158 A BIOLOGY OF CRUSTACEA 



Shrimps are also caught in fixed ' engines ' on the shore. These 

 are wide-mouthed conical nets or baskets arranged with the mouths 

 facing the ehh tide. Large numhers of such traps may he arranged 

 to form an almost solid wall, so that a large volume of water passes 

 through them, leaving the shrimps trapped in the narrow end. 

 Variants of such traps are found throughout the world, from the 

 Severn Estuary to Singapore. 



An interesting addition to the normal commercial fishery in 

 Texas has recently appeared. The increased interest in sea-fishing 

 for sport has led to a demand for live bait, and shrimps are very 

 suitable for this purpose, particularly as they form over 70 per 

 cent of the food of some sport fish, such as the speckled sea trout 

 (Cynoscion nebulosus). The bait shrimpers operate smaller nets, and 

 use them for short periods, since they are not trying to catch great 

 numhers, but want moderate numbers in good condition. The bait 

 boats are often equipped with tanks and running sea water for 

 transporting the shrimps, others merely place the shrimps in a live 

 box which is towed behind the boat. 



The use of crabs as bait has been long established on the 

 Northern Adriatic shores of Jugoslavia. Here the common shore 

 crab (Carcinns maenas) is ground up and used as a lure for shoals 

 of sardines. 



Crustacean meat is relatively valuable. A comparison with one 

 of the most valuable marine fish, the sole, Solea solea, gives an idea 

 of the value of the Crustacea eaten in Britain. In 1955 the sole was 

 valued at / 13 6s. $d. per cwt., lobsters at £19 8s. 6d. per cwt., and 

 prawns at £33 is. id. per cwt. Crabs were much less valuable at 

 £3 us. 4d. per cwt., so were shrimps at £4. os. 1 id. per cwt. These 

 weights include the shells, and the lower value of crabs and shrimps 

 is probably due to the greater labour involved in preparing a given 

 weight of edible meat, as well as to the superior flavour of prawns 

 and lobsters. 



The prices of Crustacea in Britain have risen sharply over the 

 last twenty years. To take only a couple of examples: in 1938 

 shrimps were valued at £1 9s. 3d. a cwt., while prawns were 

 £18 9s. 8d. a cwt., these prices form a sharp contrast with those 

 quoted for 1955. The Norway lobster, Nephrops norvegicus, has also 

 increased rapidly in price during the last few years. The price in 

 Scotland rose from £1 17s. od. a cwt. in 1950 to £3 12s. od. a cwt. 

 in 1952; the average price in Britain during 1955 was £4. 4s. 7d., 

 compared with £1 4s. 6d. per cwt. in 1938. 



