Fisheries Science

Summary

Fisheries science is an interdisciplinary study concerned with the hunting and farming of aquatic organisms in oceans and bodies of fresh- or saltwater as part of the ongoing effort to feed the world's population. Until recently, most aquatic organisms from fisheries were wild creatures. Farming and the use of genetic-engineering techniques to produce desirable domesticated aquatic food organisms are widespread, but the majority of fisheries science still involves the management of wild fish stocks for the sustainability of the resource.

Definition and Basic Principles

Fisheries science is concerned with the continued extraction of aquatic organisms from marine, brackish, and freshwater environments for subsistence, commercial, or recreational purposes. As such, fisheries science necessarily involves issues of yield (the number of fish harvested from a given stock) and sustainability (the number of fish that must not be harvested if the particular fish stock is to demonstrate continued productivity). This seemingly simple biological situation, however, is made much more complex by ecological, economic, and social considerations.

No aquatic species—not even farmed fish—exists in isolation, unconnected to the food web of its surrounding ecosystem. To the extent that fishing or aquaculture alters the population of one species, it also inevitably alters the populations of other species in the same environment. The health of a fishery is dependent as much on the health of the entire ecosystem as it is on any particular species. Sustainability, then, must ultimately take into account not just the numbers of a particular fish stock harvested or left behind but also the health of that fish stock's entire ecosystem.

Fisheries science is further complicated by the fact that fish, particularly in the sea, have long been assumed to be a limitless resource, available to all for the taking. Depleted stocks and increasing competition for declining numbers of fish have led to an understanding that even fish in the sea are also a limited resource. This has led to the search for new ways to manage marine fisheries and to produce more fish aquaculturally through fish farming of various types. Basic, applied, and developmental research in fisheries science is deeply involved with aquaculture and fisheries management. These are fields in which biological sustainability and productivity must be balanced with the economic productivity of those employed in the fishing and fish-farming industries and with the social productivity of communities that have long been dependent on the harvest of aquatic organisms.

Background and History

Evidence of aquaculture (particularly the raising of fish in ponds or estuaries) goes back at least 5,000 years, and evidence of the hunting and gathering of aquatic organisms goes back significantly more than 100,000 years. However, it was only in the twentieth century that fisheries science developed out of the biological study of aquatic organisms. The development of the discipline can be traced to the fact that, although there had been occasional spot depletions of fish stocks (particularly in freshwater environments or among large sea mammals such as whales), widespread depletions of fish stocks did not become a concern until the twentieth century.

These depletions and eventual collapses of fisheries resulted from technological advances in the fishing industry that increased both the efficiency in how a given fish stock was harvested and the rate at which that stock was exploited. Through the first half of the twentieth century, these technological advances were primarily mechanical. More powerful steam and then diesel engines allowed larger and sturdier fishing vessels, hauling larger and stronger fishing gear, to travel farther and, along with better refrigeration, stay at sea longer. During the second half of the twentieth century, technological advances were primarily electronicsonar and the Global Positioning System (GPS), along with many other informational technologies, made it possible to find the fish more accurately and extract them.

Over the course of the twentieth century, each new technological advance allowed fishers to eat deeper into the natural capital of a given fish stock. Short-term-oriented market forces, driving an extractive technological arms race within the context of open-access fisheries, often reached the point that the fish stocks in question collapsed entirely. The need to manage fish stocks more rationally became increasingly obvious, and fisheries science has begun to serve this need.

How It Works

The core of fisheries science is biological. It is concerned with understanding the life cycles of individual aquatic organisms, including growth rates, ages of sexual maturity, longevity, predation, and mortality. How these factors affect estimates of fish-stock population sizes and long-term population management of fish stocks are also all of key importance in fisheries science. Fisheries science also requires practical understanding of fish tagging and fish marking, the particular fishing gear used in specific fisheries, habitat improvement and bioremediation, fishways, screens, and guiding devices, the role of hatchery-raised fish and stocking, and small-pond, floating-enclosure, or net-pen management (these last being particularly important in aquacultural contexts).

Whether in aquacultural or traditional fishing approaches, however, fisheries scientists find they must go beyond a simply biological understanding of fish stocks. Fisheries science is profoundly influenced by the context of the cultural and legal framework within which fisheries management takes place. An important part of this framework is the common-law doctrine of the “public trust,” particularly the idea that the resources of the rivers and seas within a nation's jurisdiction belong to the people, and the government holds them in trust for the public.

Fisheries as a Public Trust. The idea of the public trust has its roots in the principle of ancient Roman law that things such as the air, running water, the sea, and the shores of the sea are incapable of private ownership. In English law, and later in US law, the fish and wild beasts were added to the list of “common property” that the government holds in trust for the public. Resources relating to the public good cannot be given away to private interests, because public trust resources are inalienable—that is, they cannot be given over or transferred by the government to other entities or individuals. The government also must, by law, exercise continuing stewardship responsibility and authority over public trust resources, including fisheries.

In conjunction with improved extractive technologies and largely unregulated market forces, the open-access nature of fisheries in many cases resulted in the degradation of those fisheries. It thus became increasingly clear that government, as trustee of the fisheries, ought to exercise its stewardship authority over these public trust resources. In the United States, this stewardship responsibility is seen most clearly in the Magnuson-Stevens Fishery Conservation and Management Act of 1976 (which extended to 200 miles offshore the nation's jurisdiction over the sea as an “exclusive economic zone” for fishing) and the Sustainable Fisheries Act of 1996 (which called for further analysis of sustainability and closed to fishing many depleted fisheries, in hopes of their recovery).

The places where aquatic organisms (whether wild or farmed) live and from which they are to be harvested or protected from harvest will likely remain waters held primarily in public trust. As a result, the fisheries scientists will continue to serve most often in the role of knowledge expert, assessing fish stocks and advising government, industry, and the public how best to use the fish stocks that are the common property of a nation's citizens.

Assessing Estimated Population Size and Ecological Risk: Traditional Fisheries. To estimate yield, to understand basic changes in population number and composition, and as a basis for sound management, the fisheries scientist must be able to estimate fish population reliably. Like much of the rest of fisheries science, population assessment is based in mathematical and systems-analysis approaches. Although opportunities do exist for direct counting of fish, most statistics on fish populations are estimates. Some examples of methods for estimating population include area density, mark-recapture or “single census,” and catch-effort.

The area-density approach to estimating population involves counting the number of animals in a series of sample strips or plots distributed randomly or systematically throughout the total environmental area in which the fish stock population is to be determined. The sample count, once taken, is expanded to an estimate of the entire population by multiplying the aggregate sample count by a particular fraction (total area divided by the sum of sample areas). Because a subarea can also be sampled for time instead of space, the same equations applied to area density can also be applied to partial-time coverage.

In the mark-recapture method of estimating fish population, a sample of fish is collected, marked, and released, and then at a later time, a second or recapture sample is taken, which includes both marked and unmarked fish. This approach is based on the assumption that the proportion of marked fish recovered is to the total catch in the second sample as the total number of marked fish released is to the total fish population.

The catch-effort method of estimating fish population depends on the premise that all individual fish in a sample have the same chance of being caught and that the effort made by fishermen to catch the fish is constant. This approach works best when the population is closed, when chance of capture and constancy of effort remains unchanged from sample to sample, and when there are enough fish removed so that the population shows a decline.

Assessing Estimated Ecological Risk: Aquaculture. In aquaculture, population is much more controlled, so assessment emphasizes questions of ecological risk rather than determination of population. Because of the intensive nature of fish-farming practices, these questions of ecological risk include near-field and far-field effects of increased organic loading (mainly from uneaten fish feed, fish fecal material, and decomposing dead farm fish), increased inorganic loading (mainly nitrogen, phosphorus, trace elements, and vitamins in fish excretory products and uneaten feed), residual heavy metals (mainly zinc compounds in uneaten feed and fish feces), the transmission of disease organisms (often increased because of the high density of fish per volume of water in net-pen enclosures), and residual therapeutants (from biomedical treatments of the fish performed in response to the increased transmission of disease organisms resulting from crowded net-pen conditions).

Other ecological risks to be assessed for aquaculture include biological interaction of farmed fish that have escaped into wild populations and vice versa (with the potential not only for breeding but also for cross-infection with parasites and pathogens), the impact on marine habitat of fish-farm enclosures (including entanglements involving nets, anchors, and moorings), control of natural predators in the fish-farm environment, and increasing pressure on shoaling small pelagic fish populations to be fed to the farmed fish.

Applications and Products

The primary role of most fisheries scientists continues to be consultative. That consultative role usually falls into three categoriesassessor (the person responsible for making reliable estimates of fish populations, predicting what harvest levels those populations can support, and the environmental impacts of both fishing and fish-farming approaches), adviser (the person responsible for communicating to government, industry, and public all findings relevant to the health of a fishery and its environment), and educator (the person responsible for increasing governmental, industrial, and popular awareness of both the economic and ecological importance of aquatic organisms).

Some fisheries scientists, however, already find themselves involved in efforts with direct applications and products. These include new ways of growing or harvesting aquatic organisms, some as revolutionary as genetic modification of farmed fish, some as evolutionary as the development of more efficient fishing gear.

Aquatic and Marine Food. Fisheries scientists, as experts in the health of individual fish species and overall fishery populations, help industry provide high-quality seafood products for the consumer—an important activity, considering that seafoods are one of the world's primary sources of high-quality protein. Fisheries scientists are involved in product development, physicochemical principles, and process technology for aquatic food and marine bioproduct utilization, as well as in examining and improving aquatic and marine products and manufacturing processes.

In the aquacultural context, fisheries science helps to increase the aquacultural contribution to the food supply while also developing new methods of production and improved cultural practices for selective species. These production and cultural concerns include environmental, ecological, and disease considerations, selective breeding, feeding, processing, and marketing.

Aquatic and Marine Nonfood Products. In addition to foodstuffs, however, many other products are derived from aquatic and marine organisms. Fish oil, which contains omega-3 fatty acids and anti-inflammatory eicosanoids, is important for a healthy diet. Fish meal, a high-protein food supplement used in aquaculture, is a by-product of rendering and processing fish for fish oil. Fish emulsion, a fertilizer, is produced from the fluid remainder of fish already processed for fish oil and fish meal. Fish skins, swim bladders, and bones are boiled to produce fish glue for specialized uses, while isinglass, a form of collagen obtained from dried swim bladders, is used for clarifying and refining wine and beer, for preserving eggs, and for conserving parchment. Kelp is steadily growing in popularity as a fertilizer and has long been a major source of iodine. Traditional royal or Tyrian purple is derived from sea snails of the Murex genus. Pearls and mother-of-pearl are key components of lustrous jewelry.

Fisheries scientists continue to explore aquatic and marine bioresources for pharmaceuticals, nutraceuticals, and novel biomaterials as well as investigate distribution and biodiversity of marine organisms important to industrial utilization. In finding innovative uses for aquatic and marine products and thereby increasing the value of specific fish stocks, fisheries scientists also make more likely the prospect that a given stock will be more sustainably harvested over the long term.

Aquaculture. In the aquaculture context, fisheries scientists not only examine the impacts of aquaculture practices on the environment (including habitat alteration, release of drugs and chemicals, interaction of cultured and wild organisms, and related environmental and regulatory issues) but also propose and evaluate methods for reducing or eliminating those impacts, including modeling, siting, and monitoring of aquaculture facilities and the use of polyculture and water-reuse systems. Fisheries scientists propose the design criteria, provide operational analysis, and develop management strategies for selected species in water-reuse systems.

Fisheries scientists provide an in-depth understanding of the natural and social ecology of aquaculture ecosystems, applying principles of systems ecology to the management of the world's aquaculture ecosystems. They also evaluate the nature, causes, and spread of diseases limiting the success of freshwater and marine aquaculture projects. They provide diagnoses of diseases affecting hatchery management and other aquacultural contexts, as well as define appropriate prevention, control, and treatment strategies for those diseases.

Traditional Fisheries. For traditional or wild fisheries, much fisheries science involves advising and educating government, industry, and the public on the biology of aquatic-resource animals and assessing fisheries' populations, stock abundance, and overall ecological health. Fisheries scientists also help frame the debate concerning aquatic resource management, conservation legislation, rehabilitation of depleted fisheries, and socioeconomic considerations involved in national and international fishery issues, practices, patterns, and public policy.

Fisheries scientists are also involved in developing new fish-catching methods and technologies, including developing and assessing electronic enhancements to fishing and fishing vessel operations that have increased fishing power. Fisheries science contributes to applying these new methods to scientific sampling, commercial harvesting, and recreational and subsistence fishing. Fisheries scientists contribute to advancements and innovations in fishing gear construction, maintenance, and operation and the evaluation—through empirical, theoretical, model scaling, and statistical analysis techniques—of the behavior and performance of fish-capture systems.

Careers and Course Work

Career titles in fisheries science involve both traditional wild fisheries and aquaculture. They include aquarium director, biologist, conservation ecologist, conservation officer, environmental consultant, fish culturist, fish-processing manager, fisheries manager, fisheries technician, fisheries biologist, fisher, hatchery manager, lab technician, museum or aquarium curator, marine biologist, natural-resource specialist, nature interpreter, lake or pond manager, researcher, vessel captain, and wildlife manager.

Courses in ecology, biology, chemistry, and mathematics are foundational for students wishing to pursue careers in fisheries science. A fisheries technician, fish-hatchery manager, fish-processing manager, lab technician, or nature interpreter may need little more than this background and some basic mechanical, electrical, or systems engineering skills.

The pursuit of master's and doctoral degrees—which are often the necessary minimum qualification for more advanced academic, governmental, or industrial careers in fisheries science—generally requires more specialized course work beginning at the upper division of undergraduate studies or the beginning of graduate studies. More specialized courses may include genetics, marine biology, limnology, ichthyology, oceanography, and veterinary medicine.

Although fisheries science is primarily biological at its root, it is also strongly interdisciplinary and advisory, so a background in fields such as hydrology, anthropology, law, economics, and political science can also prove very helpful.

Social Context and Future Prospects

As more of the world's fisheries become overfished or fished out and wild fish stocks are threatened globally, there is increased pressure to switch from the mechanized hunting-gathering approach of commercial fishing to aquaculture. This must be done in decades rather than the millennia involved in the analogous changeover to agriculture. Concerns about potential ecological risks, ranging from aquaculture's inherently dense and intense practices to genetic modification of fish species, have also increased as the rapidity of this changeover has increased.

One of the most pivotal roles of fisheries science in the future will be assessing how much of the near-shore oceans should remain wild and how much should be intensively farmed. This will involve not only the assessment of ecological risk associated with the growing aquaculture industry but also the determination of how fully and rapidly depleted or damaged fisheries can recover. Marine reserves, aquatic refuges, and bioremediation all have roles to play here, as do concerns associated with reef die-offs, pollution, climate change, and economic and political pressures on the remaining fisheries worldwide that are not yet fully exploited.

During the twenty-first century, the survival or extinction of many aquatic organisms will depend on how the growing population of terrestrial organisms with a fondness for seafood—the human species—interacts with its global environment. As assessors and advisers, fisheries scientists are key to helping shape that interaction.

The COVID-19 global pandemic caused most surveys of wild fish populations to be canceled. This made it challenging, if not impossible, for fisheries scientists to assess the stock of harvested species. In 2021, fisheries scientists worked to remedy the research gaps caused by this disruption to protect low populations and fragile ecosystems. By 2023, more than 90 percent of the fisheries managed by the National Oceanic and Atmospheric Administration stayed within the catch limits of sustainable fishing guidelines.

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