In terms of enduring popularity, many species of prawn, shrimp, lobster, crab, scallop, abalone, mussel, and oyster are highly rated. This is particularly apparent in regions of North Asia, where the ability to source exotic seafood is frequently seen as an important status symbol. In the wild, these creatures depend upon a clean environment with plentiful stocks of marine plankton, fish and other organisms. Many of the crustaceans are natural scavengers, living among floating sea grasses, rocky shelves and reefs. They provide an essential service by consuming marine detritus before it spoils and alters water quality. The bivalves, including clams, oysters, scallops, and mussels, obtain most of their nutrients through fluid filtration, leaving them particularly vulnerable to adverse changes in water quality. Many of these creatures are harvested from the wild by commercial and amateur fishers. There is also captive rearing which has been practiced for centuries in many regions of the world.

Prawn farming

Commercial prawn farming attracts levels of controversy similar to that of farmed salmon. While their food conversion efficiency is almost twice that of salmon, they are dependent on the same unsustainable supplies of fish meal and oils.

As an industry, some of the largest commercial prawn farming operations have been established in developing countries with extensive coastal access. In attempts to increase their efficiency and profits, prawn farmers have encroached upon important marine habitats such as the coastal wetland and mangrove forests of tropical Asia. These habitats which are also destroyed by other forms of land reclamation and development are among the most ecologically diverse on the planet. Within Asia alone, several million acres of pond have been developed for the farmed prawn industry. This enables several hundred thousand tons of prawns to be produced each year along with jobs and income for the respective regions.

The impact on coastal environments

From an environmental perspective, these short term economic advantages are often outweighed by their lack of sustainability and negative impact on other natural resources. The damage caused by poorly managed farms is often dramatic. When biological waste and other pollutants get drained from concrete ponds into coastal waterways, they influence water chemistry by increasing salinity and reducing the oxygen carrying capacity. At the same time, untreated prawn effluent encourages disease and bacterial organisms to multiply.

It is however unrealistic to avoid the fact that the prawn industry has enabled some previously isolated regions to develop an infrastructure of housing, roads, hospitals, and schools.

The most practical solution at this point appears to be a combination of industry restructuring and the implementation of tighter controls. From an environmental perspective, an efficient and effectively regulated farming sector is required since the demand for prawns cannot be attained by other sustainable means. Net trawling not only kills several endangered species of fish and turtle, it rakes sediment and can alter the normal growth of natural corals and kelp plantations.

Oyster and mussel farming

For centuries, oysters and mussels have been raised in captivity either as a food source or for the cultured pearl industry. Unlike farmed prawns, they gather their nutrients directly from seawater and have minimal impact on the surrounding environment.

In recent times, some of the food scares associated with edible farmed bivalves have resulted in stricter hygiene regulations and increased monitoring of water conditions.

On a regional basis, the farmed oyster industry has experienced difficult times. This has been attributed to climate change, decreased water purity, and the social and economic factors which influence such labour intensive operations.

The traditional model of building farms along the harbours and tidal rivers of populated areas is rapidly declining. Despite numerous restrictions which have resulted in cleaner waterways with improved safety, there are still too many risks for farms situated near population centres. This has resulted in a gradual shift toward species which can be accommodated in remote cooler regions with less exposure to industrial discharge, sewage, and other forms of pollution. They are reared in seawater enclosures and distributed directly to fresh produce markets and restaurants.

Organic certification and the future of farmed shellfish

Organic standards for farmed shellfish are slowly coming into effect, and there are predictions that bivalves such as oysters and mussels will be highly successful in terms of their sustainability, cost efficiency and popularity with consumers. Organically farmed prawns are currently available in Europe and the United States. There is increased investor interest in prawn farming precipitated by the development of cost effective organic feeds and a water sterilisation system based on ultra violet radiation.

Consumers are increasingly aware of the environmental damage and health risks associated with conventional farming practices. They are looking for healthy shellfish raised in controlled environments, unaltered by chemical toxins, genetic modification, or antibiotics.

Edible fish is a popular and important food resource in many regions of the world. A seventy percent majority of the overall supply is obtained from wild stocks frequenting oceans, coastal estuaries, and inland rivers.

Since the beginning of the industrial age, the natural habitats of wild fish stocks have suffered from various forms of pollution and ecological degradation. Recent surveys of wild fish populations have confirmed the negative impact of commercial fishing. Well publicised depletions include the orange roughy, bluefin tuna, swordfish, and toothfish. With the technologies currently available to large scale commercial fishing enterprises, it is not surprising that wild fish stocks are decreasing. Migratory ocean fish like tuna are routinely tracked with sophisticated satellite and sonar equipment. Factory fleets contain entire seagoing workforces trained to process vast quantities of frozen seafood for the supermarket chillers.

Quota restrictions are ineffective

Most attempts to regulate and control overfishing are based on establishing quota restrictions within national maritime boundaries (exclusive economic zones) and bans on fishing endangered species in international waters.

Regional quotas and other restrictions have altered the commercial fishing industry by favouring well-established organisations at the expense of small or seasonal operators. While economic rationalists might appreciate the inherent efficiency of eliminating weaker competitors, the impact upon most fish stocks has been largely negative. Consider the scenario of a bad fishing season with numerous small operators competing for limited supplies of fish. Under financial necessity, some of the operators may choose to reduce or suspend their fishing activities until stocks improve. The unfilled quota can be sold on to competitors but may not be an attractive proposition unless the competitors own quota can be easily filled. This situation often results in unfilled quota which will then assist the short term recovery of fish populations. When large and well-established operators dominate the fishing industry, there is an increased catch efficiency which tends to override the impact of declining fish populations. This creates fewer opportunities for unfilled quotas and short-term recovery.

At present, there is limited consensus regarding the methods which should be applied to determine effective quotas and restrictions on various endangered fish species. Sceptics of the current system claim that many of the statistical methods used to estimate population densities are flawed, resulting in substantial errors.

Even when there is widespread acknowledgement of serious species decline, there is always the opportunity for significant economic interests to prevail. This is clearly evident in the case of orange roughie which has recently been exposed to an Australian government approved quota in excess of five hundred tonnes each year. While this is modest in comparison to the unrestricted hauls of earlier decades, there is little doubt that current populations are less than ten percent of those existing prior to commercial exploitation in the seventies and eighties. Orange roughie is an extremely popular table fish which inhabits deeper waters and requires many decades to mature. Adult specimens engage in large spawning aggregations, leaving themselves exposed to easy capture. At the height of their seasonal exploitation in the early eighties, up to five tonnes were being removed every hour off the coast of New Zealand.

Illegal fishing

As many wild fish populations continue to decline, those remaining are increasingly vulnerable to the illegal fishing trade. The economic value of seafood has resulted in a sophisticated network of recalcitrants who risk serious penalties and widespread condemnation to generate illicit profits. Unlike the earlier stereotype of small and desperate outfits, most of the illegal operations are now efficient and well resourced. They are financed by international criminals, dubious corporations, and in some instances they operate under the tacit consent of sovereign states and territories.

Eco-labelling

In view of these problems, it is helpful when consumers of seafood can clearly identify those fish which are legally captured in healthy environments under ecologically sustainable guidelines. This approach has been taken in several countries which use eco friendly labelling schemes to encourage long term sustainability within the fishing industry. There are also encouraging efforts to apply similar labelling on an international basis. Ultimately, the success of these initiatives will depend upon developing new collaborative research networks and the uniform approach to practical issues like standardised naming of individual fish species.   

Until recently, ocean based aquaculture has focused on a limited range of fish species. Atlantic salmon remains the predominant species, with smaller stocks of ocean trout, sea bass, cod, and halibut.

The farmed salmon industry began in Scotland and Norway during the seventies and the technology was gradually distributed to other locations, including the southern hemisphere. Today, salmon are intensively farmed in the cool coastal regions of Iceland, North America, Ireland, Chile, Australia, and New Zealand.

When affected by deficient planning or management, seawater farms have the capacity to severely threaten coastal environments and disrupt their natural ecosystems. Choosing an appropriate site is probably the most critical consideration for effective waste management and pollution control. From the perspective of raising large fish with minimal losses, well-protected bodies of water were originally preferred. In many cases their lack of tidal movement caused steady accumulations of uneaten food and fish droppings. A release of nitrogen and other alterations in water chemistry resulted in algal blooms which suffocated and poisoned the fish and other living creatures by depriving them of oxygen. When affected regions were surveyed, their aquatic habitats were often found to be significantly altered. As a result of this, stocks of wild fish were depleted, with several important species failing to recover.

Burdening marine habitats

Like other primary sectors, the aquaculture industry is subject to numerous restrictions imposed to limit the risk of environmental damage and depletion of wild stock species. While several of these restrictions are clearly inadequate or poorly enforced, progress is limited by the small amounts of research undertaken each year. Even when there is conclusive evidence of problems, it may still require years before all of the concerns are addressed in the manner which enables a practical ban or restriction to be imposed. When uncertainties or differences of opinion occur, the process may drag on indefinitely. With the exception of some organic representatives, the conventional aquaculture industry has failed to address many of the concerns raised by scientists monitoring marine habitats and wild fish populations.

Ocean based aquaculture has the potential to influence the health and diversity of wild fish populations in several ways: As described above, the biological waste and pollutants can alter the habitats of wild fish species. There is the ongoing risk of disease and parasites transferring from farmed fish to wild fish stocks. This has already occurred with infectious anaemia and sea lice. Despite best efforts to contain them, farmed salmon do escape in significant numbers. It is assumed that some of these escapees will eventually breed with wild fish of the same or related species. Because farmed salmon are selectively bred for production purposes, their genes can potentially interfere with the process of natural selection occurring among wild stocks.

The real cost of processed pellet food

The Atlantic salmon is largely a carnivorous species, normally dependent on a diet of crustaceans and insects. During their accelerated growth cycles in captivity, they consume several times their adult weight in fish meal and oils which are usually processed as a pellet feed. The raw materials for this are removed in vast quantities from the North Atlantic and Southern Pacific oceans. An excess of five million tons of small pelagic fish are currently required to feed captive salmon stocks every year. The species involved include sardines, herring, anchovies, and mackerel. While still considered abundant, the slow decline for many of these populations is undoubtedly impacting on their natural predators in the ocean. These include many pelagic fish species, migratory birds including penguin, albatross, and the oceanic mammals like seal and dolphin.

It has been suggested that every kilogram of farmed salmon requires two and a half kilograms of fish to be taken from the ocean and processed into farmed stock feed. The apparent inefficiency of salmon farming suggests that ocean resources are being utilised in an unsustainable manner. While several attempts have been made to identify and utilise alternative feed sources, salmon farming remains largely dependent on fish meal.

The future may lie in developing farming technologies for other ocean species, particularly those which provide superior food conversion efficiency.

Despite its emergence as a newly developed primary sector, fish farming can trace its origins to regions of china where it was first practiced several thousand years ago. Edible carp, eel, and catfish, were cultivated in reservoirs linking the canal networks used for crop irrigation. These farms were low intensity by today’s standards and had the advantage of collaborative resource efficiency. Because they used natural materials and sought to maintain the biological integrity of their product the farms were, in effect, organic.

On account of global competition and economic rationalisation, most fish farms are now designed to deliver high yields. In order to meet their production targets, conventional aquaculture farms frequently engage in husbandry practices which are harmful to their stock and potentially unsafe for the consumer.

Controlling the lifecycle of farmed fish

In the wild, fish of the same species will grow and reach sexual maturity at different rates, depending on their local conditions. Water chemistry, temperature, food availability, and population size are some of the factors which contribute to this variable growth.

For commercial fish farmers, there is considerable incentive to control the growth and sexual development of stock. Upon reaching sexual maturity, fish lose weight and decrease their stores of fat. Because this reduces the value of their stock, many conventional producers seek to influence the course of nature. In addition to growth and sexual development, interventions are applied to restrict the physical damage caused by overcrowding, to prevent disease, and to effect alterations in the colour, texture, and flavour of their farmed seafood. In theory, the capacity to control these factors should help to facilitate the most efficient application of resources. With these efficiencies in place, the anticipated outcome is a standardised fish product which can be promoted to consumers as a dependable source of fresh protein.

The reality of conventional fish farming

When stressed by overcrowding, pollution, or changes in their regular environment, farmed salmon are susceptible to disease and parasitic organisms. Infestations of sea lice (lepeophtheirus salmonis) are very common. They interfere with feeding, lower immunity and eventually break down the mucus layer which provides external protection against bacterial infection. Without treatment, fish usually succumb to a slow and agonising death.

Most conventional fish farms treat serious infestations with organophosphate pesticide. Despite claims to the contrary, these chemicals contaminate a significant proportion of conventionally farmed seafood. They contribute to a combined toxic load which can include polychlorinated biphenyls (PCBs), dioxins, and heavy metals like mercury. Sea lice are less problematic when fish populations are restricted to environmentally sustainable levels. Salmon raised on overcrowded farms may require antibiotics and other medications to control inflammatory tumours which debilitate and kill large numbers of fish every year. Seriously contagious diseases such as infectious anaemia have the potential to wipe out significant stocks of farmed fish. In the United Kingdom, outbreaks of this disease must be reported. Since no effective treatments are currently available, the usual obligation is to destroy the afflicted stocks.

Wild salmon eat a varied diet which is particularly rich in crustaceans. Their natural red colouring comes from the keratin protein of shrimp, crabs, and other shelled creatures. When farmed on a diet of processed fish meal, their flesh becomes pale pink or an unpalatable grey colour. Since consumers expect their salmon to be brightly coloured, most conventional farmers supplement their feed with artificial colouring agents like canthaxanthin and astaxanthin. Some organic farmers use a yeast compound to enhance the colour of their product while others achieve a brighter colour by including crustacean shells in their feed.

Genetic modification

In recent years, several fish species have been genetically modified in efforts to improve their cost efficiency and manageability as commercially farmed stock. The biotechnology scientists have experimented with gene manipulation to alter food conversion efficiency in farmed salmon and trout. They have attempted to increase the fish’s capacity to withstand extreme cold by inserting mammalian growth hormone genes into fertilised fish eggs to encourage accelerated growth and weight gain. These technologies are often widely condemned when applied to conventionally farmed land animals. In the case of fish, many consumers are confused or genuinely surprised to be informed of them. Unless there is an adequate evaluation of the health and environmental consequences of these technologies, consumers are advised to avoid them. The alternative is to obtain unaltered seafood captured from the wild, or to consider farmed products with an organic certification.

According to most accounts, the organic movement was established in response to problems associated with conventional crop agriculture. Shortly after the Second World War the industrialised manufacture and widespread use of agricultural fertilisers, pesticides, and other chemicals had permanently changed the way crops were grown, distributed, and sold to the consumer. In contrast to earlier times, most agriculture became highly specialised, capital intensive and the scale of commercial operations increased dramatically.

In response to these developments, ecologists and consumer groups were learning about the environmental impact and the consequences for human health. A drive for environmental awareness and sustainability during the sixties and seventies revealed many disturbing facts. Among these, it was widely reported that agricultural chemicals were being routinely detected in marine organisms.

For some reason, the problem of the oceans slipped easily from public consciousness. Perhaps this was due to their inaccessibility or the fact that relatively few individuals depended on the sea for the majority of their food resources. It is also true that commercial exploitation of the oceans lagged several decades behind that experienced on the land.

Prior to the seventies, most aquaculture was based on traditional practices and did not impact heavily upon the environment or human health. This changed rapidly with the emergence of new technologies and economic incentives which encouraged intensive farmed production of several fish and shellfish species.

Like the response to land based agriculture, the trend towards organic aquaculture is developing through the cooperation and shared interests of ethical producers and consumers. At the present time, a small quantity of farmed seafood is organically certified. Because the dependence on wild caught seafood is likely to continue, there may be some legitimacy in current arguments to include sustainable harvesting operations within the organic umbrella.

The way forward

Sustainable and organic practices are a relatively new development in ocean-based aquaculture. In order to achieve their provisional organic status, aquatic farms must establish a range of ecologically sound practices which include their commitment to stock welfare, habitat protection, prohibitions on chemical use, and consumer safety. A distinctive characteristic of most organic farms is their scale of operation. By raising smaller quantities of fish, the potential for disease and habitat degradation is significantly decreased. This assists organic sea farmers in maintaining high standards of product quality and also increases their ability to respond quickly to consumer demands and preferences.

At present, most of the organic standards established for aquaculture are preliminary and incomplete. This is well demonstrated by the absence of consensus regarding the sustainability of industry practices with regard to natural resources. The majority of conventional and organically certified salmon farms are dependent on the large-scale harvest of oceanic fish stocks each year. The harvested fish are processed into pellets which still provide the principle feed supply for captive salmon stocks.

Several organic certifiers have commissioned preliminary research to investigate alternative processed feeds as well as opportunities for raising live feed for captive salmon. In the absence of a fully developed standard, the organic certification authorities contribute various elements of their own philosophy. At times this has been frustrating for producers and consumers, but the popularity of organic produce continues to gain strength partly on account of its perceived integrity and dedication to such processes.

Location, reputation and stock management practices

With the interest of promoting themselves in a positive way, several of the larger organic seafood farms have used the internet and other resources to provide consumers with additional information about their organization’s philosophy and stock management procedures. While the information is informative, there appears to be an emphasis on focusing on certain aspects which can effectively differentiate their organic product from others. For example, there are organic fish farms now operating in Malaysia which outline the benefits of their fully enclosed and tightly controlled artificial environments. The farmers of organic salmon situated on the Orkney Islands of Northern Scotland promote the advantages of their own remote location and refer to the regions longstanding reputation for high quality standards and the purity of its natural produce. In Canada, one organic producer has highlighted the fact that their captive fish stocks are based on native species. They claim to have reduced the ecological risk of displacement which can occur whenever introduced fish escape and compete with native stocks for their habitats and food resources.

As the range of organically farmed seafood products continues to increase, the marketing aspect will intensify. This should enable consumers to identify the important product features which motivate their decision to choose organic. 

Pushing the boundaries

While representatives of the farmed seafood sector have slowly increased their status with various organic and food certification authorities, the companies and individuals involved in the harvest of wild stocks have been largely unsuccessful. The appeals for their legitimate inclusion within the organic umbrella have been rejected on several counts. At a fundamental level, the certification bodies have been established to regulate those items which are clearly produced or manufactured with human intervention. Wild seafood stocks captured from oceans, coastal estuaries, and rivers are not generally considered to fall within this category. Secondly, it is very difficult, if not impossible to control the living conditions of species in the wild. Due to repeated failures of legislation and management, most natural habitats are now affected by a range of industrial pollutants, agricultural chemicals, and the disease and ecological imbalances caused by introduced species.

In refusing organic status to wild caught fish, the certification authorities are less convincing when they refer to the depletion of wild stocks as a consequence of commercial fishing activities. When pressed, most of the certification authorities admit their interest in protecting the equity contained in their public identity and reputation among consumers. In effect, the certifiers are sustained by consumers who agree to pay a premium for their organic produce. At the present time there is insufficient motivation to extend the established boundaries which separate organic farmed fish and those harvested from the wild.