Scallop aquaculture is the commercial activity of farming scallops until they reach a marketable size and can be sold as a consumer product. The first attempts to fully cultivate scallops in farm environments were not recorded until the 1950s and 1960s. Traditionally, fishing for wild scallops has been the preferred practice, since farming can be expensive. However worldwide declines in wild scallop populations have resulted in the growth of aquaculture. Globally the scallop aquaculture industry is now well established, with a reported annual production totalling over 1,200,000 metric tonnes from about 12 species.
There are a variety of aquaculture methods that are currently utilized for scallops. The effectiveness of particular methods depends largely on the species of scallop being farmed and the local environment.
Pearl nets used to grow spat to juveniles.
Once scallop spat have been collected, the most common way of growing them further is in pearl nets (small pyramid shaped nets usually about 350mm across with 2-7mm mesh). Here, they are usually grown to approximately 15mm in high stocking densities. Pearl nets are typically hung ten to a line and have the advantage of being light and collapsible for easy handling. Scallops are usually not grown to larger sizes in pearl nets due to the light construction of the equipment. Once juveniles have reached a desired size they can be transferred to another form of culture.
Lantern nets were first developed in Japan and are the most common method of growing out scallops following removal of juveniles from pearl nets. They allow the scallops to grow to adulthood for harvest due to their larger size and more sturdy construction. Lantern nets are employed in a similar fashion in the mid-water column and can be utilized in relatively high densities. Flow rate of water and algae is adequate and scallops will usually congregate around the edges of the circular net to maximise their food intake.
1).Lantern Nets for bivalves farming
Within the aquaculture sector, the suspended cultivation with Japanese type lantern nets has proven to be the most efficient for farming a wide variety of mollusc bivalves. Among the farmed species with lantern nets are oysters, clams and scallops. On top of that, great results have been achieved with gastropods, crustaceans and octopuses.
2).Lantern Nets for Intermediate cultivation
After the spat catching with collector collector bags , for the initial farming phase, both lantern nets and pearl nets can be used. For this purpose, both are made of raschel net with meshes sizes from 2 to 9 millimeters that effectively protects the larvae from predators.
The lantern nets models for this phase are available with a convenient velcro closing system and the pearl nets with an anti-rust plastic zip.
3).Lantern Nets for Adult cultivation
Lantern nets with a bigger mesh are used from the intermediate cultivation phase to the final one, using mesh sizes ranging from 9 to 31 mm. These lantern nets are made with knotted net of 100% pure high density polyethylene that warranties an optimal protection for the larvae.
The steel frame used in our lantern nets and pearl nets are first welded and secondly coated with plastic, in order to avoid any rust. This special feature together with our top class nettings give an exceptional lifespan to our lantern nets and pearl nets.
Rope culture is very similar in principle to ear hanging with the only difference being the method of attachment. In rope culture, instead of scallops being attached by an ear hanging, they are cemented by their flat valve to a hanging rope. This method results in a similar growth and mortality rates as ear hanging but has the advantage of being able to set scallops from a small size. New cementing technologies are being continually developed with the aim of producing quicker setting adhesives to minimize the time scallops spend out of water so to minimize stress.
Pocket netting involves hanging scallops in individual net pockets. Pockets are most often set in groups hanging together. Pocket nets are not used extensively in larger farms due to their cost. However, handling time is low and so can be considered in smaller operations.
Growing scallops in suspended plastic trays such as oyster cages can serve as an alternative to equipment like lantern nets. However, such systems can be expensive and have a rigid structure so cannot be folded and easily stored when not in use. In general, plastic trays are mostly used for temporary storage of scallops and for transportation of spat.
Methods of bottom culture can be used in conjunction with or as an alternative to hanging culture. The main advantage of using methods of bottom culture is in the lower cost of reduced buoyancy needs as equipment is supported by the seabed. However, growing times have been noted as being longer in some cases due to the loss of use of mid-water plankton.
Plastic bottom trays
Plastic trays such as oyster cages can again be utilized in bottom culture techniques. They provide simple and easy to use system. Plastic trays are effective in large numbers but their size is limited by the growth rates of scallops near the centre of cages due to reduced water and food flow rates.