Mystic Aquarium

In zoos and aquariums the staple diet for marine mammals and piscivorus (fish-eating) birds is freshly thawed, previously frozen fish and squid. Challenges to these facilities include the procurement of quality food-grade fish and the maintenance of diet diversity as over-harvesting has lead to a diminished supply of some species of fish that were once considered dietary staples of captive marine mammals.

The depletion of natural populations of wild fish to feed captive animals is in direct conflict with the conservation directives of most zoological institutions. The development of a consistent and easily obtainable prepared fish analog utilizing underexploited “trash fish” to supplement standard frozen fish diets is important for maintaining high quality nutrition and reducing dependence on declining wild fish stocks.

In 1996, MAZURI (a zoological brand of diet marketed by Purina Mills, St. Louis , MO ) produced a palatable gel-based fish substitute. Thus far, research evaluating fish analog diets in marine mammals has focused on palatability only. The study being conducted by scientists at Mystic Aquarium is unique in that it will evaluate measures of health status in addition to evaluating palatability of the fish substitute in beluga whales. Body condition (girth, blubber thickness), blood chemistry, vitamin A and E levels, components of the somatotropic axis, immune function and GI function will be our measures of health status evaluated on a bi-monthly basis.