Aquaculture—Natural Resource Managers' Ally?

Nick C. Parker
U. S. Fish and Wildlife Service
Soulheastern Fish Cultural Laboratory
Marion, Alabama


Continual adaptation and change are necessary for biological organisms, political systems, businesses and managers of natural resources to maintain their positions in the world. Just as Darwin's finches adapted to unfilled niches to avoid competition and to survive side-by-side, aquaculturists, commercial fishery operators, anglers, natural resource managers and others must adapt to rapidly changing conditions. Conflict becomes inevitable as demands on a limited resource exceed the maximum sustainable yield. However, conflicts can be avoided, or at least reduced, if competing interests recognize the positive aspects of change and that continual change is the only way to maintain homeostatic conditions. Aquaculture, which has been described as "the emerging giant," has drastically altered management of some aquatic resources and has the potential to alter others. My objectives here are to explore some of the ways in which aquaculture may affect natural resource managers and some possible actions that may reduce conflict between producers of farm-raised fish and managers of wild stocks.

The first professional managers of natural aquatic resources in the United States were probably the fish culturists who lobbied Congress in 1871 to establish the Commission on Fisheries, with Spencer F. Baird, Assistant Secretary of the Smithsonian Institute, as the first commissioner (Thompson 1970). These early managers lobbied Congress to appropriate funds for the propagation and introduction of shads (Alosa spp.), salmonids (Salmo spp.) and other valuable fishes throughout the country. The goals of both public officials and private producers were to provide fish for the food market and to provide species acceptable to new immigrants. To help meet this goal, they probably first introduced the common carp (Cyprinus carpio) into this country from France in 1831 or 1832 (Radonski et al. 1984) and, by 1875, the fish were well-established in California and New York (Bowen 1970). With some fanfare and at the request of Spencer Baird, Congress appropriated $5,000 in 1877 to construct culture ponds to rear common carp on the grounds of the Washington Monument. Over the next several years, farm-raised fish, including introduced brown trout (Salmo trutta) and common carp, were promoted by private aquaculturists and government officials to increase angling opportunities. These culturists voiced their concerns about pollution from manufacturing plants, sawmills, dams, siltation, and other industrial and municipal sources (Thompson 1970). Fish culturists sought to preserve the aquatic environment to support fish and fishing.

After the death of Spencer Baird in 1887, the value of cultured fish in the management of natural resources began to be questioned and funding for research became more limited. By 1897, when A Manual for Fish Culture was published by the Commission, fish culture was a well-developed practice of state and federal fish hatcheries, as well as in the private business sec (Brice 1897). The manual contained descriptions for the culture of more than 40 species or groups of finfish, plus lobsters, oysters, clams and frogs. Fry produced in hatcheries were widely stocked along the Atlantic Coast from about 1870 to 1900; the programs then were abandoned because they did not appear to influence commercial landings of shad, striped bass or other estuarine fishes.

Conflicts of Aquaculturists and Natural Resource Managers

Now, about 100 years later, resource managers view aquatic resources as part of the public domain and consider that hatchery-produced fish to be one more tool to be used to manage these aquatic resources (McCraren 1986). Private producers view aquaculture as agriculture in the aquatic environment and believe the products produced should be treated no differently than poultry, beef or soybeans. These opposing views are a major source of conflict.

Channel catfish (Ictalurus punctatus) and chiefly rainbow trout (Salmo gairdneri), the most commonly cultured fishes, are defined as agriculture crops in come states— channel catfish in Mississippi, trout in Idaho and all farm-raised aquatic organisms in Missouri-and these farm-raised fish are not regulated by the state conservation and natural resources agencies. Other species, such as striped bass (Morone saxatilis), red drum (Sciaenops ocellata) and largemouth bass (Micropterus salmoides), are now attracting the interest of commercial producers (Durpee and Huner 1984) and may ultimately force changes in existing regulations. Will these changes harm or benefit anglers, commercial operators, consumers and the nation's aquatic resources?

Demand for Game Fish Increases

According to a survey conducted by the U. S. Fish and Wildlife Service in 1985, 58 million anglers spent $28.2 billion in 987 million-angler days (U. S. Fish and Wildlife Service 1986). Sport fishing is projected to double by the year 2030. The fishing pressure on public waters is expected to increase much more rapidly than the ability of the resource to produce. Even today, some anglers have abandoned public waters to fish in more productive private waters. The public waters of Texas yield slightly less than 1 legal-size bass in 10 hours of fishing, whereas 30-40 bass can be taken from privately owned and managed lakes in only 3 or 4 hours (Trosclair 1987a). Land owners are willing to buy catchable-size fish to be stocked in private ponds for recreational purposes. For example, a company in Bryan, Texas has sold l-kilogram rainbow trout to landowners in Texas to stock for recreational fishing.

Other aquaculturists are producing hybrids of striped bass and white bass, Florida strain largemouth bass and other warmwater species for food and sport fish. In Danbury, Texas, some anglers have paid $900 per day for the opportunity to catch 3-kilogram trophy-size bass in private waters and other fishermen routinely pay $90 in the off-season and $165 per day in the peak season to catch 1- to 2-kilogram fish (K. Zwhar personal communication: 1988). Largemouth bass are being reared in protected nursery ponds and then transferred into larger ponds for recreational use.

Anglers may catch and release multiple fish but keep only their largest one as a trophy. Various personal services, such as catering of meals, and use of lodges and equipment, are included in the $300-900 daily charges, but fewer services are provided for the $90 per day charge. Are these practices the same as sport fishing in public waters? Are they indicative of future practices? Or are they just an innovative way to harvest an agricultural crop?

States require most anglers fishing in state waters to have a valid recreational fishing license. However, in some states, such as Alabama, Arkansas and Missouri, anglers fishing in privately owned water for farm-raised fish are exempt from licensing requirements. Although these establishments provide recreational opportunities, the catch of fish is frequently so high that it resembles a supermarket activity. In a single day, anglers have harvested more than 500 kilograms of channel catfish from a 0.1hectare pond in Longview, Texas (R. Lackey personal communication: 1988). Do activities such as these relieve the fishing pressure on public waters? I believe that they do—at least they provide recreational opportunities in excess of those available on public waters. To the extent that fishing in private waters removes fishermen from public waters, these programs work in concert with—not in conflict with— public programs.

Game Fish or Food Fish?

Natural resource managers have often been reluctant to allow the sale of farm-raised fish. The two major obstacles preventing the sale of the hybrids of striped bass x white bass (M. chrysops) were identified by Carlberg and Van Olst (1987) as: "1) The inability or unwillingness of enforcement agencies to distinguish farm-raised hybrids from wild-caught striped bass that are prohibited from sale in many states, and 2) laws prohibiting the sale of striped bass because it is a game fish." Producers of channel catfish and trout faced these same obstacles as they developed commercial markets for farm-raised fish. How were conflicts resolved? To my knowledge, both farm-raised catfish and trout can be legally sold in all states. Before 1960, when there were only 160 hectares or commercial catfish ponds, there were significant commercial fisheries for catfish in inland waters, such as the Tennessee and Mississippi rivers. Today, after numerous incidence of environmental degradation, including release or spills or mercury, PCBs, chlorinated hydrocarbons, and other toxicants and contaminants, the public no longer associates quality and safety with wild-caught species, but more frequently with farm-raised products. In 1987, about 182.000 metric tons (S. Hinote personal communication: 1988) of farm-raised catfish and 23,000 metric tons of farm-raised trout were processed as food fish. Existing catfish-processing plants had the capacity to process more than 227,000 metric tons per year (Trosclair 1987b). Many other farm-raised fish were sold directly to consumers or for restocking as recreational fish. The development of the catfish and trout industries appears to have almost eliminated the importance of the commercial catch. Fishing pressure on wild stocks of these inland species may continue until the last fish is caught, but the relative value of the wild fish will decline as farm production increases. The commercial production of Atlantic salmon has similarly expanded at a phenomenal rate in the past three to four years. About 50,000 metric tons of farm-raised Atlantic salmon were imported into the United States in 1987, whereas, commercial bandings from the Atlantic Ocean were only about 10,000 metric tons. Foreign investors from Norway, Sweden, Iceland and Japan have recently established several net-pen fish farms to culture both Atlantic and Pacific salmonids in North America. Most of these farms have been placed in Canadian waters, primarily British Columbia, because regulations there are less restrictive than in the United States (Morrison 1987). Alaska fishermen recognize the threat of this foreign competition, and even though they would prefer to continue to fish for wild stocks, they recognize the potential profit of net-pen culture and are ready to "jump on the band wagon and farm salmon" when state laws are modified to permit this activity (Rosenberry 1987).

Demand for Food Increases

The demands for fish and fishery products in this country are expected to expand faster than the supply of fish will. Imports of fish and fishery products into the United States were valued at $365 million in 1960 and $7.6 billion in 1986, when the imports consisted of $2.8 billion worth to nonedible products (animal feeds, industrial products, etc.) and $4.8 billion for edible fishery products. Imports expanded at an average annual rate of $278 million from 1960-1986 and increased much more rapidly after 1980 than before 1980. The annual per-capita consumption of fish increased over 20 percent from 1975-1986, when the per-capita rate reached 6.7 kilograms; it is expected to be 13.6 kilograms by the year 2020. The world's catch of fish (millions of metric tons) was 27 in 1954, 57 in 1966, 74 in 1976, 83 in 1984 and 90 in 1986 (McIntyre 1987, Parker in press). The catch has increased with the demand only because previously unused resources-those formerly classified as trash fish-are now being captured and processed into consumer-acceptable forms, such as imitation lobster, shrimp and scallops The ocean's resources are recognized as finite, having an estimated maximum sustainable yield of about 100-120 million metric tons. The expansion of demand in a market with limited supply is expected to continue to drive prices up and make fish farming even more lucrative than it is today, when more than 11 percent of global fish landings are produced by aquaculture (McIntyre 1987). The forecast is for the global yield from aquaculture to increase to 22 million tons by the year 2000, when farm-raised species will represent 25 percent of the world's harvest of aquatic organisms (Rhodes 1987).

Distinguishing Between Wild and Farm-reared Fish

Aquaculturists, resource managers and law enforcement personnel have tools and techniques today that were not available when many of the rules and regulations were written to protect aquatic resources. For example, few of the states' laws address hybrid fish. In some states-e.g., Maryland-hybrid striped bass were considered to be striped bass for purposes of regulation. In other states-e.g., New Jersey and Massachusetts-hybrids were not even mentioned in the regulations. Some states— e.g., Florida, Virginia, North Carolina, Georgia and Mississippi-began to re-examine and modify their laws in 1987 to allow for possession and sale of farm-raised striped bass and hybrids (Smith 1988).

The availability of reproductively sterile hybrids and triploid fish has promoted some states to re-evaluate and modify their regulations for some species. For example, in 1978, grass carp (Ctenopharyngodon idella) had been in at least 35 states at one time or another, regardless of the species legal status (Guillory and Gasaway 1978). By 1987, however, 12 states had no restrictions on the species, 15 had specific policies for them, 4 permitted research with triploid forms and the other 19 states technically prohibited all grass carp, even though some exceptions were made (Allen and Wattendorf 1987). Presumably sterile hybrids of grass carp x bighead carp (Aristichthys nobilis) were first legalized in some states, but preference shifted to the use of triploid grass carp. For grass carp, the impetus to modify state regulations came not only from the producers, but also from state fishery biologists seeking to use these highly herbivorous fishes for biological control of aquatic vegetation in public waters. Anglers, boaters and owners of lakefront property became the driving force to modify regulations. Producers of triploid grass carp use specialized medical equipment-a Coulter1 counter (cost about $20,000 each) to verify that each fish certified as a triploid does indeed have three and not two (diploid) sets of chromosomes (Wattendorf 1986). The equipment and procedures for this test are expensive; the test cannot be performed in the field by law enforcement personnel. Nevertheless, the procedures and paper trails established seem to provide a workable solution acceptable to law enforcement personnel, resource managers and aquaculturists.

The production of monosex-either all-male or all-female—populations is another tool available to aquaculturists and resource managers to limit reproduction of fish. A considerable amount of research has been conducted to develop monosex populations of tilapia to limit reproduction in culture ponds. Techniques used include production of hybrids with highly skewed ratios of males and females, and production of all-male populations by feeding androgenic steriods to immature genetic females to induce sex-reversal. Other techniques used to alter sex ratios include gynogenetic production of female fish by fertilizing eggs with sperm that has been irradiated with ultraviolet light to denature the genetic material, the DNA. Once development of the egg has been activated by the irradiated sperm, eggs are shocked by exposure to heat, cold or pressure to disrupt normal cell development and produce a diploid zygote with no genetic contribution from the male (Benfoy and Sutterlin 1984). Some of these resulting all-female fish can then be fed androgenic hormones to produce functional males (genetically female) and mated back with their siblings to produce a second generation of all female fish.

When these techniques are further perfected, they will allow aquaculturists to produce fish with selected traits, such as rapid growth, disease resistance and tolerance to high or low temperature. It is expected that desirable traits can be propagated in cultured species much more rapidly with these techniques than through the normal process of selective mating.

Similar techniques will almost assuredly be used to produce sterile exotic fish for recreational fishermen. If anglers will pay $300-900 per day for the opportunity to catch a trophy-sized largemouth bass weighing 3-4 kilograms what would they pay to catch a 50-kilogram freshwater fish? Several exotic species, including Nile perch (Lates niloticus), reach or surpass this size. How long will it be before reproductively sterile exotic fish are available in private waters to anglers? Once trophy-size sterile exotics are available, will there be a demand for put-grow-and-take fisheries in public waters? Will sterile classification reduce the threat to native stocks enough to make these fish acceptable? If grass carp can be used as an example. I fully expect to see other sterile exotics, produced by fish farmers and in state hatcheries, to be stocked by resource managers for sport fishermen.

In several states, laws have been modified or regulations developed to allow the possession, culture and sale of farm-raised fish as food fish, bait or for restocking. In other states, regulations prohibit the sale of all game fish as food fish, but do not limit the possession, culture and sale of fish for restocking.

'Reference to trade names or manufacturers does not imply endorsement by the United States Government.

Law Enforcement

Laws designed to protect game fish appear to be one of the major restraints limiting expansion of aquaculture in many states and the expansion of culture of species other than catfish and trout. Law enforcement personnel are probably not "unwilling" (Carlberg and Van 01st 1987) to distinguish between wild-caught and farm-raised fish, but cannot do so within their existing budgets and with field techniques now available to them. Prohibition on the sale of game fish as food fish creates an illegal market somewhat similar to that for alcohol during the era when all sales of alcoholic beverages were illegal in the United States. The increasing demand for fish and fishery products is expected to stimulate the illegal market. However, farm-raised fish could fill the market and reduce poaching of wild stocks. Poaching pressure would decline only when economic incentives were lowered to make it unattractive; some enforcement personnel do not expect the aquaculture production of highly desirable fish, such as hybrid striped bass, ever to be abundant enough to meet the market demand (D. Searcy personal communication: 1988). Some enforcement personnel further believe that protecting wild stocks of fish from poaching in the presence of legal sales of farm-raised fish creates enforcement problems even greater than alcohol sales during prohibition.

Tools that law enforcement personnel could use to distinguish between wild and cultured fish are now being used in other areas of law enforcement. Forensic scientists are developing techniques (i.e., capillary zone electrophoresis-mass spectrometry, CZE-MS) that will sample volumes one billionth of a liter is size to detect and analyze compounds at concentrations one thousandth of that possible with existing techniques (Hattangadi 1988). The analyses of fragmented DNA molecules yields genetic fingerprints that have been used to provide positive identification of individuals when the only evidence at the scene of a crime was a small sample of dried blood, semem or other tissue (Weiss 1988). The technique of electrophoresis with isoletric focusing has been used to determine species of raw muscle tissue (D'Andrea and Leedham 1985) to distinguish between trout and salmon (Sutton 1982) and to identify the four species of Morone and their congeneric hybrids (Harvey and Fries in press).

The equipment for electrophoresis and other analytical assay techniques is commonly available in most universities and even in some fish hatcheries. Other techniques to distinguish between wild and cultured fish include analysis of daily growth rings on scales or otholites, scale-shape analysis, elemental composition of scales and bone, lipid profile analysis, detection of such tracer compounds as tetracycline and calacine in farm-raised fish, and morphometric differences. Some of these techniques have been used to distinguish striped bass taken from freshwater from those taken from saltwater (Belanger et al. 1987) and between Chesapeake Bay and Hudson River stocks (Fabrizio 1987). These and other sophisticated techniques are routinely used in forensic laboratories (Weiss 1988), but may require more laboratory support than current fish and wildlife enforcement budgets provide unless priorities are altered. These techniques, in conjunction with paper-trails to document source and movement of farm-raised fish, are tools now available to enforcement personnel. It is expected that, if there is a real market for field test kits that would allow enforcement personnel to distinguish between farm-reared and wild fish, such products will be developed. Law enforcement personnel now use a field kit that detects lead, to distinguish between game taken with a bow and arrow and that taken by gunshot. Similar field tests may be developed to detect trace elements in farm-raised fish. For several years, kits have been available that enable diabetics to monitor their blood sugar and for women to test for pregnancy. Pharmaceutical firms are attempting to develop a simple and rapid test to detect the virus responsible for AIDS-the fatal anti-immune deficiency syndrome. Similar on-the-spot tests used in the medical field can very likely be adapted to detect chemical and biochemical differences in cultured and wild fish. It is even conceivable that, through bioengineering, future cultured fish may have hidden marks that become visible or undergo a color change when exposed to ultraviolet light or some other activator. A blue microbe has been developed (and patented) that will degrade PCBs; the blue color allows the organism to be easily traced in the environment and distinguished from other wild-type bacteria.

Techniques available to law enforcement personnel today include use of various markers and tags to identify fish and trace them through the market system. For example, fish have been marked with tetracycline (which fluoresces under ultraviolet light), fluorescent pigments (Scientific Marking Materials, Inc., Seattle, Washington) and color-coded plastic chips, Microtaggants (Klar and Parker 1986). Some law enforcement personnel have used these materials to mark fish in illegal nets and then to trace them through the market system. In at least one case, PIT tags (passive inductive transponders-Biosonics, Inc., Seattle Washington) were used to identify fish stolen from the Southeastern Fish Cultural Laboratory of the U. S. Fish and Wildlife Service, Marion, Alabama. The PIT tag is a small glass-encased electronic device that can be implanted, with the aid of a special syringe, in fish or other animals. The PIT tag derives power from an external transmitter to drive an internal transmitter and broadcast a unique 12-digit hexadecimal number detected and displayed on a monitor. Another type of small internal tag, the coded-wire tag, was used to mark about 1.2 million hatchery-reared striped bass released into Chesapeake Bay from 1985 through 1987, and has been used to mark millions of salmonids along the Pacific Northwest coast of the United States and throughout the world. Similar techniques might be used by management biologists to access stocks in inland reservoirs. Law enforcement personnel could then use this mark to identify fish taken from state waters.

In August 1987, at a conference on aquaculture in South Carolina, law enforcement personnel proposed a resolution that all states establish a 12-digit numbering system to identify individually all hybrid striped bass produced on farms for the food fish market. Under this proposal, each fish would bear a unique tag. After conversations with some commercial producers in Alabama, Arkansas, California and Mississippi, it seems improbable to me that this proposal will gain support of the aquaculture industry. It appears more likely to strengthen the resolve of aquaculturists that aquaculture is agriculture and increase pressure to have hybrid striped bass classified as farm products not controlled by natural resource managers. How will aquaculturists and resource managers deal with other cultured species-red drum, orangemouth corvina (Cynoscion xanthulus), Florida pompano (Tranchinotus Carolinas)-and the numerous hybrid crosses that will surely be made? It seems reasonable that cultured fish will become much more important in the American economy. The culture of Florida pompano was of interest a few years ago, but never developed into an economically viable commercial industry. The Florida pompano fishery is now only one-tenth of that 12 years ago, due to overharvest (McMasters 1987). Florida pompano have reportedly retailed for $26 per kilogram, when particularly scarce, and in 1987, commonly sold for $11 per kilogram (up from $4.40 per kilogram in 1974). Even though earlier attempts to produce Florida pompano on farms failed financially and they are not farm products today, it seems very likely that production will become economically feasible as the demand increases.

Benefits of Cooperation

It is time for natural resources managers and aquacultrists to evaluate where we are and where we are going. There appears to be room for compromise on both sides. For example, trout, catfish, salmon, beef steaks, pork loins and chicken are not individually numbered as a condition of marketing. Food fish and shellfish, unless specifically identified as an injurious species, may be imported into the United States and are not required to be numbered individually or even federally inspected. Boxes must be clearly labeled to identify contents. shipper and consignee. So why, the aquaculturists ask. should trade in American-produced farm products be restricted by the cumbersome process of individually tagging selected farm-reared aquatic species? Although some aquaculturists may wish to identify all farm-raised crops as agriculture, they must recognize the potential impact of cultured fish on wild stocks and work with resource managers to reduce the chances for damage. Until domesticated brood stocks are developed, aquaculturists must depend on wild stocks and work closely with natural resource managers to protect those stocks from overexploitation and genetic alteration. Maintaining high quality in the aquatic environment is of prime importance to both aquaculturists and resource managers.

It seems that, as demand for aquatic resources increases with the continual growth of the world's population, strict preservationists and potential exploiters must both alter their positions and agree to some changes. The combined demands of anglers, recreational fisherman and commercial fishermen exceed the supply of fish on a worldwide basis. Either catches must become severely limited as demand increases or aquaculture must expand to fill the void. Projections have been made that, within the next 50 years, aquaculture products will equal or surpass the wild production of fish (Larkin 1988). Some sport fishermen in Texas and other states have already recognized the value of aquaculture to their interests and have helped to fund and establish hatcheries to culture red drum and other species to be stocked in coastal and inland waters (Rutledge 1986). It appears that aquaculture holds tremendous potential for sportsmen, consumers and producers, and it could become an even stronger tool of natural resource managers.

In summary, it appears that aquaculture can provide at least nine useful benefits.

1. Provide fish for commercial markets to lessen the pressure on wild stocks.

2. Allow some commercial stocks to be redirected to the sport fishery where they have greater economic value.

3. Provide specialty fish for management purposes.

4. Provide recreational opportunities on private waters, thus reducing fishing pressure on public waters.

5. Provide employment for significant numbers of individuals. 6. Stabilize price fluctuations in markets.

7. Provide products for export markets.

8. Provide fish for markets now being filled through import. 9. Improve the nation's foreign trade balance.


I thank B. Jaco (Tennessee Valley Authority, Muscle Shoals, Alabama), D. Searcy (U. S. Fish and Wildlife Service, Atlanta, Georgia), and B. Simco (Memphis State University, Memphis, Tennessee) for reviewing the manuscript, and numerous aquaculturists, resource managers and researchers who willingly discussed this issue.

References Cited