Most marine fish (and invertebrates) have a complex life cycle that involves a dispersing, planktonic larval stage—the time from egg hatching to juvenile development. These fish generally produce high numbers of eggs with larvae that develop in the open ocean for long periods (weeks to months).
Fish larvae are fascinating animals. They are rarely seen underwater; enormously diverse in their developmental patterns; and physiologically, morphologically, behaviorally, and ecologically different from adult fishes. At hatching, they are generally microscopic (2–4 mm) and undeveloped, living off yolk, and incapable of feeding and swimming against currents. They learn to swim, hunt, and avoid predators as they mature through various stages. Many fish larvae are odd looking and have temporary specializations to survive in the pelagic environment such as freakishly large fins, heads, or eyes, as well as intricate and/or elongated spines, body armor, and/or various pigment patterns. When larvae are close to transitioning into juveniles, they typically use the sun, currents, and reef sounds and smells to find a new home. They make their final approach at night because the reef has many larval predators. Divers rarely encounter fish larvae. In fact, less than 10 percent of fish larvae have been described, much less photographed. Fish larvae are important in many aspects of aquaculture, fisheries conservation, and biology.
The Larval Fish Project utilizes wild egg collection, hatchery spawning, and larval rearing techniques to study the reproductive patterns, culture requirements, and larval development of marine fish. Its specific objectives are to:
- identify spawning areas and times;
- develop culture protocols;
- show the diverse morphology, pigmentation, and natural beauty of live marine larvae using photography.
The project raises fish larvae from hatchery spawned eggs as well as eggs collected from the ocean to allow for the rearing of more species. Fish larvae are cultured through settlement in small 10–20 gallon (37–75 L) tanks using microalgae and live foods; including wild and cultured copepod nauplii, rotifers, ciliates and artemia.
Fifty-five species from 26 families have been reared through settlement since 2011.
Fish Species Cultured from Egg to Juvenile for the Hawaii Larval Fish Project
Baensch, F. 2014. The Hawaii Larval Fish Project. CORAL 11 (2): 64–77. PDF available upon request.