SEA-FISHERIES LABORATORY. ; 251 



near the shore during the summer and autumn, that they 

 have been attracted by the abundance of small shell-fish. 

 The common starfish or crosnfish soon destroy a mussel 

 bed once they settle upon it. Gulls, as we know, help very 

 considerably to destroy young cockles. They have doubt- 

 less done so from very early days, and if unchecked can 

 cause great local destruction. 



The chief cause of the fluctuation of the fisheries for 

 shell-fish along the Lancashire coast is due to natural 

 influences. Some marine animals are more susceptible 

 than others to the climatic changes that are always going 

 on around us, and naturally suffer from a sudden rise or 

 fall of the temperature of the sea. The eggs produced by 

 a spawning cockle are fewer in number than is the case 

 with the mussel, and spawning takes place in the early 

 spring. The spat from the bed of cockles may, therefore, 

 be completely destroyed by the sea water becoming 

 suddenly cooled as it flows over the surface of very cold 

 sands. A whole year will elapse before another production of 

 spat will take place. An intense frost will kill large numbers 

 of cockles wherever its influence is felt. In the winter of 

 1894-5 the whole of the Lancashire coast line was covered 

 with ice-floes for a considerable time and many hundreds 

 of tons of dead cockles were washed up by the first gale 

 after the frost had disappeared. The extreme cold of that 

 winter had a marked effect on the fishery at Flookburgh 

 and the total quantity of shell-fish sent oif during 1895 

 was only 743 tons. The beds may become sanded up by 

 heavy seas washing over them, or through the shifting of 

 the numerous channels, and the shell-fish are smothered. 



Over-fishing may also occasionally take place, and it 

 is a well known fact that some beds take longer than others 

 to produce marketable shell-fish once they have been 

 depleted. The fisherman to his own advantage ought to 



