SoLWAv Nature Kotes, 163 



fish, and I have little doubt they are inflicted by the teeth ot 

 porpoises. 



Many of the fishermen have told me of times when they 

 have seen porpoises attack salmon, and in many instances 

 these accounts were given my men whose word I could rely- 

 on . 



One reason why porpoises are particularly destructive to 

 the salmon in the Solway is that by spreading out across a 

 channel and working up slowly on the flood and back again 

 on the ebb a shoal forms a barrier which every running fish 

 must pass. Like the otter, I am inclined to think the por- 

 poise hunts for sport when he is not hungry, and this pro- 

 bably accounts for the very large number of salmon which 

 are marked. 



I believe that in a previous paper I pointed out that the 

 presence of fish of any kind in the Solway is dependent abso- 

 lutely on the presence of a suitable food supply. If this is 

 not available, the fish simply leave for other places where it 

 is. The food of the fish is, of course, dependent on its food, 

 and so on right down to the simplest forms of life and on nto 

 the vegetable kingdom. 



In fresh water much has been learned concerning food 

 for fish and the conditions which will be favourable to an 

 abundant supply, and in very many cases where lochs have 

 been deficient in food this has been remedied, so that instead 

 of small and worthless fish a much better size and quality 

 has been produced. 



Applying what we know of natural fish foods in fresh 

 water, it would seem that valuable work might be done in the 

 sea; and the Solway, by reason of the accessibility of large 

 areas of bottom, should be an excellent experimenting ground. 



It may be urged that to undertake any scheme for the 

 production of fish food in the sea would be a task hopel-^ssly 

 beyond our powers. So it would seem at first sight, bat a 

 '4ttle consideration and observation will dispel this illusion. 



Let us consider a bare and barren Solway sandbank. To 

 all appearances it fosters no life of any kind. Walking over 

 ir, one might say there is nothing but sand here. This would 

 be a mistake. Take a spade and dig. At certain times a 



