Since 2000, global piscivorous aquaculture has developed into a major food production system. This expansion has resulted in the exploitation of wild fish for feed and adverse impacts on ecosystems, but onshore recirculating systems, polyculture techniques, and plant-based diets have reduced these problems.
Extractive molluscs and algae have also doubled in volume and provide ecosystem services. However, they are still a small fraction of global aquaculture.
Fish
Over the past two decades, growing demand for seafood and a shift toward more nutritious diets have led to increased production of farmed fish species. In addition to supplying a broad range of foods, aquaculture products are used in other industries, including the production of fuels, pharmaceuticals and cosmetics.
Fish farming can take place in recirculating tanks or ponds (aquaponics), lakes or other bodies of water, such as ocean ranching; on fenced/enclosed sections of open sea away from shore (offshore aquaculture); or in artificial facilities such as raceways, ponds or net pens.
The earliest stage of fish aquaculture is the hatchery, where breeding, egg incubation and rearing through early life stages takes place. Then the fish are moved to the farm, where they are raised to harvest size. Aquaculture also includes recirculating systems where the water is filtered, reused and recycled. This system reduces the use of pesticides, antibiotics and other chemicals in the fish feed and improves the quality of the harvested fish.
Molluscs
Mollusc aquaculture is a substantial contributor to global marine seafood production. However, molluscs are susceptible to infectious diseases that can devastate production. Genetic improvements in resistance are therefore key to reducing the impact of these diseases on molluscan production.
While selective breeding has been successful in many major agricultural and finfish species, molluscan breeding programmes require tailored approaches due to their distinctive reproductive and life history characteristics. Genome editing has the potential to accelerate this development by allowing a more targeted identification of functional variants affecting disease resistance traits.
The main molluscan aquaculture species in Peninsular Malaysia are true oysters (Crassostrea belcheri & C. iredalei), green-lipped mussel (P. viridis), and blood cockle (Tegillarca granosa). However, more R&D is needed to expand the shelled mollusc farming industry, especially for non-native species. This includes research into culture methods, stock management, and potential culture sites.
Seaweed
Seaweeds are any of thousands of species of red, green, brown, or black marine algae that grow along the ocean shore. They are anchored to the sea floor or other solid surfaces by rootlike “holdfasts” that perform just that single function and extract no nutrients like the roots of higher plants.
Doumeizel and other advocates of the fast-growing seaweed industry see it as part of a solution to many social and environmental problems. Seaweeds don’t need fresh water or arable land, they can be grown in large amounts on a small area of the ocean surface, and their production absorbs CO2, counteracts acidification, and helps remove run-off nutrients that pollute marine life and terrestrial ecosystems.
The ASC and MSC have endorsed a joint standard for environmentally sustainable and socially responsible seaweed harvesting and farming that requires a third party conformity assessment body to audit operations (see our Get Certified guide). These requirements are meant to minimize the impacts of seaweed farms on natural habitats and biodiversity, including the physical structure of aquatic environments, primary and secondary productivity, and native fisheries.
Aquaponics
Aquaponics is a food-growing method that utilizes fish and plants in a recirculating system. The plant kingdom recycles its waste through nitrifying bacteria and the resulting nutrients are provided to the fish in a closed loop.
Achieving a successful aquaponics operation requires close control of many different parameters. Among these are nutrient balance, maintaining optimal conditions for fish and plants, water quality and the ability to grow enough nitrifying bacteria to keep up with the fish’s waste.
The type of media used for the growing beds in aquaponics is important. It should be inert, with a good porosity for healthy nitrifying bacteria and good handling properties.
Prospective aquaponic producers should also consider their market and whether there is a segment willing to pay premium prices for fresh, locally grown vegetables and herbs. They should also carefully consider production costs and what their break-even point will be. This will help them decide how large a system to build.
