Tuesday, February 10, 2009

Forage Fish: challenged to support aquafarming and the marine ecosystem balance

In previous posts I have referred to the challenges and potential of aquafarming. While it holds considerable promise in meeting the commercial demand for seafood, it is an industry in its infancy and is experiencing its technological growing pains as it addresses issues from parasite control to pollution from the waste products of concentrated, confined fish populations.

Another challenge cited in a recent issue of Annual Review of Environment and Resources has to do with the feeding of aquafarmed fish. Small to medium-size fish like anchovies, sardines, and mackerel - often referred to as forage fish - are being harvested in great numbers to feed poultry, pigs and other terrestrial animals. That puts enough pressure on the populations of forage fish as it is, but now there is the added pressure of supplying them to the growing aquafarm industry. This further deprives pelagic predators and many seabirds of a primary food source.

When I engage audiences in discussing the importance of apex predators like sharks, I often refer to the predator-prey pyramid. This hierarchy of survival is depicted as a pyramid because at the wide base of the pyramid are the plankton and small forage fish - available in large numbers because of a high reproductive rate - which serve as a foundation. And as you ascend up the pyramid to larger and larger predators, the pyramid narrows, representing nature's ability to control those populations through reduced reproductivity.

All well and good but as we continue to harvest more and more forage fish, which are relatively easy to catch, we begin to undermine the foundations of that pyramid. This not only impacts nature's balance and reduces the forage fish populations and potentially the animals that feed on them, but it also affects commercial demand and the price of forage fish can increase - which hampers developing nations who rely on forage fish for food and to build aquafarming as a viable alternative to other negative fishing practices.

As we jockey resources in an attempt to fulfill our needs, we may ultimately have to address the 800-pound gorilla in the room that we have tried to ignore: 6.7 billion people and rising.

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