Grunion
Encyclopedia
Grunion are two fish species of the genus
Leuresthes: the California grunion, L. tenuis, and the Gulf grunion L. sardinas. They are sardine
-sized teleost
fish of the Atherinopsidae family of New World
silversides
, found only off the coast of California
, USA, and Baja California
, Mexico where the species is found on both the Pacific Ocean
and Gulf of California
coasts.
Grunion are known for their unusual mating ritual whereby at very high tides
the females come up on to sandy beaches where they dig their tails into the sand to lay their eggs. The male then wraps himself around the female to deposit his sperm and for the next ten days the grunion eggs remain hidden in the sand. At the next set of high tides the eggs hatch and the young grunion are washed out to sea.
A related species the false grunion (Colpichthys regis) lives in the Gulf of California
. Although the fish looks and acts similar, it does not have the same breeding method.
silversides including the jacksmelt and topsmelt. The California grunion, Leuresthes tenuis, is found along the Pacific Coast from Point Conception
, California, to Point Abreojos, Baja California. They are rarely found between San Francisco in the north and San Juanico Bay, Baja California, in the south. The Gulf grunion L. sardina is found along the coast of Baja California in the Gulf of California.
They are small, slender fish with bluish green backs, silvery sides and bellies. Their snouts are bluntly rounded and slippery. Silversides differ from true smelts of the family Osmeridae in that they lack the trout
-like adipose fin. Inhabiting the nearshore waters from the surf to a depth of 60 feet (18.3 m), marking experiments indicate that they are non-migratory.
Young grunion grow rapidly and are about five inches long by the time they reach one year old and are ready to spawn. Adult fish normally range in size from 6 to 7 inches (15 – 17 cm) with a maximum recorded size of 8.5 inches (21.6 cm) (La Jolla Ca.,05-11-05(19 cm).
Average body lengths for males and females are 4.5 and 5.0 inches (11.5 and 12.7 cm) respectively at the end of one year, 5.5 and 5.8 inches (14.0 and 14.7 cm) at the end of two years, and 5.9 to 6.3 inches (15.0 to 16.0 cm) at the end of three years.
The normal life span of the grunion is three to four years although individuals up to five years old have been found. Their growth rate slows after the first spawning and stops completely during the spawning season. Consequently, adult fish grow only during the fall and winter. This growth rate variation causes annuli to form on the scales, which have been used for aging purposes. The Gulf grunion, with its smaller eggs, is unique in that it may spawn
during daytime.
California grunion spawn on beaches from two to six nights after the full and new moon beginning soon after high tide and continuing for several hours. As a wave breaks on the beach, the grunion swim as far up the slope as possible. The female arches her body whilst keeping her head up and excavates the semi-fluid sand with her tail. As her tail sinks, the female twists her body and digs tail first until she is buried up to her pectoral fins. After the female is in the nest, up to eight males attempt to mate with her by curving around the female and releasing their milt
as she deposits her eggs about four inches below the surface. After spawning, the males immediately retreat toward the ocean. The milt flows down the female’s body until it reaches the eggs and fertilizes them. The female twists free and returns to the sea with the next wave. The whole event can happen in 30 seconds but some fish remain on the beach for several minutes. Spawning may continue from March through August, with occasional extensions into February and September. However, peak spawning is from late March through early June. Once mature, an individual may spawn during successive spawning periods at about 15-day intervals. Most females spawn about six times during the season. Counts of maturing ova to be laid at one spawning ranged from about 1,600 to about 3,600, with the larger females producing more eggs. A female might lay as many as 18,000 eggs over an entire season. The milt from the male might contain as many as one million sperm
. Males may participate in several spawnings per run.
The eggs incubate a few inches deep in the sand above the level of subsequent waves. They are not immersed in seawater but are kept moist by the residual water in the sand. While incubating they are subject to predation by shore birds and sand-dwelling invertebrates. Under normal conditions they do not have an opportunity to hatch until the next tide series high enough reaches them 10 or more days later. Grunion eggs can extend incubation and delay hatching if tides do not reach them for an additional four weeks after this initial hatching time. Most of the eggs will hatch in 10 days if provided with seawater and the agitation of the rising surf. The mechanical action of the waves is the environmental trigger for hatching. The rapidity of hatching, which occurs in less than one minute, indicates that it is probably not an enzymatic function of a softening of the chorion
as in some other fishes.
Grunion feeding habits are not well known. They have no teeth and feed on very small organisms such as plankton
. In a laboratory setting grunion eat live brine shrimp
. Humans, larger fish, and other animals prey upon grunion. An isopod, two species of flies, sandworm
s, and a beetle
have been found preying on the eggs. Some shorebirds such as egret
s and heron
s prey on grunion when the fish are on shore during spawning. Seagulls, sea lion
s and sand shark
s have also been observed feeding on grunion during a grunion run. The reduction of spawning habitat due to beach erosion, harbor construction and pollution is believed to be the most critical problem facing the grunion species.
In the 1920s recreational fishing of grunion caused definite signs of depletion resulting in a regulation passed in 1927 that established a closed season of three months from April until June. Grunion stocks improved and in 1947 the closed season was shortened from April through to May. This closure is still in effect to protect grunion during their peak spawning period.
The periodic appearance of the grunion on Southern California beaches, and the act of catching them, is locally known as a "grunion run." A fishing license is required for persons 16 years and older to catch grunion and they may be taken by sport fishermen using their hands only. No appliances of any kind may be used to catch grunion, and no holes may be dug in the beach to entrap them. Grunion may be taken on specified dates between March and the end of August. There is no limit, but fishermen may take only what they can use, as under Californian law it is unlawful to waste fish. With these regulations, the resource seems to be maintaining itself at a fairly constant level.
Grunion were mentioned by Spanish explorer Juan Cabrillo in his ship's log dated c. 1542.
Scientists first identified grunion in San Francisco Bay in 1860.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Leuresthes: the California grunion, L. tenuis, and the Gulf grunion L. sardinas. They are sardine
Sardine
Sardines, or pilchards, are several types of small, oily fish related to herrings, family Clupeidae. Sardines are named after the Mediterranean island of Sardinia, around which they were once abundant....
-sized teleost
Actinopterygii
The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize...
fish of the Atherinopsidae family of New World
New World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
silversides
Silverside (fish)
The Old World silversides are a family, Atherinidae, of fish in the order Atheriniformes. They occur worldwide in tropical and temperate waters...
, found only off the coast of California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, USA, and Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, Mexico where the species is found on both the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
and Gulf of California
Gulf of California
The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...
coasts.
Grunion are known for their unusual mating ritual whereby at very high tides
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
the females come up on to sandy beaches where they dig their tails into the sand to lay their eggs. The male then wraps himself around the female to deposit his sperm and for the next ten days the grunion eggs remain hidden in the sand. At the next set of high tides the eggs hatch and the young grunion are washed out to sea.
A related species the false grunion (Colpichthys regis) lives in the Gulf of California
Gulf of California
The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...
. Although the fish looks and acts similar, it does not have the same breeding method.
Natural history
Grunion were originally classified as part of the Atherinidae family of silversides but are now classified in the family Atherinopsidae, along with other New WorldNew World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
silversides including the jacksmelt and topsmelt. The California grunion, Leuresthes tenuis, is found along the Pacific Coast from Point Conception
Point Conception
Point Conception is a headland along the Pacific coast of U.S. state of California, located in southwestern Santa Barbara County. It is the point where the Santa Barbara Channel meets the Pacific Ocean, and as the corner between the mostly north-south trending portion of coast to the north and the...
, California, to Point Abreojos, Baja California. They are rarely found between San Francisco in the north and San Juanico Bay, Baja California, in the south. The Gulf grunion L. sardina is found along the coast of Baja California in the Gulf of California.
They are small, slender fish with bluish green backs, silvery sides and bellies. Their snouts are bluntly rounded and slippery. Silversides differ from true smelts of the family Osmeridae in that they lack the trout
Trout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...
-like adipose fin. Inhabiting the nearshore waters from the surf to a depth of 60 feet (18.3 m), marking experiments indicate that they are non-migratory.
Young grunion grow rapidly and are about five inches long by the time they reach one year old and are ready to spawn. Adult fish normally range in size from 6 to 7 inches (15 – 17 cm) with a maximum recorded size of 8.5 inches (21.6 cm) (La Jolla Ca.,05-11-05(19 cm).
Average body lengths for males and females are 4.5 and 5.0 inches (11.5 and 12.7 cm) respectively at the end of one year, 5.5 and 5.8 inches (14.0 and 14.7 cm) at the end of two years, and 5.9 to 6.3 inches (15.0 to 16.0 cm) at the end of three years.
The normal life span of the grunion is three to four years although individuals up to five years old have been found. Their growth rate slows after the first spawning and stops completely during the spawning season. Consequently, adult fish grow only during the fall and winter. This growth rate variation causes annuli to form on the scales, which have been used for aging purposes. The Gulf grunion, with its smaller eggs, is unique in that it may spawn
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
during daytime.
Milt
Milt is the seminal fluid of fish, mollusks, and certain other water-dwelling animals who reproduce by spraying this fluid, which contains the sperm, onto roe .-Milt as food:...
as she deposits her eggs about four inches below the surface. After spawning, the males immediately retreat toward the ocean. The milt flows down the female’s body until it reaches the eggs and fertilizes them. The female twists free and returns to the sea with the next wave. The whole event can happen in 30 seconds but some fish remain on the beach for several minutes. Spawning may continue from March through August, with occasional extensions into February and September. However, peak spawning is from late March through early June. Once mature, an individual may spawn during successive spawning periods at about 15-day intervals. Most females spawn about six times during the season. Counts of maturing ova to be laid at one spawning ranged from about 1,600 to about 3,600, with the larger females producing more eggs. A female might lay as many as 18,000 eggs over an entire season. The milt from the male might contain as many as one million sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
. Males may participate in several spawnings per run.
The eggs incubate a few inches deep in the sand above the level of subsequent waves. They are not immersed in seawater but are kept moist by the residual water in the sand. While incubating they are subject to predation by shore birds and sand-dwelling invertebrates. Under normal conditions they do not have an opportunity to hatch until the next tide series high enough reaches them 10 or more days later. Grunion eggs can extend incubation and delay hatching if tides do not reach them for an additional four weeks after this initial hatching time. Most of the eggs will hatch in 10 days if provided with seawater and the agitation of the rising surf. The mechanical action of the waves is the environmental trigger for hatching. The rapidity of hatching, which occurs in less than one minute, indicates that it is probably not an enzymatic function of a softening of the chorion
Chorion
The chorion is one of the membranes that exist during pregnancy between the developing fetus and mother. It is formed by extraembryonic mesoderm and the two layers of trophoblast and surrounds the embryo and other membranes...
as in some other fishes.
Grunion feeding habits are not well known. They have no teeth and feed on very small organisms such as plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
. In a laboratory setting grunion eat live brine shrimp
Brine shrimp
Artemia is a genus of aquatic crustaceans known as brine shrimp. Artemia, the only genus in the family Artemiidae, has changed little externally since the Triassic period...
. Humans, larger fish, and other animals prey upon grunion. An isopod, two species of flies, sandworm
Sandworm
Sandworm may refer to:Living animals :* Arenicola marina , called "sandworm" in the UK* Nereis virens , called "sandworm" in the US...
s, and a beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
have been found preying on the eggs. Some shorebirds such as egret
Egret
An egret is any of several herons, most of which are white or buff, and several of which develop fine plumes during the breeding season. Many egrets are members of the genera Egretta or Ardea which contain other species named as herons rather than egrets...
s and heron
Heron
The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....
s prey on grunion when the fish are on shore during spawning. Seagulls, sea lion
Sea Lion
Sea lions are pinnipeds characterized by external ear-flaps, long fore-flippers, the ability to walk on all fours, and short thick hair. Together with the fur seal, they comprise the family Otariidae, or eared seals. There are six extant and one extinct species in five genera...
s and sand shark
Sand shark
Sand sharks, also known as sand tiger sharks or ragged tooth sharks, are lamniform sharks of the family Odontaspididae . They are found worldwide in temperate and tropical waters, including on both sides of the Atlantic coast, but most notably in the Western Indian Ocean and in the Gulf of Maine...
s have also been observed feeding on grunion during a grunion run. The reduction of spawning habitat due to beach erosion, harbor construction and pollution is believed to be the most critical problem facing the grunion species.
Status of the population
Despite local concentrations, the grunion is not an abundant species. While the population size is not known, all research points to a restricted resource that is adequately maintained at current harvest rates under existing regulations.Grunion fishing
The periodic appearance of the grunion on Southern California beaches, and the act of catching them, is locally known as a "grunion run." A fishing license is required for persons 16 years and older to catch grunion and they may be taken by sport fishermen using their hands only. No appliances of any kind may be used to catch grunion, and no holes may be dug in the beach to entrap them. Grunion may be taken on specified dates between March and the end of August. There is no limit, but fishermen may take only what they can use, as under Californian law it is unlawful to waste fish. With these regulations, the resource seems to be maintaining itself at a fairly constant level.
History
The coastal Indians in California harvested grunion during spawning runs. Archeologists have found fossil grunion otoliths (tiny, bonelike particles or stony platelike structures in the internal ear of lower vertebrates) at various Indian campsites.Grunion were mentioned by Spanish explorer Juan Cabrillo in his ship's log dated c. 1542.
Scientists first identified grunion in San Francisco Bay in 1860.
Grunion in popular culture
- Music: Frank ZappaFrank ZappaFrank Vincent Zappa was an American composer, singer-songwriter, electric guitarist, record producer and film director. In a career spanning more than 30 years, Zappa wrote rock, jazz, orchestral and musique concrète works. He also directed feature-length films and music videos, and designed...
wrote a song named "Grunion Run" (originally released as a single by The Hollywood Persuaders), as has Jonathan RichmanJonathan RichmanJonathan Michael Richman is an American singer, songwriter and guitarist. In 1970 he founded The Modern Lovers, an influential proto-punk band. Since the mid-1970s, Richman has worked either solo or with low-key, generally acoustic backing...
("Grunion Run" on his album "I, Jonathan"). There have also been "Grunion Run" songs by Peter Yates, the Halibuts and the Insect Surfers. Sandra Tsing LohSandra Tsing LohSandra Tsing Loh is a Los Angeles, California-based writer, actress, performance-artist, pop-culture analyst, and radio commentator.-Biography:Loh is the daughter of a Chinese father and a German mother...
, on her "Pianovisions" album has "Night of the Grunion," a jazz piano solo performed by her and a chamber orchestra at Malibu Beach in 1989. - Grunion feature at the beginning of the first episode of the 1970s documentary series The Ascent of ManThe Ascent of ManThe Ascent of Man is a thirteen-part documentary television series produced by the BBC and Time-Life Films first transmitted in 1973, written and presented by Jacob Bronowski...
written and presented by Jacob BronowskiJacob BronowskiJacob Bronowski was a Polish-Jewish British mathematician, biologist, historian of science, theatre author, poet and inventor...
. - Television: In the eighth episode of season one of the series, "Burke's Law", series regular Gary Conway's character begs to be let off of an investigation early, so that he can go to the annual Grunion run. He is told to 'get back on the case', by his boss, Gene Barry (the "Burke" of the title).
- Television: Three episodes of The Beverly HillbilliesThe Beverly HillbilliesThe Beverly Hillbillies is an American situation comedy originally broadcast for nine seasons on CBS from 1962 to 1971, starring Buddy Ebsen, Irene Ryan, Donna Douglas, and Max Baer, Jr....
(originally aired in 1971) were about an expected grunion run ("The Grunion Invasion", "The Girls from Grun", and "The Grun Incident"). The Hillbillies prepare for an invasion of grunion, which they think are foreign invaders. - Television: An episode of Beverly Hills, 90210Beverly Hills, 90210Beverly Hills, 90210 is an American drama series that originally aired from October 4, 1990 to May 17, 2000 on Fox and was produced by Spelling Television in the United States, and subsequently on various networks around the world. It is the first series in the Beverly Hills, 90210 franchise...
had the gang at the beach during a grunion run. - Television: An episode of Three's CompanyThree's CompanyThree's Company is an American sitcom that aired from March 15, 1977, to September 18, 1984, on ABC. It is based on the British sitcom, Man About the House....
where Larry's sister visited included a grunion run, which (in the series' signature style) had everyone suspect Jack of trying to woo her. - Television: A humorous reference was made to the unusual—albeit necessary—technique for catching grunion toward the end of the Walker, Texas RangerWalker, Texas RangerWalker, Texas Ranger is an American television action crime drama series created by Leslie Greif and Paul Haggis, and starring Chuck Norris as a member of the Texas Ranger Division. The show aired on CBS in the spring of 1993, with the first season consisting of three pilot episodes. Eight full...
episode "The Siege." - Social: The phrase "running of the grunion" was used for several years during the 1950s and 1960s by adolescent boys as part of a seduction "line" to get their dates alone in a site overlooking the sea, much like "the submarine races".
- Poetry: Charles BukowskiCharles BukowskiHenry Charles Bukowski was an American poet, novelist and short story writer. His writing was influenced by the social, cultural and economic ambience of his home city of Los Angeles...
in his book "Mockingbird Wish Me Luck" (Black Sparrow Press 1972) wrote several poems about grunion runs including "the hunt" and "grab for grunion". Below is an excerpt from "the hunt":
- Movies: Don't Tell Mom The Babysitter's DeadDon't Tell Mom the Babysitter's DeadDon't Tell Mom the Babysitter's Dead is a 1991 comedy film directed by Stephen Herek starring Christina Applegate.Applegate stars as a teenager whose mother leaves for a two-month summer vacation in Australia, putting all five siblings in the care of a strict tyrannical elderly babysitter...
features a romantic scene amidst a grunion mating - Books: F. Scott FitzgeraldF. Scott FitzgeraldFrancis Scott Key Fitzgerald was an American author of novels and short stories, whose works are the paradigm writings of the Jazz Age, a term he coined himself. He is widely regarded as one of the greatest American writers of the 20th century. Fitzgerald is considered a member of the "Lost...
included a scene in which the two main characters are on the beach during grunion mating season in his final unfinished novel, The Last TycoonThe Love of the Last TycoonThe Love of The Last Tycoon: A Western is an unfinished novel by F. Scott Fitzgerald, compiled and published posthumously.-Publication history:The novel was unfinished and in rough form at the time of Fitzgerald's death at age 44...
.
- Sports: The Santa Barbara RugbyRugby footballRugby football is a style of football named after Rugby School in the United Kingdom. It is seen most prominently in two current sports, rugby league and rugby union.-History:...
Football Club is known as the Grunions
- Movies: James Cameron's first directed film Piranhas II: The Spawning features these fish, despite the title of the film.
Further reading
- Paul A. Gregory, California’s Marine Living Resources: A Status Report - Grunion, California Department of Fish and Game, December 2001.
External links
- grunion.org
- The Amazing Grunion (California Dept. of Fish & Game)
- Grunion Greeters (volunteer observers)
- The Cabrillo Museum Grunion Programs in San Pedro, CaliforniaSan Pedro, Los Angeles, CaliforniaSan Pedro is a port district of the city of Los Angeles, California, United States. It was annexed in 1909 and is a major seaport of the area...
- Does Beach Grooming Harm Grunion Eggs?
- Fishbase Leuresthes tenuis (Ayres 1860) California grunion
- Fishbase Leuresthes sardina (Jenkins & Evermann 1889) Gulf grunion
- Fishbase Colpichthys regis (Jenkins & Evermann, 1889) False grunion
- Decoding the Grunion's Ways - LA Times article