Agriculture and Environment: Shrimp

Better Management Practices: Reduce Use of Fish Meal

Most shrimp farmers are becoming more efficient in managing the feed conversion ratios (FCRs) on their farms.

As a consequence, they are using less fish meal. A smaller number of producers are actually trying to reduce not only overall feed use, but the actual proportion of fish meal in the feed as well.


Ideally, farmers should produce their shrimp with an amount of fish meal that represents a weight of wild fish that is equal to or less than the shrimp being produced. It may take some time to achieve this ideal throughout the industry, however.

Focussing on omnivorous shrimp species
There are several ways that fish meal use can be reduced. For example, omnivorous shrimp require less fish meal than carnivorous species. (As an aside, fish in general are the only carnivores that are still consumed in any quantity by people.)

Farmers should focus on omnivorous species. In addition, domestication programs should focus on omnivorous species. Moving aquaculture production down the food chain will reduce considerably its overall environmental impact.

Some shrimp producers have reduced fish meal use to such an extent that they can produce a kilogram of shrimp using only 0.7 kilograms of wild fish as feed. In part, the success has been due to increasing the production of food within the water column. Part of such success also has been achieved by converting production from more carnivorous to more omnivorous shrimp species.

Large operational costs for shrimp farmers
Given that feed is the largest single operational cost of most shrimp farmers (some 40-60% of total costs) and the industry spends some $1.5 billion on shrimp feed, using feed more efficiently is an area that will assume far more importance in the future as the markets become more competitive (World Bank et al. 2002).

Another way that shrimp farmers have fund to reduce fish meal use and the overall cost of producing shrimp is to shorten production cycles and harvest earlier. By harvesting aquaculture shrimp at an earlier stage, farmers are able to use less feed of any kind, and this has considerable implications for the amount of fish meal that is used.

The downside is that the shrimp are smaller and tend to be sold with their heads on. Neither of these characteristics is valued in the U.S. market. However, in many parts of the world intact shrimp are more highly valued because it is clear that they are not diseased.

Finally, another strategy to improve feeding efficiency and conversion ratios is to use feeds that are inoculated with beneficial microbes that help improve feed digestion and assimilation. Experiments with this have occurred in both Thailand and Costa Rica (Panfilo Tabora, personal communication).

Credits

Extracts from "World Agriculture & Environment" by Jason Clay - buy the book online from Island Press

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