Impacts of Aquaculture
Weighing the Effects of an Industry
As an industry, aquaculture has the potential to be a sustainable source of seafood that could help to alleviate some of the pressure on the world’s oceans as a food source. Yet there are several downsides that must be considered.
Feeding Carnivores: Assessing the Use of Fish Meal to Feed Farmed Fish
One of the biggest detractors from the sustainability of some types of aquaculture is the use of fish meal as a food for the farmed fish. Fish meal, a mixture of chopped up fish and fish oil, is produced from the waste of fish production and from the input of wild bait fish that are caught specifically for the meal.
The major aquaculture that makes use of fish meal is the farming of salmonids and other carnivorous fish. For salmon, it can take an estimated two to three pounds of protein input in feed to yield one pound of salmon meat. This is still a negative impact on the ocean overall when it’s considered that the input is greater than the output.
Taking a page from farms that specialize in omnivorous fish, such as Tilapia, it’s been thought a response to the problem of fish meal is to create feeds that are based on vegetable protein rather than animal protein. This would relieve some of the pressure on fish stocks in the ocean by eliminating the need to catch fish to feed those that are being farmed.
Environmental Impacts: Changing the Natural Habitat to an Unnatural One
One of the major concerns of establishing aquaculture is its impact on the surrounding environment. Because many of the animals that are farmed have several stages in their life history, it is common that several different types of enclosures must exist in one facility.
As the number and types of enclosures increases, so does the risk for the deposit of wastes from the facility. The wastes can come in many forms, but there are two categories that are of particular concern: biological waste and chemical waste.
Biological waste can be anything from extra food in pens building up on the bottom to the large amounts of waste from the fish contaminating the surrounding water. Biological wastes are of particular concern because they can lead to an overabundance of nutrients, like nitrogen, in the water that could create dangerous algal blooms.
Chemical wastes, like those from extra fish medications, are a concern because their presence in the environment could make it toxic to other naturally occurring organisms. Chemical wastes are also a lot harder to get rid of than biological wastes because they have a tendency to build up in an environment and can remain there for extensive periods of time.
Risk to Wild Stocks: Risk of Disease and Competition from Farm Escapees
One of the biggest concerns of aquaculture is its impact on wild stocks. These include the risk of disease transmission and what happens to the wild stock when farmed fish escape from pens.
Since farmed fish live in often crowded conditions, with the maximum amount of fish occupying a given space, diseases or parasites have ample opportunity to foster and eventually could be transmitted to the wild fish.
This becomes especially likely if farmed fish escape from the enclosures. Unless the fish are kept in enclosures that are strictly isolated from the natural environment, there is a chance of escapees.
The concern is that when these fish escape they will transmit disease or parasites that the wild stocks have no natural defenses for. This would give the farmed fish a competitive advantage, which some say put the wild stocks at risk of being overrun by escaped farm fish.
While there are still risks involved with aquaculture, there is much work being done to lower the risks and increase the benefits of the industry.
Fish Farm
|
What do you think about this article?
More in Science & Nature
Latest Articles