159. The vast majority of trout transported within the UK travel by road in tanks placed on flat bed vehicles. An oxygen supply is also carried and concentrations are constantly monitored and maintained at an appropriate level. Information is relayed automatically to the driver who has the facility to adjust oxygen levels from the cab of the vehicle. Fish are loaded into, and unloaded from, their transport containers either by use of vacuum pumps or by hand with the use of nets. These nets should be designed so that they do not injure the fish. Salmon smolts, when transferred from fresh water to sea cages, are transported either in a purpose-designed tank slung below a helicopter, by road similarly to trout, or by sea in specially designed well-boats. Adult salmon are sometimes transported live from their sea cages in well-boats for slaughter.
160. Fish in transit should be inspected regularly. It is essential that oxygen levels in transport tanks are maintained at above 6 mg/l, carbon dioxide levels are kept low and excessive changes in water temperature and pH are avoided. Delays in transport should be minimised to reduce the risk of adverse conditions developing.
161. Before transport it is current practice to deprive fish of food for 48 hours, or longer under cold conditions, to achieve gut clearance. This practice reduces faecal contamination of water in the transport tank and minimises the metabolic load when the fish are crowded together for collection before and during transport. The period of crowding prior to transport should be kept to a minimum.
162. Care should be taken to ensure that dead fish are not loaded for transport. Any which die in the course of the journey should be separated from the live fish on arrival with a minimum of delay. Transport containers should be cleaned and disinfected after conveyance of each consignment of fish to prevent the spread of disease.
163. Under the Diseases of Fish Acts (1937, 1983) all farm sites are obliged to record all movements of live fish, fry and eggs onto and off the site. The purpose is to trace possible origins of infection and is not directed to the welfare of the fish. The Welfare of Animals during Transport Order 1994 (as amended) states that a record must accompany the fish during transport stating, amongst other things, the origin and ownership of the fish; the place of departure and place of destination; and the date and time of departure. The Fish Health Regulations 1992 (as amended) prohibit the loading of fish showing clinical signs of disease, and require that the means of transport must be cleaned and disinfected prior to despatch. They also require that the duration of the journey be as short as possible; that water cannot escape from the transport vehicle; that all reasonable steps should be taken to safeguard the health of the fish, including, if appropriate, changing the water in which they are transported; and that water used should be changed only at an approved water station.