Internal Transport and Size Grading
Various forms of handling are necessary in all aquaculture activity. In extensive farming the fish are handled very few times, but frequency increases when the farming becomes more intensive. There are several reasons for handling fish and other aquatic organisms. They are transported within or between farms, or from farms to slaughterhouse; examples include the transport of fry to on-growing farms, and adult fish from on-growing farms to slaughterhouse. The need for this type of transport, of course, depends on the production strategy of the farm; however, most is performed inside the farm area. Internal transport is performed for various reasons in connection with other handling activities, such as division of fish groups, size grading, weight sampling and vaccination.
Independent of the handling procedures and equipment used, it is important that the operation is performed by trained personnel and in a way that minimizes the possibility for injury and stress to the fish.
When deciding on fish handling systems, it is important to consider the entire operation starting from when the fish are moved from the production unit and ending when the fish have been returned to the production unit or are in the unit that trans-ports the fish out of the farm. Several handling operations may be necessary throughout these processes. One example of a handling line for internal transport of fish on a farm with tanks can be:
· Crowding in tank
· Dip net for lifting fish out of the tank
· Bucket for internal transport of the fish
· Dip net for lifting of the fish from the bucket an into the new tank.
It is important that the separate handling methods and equipment used in the handling line are compatible. The handling methods may also be an integral part of the farm construction, and therefore be designed and the equipment selected before planning and building the farm. Use of ‘alternative models’, where alternative methods for performing the different handling operations in the line are included, can be an effective tool for selecting handling methods.