Industrial-scale fishing of most of the commercial species of fish has exceeded their reproductive capacity for recruitment. Overfishing, destructive fishing methods, widespread harvesting of broodfish, capturing of virgin class, degradation of habitat and ecological connectivity, loss of marine biodiversity and the impact of climate change have threatened the sustainability of our commercial seafood supply as never before. Decline in catch per unit effort and proportion of larger-sized fish in the catch, as well as change in catch composition are among the very visible signs of the problem.
To bridge the widening gap between the supply and demand of seafood, the aquacultural industry has been expanding at the rate of 10%, which makes it the fastest growing food producing sector. Global fish productions, according to the Food and Agriculture Organization amounts to 154 million tons. From this, capture fisheries contributes 90.4 million tons, while aquaculture contributes 63.6 million tons.
The rapid growth of aquaculture has taken sharp criticism for adverse environmental impacts, directed at the technology-driven industrial-scale aquaculture. Discharge of effluents, use of antibiotics and dependence on fish meal and oil have compromised the image of aquaculture as a responsible supplier of seafood.
We are now witnessing a surge of interest in a new approach that envisages environmental concerns which are not just about mitigating its impact, but actively contributing to solution of many environmental problems.
This new perspective is termed ‘Ecological Aquaculture’. It offers a framework for the sustainability of seafood production, environmental compatibility of production methods and responsibility towards public health.
Innovative ideas, best practices in environmental management, mitigation and enhancement of aquatic ecosystem can make ecological aquaculture a commercial venture worth pursuing. Being new, it is still a work-in-progress towards the ‘blue revolution’. There is no alternative to the blue revolution at a time when the population is growing and seeking high-quality seafood, and when land-based food production is challenged by erratic and extreme weather conditions. In this new paradigm, problems are considered as opportunities and remind us to conduct our activities in harmony with natural processes, thus motivating us to learn from nature and bring into practice the methods that simulate conditions that use inherent mechanisms to sustain production. In this context, the opinion of Peter Drucker, Economist and Nobel Laureate, “Aquaculture, not the internet, represents the most promising investment opportunity of the 21st century” resonates with the ground realities and make a lot of sense. If the 21st century aquaculture is ‘Ecological Aquaculture’, these words of wisdom find a common ground with the new ecological vision for modern and future aquaculture ventures.
The Integrated Multi-Trophic Aquaculture (IMTA) is a system which represents an ideal model of ecological aquaculture. It combines multiple species wherein waste from one species serves as input (food or fertilizer) for another. Species used in fed aquaculture (for example, fish and shrimp) are integrated with inorganic extractive species (for example, seaweed) and organic extractives (for example, shellfish). This creates a balanced system for bioremediation, economic benefits (lower cost, better output and product diversification) and public acceptance due to responsible means of production employed.
The operation of the IMTA system is based on synergism that multiples yield and respects the health of the environment and that of consumers. Obviously, the quality of the environment and biodiversity are important. In IMTA aquaculture, we start with water and food chain. If the necessary links in the food chain are available, there is no need for external inputs of artificially formulated feed. In fed aquaculture, the dietary ingredients originating from prey fish do not make aquaculture a positive contributor to aquatic production, since the farmed carnivorous fish consume a greater quantity of prey fish compared to production of their own biomass. The ecological aquaculture capitalizes on insights into primitive systems but embraces modern knowledge and technology to make industrial-scale use of natural wisdom.
With a more intensive and focused research, the IMTA will yield impressive outputs and be able to attract small and medium enterprises as well as industries seeking to penetrate organic food and blue label markets. Topics such as bioremediation of water quality in the culture system using nitrifying bacteria, new products that provide surfaces for these bacteria to build their density such as Aquamats and CrystalBio, engineering designs for effective recirculating aquaculture systems, and efficient filters and diffusers need more R & D investment.
While we should continue intensive research in various forms of low carbon or zero carbon seafood production systems, we still need to make progress in aquaculture of target species where so much has been invested and which continue to contribute substantially to the total aquaculture production. One such example is the culture of coral reef fish, particularly groupers. Groupers are the most sought-after species in south-east Asia and other regions. They are the main species in live fish trade and export. The insatiable demand for groupers has led to destructive methods of fishing in coral reef areas which are marine biodiversity hotspots. The grouper seed production in the hatcheries remains insufficient or unsustainable, unable to meet the demand. There are problems related to high cost of broodstock, sex differentiation, fertility, low larval survival, limited space in hatcheries for conditioning of sufficient number of broodstock and red tides in case they are held in sea cages. Hybrids produced by crossing high value species such as giant grouper (Epinephelus lanceolatus) and tiger grouper (E. fuscoguttatus) to some extent addressed the shortage of seed supply, though it remains to be seen if the F1 generation is fertile (capable of producing the next generation) and more resistant to environmental variability and disease challenge.
The humphead wrasse is long lived, but has a very slow breeding rate. Its numbers have declined due to a number of threats, such as:
1. Intensive and species-specific removal in the live reef food fish trade.
2. Spearfishing at night with SCUBA gear.
3. Destructive fishing techniques, including sodium cyanide and dynamite.
4. Habitat loss and degradation.
5. Juveniles being taken from the wild and raised or “cultured” in floating net cages until saleable size.
6. A developing export market for juvenile humphead wrasse for the marine aquarium trade.
7. Lack of coordinated, consistent national and regional management.
8. Illegal, unregulated, or unreported (IUU) fisheries.
In December 2003, Australia prohibited all take and possession of humphead wrasse, other than for limited educational purposes and public display. In the Guangdong province, southern mainland China, permits are required for the sale of this species; Indonesia allows fishing only for research, mariculture, and licensed artisanal fishing; the Maldives instituted an export ban in 1995; Papua New Guinea prohibits export of fish over 2 feet (65 cm) Total Length; and Niue has banned all fishing for this species. The humphead wrasse is a U.S. National Marine Fisheries Service Species of Concern. Species of Concern are those species about which the U.S. Government’s National Oceanic and Atmospheric Administration, National Marine Fisheries Service, has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S. Endangered Species ACT (ESA).
OCEAN ACIDIFICATION AND THRESHOLD LIMITS
The resilience of the current systems of farming and of the species to our changing climate has not been established. It is something that we can ignore at the peril of the sustainability of the aquaculture industry and seafood security. A major part of the aquaculture production is done in sea cages and sea water is undergoing acidification as a result of the changing climate. The pH of seawater is reported to have declined from 8.25 to 8.14 between 1951 and 1994, representing an increase of 30% in the acidity (H+ concentration). The rate at which ocean acidification is taking place now is far greater than in the past 20 million years. Marine organisms develop adaptations to the environment over a long period of evolution. This acidification rate is too fast for them to adapt to, however. It is imperative to introduce climate change adaptations in aquaculture as fast as we can to prevent a disruption of our seafood supply chain.
The concept of ecological aquaculture should also be linked to sustainable seafood solutions. It can be viewed as a fundamental element in the solution to provide a sustainable seafood source that helps to satisfy the fish demand while providing a healing touch to the highly stressed capture fisheries.
For aquaculture to help fisheries, it has to be compatible with environment. While reducing pressure on the wild population is extremely important, the population restoration by hatchery-produced seed should be pursued in responsible ways. Worth mentioning in this connection is the humphead wrasse (Cheilinus undulates). It is the largest and the most expensive coral reef fish in the world. The fishing pressure on this particular species has been so intense that it has led to local extinction of this species in many places where its populations once thrived. This species is now protected under the Convention on International Trade in Endangered Species (CITES). Aquaculture of humphead wrasse can potentially meet the market demand and contribute to conserving the wild populations by way of breed-and-release strategy. There are numerous challenges in the aquaculture of the humphead wrasse, but research can address those challenges.
At the hatchery of the Borneo Marine Research Institute, studies are being carried out on broodstock conditioning, behaviour, nutrition and growth. Because of late maturity, progress of research on captive breeding of the humphead wrasse will take time. Trials on stock rebuilding of shrimp have started in Sabah. Success of this project will depend on the progress of our ecosystem restoration and on the cooperation of the community, not only in control of fishing operations but also in maintaining the health of the environment where shrimp ranching is being carried out.
In conclusion, the blue revolution is a key to seafood security. It should guide research and development oriented towards reviewing the aquaculture practices and preparing the enterprise for bold reforms. The cost of inaction will be far greater than the cost of investment in research.
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