Broodstock

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Broodstock, or broodfish, are a group of mature individuals used in aquaculture for breeding purposes. Broodstock can be a population of animals maintained in captivity as a source of replacement for, or enhancement of, seed and fry numbers. [1] These are generally kept in ponds or tanks in which environmental conditions such as photoperiod, temperature and pH are controlled. Such populations often undergo conditioning to ensure maximum fry output. Broodstock can also be sourced from wild populations where they are harvested and held in maturation tanks before their seed is collected for grow-out to market size [2] or the juveniles returned to the sea to supplement natural populations. [1] This method, however, is subject to environmental conditions and can be unreliable seasonally, or annually. [2] Broodstock management can improve seed quality and number through enhanced gonadal development and fecundity. [3]

Contents

Management

Broodstock management involves manipulating environmental factors surrounding the broodstock to ensure maximum survival, enhance gonadal development and increase fecundity. [3] Such conditioning is necessary to ensure the sustainability of aquaculture production, [4] and to increase the number and quality of eggs produced and control the timing of maturation and spawning. [5] Management of the technologies for gamete production in captivity is one of the essential step for aquaculture that would ensure the growth to this sector. Unfortunately, most fish when reared in captivity condition, exhibit some degree of reproduction dysfunction. Many species of captive fish are able to reach reproduction maturity in aquaculture conditions and gonadal growth occurs normally. However, some of female species often fail final oocyte maturation stage. [6] Hormonal manipulation and acceleration of final oocyte maturation due to the economics of broodstock management is important. For instance, in Salmoniformes, the need to collect the eggs by stripping is a serious limitation, while the time of ovulation must be predicted with accuracy, as over-ripening may take place in minutes or hours after ovulation [7] Therefore, control of broodstock reproductive is essential for the sustainability of commercial aquaculture production [8]

Choosing species to use requires consideration of the biology of the species. This includes their size at maturity, method of reproduction, feeding behaviour and ability to tolerate adverse conditions [9] Farms also consider whether they grow their own broodstock or obtain them from natural populations. Where natural populations are excluded, the farm can be considered a self-sustaining unit independent of external genetic influence. [10]

Pond-reared broodstocks are selected, often as immature juveniles, and grown out in suitable conditions to sexual maturity. These animals require stable water characteristics and a well-balanced, species-dependent, protein rich diet. [9] This enhances the germinal tissue for future seed stock as it is formed in juveniles. [9]

The pond or tank in which broodfish are held must be a suitable size to hold and condition the broodstock. [11] Dependent on the species involved you need to alter the number of individuals, and often separate the sexes. [11] Sex separation enables the broodstock males and females to be subjected to different conditions where necessary. For example, male and female sturgeons respond to different hormone levels, [12] this also allows more control over eggs and sperm.

The characteristics of the water in which the mature broodstocks are held must be manipulated. The aquaculturist must consider the appropriate oxygen concentration, temperature, and pH of the water [4] [9] [13] all of which can be species specific.

The feeding regime of broodstocks is species specific [10] and requires consideration of timing and composition of the food. [3] Protein, lipid and fatty acid composition is particularly important. [3] The quantity of food intake can be altered to influence spawning and maturity, for example low rations have been shown to reduce the number of fish reaching maturity while increasing the fecundity of those which do. [5]

When fry are desired, spawning can be induced in broodstocks by manipulation of relevant environmental factors. In particular the photoperiod can be altered to imply that it is time to spawn. [4] A shortened photoperiod is known to advance spawning times while a lengthened photoperiod can delay spawning. [14] Artificial light can be used to change the apparent day length and indicate different seasonal features so as to delay spawning. [5] Water temperature can be increased for the same purpose. [4] Following spawning the female broodfish are often stressed and have lost weight. They require extra care and abundant feeding at this time to ensure survival to the next spawning season.

Advantages

Managers can select for reproductive characteristics which influence the egg producing capability of individuals and increase fecundity by providing them with optimal environment and diets. [5] [15] This is further possible in pond-reared populations where traits can be selected for over generations for example, for higher fecundity. [5]

The breeding season and spawning times can be shifted thus expanding the seasonal range of production. This leads to more efficient aquaculture because fry are available to the market year round. [5] Hormonal treatments can advance spawning by two to three weeks. [5] Manipulating photoperiod can alter spawning time by over four months and is cheap and straightforward to achieve. [5]

Broodstock managers can use or select for traits such as fast growth rates or disease resistance over generations to produce more desirable fish. [15] This ability for genetic improvement of stocks is more efficient and produces higher value stock. Broodstocks also enable you to selectively plan and control all matings. Selective breeding is an important part of the domestication of aquaculture species.

Pond-reared broodstocks benefit from the removal of predation which can be a significant cause of mortality in natural populations. [16] They further benefit from the removal of variable environmental impacts.

Holding broodstock in an accessible pond or tank offers readily available breeding adults whenever required.

Disadvantages

When broodstocks are used to supplement natural populations they face different selective pressures to normal. [1] Thus they may not have adequate fitness to survive the natural environment, or can alter and decrease natural genetic diversity due to the bottleneck nature of breeding from a smaller population. [1]

Broodstocks require supplementation from outside sources regularly to prevent negative effects of closed populations. Domestication of broodstocks in hatcheries can reduce reproductive capabilities [16] and alter other genetic characteristics. [16] For example, a trout stock maintained as a closed population for 20 generations showed reduced number and size of egg production. [17]

Examples

Penaeidae

Shrimp, particularly of the family Penaeidae, are one of the largest internationally traded species. [18] Native stocks are usually collected as sources of broodstock supply . [18] [19] There are also examples of pond-reared Penaeidae broodstocks. [2] These shrimp are raised in suitable environmental conditions including a 12–14 hour/day photoperiod, a water temperature of 25–29 °C and full seawater salinity with high water exchange rates. [19]

Sydney rock oyster

The Sydney rock oyster, Saccostrea glomerata, has been farmed in New South Wales, Australia for over 100 years. [20] Due to declines in the supply in the past 30 years, [20] New South Wales introduced a selection program in 1990 to breed faster growing stocks. [21] The utilised broodstocks are held in artificial ponds of around 0.11 ha in size, and at low densities. [22] Broodstocks provided higher numbers of larvae and could be spawned readily providing a more definite source of Sydney rock oysters. [22]

Rainbow trout

Global production of rainbow trout, Oncorhynchus mykiss, requires over 3 billion eggs per year. [5] This number is met because of broodstocks which undergo selection and conditioning in hatcheries. [5] Trout have been reared artificially for over 80 years. [23] Rainbow trout broodstocks are commonly manipulated to delay maturation and spawning time in order to provide eggs regularly and optimise supply. [5] Artificial selection has favoured larger fish due to evidence of correlations between fish size and fecundity. [15]

Related Research Articles

Trout Number of species of freshwater fish

Trout are species of freshwater fish belonging to the genera Oncorhynchus, Salmo and Salvelinus, all of the subfamily Salmoninae of the family Salmonidae. The word trout is also used as part of the name of some non-salmonid fish such as Cynoscion nebulosus, the spotted seatrout or speckled trout.

Selective breeding Breeding used to develop desired characteristics

Selective breeding is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together. Domesticated animals are known as breeds, normally bred by a professional breeder, while domesticated plants are known as varieties, cultigens, cultivars, or breeds. Two purebred animals of different breeds produce a crossbreed, and crossbred plants are called hybrids. Flowers, vegetables and fruit-trees may be bred by amateurs and commercial or non-commercial professionals: major crops are usually the provenance of the professionals.

Indian prawn Species of crustacean

The Indian prawn, is one of the major commercial prawn species of the world. It is found in the Indo-West Pacific from eastern and south-eastern Africa, through India, Malaysia and Indonesia to southern China and northern Australia. Adult shrimp grow to a length of about 22 cm (9 in) and live on the seabed to depths of about 90 m (300 ft). The early developmental stages take place in the sea before the larvae move into estuaries. They return to the sea as sub-adults.

Rainbow trout Fresh-water species of fish

The rainbow trout is a trout and species of salmonid native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead is an anadromous (sea-run) form of the coastal rainbow trout(O. m. irideus) or Columbia River redband trout (O. m. gairdneri) that usually returns to fresh water to spawn after living two to three years in the ocean. Freshwater forms that have been introduced into the Great Lakes and migrate into tributaries to spawn are also called steelhead.

Cutthroat trout Species of fish

The cutthroat trout(Oncorhynchus clarkii) is a fish species of the family Salmonidae native to cold-water tributaries of the Pacific Ocean, Rocky Mountains, and Great Basin in North America. As a member of the genus Oncorhynchus, it is one of the Pacific trout, a group that includes the widely distributed rainbow trout. Cutthroat trout are popular gamefish, especially among anglers who enjoy fly fishing. The common name "cutthroat" refers to the distinctive red coloration on the underside of the lower jaw. The specific name clarkii was given to honor explorer William Clark, coleader of the Lewis and Clark Expedition.

Apache trout Species of fish

The Apache trout, Oncorhynchus apache, is a species of freshwater fish in the salmon family of order Salmoniformes. It is one of the Pacific trouts.

<i>Oncorhynchus</i> Genus of fishes

Oncorhynchus is a genus of fish in the family Salmonidae; it contains the Pacific salmon and Pacific trout. The name of the genus is derived from the Greek ὄγκος + ῥύγχος, in reference to the hooked jaws of males in the mating season.

Fish hatchery Aquaculture facility

A fish hatchery is a place for artificial breeding, hatching, and rearing through the early life stages of animals—finfish and shellfish in particular. Hatcheries produce larval and juvenile fish, shellfish, and crustaceans, primarily to support the aquaculture industry where they are transferred to on-growing systems, such as fish farms, to reach harvest size. Some species that are commonly raised in hatcheries include Pacific oysters, shrimp, Indian prawns, salmon, tilapia and scallops.

Lahontan cutthroat trout Subspecies of fish

Lahontan cutthroat trout is the largest subspecies of cutthroat trout, and the state fish of Nevada. It is one of three subspecies of cutthroat trout that are listed as federally threatened.

Pacific oyster Species of bivalve

The Pacific oyster, Japanese oyster, or Miyagi oyster, is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand.

Oyster farming Commercial growing of oysters

Oyster farming is an aquaculture practice in which oysters are bred and raised mainly for their pearls, shells and inner organ tissue, which is eaten. Oyster farming was practiced by the ancient Romans as early as the 1st century BC on the Italian peninsula and later in Britain for export to Rome. The French oyster industry has relied on aquacultured oysters since the late 18th century.

The Dexter National Fish Hatchery & Technology Center is a U.S. Fish and Wildlife Service facility dedicated to fish culture techniques for threatened and endangered fishes of the American Southwest. Located in Dexter, New Mexico, it is the only federal facility in the nation dedicated to studying and holding only threatened and endangered fish. Scientists at the Dexter facility perform life history studies and carefully analyze fish genetics while maintaining a refuge for 16 imperiled fish species. Dexter National Fish Hatchery was established in 1931, to satisfy demands for game fish throughout the Southwest. New laws brought changes to the hatchery in the 1970s.

Brook stickleback Species of fish

The brook stickleback is a small freshwater fish that is distributed across the US and Canada. It grows to a length of about 2 inches. It occupies the northern part of the eastern United States, as well as the southern half of Canada. Small populations are scattered throughout the Mississippi-Great Lakes basin extending to Colorado, New Mexico, Kentucky, Tennessee, etc., though some of these areas are not native to the species. This small fish inhabits clear, cool streams and lakes. They eat small invertebrates, algae, insect larvae, and occasionally their own eggs. They are also preyed upon by smallmouth bass and northern pike. Feeding time is usually dawn and sunset. The brook stickleback does have active competition mostly from minnows, but feeding times are different, along with diet. Spawning occurs in midsummer. Males secure a territory, build a nest, and mate with females. Males provide protection for the eggs, ward off predators, and usually die later in the season. This is considered an annual species. The nests are built out of aquatic grasses. Though the brook stickleback is not considered a threatened species, deforesting and changing waters are altering ecosystems of the species. Harvesting of trees around riparian environments is having a large effect of the stream ecosystem where the brook stickleback resides.

Aquaculture of salmonids Farming and harvesting of salmonids under controlled conditions

The aquaculture of salmonids is the farming and harvesting of salmonids under controlled conditions for both commercial and recreational purposes. Salmonids, along with carp, and tilapia are the three most important fish species in aquaculture. The most commonly commercially farmed salmonid is the Atlantic salmon. In the U.S. Chinook salmon and rainbow trout are the most commonly farmed salmonids for recreational and subsistence fishing through the National Fish Hatchery System. In Europe, brown trout are the most commonly reared fish for recreational restocking. Commonly farmed nonsalmonid fish groups include tilapia, catfish, sea bass, and bream.

Aquaculture of sea cucumbers

Sea cucumber stocks have been overexploited in the wild, resulting in incentives to grow them by aquaculture. Aquaculture means the sea cucumbers are farmed in contained areas where they can be cultured in a controlled manner. In China, sea cucumbers are cultured, along with prawns and some fish species, in integrated multi-trophic systems. In these systems, the sea cucumbers feed on the waste and feces from the other species. In this manner, what would otherwise be polluting byproducts from the culture of the other species become a valuable resource that is turned into a marketable product.

Eyestalk ablation The removal of one or both eyestalks from a crustacean

Eyestalk ablation is the removal of one (unilateral) or both (bilateral) eyestalks from a crustacean. It is routinely practiced on female shrimps in almost every marine shrimp maturation or reproduction facility in the world, both research and commercial. The aim of ablation under these circumstances is to stimulate the female shrimp to develop mature ovaries and spawn.

The olfactory system is the system related to the sense of smell (olfaction). Many fish activities are dependent on olfaction, such as: mating, discriminating kin, avoiding predators, locating food, contaminant avoidance, imprinting and homing. These activities are referred to as “olfactory-mediated.” Impairment of the olfactory system threatens survival and has been used as an ecologically relevant sub-lethal toxicological endpoint for fish within studies. Olfactory information is received by sensory neurons, like the olfactory nerve, that are in a covered cavity separated from the aquatic environment by mucus. Since they are in almost direct contact with the surrounding environment, these neurons are vulnerable to environmental changes. Fish can detect natural chemical cues in aquatic environments at concentrations as low as parts per billion (ppb) or parts per trillion (ppt).

Little Kern golden trout Subspecies of fish

The Little Kern golden trout is a brightly colored subspecies of rainbow trout native to the main stem and tributaries of the Little Kern River in Tulare County, California. Together with the California golden trout and the Kern River rainbow trout, the Little Kern golden trout forms what is sometimes referred to as the "golden trout complex" of the Kern River basin.

Bellvue-Watson Fish Hatchery

The Bellvue-Watson Fish Hatchery is a Colorado Parks and Wildlife cold water fish production facility located near Cache la Poudre River and Watson Lake State Wildlife Area in Larimer County, Colorado. Hatchery staff works to support the raising of approximately 1.5 million sub-catchable trout annually. The Watson Lake Rearing Unit, a division within the hatchery, is responsible for rearing approximately 300,000 catchable trout each year. The hatchery stocks fishing sports in Wellington, Fort Collins, Loveland, Longmont and Jumbo Reservoir near Julesburg and Hale ponds.

<i>Saccostrea echinata</i> Tropical black-lip rock oyster, found in the Indo-Pacific

Saccostrea echinata, commonly known as the tropical black-lip rock oyster, blacklip rock oyster, blacklip oyster, and spiny rock oyster, is one of several tropical rock oyster species, occurring in tropical seas across the Indo-Pacific, including coastal waters across northern Australia to Noumea.

References

  1. 1 2 3 4 Waples, R.S., and C. Do. 1994. Genetic risk associated with supplementation of Pacific salmonids: Captive broodstock programs. Canadian Journal of Fisheries and Aquatic Science,51(1), 310–329.
  2. 1 2 3 Fast, A. W. (1994). Effects of broodstock size and source on ovarian maturation and spawning on Penaeus monodon Fabricius from the Gulf of Thailand. Journal of the World Aquaculture Society, 25(1), 41–49.
  3. 1 2 3 4 Izquierdo, M. S., Fernandez-Palacios, H. And Tacon, A. G. J. (2001). Effect of broodstock nutrition on reproductive performance of fish. Aquaculture, 197, 25–42.
  4. 1 2 3 4 Mylonas, C. C., Fostier, A. And Zanuy, S. (2010). Broodstock management and hormonal manipulations of fish reproduction. General and Comparative Endocrinology, 165(3), 516–534.
  5. 1 2 3 4 5 6 7 8 9 10 11 Bromage, N., Jones, J., Randall, C., Thrush, M., Davies, B., Springate, J., Duston, J. and Barker, G., (1992), Broodstock management, fecundity, egg quality and the timing of egg production in the rainbow trout (Oncorhynchus mykiss).Aquaculture, 100, 14.
  6. ↑ Yousefian, M., Mousavi, S. E.(2011). The mechanism of reproduction and hormonal function in finfish species: A review. Scientific Research and Essays, 6(17), 3561-3570.
  7. ↑ Mousavi, S. E. (2013). Hormonal induction and synchronization of ovulation in endangered Caspian brown trout (Salmo trutta caspius Kessler, 1877) and its effect on egg quality.Journal of current research in science, 1(4), 192-198.
  8. ↑ Yousefian, M., Mousavi, S. E.(2011). A review of the control of reproduction and hormonal manipulations in finfish species. African Journal of Agricultural Research, 6(7), 1643-1650.
  9. 1 2 3 4 Demoulin, F. (1999). Guidelines for broodstock and hatchery management; Support for technical services. Food and Agriculture Organisation of the United Nations, Bangkok.
  10. 1 2 Hussain, M. G. and Mazid, M. A. (1999). Broodstock management status and some suggestions to control negative selection and inbreeding in hatchery stocks in Bangladesh. The ICLARM Quarterly, 22(4), 24–27.
  11. 1 2 Helm, M. M., Bourne, N. and Lovatelli, A. (2004).Hatchery Culture of Bivalves: A practical manual. Food and Agriculture Organisation of the United Nations, Rome.
  12. ↑ Perry's Semenkova, T., Barannikova, I., Kime, D. E., McAllister, B. G., Bayunova, L., Dyubin, V. and Kolmakov, N. (2002). Sex steroid profiles in female and male stellate sturgeon (Acipenserstellatus Pallas) during final maturation induced by hormonal treatment. Journal of Applied Ichthyology, 18, 375–381.
  13. ↑ Moorhead, J. A. and Zeng, C. (2011). Breeding of the forktail blenny Meiacanthus atrodorsalis: Broodstock management and larval rearing. Aquaculture, 318, 248–252.
  14. ↑ Prat, F., Zanuy, S, Bromage, N. and Carrillo, M. (1999) Effects of constant short and long photoperiod regimes on the spawning performance and sex steroid levels of female and male sea bass. Journal of Fish Biology, 54, 125–13.
  15. 1 2 3 Bromage, N., Hardiman, P., Jones, J., Springate, J., and Bye, V. (1990) Fecundity, egg size and total egg volume differences in 12 stocks of rainbow trout, Oncorhynchus mykiss Richardson. Aquaculture and Fisheries Management, 21(3), 269–284.
  16. 1 2 3 Berejikian, B. A. (1995) The effects of hatchery and wild ancestry and experience on the relative ability of steelhead trout fry (Oncorhynchus mykiss) to avoid a benthic predator. Canadian Journal of Fisheries and Aquatic Sciences, 52, 2476–2482.
  17. ↑ Gall & Gross, 1978
  18. 1 2 Anyanwu, P. E., Ayinla, O. A., Ebonwu, B. I., Ayaobu-Cookey, I. K., Hamzat, M. B., Ihimekpen, A. F., Matanmi, M. A., Afolabi, E. S., Ajijo, M. R. and Olaluwoye, B. L. (2011). Culture possibilities of Penaeus monodon in Nigeria. Journal of Fisheries and Aquatic Science, 6(5), 499–505.
  19. 1 2 Peixoto, S., Wasielesky, W., Cavalli, R. O. (2011). Broodstock maturation and reproduction of the indigenous pink shrimp Farfantepenaeus paulensis in Brazil: An updated review on research and development. Aquaculture, 315, 9–15.
  20. 1 2 Troup, A. J., Cairns, S. C. and Simpson, R. D. (2005). Growth and mortality of sibling triploid and diploid Sydney rock oysters Saccostrea glomerata (Gould), in the Camden Haven River. Aquaculture Research, 36(11), 1093–1103.
  21. ↑ Nell, J. A., Smith, I. R. and McPhee, C. C. (2000). The Sydney rock oyster Saccostrea glomerata (Gould 1850) breeding programme: progress and goals. Aquaculture Research, 31, 45–49.
  22. 1 2 Maguire, G. B., Wisely, B. and Skeel, M. E. (1981). Cultivation of the Sydney rock oyster Crassostrea commercialis (Iredale and Roughley) in prawn farming ponds. Aquaculture, 24, 63–75.
  23. ↑ Gall, G.A.E. and Gross, S.J., 1978. A genetics analysis of the performance of three rainbow trout broodstocks. Aquaculture, 15, 113–127.
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