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61-499: The hatchery was built in 1963 to offset the loss of fish spawning habitat due to the construction of Camanche Dam . From 1987 to 1992, there was a drought in the area. Low flows and a series of fish kills reduced the Mokelumne River steelhead run during the 1980s. In response, EBMUD implemented several programs to improve water quality , flow regimes, and physical habitat in the lower Mokelumne River . The hatchery

122-464: A breeding site. The females choose large males that are successfully defending prime breeding sites which the females find attractive. For example, sculpin males defend "caves" underneath rocks which are suitable for the incubation of embryos. Another way males get to mate with several females is through the use of leks. Leks are places where many fish come together, and the males display to each other. Based on these displays, each female then selects

183-480: A classification of the spawning behaviours of fish by Balon (1975, 1984) into reproductive guilds . This classification is based on how the eggs are fertilized (internal or external spawners), where the eggs are deposited ( pelagic or benthic spawners), and whether and how the parents look after the eggs after spawning (bearers, guarders and nonguarders). Nonguarders do not protect their eggs and offspring after spawning Open substrate spawners scatter their eggs in

244-583: A distinct environment, larvae may be given shelter from predators and reduce competition for resources with the adult population. Animals in the larval stage will consume food to fuel their transition into the adult form. In some organisms like polychaetes and barnacles , adults are immobile but their larvae are mobile, and use their mobile larval form to distribute themselves. These larvae used for dispersal are either planktotrophic (feeding) or lecithotrophic (non-feeding) . Some larvae are dependent on adults to feed them. In many eusocial Hymenoptera species,

305-772: A few days and replace the dominant male. This is found amongst coral reef fishes such as groupers , parrotfishes and wrasses . It is less common for a male to switch to a female ( protandry ). As an example, most wrasses are protogynous hermaphrodites within a haremic mating system. Hermaphroditism allows for complex mating systems. Wrasses exhibit three different mating systems: polygynous, lek-like , and promiscuous mating systems. Group spawning and pair spawning occur within mating systems. The type of spawning that occurs depends on male body size. Labroids typically exhibit broadcast spawning, releasing high amounts of planktonic eggs, which are broadcast by tidal currents; adult wrasses have no interaction with offspring. Wrasse of

366-840: A forage fish of the smelt family found in the Atlantic and Arctic oceans. In summer, they graze on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat krill and other crustaceans . The capelin move inshore in large schools to spawn and migrate in spring and summer to feed in plankton rich areas between Iceland , Greenland , and Jan Mayen . The migration is affected by ocean currents . Around Iceland maturing capelin make large northward feeding migrations in spring and summer. The return migration takes place in September to November. The spawning migration starts north of Iceland in December or January. The diagram on

427-622: A larval phase of their life cycle . A larva's appearance is generally very different from the adult form ( e.g. caterpillars and butterflies ) including different unique structures and organs that do not occur in the adult form. Their diet may also be considerably different. In the case of smaller primitive arachnids, the larval stage differs by having three instead of four pairs of legs. Larvae are frequently adapted to different environments than adults. For example, some larvae such as tadpoles live almost exclusively in aquatic environments, but can live outside water as adult frogs . By living in

488-400: A pair of gonads , which release sperm in response to hormones in the female's bloodstream indicating egg release. This ensures that, when the female is ready to spawn, she has a mate immediately available. A single anglerfish female can "mate" with many males in this manner. Polygynandry occurs when multiple males mate indiscriminately with multiple females. This mutual promiscuity is

549-503: A particular subgroup of the family Labridae , Labrini, do not exhibit broadcast spawning. Less commonly hermaphrodites can be synchronous , meaning they simultaneously possess both ovaries and testicles and can function as either sex at any one time. Black hamlets "take turns releasing sperm and eggs during spawning. Because such egg trading is advantageous to both individuals, hamlets are typically monogamous for short periods of time–an unusual situation in fishes." The sex of many fishes

610-488: A relatively small number of embryos and retain them for a few weeks to 16 months or longer. The shorter times spans are characteristic of species that eventually deposit their embryos in the environment, surrounded by a horny capsule; whereas the longer periods are characteristic of sharks that retain the embryos until they are ready to emerge as actively swimming young." However, some fish do not fit these categories. The livebearing largespring gambusia ( Gambusia geiseri )

671-400: A significant temperature change, often in spring. Males chase females, prompting them to release their eggs by bumping and nudging them. As the female goldfish spawns her eggs, the male goldfish stays close behind fertilizing them. Their eggs are adhesive and attach to aquatic vegetation. The eggs hatch within 48 to 72 hours. Within a week or so, the fry begins to assume its final shape, although

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732-605: A species is all-male or all-female. Unisexuality occurs in some fish species, and can take complex forms. Squalius alburnoides , a minnow found in several river basins in Portugal and Spain, appears to be an all-male species. The existence of this species illustrates the potential complexity of mating systems in fish. The species originated as a hybrid between two species, and is diploid , but not hermaphroditic. It can have triploid and tetraploid forms, including all-female forms that reproduce mainly through hybridogenesis . It

793-423: A species is either male or female, and remains that way throughout their lives. Most fish are gonochorists, but hermaphroditism is known to occur in 14 families of teleost fishes. Usually hermaphrodites are sequential , meaning they can switch sex, usually from female to male ( protogyny ). This can happen if a dominant male is removed from a group of females. The largest female in the harem can switch sex over

854-438: A substrate and guard them until the eggs hatch. After hatching, the female picks up the fry and keeps them in her mouth. When the fry can fend for themselves, they are released. Some eartheaters are larvophile mouthbrooders. The beginning of the evolutionary process of livebearing starts with facultative (optional) internal bearing. The process occurs in several species of oviparous (egg-laying) killifishes which spawn in

915-437: A year may pass before they develop a mature goldfish colour; until then they are a metallic brown like their wild ancestors. In their first weeks of life, the fry grow quickly—an adaptation born of the high risk of getting devoured by the adult goldfish. Carp typically spawn in the spring and summer, depending on the climate and conditions. Oxygen levels of the water, availability of food, size of each fish, age, number of times

976-438: Is also true of cartilaginous fishes (such as sharks , rays and skates ). Spawn consists of the reproductive cells ( gametes ) of many aquatic animals, some of which will become fertilized and produce offspring. The process of spawning typically involves females releasing ova (unfertilized eggs) into the water, often in large quantities, while males simultaneously or sequentially release spermatozoa ( milt ) to fertilize

1037-444: Is an "investment by parents in offspring that increases the offspring's chances of surviving (and hence reproducing). In fish, parental care can take a variety of forms including guarding, nest building, fanning, splashing, removal of dead eggs, retrieval of straying fry, external egg carrying, egg burying, moving eggs or young, ectodermal feeding, oral brooding, internal gestation, brood-pouch egg carrying, etc." Territorial behaviour

1098-441: Is an external method of reproduction where the female releases many unfertilised eggs into the water. At the same time, a male or many males release a lot of sperm into the water which fertilises some of these eggs. The eggs contain a drop of nutrient oil to sustain the embryo as it develops inside the egg case. The oil also provides buoyancy, so the eggs float and drift with the current. The strategy for survival of broadcast spawning

1159-615: Is called coral because it turns bright red when cooked. Roe (reproductive organs) are usually eaten either raw or briefly cooked. "The reproductive behaviour of fishes is remarkably diversified: they may be oviparous (lay eggs), ovoviviparous (retain the eggs in the body until they hatch), or viviparous (have a direct tissue connection with the developing embryos and give birth to live young). All cartilaginous fishes—the elasmobranches (e.g., sharks, rays, and skates)—employ internal fertilization and usually lay large, heavy-shelled eggs or give birth to live young. The most characteristic features of

1220-408: Is difficult for fish to find partners, or when both sexes look after the young. Many tropical cichlids , which rear their young together in locations where they must fiercely defend against competitors and predators are monogamous. "In some pipefishes and seahorses , development of eggs takes a long time before the female can place them in the brood pouch of a male, where they are fertilized. While

1281-610: Is dominated by large and aggressive males. Cuckoldry is a variant of polyandry, and can occur with sneak spawners (sometimes called streak spawners ). A sneak spawner is a male that rushes in to join the spawning rush of a spawning pair. A spawning rush occurs when a fish makes a burst of speed, usually on a near vertical incline, releasing gametes at the apex, followed by a rapid return to the lake or sea floor or fish aggregation. Sneaking males do not take part in courtship. In salmon and trout, for example, jack males are common. These are small silvery males that migrate upstream along with

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1342-489: Is generally necessary for guarders, and the embryos are almost always guarded by males (apart from cichlids). There is a need to be territorial because looking after embryos usually includes defending the site where they are being looked after. It also often means there is competition for the best egg-laying sites. Elaborate courtship behaviour is usual among guarders. Guarding males keep the embryos safe from predators, keep oxygen levels high by fanning water currents, and keep

1403-450: Is not fixed, but can change with physical and social changes to the environment where the fish lives. Particularly among fishes, hermaphroditism can pay off in situations where one sex is more likely to survive and reproduce, perhaps because it is larger. Anemone fishes are sequential hermaphrodites which are born as males, and become females only when they are mature. Anemone fishes live together monogamously in an anemone , protected by

1464-517: Is often associated with r-strategists . However, most fish and other spawning animals are iteroparous. When the internal ovaries or egg masses of fish and certain marine animals are ripe for spawning they are called roe . Roe from certain species, such as shrimp , scallop , crab and sea urchins , are sought as human delicacies in many parts of the world. Caviar is a name for the processed, salted roe of non-fertilized sturgeon . The term soft roe or white roe denotes fish milt . Lobster roe

1525-494: Is often necessary to construct fish ladders and other bypass systems so salmon can navigate their way past hydroelectric dams or other obstructions such as weirs on their way to spawning grounds. Coastal fish often use mangroves and estuaries as spawning grounds, while reef fish can find adjacent seagrass meadows that make good spawning grounds. Short-finned eels can travel anything up to three or four thousand kilometres to their spawning ground in deep water somewhere in

1586-509: Is rare to find true parthenogenesis in fishes, where females produce female offspring with no input from males. All-female species include the Texas silverside , Menidia clarkhubbsi as well as the Amazon molly . Parthenogenesis has been recently observed in hammerhead sharks and blacktip sharks . It is also known to occur in crayfish and amphibians. This section is patterned after

1647-544: Is the eggs and sperm released or deposited into water by aquatic animals . As a verb, to spawn refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is known as spawning . The vast majority of aquatic and amphibious animals reproduce through spawning. These include the following groups: As a general rule, aquatic or semiaquatic reptiles , birds , and mammals do not reproduce through spawning, but rather through copulation like their terrestrial counterparts. This

1708-503: Is the egg yolk, as in externally spawned eggs. This situation, also referred to as ovoviviparity , is characteristic of marine rock fishes and the Lake Baikal sculpins . This strategy allows these fish to have fecundities approaching those of pelagic fish with external fertilization, but it also enables them to protect the young during their most vulnerable stage of development. By contrast, sharks and rays using this strategy produce

1769-476: Is to disperse the fertilised eggs, preferably away from the coast into the relative safety of the open ocean. There the larvae develop as they consume their fat stores, and eventually hatch from the egg capsule into miniature versions of their parents. To survive, they must then become miniature predators themselves, feeding on plankton. Fish eventually encounter others of their own kind ( conspecifics ), where they form aggregations and learn to school. Internally,

1830-595: The California Department of Fish and Game and is open every day (including holidays) from 7:00 am to 3:00;pm. It is located in northeast San Joaquin County, California at the base of the Camanche Dam and is reached by taking McIntire Road north from State Route 12 . A limited number of educational tours are provided for schools and other organized groups. The topics covered by the tour are:

1891-618: The Coral Sea . Forage fish often make great migrations between their spawning, feeding and nursery grounds. Schools of a particular stock usually travel in a triangle between these grounds. For example, one stock of herrings have their spawning ground in southern Norway , their feeding ground in Iceland , and their nursery ground in northern Norway. Wide triangular journeys such as these may be important because forage fish, when feeding, cannot distinguish their own offspring. Capelin are

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1952-570: The bluegill sunfish in fresh water. Sneaker males that become too large to hide effectively become satellite males . With bluegill sunfish, satellite males mimic the behaviour and colouration of the females. They hover over a nest containing a pair of courting sunfish, and gradually descend to reach the pair just as they spawn. Males may need to be 6 or 7 years old to function capably as parental males, but may be able to function as sneaker or satellite males when they are as young as 2 or 3 years old. The smaller satellite and sneaker males may get mauled by

2013-662: The sardine run occurs when millions of sardines migrate from their spawning grounds south of the southern tip of Africa northward along the Eastern Cape coastline. Chinook salmon make the longest freshwater migration of any salmon, over 3,000 kilometres (1,900 mi) up the Yukon River to spawning grounds upstream of Whitehorse , Yukon. Some green sea turtles swim more than 2,600 kilometres (1,600 mi) to reach their spawning grounds. Goldfish , like all cyprinids , are egg-layers. They usually start breeding after

2074-421: The abdomen. Male sharks and rays can pass sperm along a duct into a seminal vesicle , where they store it for a while before it is expelled, while teleosts usually employ separate sperm ducts. Externally, many marine animals, even when spawning, show little sexual dimorphism (difference in body shape or size) or little difference in colouration . Where species are dimorphic, such as sharks or guppies ,

2135-472: The anemone stings. The males do not have to compete with other males, and female anemone fish are typically larger. When a female dies a juvenile (male) anemone fish moves in, and "the resident male then turns into a female and reproductive advantages of the large female–small male combination continue". In other fishes sex changes are reversible. For example, if some gobies are grouped by sex (male or female), some will switch sex. Unisexuality occurs when

2196-420: The approach most commonly used by spawning animals, and is perhaps the "original fish mating system." Common examples are forage fish , such as herrings , which form huge mating shoals in shallow water. The water becomes milky with sperm and the bottom is draped with millions of fertilized eggs. Alternate male strategies which allow small males to engage in cuckoldry can develop in species where spawning

2257-448: The area free from dead embryos and debris. They protect the embryos until they hatch, and often look after the larval stages as well. The time spent guarding can range from a few days to several months. Some guarders build nests ( nest spawners ) and some do not ( substrate spawners ), though the difference between the two groups can be small. Substrate spawners clean off a suitable area of surface suitable for egg laying, and look after

2318-432: The area, but they do not actively build a nest. Bearers are fish that carry their embryos (and sometimes their young) around with them, either externally or internally. Mouth brooders - carry eggs or larvae in their mouth. Mouth brooders can be ovophiles or larvophiles. Ovophile or egg-loving mouth-brooders lay their eggs in a pit, which are sucked up into the mouth of the female. The small number of large eggs hatch in

2379-506: The biology of Chinook salmon and Steelhead trout, the purpose and operations of the hatchery, and the importance of conserving river watersheds . Casual visitors may take a self-guided tour. The hatchery is also a popular destination for fishing , wildlife watching, and hiking . All trails at the hatchery are paved and wheelchair accessible . 38°13′31″N 121°01′35″W  /  38.22528°N 121.02639°W  / 38.22528; -121.02639 Spawn (biology) Spawn

2440-477: The brooding but cannot handle all the eggs the female produce, such as with some pipefish . The males in some deep sea anglerfishes are much smaller than the females. When they find a female they bite into her skin, releasing an enzyme that digests the skin of their mouth and her body and fusing the pair down to the blood-vessel level. The male then slowly atrophies , losing first his digestive organs, then his brain, heart, and eyes, ending as nothing more than

2501-476: The eggs. The fungi ( mushrooms ), are also said to "spawn" when they release a white, ‘fibrous’ matter, forming the matrix from-which they grow. There are many variations in the way spawning occurs, depending on sexual differences in anatomy, how the sexes relate to each other, where and how the spawn is released and whether or how the spawn is subsequently guarded. Marine animals, and particularly bony fish , commonly reproduce by broadcast spawning . This

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2562-507: The environment. They usually spawn in shoals without complex courtship rituals, and males outnumber females. Broadcast spawners : release their gametes (sperm and eggs) into open water for external fertilisation. There is no subsequent parental care. About 75% of coral species are broadcasters, the majority of which are hermatypic, or reef-building corals. Brood hiders hide their eggs but do not give parental care after they have hidden them. Brood hiders are mostly benthic spawners that bury

2623-532: The fertilized eggs. For example, among salmon and trout the female digs a nest with her tail in gravel. These nests are called redds . The female then lays her eggs while the male fertilizes them, while both fish defend the redd if necessary from other members of the same species. Then the female buries the nest, and the nest site is abandoned. In North America, some minnows build nests out of piles of stones rather than dig holes. The minnow males have tubercles on their head and body which they use to help them defend

2684-467: The fish has spawned before and water temperature are all factors known to effect when and how many eggs each carp will spawn at any one time. Larvae A larva ( / ˈ l ɑːr v ə / ; pl. : larvae / ˈ l ɑːr v iː / ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects , some arachnids , amphibians , or cnidarians typically have

2745-415: The host. The same female may use a number of mussels, and she deposits only one or two yellow, oval eggs into each. Early developmental stages are protected from predation within the body of the mussel. After 3 to 4 weeks larvae swim away from the host to continue life on their own. Guarders protect their eggs and offspring after spawning by practicing parental care (also called brood care ). Parental care

2806-407: The larvae are fed by female workers. In Ropalidia marginata (a paper wasp) the males are also capable of feeding larvae but they are much less efficient, spending more time and getting less food to the larvae. The larvae of some organisms (for example, some newts ) can become pubescent and do not develop further into the adult form. This is a type of neoteny . It is a misunderstanding that

2867-525: The larval form always reflects the group's evolutionary history . This could be the case, but often the larval stage has evolved secondarily, as in insects. In these cases , the larval form may differ more than the adult form from the group's common origins. Within Insects , only Endopterygotes show complete metamorphosis, including a distinct larval stage. Several classifications have been suggested by many entomologists , and following classification

2928-470: The male is pregnant, the female starts a new batch of eggs, which are ready at about the same time that the male gives birth to the young from the previous mating. This close timing of development promotes monogamy, especially if the likelihood of encountering another potential mate is low." Polygyny occurs when one male gets exclusive mating rights with multiple females. In polygyny, a large conspicuous male usually defends females from other males or defends

2989-533: The male they want to be their mate. For example, among the cichlid Cyrtocara eucinostomus in Lake Malawi , up to 50,000 large and colourful males display together on a lek four kilometres long. The females, which are mouth brooders, choose which male they want to fertilize their eggs. Polyandry occurs when one female gets exclusive mating rights with multiple males. This happens among fish like clownfish that change their sex. It can also happen when males do

3050-498: The males often have penis-like intromittent organs in the form of a modified fin. A species is semelparous if its individuals spawn only once in their lifetime, and iteroparous if its individuals spawn more than once. The term semelparity comes from the Latin semel , once, and pario , to beget, while iteroparity comes from itero , to repeat, and pario , to beget. Semelparity is sometimes called "big bang" reproduction, since

3111-437: The more powerful parental males, but they spawn when they are younger and they do not put energy into parental care. Hermaphroditism occurs when a given individual in a species possesses both male and female reproductive organs, or can alternate between possessing first one, and then the other. Hermaphroditism is common in invertebrates but rare in vertebrates. It can be contrasted with gonochorism , where each individual in

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3172-581: The more primitive bony fishes is the assemblage of polyandrous (many males) breeding aggregations in open water and the absence of parental care..." There are two main reproduction methods in fish. The first method is by laying eggs and the second by live-bearing (producing their young alive). Monogamy occurs when one male mates with one female exclusively. This is also called pair spawning . Most fish are not monogamous, and when they are, they often alternate with non-monogamous behaviours. Monogamy can occur when feeding and breeding grounds are small, when it

3233-434: The mother's mouth, and the fry remain there for a period of time. Fertilization often occurs with the help of egg-spots, which are colorful spots on the anal fin of the male. When the female sees these spots, she tries to pick up the egg-spots, but instead gets sperm that fertilizes the eggs in her mouth. Many cichlids and some labyrinth fish are ovophile mouthbrooders. Larvophile or larvae-loving mouth-brooders lay their eggs on

3294-399: The nest site. Bitterlings have a remarkable reproduction strategy where parents transfer responsibility for the care of their young to mussels . The female extends her ovipositor into the mantle cavity of the mussel and deposits her eggs between the gill filaments. The male then ejects his sperm into the mussel's inhalant water current and fertilization takes place within the gills of

3355-415: The normal way on the substrate, but in the process accidentally fertilize eggs that the female retains and does not spawn. These eggs are spawned later, usually without allowing much time for embryonic development. The next step in the evolution of livebearing is obligate (by necessity) internal bearing, where the female retains all the embryos. "The only source of nutrition for these embryos, however,

3416-458: The right shows the main spawning grounds and larval drift routes. Capelin on the way to feeding grounds is coloured green, capelin on the way back is blue, and the breeding grounds are red. In a paper published in 2009, researchers from Iceland recount their application of an interacting particle model to the capelin stock around Iceland, successfully predicting the spawning migration route for 2008. Referred to as "the greatest shoal on earth",

3477-412: The sexes of most marine animals can be determined by looking at the gonads . For example, male testes of spawning fish are smooth and white and account for up to 12% of the mass of the fish, while female ovaries are granular and orange or yellow, accounting for up to 70% of the fish's mass. Male lampreys, hagfish and salmon discharge their sperm into the body cavity where it is expelled through pores in

3538-482: The single reproductive event of semelparous organisms is usually large and fatal to the spawners. The classic example of a semelparous animal is the Pacific salmon , which lives for many years in the ocean before swimming to the freshwater stream of its birth, spawning, and then dying. Other spawning animals which are semelparous include mayflies , squid , octopus , smelt , capelin and some amphibians. Semelparity

3599-427: The standard, large, hook-nosed males and that spawn by sneaking into a redd (spawning nest) to release sperm simultaneously with a mated pair. This behaviour is an evolutionarily stable strategy for reproduction, because it is favoured by natural selection just like the "standard" strategy of large males. Cuckoldry occurs in many fish species, including dragonets , parrotfishes and wrasses on tropical reefs and

3660-566: Was remodeled in July 2002, enlarging the rearing space to promote fish health and fish survival rates while also making hatchery operations more efficient. Since then, the Lower Mokelumme River Fishery Resource has thrived, as evidenced by counts of fall-run Chinook salmon escapement or returning salmon. Returning salmon increased by 3,028 from 1998 to 2003. The hatchery is owned by EBUMD and operated by

3721-548: Was thought to be ovoviviparous until it was shown in 2001 that the embryos received nutrients from the mother. Spawning grounds are the areas of water where aquatic animals spawn, or produce their eggs. After spawning, the spawn may or may not drift to new grounds which become their nursery grounds. Many species undertake migrations each year, and sometimes great migrations, to reach their spawning grounds. For example, lakes and river watersheds can be major spawning grounds for anadromous fish such as salmon . These days, it

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