EFFECT OF SEAL STOCKS ON SCOTTISH MARINE FISHERIES 309 



locally, more than 50 per cent of the cod may be affected. The correlation 

 between the areas of high worm infestation and those harbouring dense 

 concentrations of seals is striking. The low infestation of cod on the Aberdeen- 

 shire coast may be explained by the fact that this section of the coast is still 

 relatively seal-free. 



The infestation percentages have been calculated on all cod from a length 

 of 20 cm upwards. If under-sized fish are disregarded and the percentages 

 based on fish of marketable size only, the proportions of affected fish are 

 even greater. Fortunately, the degree of infestation of individual fish is still 

 low in the majority of cases, but this form of infestation is cumulative so 

 that the bigger the fish the heavier the worm load. Furthermore, the number 

 of seals, on the east coast in particular, has been increasing so rapidly in 

 recent years that it is quite possible that the full effect of worm infestation in 

 cod has not yet been reaUzed. In view of the danger of turning pubhc taste 

 away from cod this threat to the market value of a fish which provides 

 about half the United Kingdom's landings of whitefish must be halted. 



Early in the present century it began to be recognized that protection of 

 fish stocks would be necessary to ensure their maintenance in the future, and 

 partly with this aim in view various regulations were drawn up prohibiting 

 or restricting fishing within Scottish coastal waters. With the exception of 

 the war years the stocks of fish round the British Isles have been heavily 

 exploited commercially since the 1920's and, in order to conserve fish stocks, 

 international conservation measures have now been in force for some time. 

 Considerable thought is also being given in different ways to the improve- 

 ment of salmon stocks. 



Meanwhile, however, salmon and marine fish stocks continue to be 

 preyed upon by large numbers of seals which remain almost unexploited. 

 One might reasonably ask not only why no effort should be made to control 

 such a harmful predator as the seal but why, in the case of the grey seal, it 

 should even be protected. Even the most embittered salmon fisherman has 

 never contemplated the extermination of seals and it should be obvious from 

 the present state of the stocks that the grey seal is no longer threatened by 

 this danger. 



It may be argued that the protection of the grey seal covers the breeding 

 season only and that fishermen could shoot them outside the closed period. 

 It has even been argued that this is the only necessary remedy ! This is done 

 as far as possible, but seals are notoriously difficult to shoot in the water and 

 evidently despite the combined efforts of fishermen, the numbers continue 

 to increase. It is clear that effective action can only be taken against them 

 where they congregate for breeding or resting, but unfortunately such 

 concentrations are often somewhat removed from the fishing grounds. 



