Fact Sheet 3 - Methods of transport and storage

In order that crustacea are housed and transported in conditions that do not cause stress it is essential that there should be:

(a) proper water temperature control;
(b) adequate aeration;
(c) suitable water quality;
(d) only compatible species kept together.

Methods to help to maintain these conditions are water purification and filtration systems and suitable water-testing procedures.

Crabs: Only crabs four and a half to five inches across the broadest part of the back may be caught. No berried (egg-bearing) or soft-shelled crabs are allowed to be captured. There are no restrictions on the number, design or size of the traps.

Live crabs should be handled as little as possible after capture, and the claws will be shed if the crab is removed from the trap or net by them. The crabs must never be left exposed on deck as sun and wind may kill them. They should be packed, back uppermost, in ventilated boxes, quite close together and preferably with wet straw or shavings in the bottom of the box. Live storage is difficult and crabs do not travel well. Where live storage is necessary, they should be tightly packed in baskets in aerated sea water.

Transit time should be as short as possible and preferably overnight, when air temperature is lower. In warm weather casualties are likely to be high.

Prawns: One method used for the transportation of prawns is in plastic tubes. It seems that, although the tubes are open-ended, the prawn stays inside of its own accord, as though it were hiding on the sea bed. The tubes are put into the hold of a ship and refrigerated sea water is pumped round the hold. The Scottish Society for the Prevention of Cruelty to Animals (SSPCA) found that transport mortality was only 1%, as compared with 40% in conventional transport.

Lobsters: As with all shellfish, and although they are by nature solitary animals, lobsters must be tightly packed in tanks and their claws bound with elastic bands to prevent them from injuring each other. It is possible that much aggression is caused as the product of an artificially stressful environment and it could be argued that stress is not only caused by such close proximity of other animals, by also by the negation of their instinct to attack/defend.

Various different methods of transportation are being considered and a larger version of the prawn plastic tube might be a possibility. This would mimic the lobster's hiding places such as rocks, crevices or weeds, and by also reducing the temperature the animal will go into a torpor. This method of transport would also do away with the need to bind their claws. At present they are not fed in the storage tanks, and go several months without food.

Little consideration is at present given to the methods of storage and transportation of other shellfish, but since all crustacea have to reach the wholesaler alive, then this, if for no other reason, should ensure that they are handled in a way which will not cause undue stress or injury, although, as we have seen with conventional methods of prawn transportation, 40% mortality appears acceptable to the industry.

The Ministry of Agriculture, Fisheries and Food (MAFF, now DEFRA) advises against long storage periods and also has a list of 'do's and don't's concerning the storage of lobsters.

Sources:

1. MAFF (DEFRA): Catching, handling and processing crabs. Note 1987.
2. MAFF (DEFRA): Storage of Lobsters (Lab. Leaflet 66) 1981.
3. Animal Welfare Advisory Council (AWAC), New South Wales Agriculture, March 1994.
4. South Devon & Channel Shellfishermen Ltd. Kingsbridge, South Devon 1997.