Animal husbandry – Entomological culture device – Egg treatment – production – or storage
Patent
1985-07-01
1986-05-20
Chamblee, Hugh R.
Animal husbandry
Entomological culture device
Egg treatment, production, or storage
A01K 6100
Patent
active
045893705
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process of cultivating oysters, in particular "cultchless" and "microcultch" oysters. The cultivation of oysters has been practised by man for a long time. Traditionally oyster larvae are induced to settle on a solid substrate, known as cultch. The settled larvae known as spat or seed oysters are then put into oyster beds where they are cultivated until they grow to a marketable size.
The cultch may take various forms ranging from old oyster shells to wooden frameworks. Within the last twenty years new processes for growing seed oysters have been developed. Of particular interest are those which give rise to "cultch-less" or "microcultch" spat.
BACKGROUND ART
A method and apparatus for growing "cultchless" oyster spat is disclosed in U.S. Pat. No 3,526,209 (Budge). The method involves causing free swimming oyster larvae to settle on a relatively smooth surface, such as a sheet made of plastic material. After the larvae have passed through metamorphosis to become oyster spat, they are removed from the sheet to provide "cultchless" oyster spat. These may then be put into tanks where they are maintained in a suspended state either by air-agitation, as disclosed in British Pat. No. 1,366,394 (Scottish Sea Farms Limited), or by upward flow of the culture medium, as disclosed in U.S. Pat. No 3,517,648 (Budge), until they have reached a size large enough to be put into oyster beds for growing to an adult size.
The process of growing "microcultch" spat is described in our copending International Patent Appln No. PCT/AU82/00013. In this process the oyster larvae are induced to settle on small solid particles within a defined particle size range. Definition of the particle size range within close limits allows particles occupied by settled larvae to be separated from unoccupied particles by a simple screening operation. The occupied particles are then maintained in a suspended state in a manner as previously described until the attached spat are 4 mm in size which is large enough for them to be used as seed oysters.
One method of growing "cultchless38 and "microcultch" seed oysters to adult size and cultivating them thereafter to a marketable condition is to enclose them in mesh bags which are then immersed in the sea or estuaries. As the oysters grow so they need to be transferred to bags of successively larger mesh. The largest mesh size which will retain the oysters is desirable in order to obtain maximum accessibility of the sea water to the oysters. Such a method has its shortcomings, such as the high labour involved in rebagging the oysters and the need to remove the fouling materials which grow on and around the bags.
DISCLOSURE OF INVENTION
We have now found another method of cultivating to maturity discrete oyster seed, as typified by "cultchless" and "microcultch" oyster seed, in which a bed of such seed is contained in a tank of sea water in which there is an upward flow of the sea water, sufficient to produce incipient suspension but not so great as to produce turbulence.
Accordingly the present invention provides a process of cultivating oysters wherein a bed of discrete oysters is placed in a vessel through which a stream of a culture medium is caused to flow upwardly and wherein the flow rate of said stream is at least that required for the oysters in the bed to be in a state of incipient suspension and is less than that which causes turbulent movement in the bed.
We use the term oyster to refer to all post free-swimming-larval stages in the life cycle of the oyster. Examples of the species of oysters to which the process of this invention is applicable include:
By discrete oysters we mean separate individual oysters which are unattached to any cultch particle or are attached to separate small particles of cultch which are less than 400 microns in size. Discrete oysters which are at least 4 mm in size are suitable for use in the process but it is within the scope of this invention that the process may be applied to any sized oyster between 4 mm
REFERENCES:
patent: 3196833 (1965-07-01), Glancy
patent: 3418138 (1968-12-01), Dennis et al.
patent: 3486486 (1969-12-01), Vanderborgh, Jr. et al.
patent: 3495573 (1970-02-01), Vanderborgh, Jr. et al.
patent: 3517648 (1970-06-01), Budge
patent: 3526209 (1970-09-01), Budge et al.
patent: 3641982 (1972-02-01), Woodridge et al.
patent: 3701338 (1972-10-01), McMillin
patent: 4052960 (1977-10-01), Birkbeck et al.
patent: 4438725 (1984-03-01), O'Sullivan et al.
Leggett Leo J.
Melvin Maxwell V.
O'Sullivan Brendan W.
Chamblee Hugh R.
ICI Australia Limited
State of South Australia
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