To survive, fish raised in the hatchery must have the ability to evade predators, forage for the proper food, and be able to blend into their surroundings. Much of our research looks at how well cultured fish handle these challenges after release, and how we can help them get up to speed with their wild counterparts.
- Cultured fish must be able to recognize, react, and avoid potential predators. Our studies have shown that while cultured winter flounder are more vulnerable than wild fish to predation by birds, predator conditioning and training is possible. In the future we plan to explore the impact of exposing cultured fish to predators in the hatchery. The work will explore whether cultured fish that witness predation are more apt to evade predators in the future, and whether fish that have been exposed to predation are able to “lead” uninitiated fish.
- Cultured fish must be able to adapt from being fed pellets several times a day to foraging, selecting, and capturing the right food once released in the wild. We‘ve found they will do this within two weeks, and it usually happens within the first four days after release. However, hatchery-reared fish sometimes eat small blue mussels which are similar in color, shape, and size to formulated feed, but do not have the same nutritive value. We are designing a series of diet trial and field cage studies that evaluate how fish raised on different feed adapt to foraging for food in the estuary. Part of this work will explore the viability and effectiveness of using different live feed cultures in the hatchery, such as mysids, polychaetes, other worms, or larger sized Artemia.
- Cultured fish must be able to blend into their environment, either by changing their color and pattern to match the background, or by selecting sediment similar to their own color and markings, or by burrowing quickly into the bottom—a particular challenge for fish raised in fiberglass tanks. When we add sand and sediment to tanks in the hatchery, our flounder have demonstrated the ability to select sediments with both grain size and color that most closely match their own pigment, and burrow quickly into the sediment substrate.