Hatchery Techniques Research Articles

Current status of marine finfish larviculture in the United States

Twenty or more species of marine finfish have been reared experimentally for stock enhancement or aquaculture purposes in United States (US) hatcheries. The development of larviculture techniques for marine finfish in the US historically has focused on the restoration of recreational and commercial fisheries rather than on development of new agribusiness opportunities to produce food for domestic consumption or export. The situation has changed in recent years in response to increasing demand for fresh seafood. Some representative species being considered for aquaculture include striped mullet ( Mugil cephalus), milkfish ( Chanos chanos), mahimahi ( Corphaena hippurus) and the Pacific threadfin ( Polydactylus sexfilis) in Hawaii; the southern flounder ( Paralichthys lethostigma), summer flounder ( P. dentatus) and red drum ( Sciaenops ocellatus) along the Atlantic coast and the Gulf of Mexico; and the white sea bass ( Atractoscion nobilis) along the West coast of the US. Spawning is controlled by exogenous hormones and/or photothermal controls. Larviculture is conducted mainly by extensive and intensive methods. In this paper, the factors influencing marine finfish production from intensive larval rearing are discussed, based on the species cultured in the US. Hatchery techniques for two regionally emerging, high-value species, the Pacific threadfin and southern flounder, are presented. In the foreseeable future, larviculture in the US will continue to pursue development of high-value species to meet fisheries management goals and to offset the high costs of aquaculture production.

Selection for Surface Feeding in Farmed and Sea-Ranched Masu Salmon Juveniles

The feeding behavior of Japanese masu salmon Oncorhynchus masou (also known as cherry salmon) 3–4 months old differed among fish from wild, farmed, and sea-ranched parents. Between feeding intervals, wild-derived fry groups stayed lower in their separate stream tanks than farmed or ranched fry. When slow-sinking food was offered, the wild fry made foraging bouts from the bottom, whereas the domesticated (farmed and sea-ranched) fry stayed close to the surface. Consequently, the domesticated fry finished their meal faster than the wild fish. Over time, all stocks moved up higher in the water column and fed faster, but a difference between wild and domesticated fish persisted. Levels of aggression were similar among the three stocks and observation periods. Sea-ranched fish were intermediate between wild and farmed fish in most recorded behaviors. Staying close to the water surface obviously is a successful strategy under standard salmon husbandry conditions, but an innate tendency to seek the surface is probably maladaptive in the wild. New hatchery techniques that teach fish to avoid the surface or prevent selection for surface-seeking behavior promise to bolster the survival of postrelease ranched salmon.

Overview of diets used in larviculture of three Caribbean Conchs: Queen Conch Strombus gigas, Milk Conch Strombus costatus and Fighting Conch Strombus pugilis

The genus Strombus is widely distributed in the Caribbean. Six species are of commercial importance: S. gigas, S. raninus, S. costatus, S. alatus, S. gallus and S. pugilis. Economically, the Queen conch, S. gigas is the most important and consequently the most widely studied. However, since 1970 a decline of S. gigas populations due to over-fishing has been observed. Many authors have studied S. gigas hatchery rearing techniques in order to address this problem; however, for these hatchery techniques to be successful, an adequate diet must be provided for the larvae. Some information of the nutritional requirements of S. gigas larvae have been reported since 1965, but a nutritionally complete diet is still not available. In this work we summarize the different diets that have been used for S. gigas, S. costatus and S. pugilis larvae rearing. Twenty one different algae species have been used: Amphidinium carteri, Chaetoceros gracilis, Dunaliella tertiolecta, Emillania huxleyi, Heterocapsa pygmacea, Isochrysis (Caicos), Isochrysis (Tahiti), Isochrysis sp., Monochrysis sp., Nannochloris, Nitzchia, Platymonas sp., P. tetraselmis, Prorocentrum minimun, Rhodomonas sp. , Skeletonema costatus, Tetraselmis chuii, Tetraselmis sp., T. suecica, Thalassiosira fluviatilis and T. weissflogii. There are other diets that have seldom been studied with Strombus veliger larvae, that could be a potential food source for these gastropods. The type and concentration of algae, larval rearing conditions are summarized along with the results attained in larval growth, metamorphosis, survival, ingestion and digestion rates.

Hatchery and wild production of Pacific salmon in relation to large-scale, natural shifts in the productivity of the marine environment

Pacific salmon have been fished extensively for at least a century and artificial production of Pacific salmon has been a management strategy to improve production for almost as long. Hatchery production is considered important because it is commonly believed that the carrying capacity for salmon in the ocean has remained more or less constant and is underutilized as a consequence of limited production of smolts in fresh water. Since the mid-1960s, there has been an increase in hatchery production, partly as a response to a desire to increase catch and partly because of improved hatchery techniques. Since the late 1970s there has been a dramatic increase in the total Pacific salmon catch. The increases in catch are now known to result from a large-scale shift in the productivity of the sub-arctic Pacific and management and enhancement actions. Environmental indices changed about 1989-1990 and may indicate that the productive regime of the 1980s has ended. This would imply that under natural conditions Pacific salmon abundance would decline. There are no clear indications of what to expect in the new regime, but it is apparent that the massive production of artificially reared Pacific salmon would not be necessary in a less productive regime. Of concern is the impact that the large numbers of artificially reared salmon will have on wild salmon stock levels.

Production of juvenile redclaw crayfish, Cherax quadricarinatus (von Martens) (Decapoda, Parastacidae) I. Development of hatchery and nursery procedures

Procedures were developed for the controlled production of juvenile redclaw crayfish, Cherax quadricarinatus in tanks over two seasons. These included broodstock handling methods and involved the definition of an in vivo ovary staging technique which permitted recognition of immature, maturing and mature females. Hatchery techniques were also defined which demonstrated that male:female ratios of up to 1:4 were equivalent for successful mating and spawning. Up to 97% of females spawned and carried eggs through to hatching when held in tanks at between 24.5 and 27.6 °C mean daily temperature and exposed to 14:10 hours light:dark day length. A sequential series of seven egg stages was defined from egg release through to hatching, based on morphological characteristics. The mean duration of each stage was measured and cumulative statistics calculated, indicating a mean incubatory period of 72.1 days (range 47 to 84) and 66.3 days (56 to 71), respectively, for the two hatchery runs. An exponential function was calculated which defines the relationship of fecundity and female size and which indicates that fecundity ranges from approximately 200 to 1000 eggs per female. Nursery procedures were developed which indicate difficulties with using the floating water plant Pistia as juvenile habitat, and the benefits of using artificial shelters. Newly hatched juveniles stocked at between 980 and 1842 m 2, and fed a combination of formulated flake food and fresh zooplankton, survived well (mean 52%) and increased in size by between 500 and 900% over 28 to 50 days. The research demonstrates that C. quadricarinatus can be easily bred in captivity and juveniles reared successfully with relatively simple facilities and techniques.

Hatchery techniques for egg and fry production of Clarias batrachus (Linnaeus)

Egg hatching, and fry growth and survival of the walking catfish, Clarias batrachus (Linnaeus), were investigated under hatchery conditions in West Java, Indonesia. Spawning was environmentally induced in a specialized breeding pond. Gravid females utilized nests containing kakaban, a fibrous matting from local palm trees ( Arenga sp.), which facilitated egg collection. Newly hatched fry fed with Artemia nauplii though day 8 (after hatching), an Artemia/cladoceran mix from days 9 to 16, and cladocerans only from days 17 to 23 resulted in over 90% survival of young from hatched eggs. Other diets examined (rotifers, cladocerans, ground fish meal, and ground Nile tilapia flesh) proved inadequate for fry through day 16. Fry reared in hatchery aquaria for 16 days versus 23 days before introduction into nursery ponds showed no significant differences in mean length, mean weight, or percent survival when harvested at day 58. Suggested guidelines are given for hatchery production of C. batrachus fry and fingerlings.

Recent innovations in cultivation of molluscs in French Polynesia

Until recently, mollusc production in French Polynesia was based on fishing to satisfy local consumption of edible bivalves (mainly the oyster Saccostrea cuccullata) and to export pearl-oyster shells. Because of parasite problems in the local oyster population, a mollusc culture program was initiated. Hatchery techniques were developed for introduced species of edible bivalves, Saccostrea echinata and Perna viridis, and cultivation methods were developed in specially fitted-up areas. Traditional shell production concerning the pearl oyster Pinctada margaritifera was recently reorganized to produce black cultured pearls, causing an increased demand for young, implantable pearl oysters. Hatchery spat production proved to be unsuccessful, and techniques of collection and cultivation in lagoons were set up to supply the pearl-oyster farming industry, and to address the problems of depleted natural stock.

Mussel culture in China

The southernmost limit of the distribution of the common mussel, Mytilus edulis L., along the mainland coast of Asia is in the northern part of the southern Yellow Sea, including Jiaozhou Bay where they occur rarely. There are two breeding seasons a year, spring and autumn. The development of their population may be limited primarily by benthic predators and the high summer temperatures in the intertidal zone. The use of rafts in culture can overcome these problems. In China, commercial mytiliculture was initiated in the early 1970s. In order to solve the problem of seed mussel shortage, we carried out research on the collection of natural seed with the aim of increasing their production and on hatchery techniques aimed at attaining large-scale rearing. The two primary factors that contributed to the successful establishment of seed grounds along the Shandong Peninsula (e.g., Jiaozhou Bay) were leaving the kelp longline rafts in the water after their harvest to serve as attaching substrata for collecting spat and maintaining sufficient adult mussels for larvae production. Over the past few years, several reports on the artificial rearing of spat have been published in China. Recent research has resulted in the improvement of collectors used in the rearing tank, amelioration of larval food supply, inhibition of bacterial growth in the rearing water with the use of cheaper drugs, etc. As a result, over 10 million spat averaging 350–400 micra in length can be steadily produced per cubic meter of tank water by the method we have devised. Floating raft culture is now the most popular method employed. Each raft is 50 or 60 m long, mostly with glass floats. Mussels are cultured for a period of about 6 months or 1 year and are harvested in March and April or in September and October. Each raft can produce 750–2500 kg of fresh mussels; rafts in Jiaozhou Bay generally produce 1500 kg.

EXPERIMENTAL CULTURE OF THE OCEAN QUAHOG, Arctica islandica

AbstractLarvae and early postlarvae of the ocean quahog, Arctica islandica, were reared under experimental hatchery conditions. Mature eggs were stripped from ripe adults and exposed to a dilute solution of ammonium hydroxide for various lengths of time prior to addition of stripped sperm. The larval clams were reared through settlement and metamorphosis using the Wells‐Glancy (centrifuged, incubated seawater) method of algal culture and/or modifications of standard hatchery techniques developed by Loosanoff and Davis. Experimental cultures were maintained at various temperatures ranging from 8.5° to 14.5°C. At temperatures of approximately 13°C, the minimum time to settlement was 32 days, while settlement was not observed in a culture maintained between 8.5° and 10.0°C until approximately 55 days after fertilization. Larval growth rates were significantly lower in the culture maintained at 8.5–10.0°C than in cultures maintained at 11.0–14.5°C. An optical micrograph sequence of larval stages from the straight‐hinge stage through metamorphosis is presented to facilitate identification of Arctica islandica specimens isolated from plankton samples. While various workers have reported exceedingly low growth rates of juvenile and adult Arctica, growth rates of larval Arctica appear to be fairly “typical” of rates encountered within the class Bivalvia.

Hatchery rearing techniques for the oyster Crassostrea rivularis Gould

Hatchery techniques were developed for the commercial production of seed of Crassostrea rivularis. Optimum larval growth required a temperature of 28°C and a salinity of 20‰. The flesh of this species remains firm at summer temperatures in Oregon estuaries. The oyster may therefore be marketable throughout the summer, and its use could increase overall oyster production in Oregon by as much as 35%.

AN INTERDISCIPLINARY STUDY ON THE FEASIBILITY OF RECIRCULATING SYSTEMS IN MARICULTURE

ABSTRACTAn interdisciplinary team of scientists (a chemist, an engineer, and two biologists) at the University of Delaware is conducting an intensive study on the potential of recirculating seawater systems for use in mariculture. The Sea Grant‐supported project is underway in a relatively large (900 m2) laboratory at the mouth of Delaware Bay. The facility is unique in that it allows the degree of environmental control usual in small laboratory situations while allowing experimentation at the pilot plant scale.The team is attempting to culture clams and oysters from egg to commercial size in a recirculating system. A product is expected 18 months after spawning. Hatchery techniques are standard, but the postlarval animals are not planted in the field. Instead they are introduced to one of six recirculating systems for subsequent growth to commercial size. Twenty thousand newly set animals have been placed in an 8,000 liter system and are fed a mixture of several species of cultured algae. A new apparatus has been developed to separate algae from their culture media for subsequent feeding to the mollusks.Each circulating seawater system was specially designed for the culture of filter feeding mollusks and consists of an 8.6 m2 biological filter, a carbon filter, and a UV treatment station. Protein skimmers and biological monitoring systems are being optimized for future incorporation into the system.A careful record was kept of changes in nitrates, nitrites, ammonia, reactive phosphorous, calcium, magnesium, heavy metals, chloride, dissolved oxygen, pH, alkalinity, salinity, and suspended matter in the recirculating systems during start‐up and subsequent operation. Chemical information is used in engineering new refinements into the recirculating system as well as in interpreting biological phenomena in the system.

Historical Review of the Management Approach to Exploitation and Introduction in SCOL Lakes

Though environmental deterioration and destruction has always concerned fishery biologists, much of their scientific and technical activities have been related to understanding and managing direct fisheries harvests, to "improving" fisheries resources through introductions of non-native species, and to assisting the reproductive process of valued stocks with a hatchery program. The history of these approaches in western countries is sketched by time periods as follows: pre-1840, gradually developing science and technology with intensifying direct exploitation; 1840–70, human food shortages in Europe, spreading of artificial propagation and development of hatchery and stocking techniques; 1870–1900, extensive introductions of non-native species, intensified exploitation because of technological advances and market forces, great expansion of artificial propagation; 1900–45, fluctuation in exploitation partly related to the socioeconomic aspects of world wars; 1945–60, conventional hatcheries closing, new fishing gear technology, more intense exploitation, growing concerns about pollution and eutrophication; 1960–70, "back to conservation" movement.

Commercial Culture of Oysters in New England

ABSTRACTAqua Dynamics Corporation was formed in 1970 for the purpose of culturing' marine species of commercial value, with initial emphasis upon the American oyster (Crassostrea virginica) and bay scallop (Aequipecten irradians). The Corporation obtains seed oysters by taking advantage of natural spawning and setting in a semi‐enclosed tidal pond. The seed is raised to marketable size in suspension, employing submerged movable racks. Scallop production will depend upon standard hatchery techniques followed by transfer to natural growing areas, but the results of this phase of the program are as yet inconclusive.

Shellfish Hatcheries—Present and Future

Abstract The history of the development of shellfish hatcheries is summarized. Studies of the salinity, temperature, pH tolerances, and food requirements of clam and oyster larvae, as determined at the Milford laboratory, are cited to show the factors that govern the location and operation of successful shellfish hatcheries. Examples of how these requirements are met in presently operating commercial hatcheries are given. Some possible directions for future shellfish culture are suggested, using hatchery techniques for developing and utilizing new genetic strains of shellfish, and using newly-developed predator control methods and improved shellfish farming practices.

Adaptability of the Chukar Partridge to Missouri Conditions

The chukar partridge (Alectoris graeca chukar) was introduced into Missouri in 1934 when the Windsor Game Farm, operated by the Game and Fish Department, purchased two pairs and an extra cock from a California breeder. There then was considerable interest in chukars in Missouri, and the Department planned to raise enough for an extensive stocking program. When the new Conservation Commission was established in 1937, there were approximately 1,000 chukars on hand, all descendants of the original pairs. Their disposal was referred to the newlyestablished Missouri Cooperative Wildlife Research Unit. Ordinarily neither the Commission nor the Research Unit would have been interested in such a problem, but the birds offered an opportunity to study experimental releases and the establishment of the species, should the latter occur. With the cooperation of associated departments in the University of Missouri, a study was planned of the life history, ecology, diseases, hatchery techniques, management, and adaptability of the species. The writer made the field investigations, with general assistance from Dr. Rudolf Bennitt of the University of Missouri and Dr. Paul D. Dalke of the U. S. Bureau of Biological Survey. The study began in September 1937. There were several initial justifications for the work: the available birds represented a considerable investment; they had received a good deal of publicity and sportsmen were interested; elimination of the ruffed grouse, prairie chicken, and wild turkey from most of their former ranges had left vacant niches which might possibly be filled by the exotic species; and there was an excellent opportunity to study the factors determining the success or failure of an apparently desirable exotic game bird, propagated artificially and released on Missouri range. Finally, if the birds were to be used, there was need to establish them under a system that would permit control if they became undesirable. The detailed life-history study was brief because the birds released in 1937 and 1938 tended to wander in widelyscattered groups. This was disadvantageous in two ways: They refused to settle down, so their range preferences could not be learned, and in no place were they sufficiently numerous to provide adequate data. By the end of the first year, one possible justification for their introduction had largely disappeared. With recovery from the 1934-36 drought and the use of changed farming practices, prairie chickens and bobwhite quail increased to where the latter were abundant on almost every type of range and the I Contribution from Missouri Cooperative Wildlife Research Unit. U. S. Fish and Wildlife Service, American Wildlife Institute, Missouri Conservation Commission, and University of Missouri cooperating.