apparent that there are only 3 to 4 nights following the highest tide that spawning conditions are right, and it is on these nights that grunion spawn. Chart : Relationship between the sun, moon, earth, tides and grunion behavior PDF.
How does the grunion know when the time is right to spawn? Evidently some biological mechanism or "internal clock" that can detect some change in the environment, sounds an alarm at exactly the right moment. The exact stimulus is not known, but it is suspected that they may be able to detect minute changes in water pressure caused by the rising tides.
Without this ability to spawn at precisely the right moment the grunion would not survive. A valid California recreational fishing license is required to take grunion for anyone age 16 or older. No take is allowed when the season is closed during April and May; however, this is an excellent time for observing runs.
Grunion may be taken by hand only—no appliances of any kind may be used, and no holes may be dug in the beach to entrap them. During the open season, there is no limit to the number that may be taken, but grunion or any fish should not be wasted per California Code of Regulations Title 14, Section 1.
Recreational fishing license holders and persons under the age of 16 may handle grunion gently during the open season, and release them back into the water unharmed. Grunion may not be pursued or handled at all during the closed season April and May. The spawning season extends from March through August, although runs in August are very small and erratic. The California Department of Fish and Wildlife issues schedules of expected grunion runs in advance of each season.
These schedules of expected runs are published in newspapers and copies are given to many sporting goods stores throughout Southern California.
If these are not available, all a grunion observer needs to make their own predictions is a tide table. Grunion runs may occur anytime from the night of highest tide throughout the descending series of high tides. Runs are most likely to occur on the second, third, fourth, and fifth nights following the night of the new or full moon. Generally, the third and fourth nights are best.
The time of the run will be 30 to 60 minutes past high tide and it will last from 1 to 3 hours. The heaviest part of the run usually occurs at least 1 hour after the run starts. Grunion runs will occur on most Southern California beaches, but may not occur every night on the same beaches and may be limited to small areas of any one beach. The ends of beaches are often the best spots. The beaches near Ensenada in Baja California also have good runs.
It is best to go to the end of an uncrowded beach. The popularity of these grunion runs means that some nights there are more people lining the beaches than grunion in the run. The eggs remain buried in the sand throughout incubation, fully out of water for approximately 2 weeks. The larvae hatch when the eggs wash out by high waves during tides before the new and full moons. Grunion spawn at the age of 1 year, and live for 2 to 4 years. Some may call them the original bodysurfers!
Ergo, La Jolla is the perfect grunion run destination! La Jolla Shores , to be exact. They host guided visits of grunion spawning areas at La Jolla Shores throughout April-June, which includes a full rundown on these mysterious creatures as well as a demonstration of hatchlings emerging from their eggs in a vial of seawater. Wednesday, May 2: pm — am Thursday, May pm — am Friday, June 1: pm — am. No nets, buckets or other gear is allowed, according to the California Department of Fish and Wildlife.
Additionally, people over 16 need a fishing license to participate, and while there is no official bag limit, it is illegal to waste them.
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