10 THE IMPOVERISHMENT OF THE SEA. 



i'.\}ierinu'iit on a scientific basis for determining whether it is possible 

 or not by human interference to materially inllueuce the productiveness 

 of a considerable arm of the sea. 



It is well known from Dr. Fulton's review of the experiments 

 {Fourteenth Annual Report of the Scottish Fishery Board) that, contrary 

 to expectations, "no very marked change took place in the abundance 

 of the food-tishes generally, either in the closed or open waters of 

 the Firth of Forth or St. Andrews Bay," as a consequence of the 

 prohibition of trawling. Nevertheless, among flat fishes a distinct 

 change was reported to have ensued in the relative abundance of 

 certain kinds. Plaice and lemon soles were reported to have de- 

 creased in abundance in all the areas investigated, whether closed or 

 open, while dabs and long rough dabs were reported to have shown 

 a preponderating, if not quite universal increase. 



This change in the relative proportions of plaice and dabs was 

 explained by Dr. Fulton as principally due to the fact that the 

 protected waters enclosed a considerable area of spawning ground for 

 dabs and long rough dabs, but not for plaice and lemon soles, which 

 spawn exclusively offshore. Moreover, while all four species were 

 subjected to capture by trawlers outside the closed waters, the smaller 

 size of dabs and long rough dabs at maturity would enable many adult 

 and all immature dabs of both kinds to escape through the meshes 

 of the trawl ; whereas all mature and a considerable number of 

 immature plaice and lemon soles entering the trawl would be captured. 

 Thus the alleged increase of dabs and long rough dabs was attributed by 

 Dr. Fulton principally to the beneficial effects of the protection of their 

 spawning grounds, while the continued decrease of plaice and lemon 

 soles was attributed to excessive destruction of adults and young of 

 both species in the open sea. 



Dr. Fulton accordingly draws the following main conclusions from 

 his examination of the results of the trawling experiments : (1) that the 

 mere closure of even large areas in the territorial waters which are 

 destitute of spawning grounds is of little practical benefit to the 

 inshore fisheries, and (2) that the most likely method of benefiting the 

 inshore fisheries would be to protect the offshore spawning grounds for 

 certain periods in the year. 



Professor Mcintosh, however, entirely rejects the conclusions drawn 

 in this report, together with the figures upon which the conclusions were 

 based, principally on the ground that the statistical methods by which 

 the results were attained are vitiated by an important error. Dr. Fulton 

 divided the ten years into two quinquennial periods, and contrasted 

 the average catches per haul of the trawl during the first period with 

 those made during the second. Professor Mcintosh points out that 



