1.6 Obstacles in Aquaculture

Similar to terrestrial livestock production, aquaculturists need to manage both environmental factors—water quality as well as diseases and parasites. Suitable conditions are required for a production facility to be sited. Often, the water source and species cultured are the biggest determinants.

Environmental Factors

Environmental factors involved with aquaculture production can be visualized as an ecological footprint including what is taken from and discharged into the surrounding environment and ecosystem. The largest facilities cause apparent cost sooner than smaller production units. If the species produced must depend on wild-caught fry to rear, the environmental cost could include depletion of decreased wild populations if fry are depleted excessively.

Another environmental consideration is the cost of invasive species that are sometimes introduced for food or ornamental purposes and then appear in the surrounding environment through escape or release. Some of these invasive species can outcompete and replace the native species. Some invasives will take over natural food sources, eliminate breeding places, or consume gametes or fry of native species.^[1]

Disease and Parasites

Disease and parasites are natural to all living animals including cultured aquatic animals. As production increases in a given volume of production water, so does the likely increased presence of pathogens and parasites. If a species does not have its nutritional requirements when it first comes into cultivation, the wild-caught fish are stressed and can be an open source of disease and parasites. The disease risk from this level of biosecurity is high and often leads to severe economic losses. Parasites will be discussed in Chapter 3, and infectious disease will be covered in Chapter 6. A high level of biosecurity is required for dense livestock production facilities. Biosecurity is discussed in more detail in Chapter 12.

Nutrition

Feed and nutrition are discussed in more detail in Chapter 6. The nutritional requirements are being worked out for the more widely produced food fish, but many emerging species are few generations removed from native or wild fish and do not have appropriate commercial diets.

There are serious hurdles when a new species is brought into captive production. But what does a species eat in its native habitat? Will the new species accept substitutions? Wild-caught fish are fed to several food-producing animals. The nutrition may not be complete since the entire diet is not being provided. Nutritional deficiencies become apparent and economic losses occur when nutrition and accepted feed are not provided. The larval fish are often the most difficult to satisfy given their small mouth gapes. Live feeds (invertebrates) are used universally in some fashion to give needed nutrients. Serious efforts are being put into research on prepared diets for fry and juvenile life stages. Success in fry nutrition will contribute to greater survivability in more species. Some species still suffer from under 10% larval survival. Much of the loss is from the correct presentation or nutritional needs of the species at that life stage not being met.

Economics

Markets and economics are key components of success. Will the market be local, national, or international? Is the product able to be shipped? How far? How much product can be supplied to the market? Can the market tolerate shortfalls in production? More species are rising to the level of international trade, and the trade is expanding for other species. Potential species considered to be important in the world market are typically high-value products. Atlantic salmon is one such example that can be sold at a profitable price in almost any market interested in consuming it.^[2]

While world markets are desirable, the greatest portion of aquaculture production is utilized more locally. China holds the status of the world’s largest aquaculture producer. The majority of aquaculture production is done in ponds.^[3] Small-scale production units make up the majority of facilities in China ^[4] and across Asia, where over 75% of the global aquaculture production occurs.