Pearl Nets

Specifications

 scallop/shellfish/pearl/oyster culture cage

aquaculture equipment

specifiction:

Diameter:30-90cm  (steel wire with plastic coated)

tiers/sections:2-25 

as customers required about material sections diameter

Advantage:efficient,the mesh with mesh uniform  high tensile strength anti-aging properties

rope bound around the ring to protect

Scallop Hanging culture

Hanging culture relies on either a raft or longline system (with buoys and lines) that floats on the sea surface from which the cultured scallops are suspended, usually on ropes to which they are attached in some manner. Rafts are considerably more expensive than the equivalent distance of longline and are largely restricted to sheltered areas. However, raft systems require much less handling time. Longlines have proved effective for most farms to date and have the added advantage of being able to be completely submerged (with the exception of marker buoys) so to reduce visual pollution. From a raft or longline a variety of culture equipment can be supported. The main advantage of any form of hanging culture is in the exploitation of mid-water algal populations that cannot be fully utilized in other forms of culture^[8].

Pearl nets used to grow spat to juveniles.

Pearl nets

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^[8].

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^[8].

Ear hanging methods were developed to be a cheaper alternative to lantern nets. Subsequently, research has shown that growth of ear-hung scallops can also be higher than those in lantern nets. Ear hanging involves drilling a hole in the scallop ear (the protruding margin of shell near where the two shells join) and attaching it to a fixed submerged line for growth. Such a process can be relatively labor intensive as each scallop must be individually handled and drilled (however, many operations now have machines for this process). Furthermore, high mortality rates can result from drilling if scallops are too small, are drilled incorrectly, or spend too much time out of water and become physiologically stressed. This has resulted in research being conducted into the optimal drilling size. This size has been shown to be species specific with small species not having good survival rates. As such, ear hanging is an effective method of growing out larger scallop species. If ear hanging is an appropriate method, scallops can be densely stocked in pairs on lines with as little as 100 mm between pairs. Scallops are maintained in this fashion until harvest. A variety of attachment products are constantly being tested with the best growth so far being obtained with a fastener called a securatie^[8].