This invention relates to a system and apparatus for cultivating and harvesting shell fish, such as oysters.
Most oysters are recovered commercially from natural oyster reefs by relatively crude harvesting procedures that usually include the hand picking of the oysters from the reef with the use of hand manipulatable tongs but sometimes without even the aid of such equipment. Such approaches to harvesting the oysters are expensive and require considerable labor that is both grueling and fatiguing to the worker. Apart from the harvesting problems which confront the shell fish industry, many coastal waters have become polluted and this has given rise to laws and regulations which preclude the commercial recovery of the oysters from the reef habitats located in the polluted areas. All of this is leading the shell fish industry toward the adoption of commercial rather than natural cultivation procedures.
In the natural development of the mature oyster, the water borne spat seeks out an appropriate base to adhere to and thereafter develop into the mature oyster. An oyster shell per se is especially attractive as a base for such spats and this of course accounts for the development of the natural reefs. Commercially, various materials may be used as the cultch or base for attracting the spats, although oyster shells are frequently preferred. In some commercial practices, the cultch material is simply dispersed along the water bottom in the selected water area. This is not the most favorable approach to commercial cultivation of oysters however, since shifting bottom sands, sediment and mud frequently cover the cultch and render it useless for its intended purposes. Apart from this, the bottom locations for maturity of the oysters provide little opportunity to change or improve on the current harvesting procedures.
The oyster has many natural enemies, among which can be mentioned Thor's the conch, leeches, boring clams, fungus, and the encrustating organisms, such as amorphous sponges, barnacles and mussels. Apart from these enemies, there are parasites and diseases which, experience has shown, can be controlled by periodic exposure of the oyster to the air and sun, as happens naturally, for example, in some tidal waters.
To avoid the shifting sands and to provide improved harvesting procedures, there have been those who advocate suspending the cultch material from floating devices that are anchored at preselected growth areas. This approach has certain advantages, but it precludes the exposure of the oyster to the sun and air and leaves room for improving on the retrieval and harvesting procedures.