Opportunities and limits of aquaculture

Dossier

Tilapia aquaculture (© Thünen-Institut/Katja Seifert)

With an annual growth rate of approximately 8% aquaculture is the strongest growing agricultural sector worldwide. Today already half of the world’s fish demand is met by aquaculture.


Necessary growth

Unlike capture fisheries, aquaculture produces fish, crustaceans, shellfish or algae under controlled conditions. Since the capture/wild fishery has already brought a number of fish stocks to the brink of extinction, the growth limits of this production system have almost been met. Aquaculture is becoming increasingly important as a food supplier to secure the protein requirements of the growing world human population. However, fish need animal protein in their own diet. Depending on the type production system, animal protein must be supplied in aquaculture.

Protein requires protein

Wheat gluten and fish meal (© Thünen-Institut/Katja Seifert)

Until a few years ago protein feed for fish consisted mainly of fishmeal. Because of its balanced composition of essential amino acids and good digestibility animal protein is particularly well suited for the production of fish feed. As protein feed prices have risen sharply, fishmeal is now increasingly being replaced by vegetable proteins, which are produced as by-products or partly sustainable at low-cost. Unfortunately, in terms of digestibility, vegetable proteins are significantly less efficient compared with fish meal.  As a consequence fish fed with vegetable protein grow more slowly. In commercial aquaculture only a portion of the fish meal is replaced in the compound-feed ration.

Old and new risks

Aquaculture: important both environmentally and socio-economically (© Thünen-Institut/Tobias Lasner)

Especially in the industrial fish farms - such as for the breeding of salmon, mussels and shellfish particularly in Southeast Asia - environmental impacts are becoming more and more problematic. Excess feed contaminates the seabed, resulting in rotting residues and endangered habitats. Diseases spread, widely applied antibiotics remain in the fish bodies and resistances are spreading. To solve both the ecological and socio-economic problems of aquaculture, scientists, policy-makers and fish producers must address these long-term, complicated tasks.

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