20 



THE SCIENTIFIC AND ECONOMIC ASPECTS 



Channel, from which it would appear that although the fish 

 were present on the surface no serious migrations to the inshore 

 feeding grounds had as yet taken place. 



A final observation, for which we are indebted to Mr. 

 Matthias Dunn of Newlyn, is therefore one of considerable 

 interest. This observer, in a letter dated October 3rd, states : 

 " We had a unique experience on Monday of this week. Just 

 off Mousehole there were evidences of large quantities of fish, 

 gannets were falling in numbers, and finally we saw a basking 

 shark. When we came directly on to the ground we observed 

 some crustaceans forming^ themselves into lonor furrows with 

 knots here and there. The shark appeared to be feeding on 

 these organisms, together with a large number of pilchards 

 and small mackerel. We finally shot our nets with the result 

 that about eleven thousand fish were taken. I took out the 

 contents of the stomach of one of the mackerel, to find some 

 well preserved specimens of Crustacea." 



" The next day we went out again to find the water of a 

 dark olive green hue shot with red, and in standing in toward 

 the coast found that this colour terminated quite suddenly, 

 leaving the water, with its burden of crustaceans, quite distinct. 

 One could tell within a yard where the coloured water ter- 

 minated and the other type began." 



" A day or two after this one of the sharks, whilst harass- 

 ing a shoal of pilchard, rose suddenly outside them and drove 

 them into one of the coves, where they were taken in a seine 

 and realized when marketed ^1,200. A few weeks prior to 

 this a catch of seined fish realized ^500. So you will under- 

 stand that the fishery is improving." 



The sample referred to consisted of one stomach contents 

 of a mackerel (not the stomach itself) contained in a glass tube, 

 and obviously it was impossible to determine whether the com- 

 ponent species were distributed in layers. Upon examination, 

 however, these were found to consist almost entirely of 

 the two Copepods, Anomalocera patter soni and Calanus 

 finmarchicus. 



In a letter to the Editor of " Nature "^^ we recorded a visi- 

 tation of the former species to Mounts Bay during the first 



20 " Nature " No. 2279, Vol. 91, p. 451. 



