Abstract

With increasing awareness of the precarious status of natural fish populations, the need for renewable and sustainable foods that can be integrated into the diets for captive marine birds and mammals becomes more critical.

To achieve an appropriate diet replacement for fish, that food item must be:

1.  Palatable

2.  Nutritionally adequate

3.  Cost effective

4.  Readily available

To date, a number of key milestones have been reached in developing a replacement diet, however, additional research and refinement will be required before a final product is ready for widespread distribution.

A gel type feed has been developed which allows a flexible, smooth-surfaced product which can be produced in a variety of sizes suitable for the target species. This product has been demonstrated as palatable across multiple species, including penguins, seals and sea lions. Most recently, as part of a preliminary study, the product has also been accepted by bottle-nosed dolphins.

Exact nutrient requirements for these fish-eating species have not yet been adequately quantified. As a result, this food has been formulated to closely match the nutrient profile of live fish. A limited set of feeding trials conducted with mature gentoo, rockhopper and king penguins indicate the product delivers adequate nutrition to maintain body weight and condition for 10 mo. Additionally, from 60 days to fledge, king penguin chicks hand-fed the gel type feed grew at rates comparable to those hand-fed a diet of fish. Finally, California sea lions and seals have been maintained with this diet as a supplement to the traditional fish diet for nearly 2 yr.

During the development period, a number of unanticipated benefits of this type of diet technology have been discovered. The first of which are the benefits to animal health. During manufacturing the product goes through a pasteurization process that significantly reduces any bacterial load. The second benefit is the flexibility of the final nutrient formulation. For the first time, complete diets can be formulated for fish-eating species to study various or specific nutritional parameters through the manipulation of the feed.

Finally, the scope of species that may benefit from this technology reaches far beyond those that have been tested to date.

At present, the diet has a cost that is comparable to the market price of high quality fish. Because the major components used in producing the diet are commonly available food industry ingredients, the problematic or seasonal availability of this product should not be a concern.