INTRODUCTION
The National Sea Grant Program was created by an Act of the Congress of the United States to accelerate the development and optimum utilization of our marine resources. This was to be accomplished through the support of research and development, education and training, and advisory service activities. Major emphasis was to be placed on the conduct of these programs through the establishment and operation of Sea Grant Colleges, the ocean equivalent of our Land Grant Colleges which were instrumental in making the United States one of the greatest agricultural nations of the world.
The Sea Grant Program, originally a part of the National Science Foundation, is now in the National Oceanic and Atmospheric Administration of the U.S. Department of Commerce. Several requirements, restrictions, and methods of operation affect the Program in important ways. Sea Grant funds may not be used for construction or maintenance purposes, or for vessel rental. Any recipient of Sea Grant support must provide at least one-third of the total cost of the project from non-Federal sources. All grantees are encouraged to develop cooperative programs with other scientists from universities, government agencies, and/or private industry. Many of our programs have, in fact, operated in this way. When the National Sea Grant Program was created by the Congress, aquaculture was one of the few fields of research specifically identified for emphasis. In carrying out this mandate, the Sea Grant Program has provided more support to this one area of research than to any other. At the present time over 20% of our research funds go into aquacultural efforts. As of 30 June 1971, we were supporting over 50 projects directly related to aquaculture. The total cost of these projects was nearly $5 million with over $3 million coming from our Program. The remainder of the funding is being provided by the universities, state agencies, and private industrial organizations participating in these Sea Grant Programs.
Due to the low level of past activity in the aquaculture field in the United States, very few research groups had any capability or experience on which to base an expanded effort. As a result, much of the early work under Sea Grant support has been devoted to the establishment of trained, experienced groups who are equipped and capable of conducting the type of research necessary to solve the many and varied problems encountered by anyone in aquaculture as a business venture. This includes studies on economics and law, environmental quality, engineering, and seafood technology as they relate to aquaculture. Such studies are not described in this paper even though they may ultimately provide the solution to the most critical problem faced by one or more aquaculture ventures.
For the purpose of this paper, the Sea Grant aquaculture projects will be described by type of organism being studied, except for a few projects of a general type.
Shrimp
The first aquaculture project to be supported by Sea Grant, the University of Miami program continues to be one of the most advanced in experimental shrimp culture. Begun in cooperation with Armour and Company, the United (Fruit) Brands Company, and Florida Power and Light Company, the main objectives have been 1) to rear large numbers of shrimp from eggs to postlarvae (about 1 cm long) and 2) to grow these postlarvae to marketable size quickly and at low cost. Since the first objective has been achieved for the most part, emphasis is now given to the problems associated with the second. Specifically, the work is now devoted to the further development of satisfactory foods and feeding methods which will provide rapid growth, high survival and yields in ponds, tanks, and cages, and to further develop techniques for pond management, including procedures for assuring adequate oxygen supply and optimization of other pond conditions such as bottom material, depth of water, and fertilizer regimen. Other efforts are underway on rapid and efficient harvesting techniques, cage culture, and testing of the important variables in the culture system such as food types, stocking density, and feeding methods.
A new rotatable cage for high density culture has been designed. It is intended to solve the problem of fouling of the mesh. Every portion of the cage is out of the water for about half the time where it is exposed to sunlight and drying and can be easily cleaned. It is not necessary to handle the animals in order to clean the cage. Harvesting will also be greatly simplified by this design.
In a related project at Miami, attempts are being made to induce maturation of ovaries and oocytes in pink shrimp, Penaeus duororum. This is a necessary step in the control of the life cycle of the animals in captivity which will relieve the commercial culturist from his dependency on wild populations for gravid females as the source of fertilized eggs. The research to date has included efforts to develop various measures of maturation and investigation of factors (light, temperature, salinity, and hormones) which enhance maturation by inhibiting molting.
Another project at Miami, aimed at the general objective of life cycle control of shrimp, involves the development of techniques to attain in vitro fertilization of ova and sperm removed from ripe animals. Included in this investigation are in vitro studies of maturation of oocytes and ovaries, effects of hormones and ovarian extracts on maturation of ovarian cells, and development of cryogenic techniques to preserve viability of ova and sperm, fertilized eggs, and cultured ovarian cells. Biochemical studies of gonad maturation are underway using electrophoretic profiles to assess maturity.
Aquacultural research at Texas A&M University is aimed at shrimp farming as a commerically feasible operation. Twenty 1/2-acre ponds (0.2 hectares) are used for study of artificial feeds, shrimp stocking rates, mortality, and growth rates. Some ponds are stocked with hatchery-reared postlarval brown shrimp. P. aztecus, supplied by the Dow Chemical Company. Yields from 1970 harvests averaged 250 pounds of shrimp per acre (280 kg/ha), with some ponds exceeding 450 pounds per acre (504 kg/ha). The wholesale market price of the shrimp at harvest ranged from $0.65 to $0.85 per pound, heads on (465-608 yen/kg). In cooperation with Ralston Purina, new feed rations have been developed. Harvesting of the 1971 crop, now in progress, should also reveal effects of pond fertilization on growth rates and survival.
Other shrimp research at Texas A&M includes studies on temperature and salinity effects on postlarvae and feeding behavior, and diet preference of postlarvae. To date one phase of this research has provided information regarding upper incipient lethal temperature, acclimation rate to temperature change, and the influence of environmental salinity on heat tolerance of postlarval brown shrimp. Present work will extend results to include white shrimp P. setiferus, postlarvae. Differences have been demonstrated between the responses to diets of postlarval brown and white shrimp. It was shown that shrimp responses to foods, including initial diet preference, survival, growth, and resistance to high temperature may vary independently.
The 4,700 square miles (12,173 km2) of brackish to marine marshlands and 1,600 square miles (4,144 km2) of bays, estuaries, bayous, and canals in southern Louisiana are potential sites for impoundments for mass culture of brown and white shrimp without supplemental feeding. A research program being conducted by biologists from Francis T. Nicholls State University has been attempting to solve the many problems involved in demonstrating that such a system is feasible. Two shallow, 10-20 acre (4-8 ha) impoundments containing water and Spartina patens marsh are being used to determine the basic productivity (shrimp production) and for measurements of the effect of fish and crab predator control on shrimp production. Natural stocking of ingressing postlarval shrimp occurs on nighttime flood tides across weirs in the impoundments. Large shrimp and predators are prevented from entering by hardware cloth screening.
Predator control is exercised in the larger, test impoundment by rotenone application for fish and baited wire traps for blue crabs. Efficient harvesting of the ponds consists of draining surface water at night across the weir into a net. Shrimp of commercial size rise to the surface and migrate out of the estuarine areas and into the Gulf at night during ebb tides. With predator control the brown shrimp grew to 34 count (heads on) in 75 days and to 12 count in 200 days; the white shrimp grew to 34 count in 60 days. The total harvest of both species for one season was 125 pounds (57 kg) of 34 count shrimp per acre. In the pond with no predator control, the total harvest was 44 pounds (20 kg) of 70 count shrimp per acre, which is probably about the natural productivity of unmanaged marshes.
In a study of the penaeid shrimp, Penaeus marginatus, aimed at developing techniques for intensive cultivation under manipulated environmental conditions, investigators at the University of Hawaii have successfully spawned females and reared the larvae through all stages. A new, intensive-culture enclosure is being built that will boost production by vertically arranging the shrimp in small cages on frames, so as to allow the use of the entire water column. Also, a shrimp nutrition study is underway. This project is to provide the technical information needed for a commercial-scale operation to be established and operated by a community group in Hawaii.
Biologists and food scientists at Louisiana State University are developing new rations (foods) for crustaceans in culture. Emphasis has been on the utilization of products such as crustacean meals, single-cell protein (torula yeast), food processing "waste" fiber and cellulosic products, and other products of the fishery processing industries. Special attention is being given to the evaluation of the nutritional value of sun-dried shrimp meal and other shrimp meal prepared by various processing procedures. These rations will be tested for feeding efficiency rates, durability and acceptability, and the effect of various attractants to stimulate shrimp feeding will be identified. A suitable ration which uses alginates as a pellet binder has been developed and is being evaluated under a range of environmental conditions. Other hydrocolloids and modified starches are also being evaluated as pellet binders. Experimental samples are being made available to investigators for testing on a range of economically valuable crustacean species, i.e., penaeid shrimp, freshwater shrimp, and crawfish.
A part of this project includes work to prepare the feeds developed as microcapsules in varying sizes and densities according to the stage of development of the animal. For example, the feed for the nauplius, zoea, mysis, and early postlarval stages will be small and have near-neutral buoyancy, whereas that for the late postlarval and juvenile stages would be larger, would sink, and exhibit good water stability. Although the microcapsules are expensive initially, they should result in healthier animals and greater survival through provision of all nutritional requirements and controlled amounts of expensive sophisticated chemicals (hormones, antibiotics, stimulants, etc.). Use of the microcapsules will also relieve the culturist from the tedious and expensive algal cultural systems now employed in most aquaculture operations.
Another study into the environmental and nutritional requirements of shrimp in culture is being carried out at the Skidaway Institute of Oceanography in Georgia. Following a series of experiments which established a suitable water flow rate, type of substrate, oxygen level, stocking density, and light intensity, preliminary nutritional studies using purified pelleted diets were conducted. Eighteen different diets which varied in level and quality of protein, carbohydrate, lipid, vitamins, and minerals were evaluated by growth rate and percent survival. Rates of ingestion under given environmental conditions, rates of assimilation of specific biochemical entities and calorie-protein relationships are now being investigated. To date, a semipurified diet, containing about 70% shrimp meal and 8% anchovy meal, fed at a rate of 15% of the total biomass daily has produced the best results (164% increase in weight with 95-100% survival during a 3-mo period).
Mass culture techniques to produce large numbers of larval stone crabs, Menippe mercenaria, and blue crabs, Callinectes sapidus, have been achieved in a project at the University of Miami. However, techniques must be improved to reduce and control the problem of cannibalism among larval stone crabs. The stone crab matures, copulates, and spawns viable eggs under conditions of captivity. F2 offspring of blue crabs have also been attained in captivity. Investigations are now underway to improve techniques of larval culture and to test feasibility of rearing crabs to marketable size in cages placed in natural waters.
A Samoan or mangrove crab, Syclla serrata, has been studied at the Hawaii Institute of Marine Biology. The Samoan crab has been maintained in cages suspended from rafts and its growth rate measured. This study indicated this crab could attain marketable size of 1 - 11/2 pounds (0.5 - 0.7 kg) in about 11/2 yr at ambient temperatures (24oC). Tests at higher temperatures (27oC) indicated that the time to reach market size could be reduced to 1 yr. Also, a diet of artificial food resulted in faster growth than natural foods.
In another crab culture project, efforts are underway at Humboldt State College in northern California to develop methods of growing the Dungeness crab, Cancer magister, using locally produced fish wastes as food. The studies are being conducted in two different environments in Humboldt Bay, in pens-one using heated effluents from an electric power plant and the other in bay ponds at ambient temperatures. The diet preference, condition. and growth are determined and evaluated. This project could provide a cheap source of food for an aquaculture operation as well as make use of what is now a waste disposal problem. Early results indicate that a food mixture of rockfish, sablefish, Dover sole, and shrimp offal produced the best results.
Research is underway at East Carolina University on the reproductive cycles and fungal parasites of the blue crab and will begin shortly on the American lobster, homarus americanus. Studies to date on the crab have included observations of the condition of the ovary as seen through the carapace, condition of eggs of ovigers, and occasion of spawning by certain individuals. The crabs which ovulated were successfully induced to attach their egg mass, something not previously reported for the blue crab. Attempts to date to isolate Lagenidium callinectes or other fungal parasites of crab eggs have been unsuccessful.
In laboratory studies at Texas A&M Universitv with young blue crabs (5-40 mm), a sand plus oyster shell substrate supported significantly better survival than did either sand alone or bare glass. The suitability of various temperatures and salinity levels were also evaluated.
One of the most highly prized seafood or~ganisms in the world, the American lobster, Homarus americanus, is being studied by geneticists at the University of California at Davis. The intent is to develop the technology necessary to grow large numbers of edible quality lobsters, to marketable size, in a short period of time, at less cost than the market value. The project is being conducted in cooperation with the State of Massachusetts Lobster Hatchery on Martha's Vineyard Island. The work includes the improvement of culture facilities; development of an economically feasible form of food; studies of the effect of selected environmental parameters on growth; application of genetics techniques for the selection of fast growing lobsters: evaluation of biochemical methods for controlling cannibalism, mating. molting, and disease; and physical methods to control cannibalism. Research, already completed has shown that it is possible to produce a 1 pound (0.45 kg) lobster in 2 yr time instead of the 7-8 yr it takes in the sea, by growing them 20oC and feeding them daily.
Work on the American lobster at the University of Rhode Island is also directed toward reducing the time required to grow the animal to market size. Here the effort has resulted in the development of methods for accelerating the hatching of eggs and the mass culture of larvae to juveniles under controlled conditions. Work is now in progress for maximizing the growth rate of juveniles to market size under optimum conditions.
Several parts of a multifaceted program of research at San Diego State College on spiny lobster, Panulirus interruptus, and American lobster involve aquacultural work. Juveniles of spiny lobster have been studied with respect to the effects of elevated temperatures (20o. 22o, 26o', and 28o C) on growth and metabolic energy budget. Studies of American lobster in progress are providing a comprehensive evaluation of the biological and economic feasibility as well as the potential benefits and dangers of establishing this species as a fishery resource in California waters. Part of this work is concerned with developing and evaluating lobster culturing techniques, with the primary aim of producing large numbers of young suitable for stocking.
In a project to develop crayfish. culture in the Pacific Northwest, biologists at Oregon State University are developing husbandry methods in controlling environments. A system for holding and breeding adult crayfish in captivity has been developed.
Juveniles are raised singly in small cells to avoid cannibalism of soft-shelled animals. Several natural and artificial diets have been tested and research on nutrition is now centered around a simulated natural diet versus a high protein vegetable pellet diet. The role of temperature and salinity on growth and survival is also under study.
Oysters
In a large multidisciplinary effort, scientists at the University of Delaware are working to improve our techniques in shellfish culture. A variety of problems are being attacked in both open and closed systems. Over 500 million oyster larvae were reared at least to the straight hinge stage in 51 separate cultures during the past year. These larvae, the results of 40 spawning attempts, were used in a variety of rearing and setting experiments. The algal culture facilities can now provide food on a year round basis and are capable of producing 150 liters of dense algal culture every 24 hr. Research on the feeding of adult oysters in being conducted to show how the oyster utilizes available food energy. Preliminary experiements have determined the caloric content of cultured algae and have shown that an oyster can assimilate at least 85% of the energy content in the food that it consumes. Research is also being conducted on the bacteria associated with supplemental feeding of oysters in closed systems, and efforts to produce viable offspring from hybridization of the Eastern (or American) oyster, Crassostrea virginica, and the Pacific oyster, C. gigas, are continuing.
A pilot-scale oyster hatchery at Newport, Oreg., is producing seed from Pacific and Kumamoto (C. gigas), Olympia (Ostrea lurida), and European (0. edulis) oysters on a routine basis. Peak production in the pilot hatchery approaches 1 million juveniles per month. The seed is being raised by growers in Oregon and Alaska, and is being used in a variety of studies by Oregon State University researchers.
Heritability studies have been completed on the Pacific oyster, and parentage is controlled to selectively breed for rapid growth, high meat production, and low mortality. The growth of hatchery seed oysters in warmed ocean water from power plant effluents is under evaluation. Successful cryogenic preservation of oyster sperm at -196oC has allowed self-fertilization of the Pacific oyster after natural sex reversal for genetic studies. Improved larval feeding schedules and diets have increased the success of setting in the hatchery.
In their program to advance the state-of-the-art in oyster culture, biologists at the Virginia Institute of Marine Sciences have developed two new methods for obtaining free oyster spat (cultchless), one for relatively clear estuarine areas mind one for areas which have heavy siltation problems. In the first method. the spat must be removed from the substrate before sufficient new shell for permanent attachment has been produced. The set takes place in fiber glass salmon-egg hatching trays in complete darkness, using filtered river water. The spat are removed from the tray bottom, to which they have temporarily attached, by a strong stream of river water, yielding cultch-free spat.
The second method delays the removal of the newly set spat from the substrate for 18-21 days. Setting is induced on Frosted Mylar2 or Herculene. A new setting tray was designed to hold the mylar upright. The spat set on the upright mylar sheets, thus avoiding most of the siltation and organic detritus. The spat is removed from the mylar sheet by simply shaking it over a container of river water. It is then dipped up and down in the container, washing the loose spat off.
A team of researchers at the Darling Center, University of Maine, is investigating the feasibility of culturing several species of marine organisms in the colder waters of that region. Although research is being conducted on the deep sea scallop and blue mussel, most of the experiments to date in this new program have been with cultchless European and American oysters. Trays of the cultchless oysters have been placed at many different locations in the Damariscotta estuary (24 km long) and at 14 sites along the coastline. These were selected to provide as good a geographic and ecological spread as possible and are being monitored for growth, survival, and presence of fouling organisms. In the first year, growth response of European oysters was excellent (to 10 cm) in even the most exposed coastal locations. The data will be utilized to develop a predictive model allowing assessment of the potential of the Maine coast for economically competitive oyster culture. A cooperative pilot hatchery is being started at Newcastle which may result in the establishment of a commercial operation.
The Departments of Agricultural and Mechanical Engineering of the University of Maine are working on oyster rafting systems which will be adaptable to this environment and compatible with multiple use concepts. A pilot model of a submersible raft has been constructed and will be field tested in 1972.
Several problems inherent in the culture of oysters and clams are being investigated at the University of Washington. The optimal horizontal spacing of oyster cultches suspended from rafts in relation to growth, mortality, and condition is being determined and the local variation in the degree and type of fouling organisms evaluated. The investigators are also attempting to determine if bacteria are responsible for some of the summer oyster mortalities. They are particularly interested in Vibrio and other types of pathogenic bacteria which may be associated with these mortalities. In related work, the gonadal development of the Manila clam, Venerupis japonica, is being studied. Also, seed of this clam species is being planted in commercial growing areas to determine the best annual planting density and minimum length of time seed must be held in the hatchery to give optimum yields to the clam grower.
In a companion program, a prototype continuous phytoplankton culture unit is being developed at the University of Washington to provide nutritious, efficiently grown feeds for the clam and oyster farm. The prototype can produce at least 14 liters per day of Monochrysis lutheri with a total yield of 2 x 1011 cells, consisting of 6.8 g ash-free dry weight, which is 22% protein.
A new hard clam culture method has been developed at the Virginia Institute of Marine Sciences. The new method involves spreading shell, gravel, or other material (aggregates) over the sand or mud bottoms before planting the seed. This type of bottom protects the young clams from their chief pre~dator, the blue crab, and other predators, such as other crabs, boring snails, bottom-dwe~hing fish, and waterfowl. Other methods of protection tried in the past included planting the young clams in screened trays or boxes, within fenced enclosures, under sheets of netting or hardware cloth, in saltwater tanks, and ~intertidally. These techniques were unreliable and expensive, caused silting and slow growth, and thus are unsuitable for commercial use.
Other work on molluscs at the University of Hawaii has included efforts to develop pond culture of the Japanese littleneck clam which was introduced to Hawaii, but whose natural populations are declining. Research to date has identified proper substrate as a key parameter with sand substratum yielding normal growth. Spawning was achieved through temperature elevation (30o-31oC) and addition of sperm.
The hatchery techniques of conditioning, spawning, and rearing the bay scallop, Aequipecten irradians, have been developed at the Virginia Institute of Marine Sciences. The scallop has been raised to market size (5-6.5 cm) with the final growth phase taking place in wooden, rectangular floats (2.1 m x 0.6 m x 15 cm) whose tops and bottoms are covered with fiber glass window screen or plastic netting. In one experiment, the scallops were grown from 1.3 to 5.7 cm in a net enclosure directly on a relatively hard mud-sand bottom. The total growth time from egg to market size was 6-7 mo. Work is continuing to determine optimum stocking densities and optimum depth for holding the scallop floats and to develop other methods for holding scallops from about 2.2 cm to market size.
The culture of four commercially important species of abalone is under study at the Scripps Institution of Oceanography, University of California. Studies of spawning phenomena, early development, settlement, growth of settled juveniles, and hybridization are being conducted. Approximately 200,000 young red abalone, Haliotis rufescens, were reared by the chief investigator in a commercial venture. This resulted in the identification of the problems being attacked in this research program. Primary attention is being given to the influence of temperature on larval development and juvenile growth, and to the behavioral problem of substrate selection by settling larvae. Other efforts are being devoted to determine the causes of larval mortalities and to identify micropredators of newly settle juveniles.
Two rather unusual species of molluscs are being studied by University of Hawaii scientists. Work on large limpets, which are in great demand for Hawaiian luaus and which sell for as much as $70 per gallon (6,000 yen/liter), is concentrating on the development of an acceptable food source. Eggs have been obtained from females and artificially fertilized successfully with the females producing several thousand eggs each. However, further ecological work is necessary to ascertain conditions under which the early larvae can be reared to acceptable size.
Research on the Day Octopus, another specialized food that is highly prized in Hawaii, has indicated a rapid growth rate with the animal reaching the marketable size of 1 pound (0.45 kg) in about 3 mo and growing to 3-4 pounds (1.36-1.8 kg) in only 4-5 mo. Current efforts are directed toward the development of an artificial food. Mating occurs readily in captivity with the females producing an average of 500,000 eggs. Difficulty has been experienced in the rearing of larvae since, while they are active and feed, they do not grow.
Salmonids
One of the oldest research efforts in the United States directed toward developing improved strains of seafood organisms is that at the University of Washington under Lauren R. Donaldson. Over a period of 40 yr, through a selective breeding program, several species of salmon and hybrids of trout have been developed, and eggs from this program have been provided to organizations all over the world. Currently Donaldson and his co-workers are working with rainbow trout, rainbow-steelhead hybrids, and chinook and coho salmon, Oncorhynchus tshawyscha and 0. kisutch. Millions of eggs are produced each year, some being used in the breeding program, some irradiated for studies of the effects of radiation exposure, and others used or provided to other organizations for other types of research or for aquaculture.
In an associated program, other University of Washington fisheries biologists are attempting to demonstrate the practicality of rearing salmonids in floating pens, in brackish water ponds, and in saltwater estuaries. In this work, which is being conducted cooperatively with private industry, the salmon are being reared for two uses: 1) direct marketing and 2) release at an advanced stage for support of sport and commercial fisheries. This same project also includes studies of the effects of environmental parameters on the success of rearing salmonids in seawater, the training of salmon to come to an underwater sound source for effective feeding and harvesting, and feasibility studies on enhancing production of 20 species of flatfishes indigenous to Puget Sound by improved cultural techniques.
A team of researchers at Oregon State University is investigating several problems associated with salmon culture. New hatchery methods which simulate natural spawning beds are being developed. The system involves raising salmon alevins (larvae) in darkness on a gravel substrate instead of on screened trays or smooth tank bottoms. Water velocity is similar to that in good quality natural spawning beds. Several hundred thousand chum salmon, 0. keta, are being produced annually by this method at an experimental hatchery located at Netarts Bay. The fry from the gravel incubator are considerably larger than fry from standard hatchery incubators and do not exhibit malformed yolks which are common in hatchery chum salmon alevins. In the laboratory at Port Orford, chinook salmon are being exposed in rearing tanks to increasing salinities to determine the feasibility of releasing juveniles directly to seawater after only a brief period of adaptation. If successful this could significantly reduce the mortalities which now occur in freshwater areas.
Other work at Oregon State University on salmon includes attempts to: improve certain strains through hybridization and selective breeding; develop methods for rearing in power plant effluents; determine the effects of infection by the trematode, Nanophyetus salmincola; and develop techniques for cryopreservation of gametes. Sperm frozen for 7 days at -196oC were thawed and used to fertilize 80% or more of fresh eggs from coho salmon and steelhead trout, Salmo gairdneri.
Seafood scientists at Oregon State University are working with several salmon diet formulations in order to develop new rations, as well as to learn more about the nutritional requirements of the salmon. Experiments now completed indicate that a pelleted fish food utilizing 40% dewatered and comminuted shrimp wastes provide results as good as those obtained with the commonly used Oregon moist pellet. Thus, a use for large quantities of raw shrimp wastes has been identified.
Coho and chinook salmon are being reared in net enclosures in the open waters of Puget Sound in a project being conducted by a private firm, Ocean Systems, Inc. This project is an outgrowth of work by the National Marine Fisheries Service whose scientists continue working on associated problems. Assistance has also been received from the Washington State Department of Fisheries and the University of Washington. The eggs were hatched and the fingerlings placed in a freshwater pond. When they reached the desired size, the fish were transferred by truck to small net enclosures (7.5 x 7.5 x 4.5 m) in the Sound and later transferred to four larger (15 x 15 x 7.5 m) growing pens which are attached to an anchored raft. The enclosures are covered by a net to protect the fish from bird predators and surrounded on four sides and the bottom by a 6.4-cm stretch mesh gill net to protect the fish from dogfish and other predators.
At the present time, approximately 230,000 coho and 270,000 chinook salmon are growing in the pens. They are fed a dry salmon pellet ration which is hand-cast over the enclosure. Although some of the salmon have reached potential market size in 8 mo, the average weight was 0.06 kg. The company, working with the National Marine Fisheries Service, will begin test marketing the 0.2-0.34 kg fish shortly after the beginning of the year. Current efforts also include an evaluation of the potential environmental effects of a large-scale operation of this type.
In northern California, at Humboldt State College, fisheries biologists are in the early stages of testing the efficacy of enriching brackish water and saltwater rearing ponds with sewage effluents for the rearing of salmon and trout. The fish are released as fry and fingerlings into two ponds, one a control seawater pond and the other contains a seawater and sewage effluent mixture. The scientists hope to determine if it is possible to rear fish to migrant size more cheaply by this method than with standard fish culture techniques. Harvest for human use would occur after the fish had been released and continued their growth in the natural environment.
At the present time there are 40,000 coho salmon (10,000 of them marked) and 2,500 steelhead trout divided between the two ponds. Growth and mortality studies are being conducted to evaluate the success of this technique.
Scientists at the University of Rhode Island are attempting to develop a new form of aquaculture, based on a closed cycle, controlled environment system, which will have almost no environmental impact and be compatible with other demands on coastal resources. Salmonids; Atlantic salmon, Salmo salar; pink salmon, Oncorhynclus gorbuscha; rainbow trout, bluefish, Pomatomus saltatrix; and striped bass, Morone saxatilis, are being grown in the project. The work is intended to provide information which will increase the operating efficiency and capacity of present day salmon hatchery and smolt production facilities as well as improve diets for fish in culture. Nutritional and physiological studies are underway, with one study the effect of the level of dietary protein and different lipids on the nutrition of rainbow trout adapted to an intermediary salinity (16o/oo) just completed.
Studies are being conducted to determine the requirements for rapid activation of biological filters in both marine and freshwater systems. Also, alternatives to biological filters for water purification in the closed circuit system are being evaluated.
One key part of this work is aimed at solving the problems resulting from the accumulation of nitrogen waste products in the closed system. Another part of this program is an analysis of the economic feasibility of commercial salmonid culture for food fish markets. A projection of production costs for a model salmonid aquaculture facility has just been completed.
In an effort to develop a controlled culture system for striped mullet, Mugil cephalus, scientists at the Oceanic Institute in Hawaii have devoted considerable effort, with success, to the induction of spawning. Successful breeding of wild, adult fish has been accomplished with injections of salmon pituitary in conduction with Synahorin, or with low doses of a partially purified Pacific salmon gonadotrophin. Spawning was also induced in captive animals using a controlled photoperiod regime followed by injections. Larval rearing studies are also underway using copepod adults and nauplii and gastropod veliger larvae as food. The veliger larvae appear to be preferred by the striped mullet larvae and are produced in the laboratory.
In a companion project, the problems associated with rearing the striped mullet in coastal ponds are being studied. Artificial seaweeds ("X" sheets of plastic) are anchored in the ponds. Algae grow on this plastic "grass" and are eaten by the fish, thus providing a cheap source of food for the fish in culture.
Young striped mullet have been studied at Texas A&M University to determine high temperature resistance and acclimation rates in laboratory tests. Salinities of 1 and 10o/oo were more suitable than 20 and 30o/oo for temperature acclimation and heat resistance of young mullet. These findings may be useful in the development of pond stocking guidelines. A two-factor laboratory study on the effects of salinity and temperature on survival and growth of striped mullet has recently been completed. Statistical analysis of the results has not been completed, but the data suggest that striped mullet are tolerant to broad ranges of both factors.
Work is underway by North Carolina State University biologists to determine the feasibility of commercial propagation of the dolphin, Coryphaena hippurus. Successful efforts, being conducted at Hatteras, N.C., and Bimini, Bahamas, have been directed toward developing artificial spawning techniques by use of sex hormones. Capturing and transporting techniques have been developed, and growth studies have yielded an average weight increase of 1 pound (0.5 kg) per week with a maximum growth of 73/4 pounds (3.5 kg) in 6 wk. Larval rearing techniques will be developed as dependable spawning is realized.
Several species of finfish (see appendix for names of species) have been studied at the Hawaii Institute of Marine Biology on Coconut Island to determine their potential for aquaculture. They were selected on the basis of their acceptability as food or bait and their ability to grow in captivity. Eggs, larvae, juveniles, or adults were collected according to their availability, and attempts were made to ascertain their environmental requirements in a variety of situations including small tanks, floating rafts, ponds, etc. Investigations were made on nutrition, growth, reproduction, and diseases of the various species.
Research at Louisiana State University has been directed toward determining the various parameters controlling growth of several species of finfish in culture. The effects of salinity and other water quality parameters on channel, blue, and white catfish (Ictalurus punctatus, 1. furcatus, and I. catus) and on Florida pompano (Trachinotus carolinus) have been identified. One notable effect of brackish water on the catfish is that it prevented outbreaks of the protozoan parasites, Ichtyophthirius multifilis, which is frequently a serious problem in freshwater catfish culture. Other studies have examined growth, development, and survival of the pompano and the Atlantic croaker, Micropogon undulatus, in culture.
For the past 6 yr, Louisiana State University (LSU), in cooperation with the Louisiana Wild Life and Fisheries Commission, has screened a number of species for suitability for culture including: three species of freshwater catfish (blue, channel, and white), pompano, mullet, croaker, crawfish, and redfish. These species are also being stocked in various combinations, polyculture. In one study, the .mullet-channel catfish combination showed promise. Total production in ponds was increased. The mullet, acting as a biological filter, helped to clean up solid wastes produced by catfish, as well as adding to total production. LSU has consistently produced over 1 ton of channel catfish per acre in ponds with salinities up to 10o/oo total salinity.
The sheepshead minnow. Cyprinodon variegatus, a valuable bait fish in Texas has been studied at Texas A&M University to determine the effect of salinity on high temperature resistance and acclimation rates in the laboratory. At 10 and 20o/oo these fish fared better than at 1 or 30o/oo.
Red Algae
One of the most advanced programs in seaweed culture in the United States is being conducted by phycologists at the University of Hawaii. The program consists of the development of techniques for growing the red alga, Eucheuma (three species), as a carrageenan source. Small, pilot-scale farm operations have been established and successfully demonstrated in the Philippines, the Trust Territory, and other Pacific areas. Hopefully, this project will lead to full-scale commercial operations which will provide a reliable supply of raw material for the U.S. carrageenan industry.
Other seaweed projects at the University of Hawaii are investigating the culturing of other red and green algae (Gracilaria, Hypnea, Cladophora, and Ulva) and their potentially useful extracts.
Two projects aimed at expanding the source of commercially valuable seaweeds in the United States are underway at the University of South Florida. One is a field and laboratory study of the carrageenan source, Eucheuma isiforme, which involves studies of growth, reproduction, morphology, and carrageenan content of tagged plants growing naturally in the ocean, plants suspended from lines 2 ft above the bottom, and plants under laboratory culture. Results to date suggest that in the ocean, growth rates are highest in the cooler months, whereas carrageenan content is highest in the warmest months. Morphology does not appear to be easily influenced by environmental changes, such as would occur in transplantation, but may be greatly influenced by nutrient levels. Reproduction appears to be limited to very brief times and may not even occur yearly.
The other project consists of experimental cultivation of about a dozen species of south Florida red marine algae in various habitats, during different seasons of the year, using three procedures: 1) vegetative growth in net-covered frames or in, or upon, other forms of substrata; 2) the "seeding" of selected substrata with a given species, and obtaining either gametophyte or sporophyte plants as desired; and 3) the placing of solid substrata in areas suitable for algal growth but lacking the necessary substrata.
The most promising results with a potential for direct application in the production of quantities of raw material for industry have come from the first procedure. Growth of Hypnea musciformis and Gracilaria folifera in net-covered cages, floating just 15 cm under the surface, during the warmer months of the year was very rapid, often doubling their weight in 1 day. These plants, growing in a very favorable environment and protected from grazers, increased their weight from 10 to 100 g in 10-14 days. The culture of Eucheuma isiforme and E. acanthocladum, using some of these techniques, will be emphasized during the next year.
Methods to culture both benthic and planktonic marine algae are being developed at the University of Washington. The phycologists have demonstrated that Iridaea cordata, Gigartina exasperata, and Agardhiella tenera var. pacifica can be successfully transplanted to habitats in which they have not previously grown, and have grown these three species, plus Sarcodiotheca furcata, in laboratory cultures. In a related effort, the investigators have completed a study on extracellular, water-soluble polysaccharides produced by various marine diatoms and isolated in axenic culture the unicellular red alga, Rhodosorus marinus for subsequent growth experiments.
A multidisciplinary team at the University of California at Santa Barbara is studying some of the varied problems encountered by the seaweed industry in the United States. Biologists and engineers are studying the settlement and growth of spores, including the effects of water motion on spore settlement and on reproductive stages. Transplants of Gelidium, Gracilaria, and Macrocystis are being made for studies of growth and colloid production.
As part of this program, economists are surveying the present and future status of the U.S. seaweed industry. An economic model is being developed for the agar weed Gelidium, which considers growth, loss, and reproduction rates; production problems; and agar content.
Future work will include an evaluation of harvesting methods and packaging operations and the development of a "breeding stock" of rapidly growing forms.
One of the oldest programs in the United States in seaweed management is the kelp research now being conducted at the Marine Laboratory of the California Institute of Technology. During their early attempts of restoring the kelp beds off southern California, the researchers simply transplanted adult plants from an existing bed to an area where a new bed was to be established or a disappearing bed strengthened. The adult plant then released spores which produced new plants. At the same time quicklime was spread over the bottom to kill the heavy grazing sea urchins. Attempts were also made to protect the young plants from grazing fish with net covers.
Recent work has been devoted to the development of techniques for raising Macrocystis plants in mass culture from liberated zoospores, through the gametophyte to the embryonic sporophyte. The embryonic sporophytes which develop on an artificial substrate are scraped free and dispersed close to the bottom in areas suitable for kelp growth. Preliminary estimates indicate that about 105 embryos must be dispersed to yield one attached Macrocystis juvenile about 15 cm tall.
The culture system now in use can produce 105 to 106 embryos per cm2 of culture substrate. Thus, the low survival rates following dispersal do not prohibit the use of this system for developing new kelp stands. Out of five areas in which this technique was attempted, young Macrocystis developed in three of them with hundreds to thousands of plants resulting in two of the areas.
Several institutions have directed research efforts toward the diseases and parasites of seafood organisms, usually looking at several different kinds of animals. Most of the animals examined are being cultured, at least experimentally, in the United States. Texas A&M University has established an Aquatic Animal Medicine Laboratory on its campus and is working with a wide variety of finfish and shellfish, looking for many types of bacteria, viruses, and other infectious agents. They have identified the microbial flora of Gulf of Mexico and pond-grown shrimp and developed new techniques for detecting certain agents and diseases in finfish and shellfish.
Microbiologists at Georgetown University have been examining several Chesapeake Bay organisms for the bacterium, Vibrio parahaemolyticus, responsible for many cases of food poisoning in Japan and some recent cases in the United States. This bacterium has been isolated from dead and dying blue crabs from Chesapeake Bay and was isolated from dead and dying cultured shrimp taken from Texas A&M University's ponds.
Several other universities, including Oregon State, Miami, Rhode Island, and Washington, have programs in marine pathology in which both wild and cultured animals are being studied. While it will be diffifult, if not impossible, to solve disease and parasitic problems in wild populations, this work could lead to solutions of problems with pathogens encountered in aquaculture.
Two projects are underway at the University of California to explore the potential of selected environments for aquaculture. The first, at the Santa Barbara campus, involves the study of a California coastal lagoon to determine its usefulness as a manageable ecosystem for aquaculture. The investigators believe that it may be possible to increase productivity by shortening the normal food chains, reducing predation and/or artificially fertilizing this ecosystem. Initial efforts are devoted to a study of the basic ecology of the lagoon, including meteorological measurements, physicochemical determinations, and biological sampling.
The second, at the Scripps Institution of Oceanography, is examining the feasibility of a large-scale seafood production unit utilizing the nutrients contained in deep oceanic waters to enrich a marine food chain. The pilot study is being carried out on Eniwetok Atoll in the Marshall Islands, where the deep water may be brought up by drilling into the coral reef rather than by using a submerged pipe. Work is in progress toward establishing ecological and productivity baselines on the trophic systems in two nuclear craters that are washed over by the tides and have become invaded with marine organisms. In preparation, moreover, are efforts to assess the water yield capacity of the reef and what changes the nutrients undergo during the seawater's passage through the coral formation.
In a somewhat related program, a team of scientists from the Lamont-Doherty Geological Observatory of Columbia University is working on St. Croix in the U.S. Virgin Islands to demonstrate the feasibility of using deep, cold ocean water for aquaculture and, later, for other uses. The total system could involve multi-usage of the water: sea thermal power production by the Claude process, air conditioning, ice-making, cooling of electric power and desalination plants to avoid thermal and brine pollution, and condensation of atmospheric moisture for freshwater production. The experimental work to date, however, has been restricted to the aquaculture portion of the total system.
A pilot-plant operation was established in which water was pumped into small ponds from a depth of 830 m through an 1,800-m long polyethylene pipeline of 7.5-cm internal diameter. The ponds are used to grow diatoms (mainly Cyclotella nana) which are fed into tanks containing trays of Eastem oysters, Crassostrea virginica, and hard shell clams, Mercenaria mercenaria. Results to date have shown the system to produce unusually fast growth rates for both types of shellfish. However, some oyster mortalities have been experienced. The culture of other types of seafood organisms utilizing this technique will be examined later and an expanded experimental system is planned.
National Sea Grant Aquaculture Programs
(By organization)
California Institute of Technology
Pasadena, CA 91109
Georgetown University
Washington, DC 20007
Humboldt State College
Arcata. CA 95521
Sea Grant Program Director, Richard Ridenhour. Academic Vice President;
telephone (707) 826-3632.
University of Miami
Miami, FL 33124
Sea Grant Program Director, Wendell Mordy, P.O. Box 9178, Coral Gables,
FL 33124; telephone (305) 350-7468.
Francis T. Nicholls State University
Thibodaux, LA 70301
North Carolina State University
Raleigh, NC 27607
San Diego State College
San Diego, CA 92115
Sea Grant Program Director, Glenn A. Flittner, Bureau of Marine Science;
telephone (714) 286-6523.
Skidaway institute of Oceanography
Savannah, GA 31406
University of South Florida
Tampa, FL 33620
1Program Director, Office of Sea Grant. NOAA. Washington. D.C. 20235.
2 Reference to trade names does not imply endorsement by the National Marine Fisheries Service. NOAA.