94 TRELIMINARY NOTE ON TRAWLING EXPERIMENTS 



An inspection of the above table will show that of the different 

 species captured, plaice and dabs occurred in far the largest numbers. 

 With regard to the relative numbers in which these two species were 

 present in the bays, the table gives no certain information ; for the 

 proportionate numbers of plaice to dabs in the several hauls varied 

 very considerably, and the number of hauls made was too few to make 

 it possible for any conclusion to be drawn. It should, however, be 

 noted that of these two species the plaice are alone important from 

 an economic point of view, since the large number of competing dabs 

 ought probably to be regarded as a positive hindrance to the well-being 

 of the plaice; and that, therefore, any discussion as to the merits or 

 demerits of the present bye-law should be almost wholly occupied with 

 the question whether the closure of the bays to trawlers is necessary 

 for the "protection of the plaice. 



It will further be observed that the plaice in the two bays differed 

 from one another in respect of size ; that while half the plaice caught 

 in Start Bay were under \2\ inches, in Teignmouth Bay the mid-length 

 was only 10 1 inches. A similar difference obtains in the case of the 

 dabs, whose mid-length was 8| inches in Start Bay, and 7A inches 

 in Teignmouth Bay. These differences are of considerable importance ; 

 they appeared in a marked manner in all the hauls taken on either 

 trip, and they imply a striking difference in character between the 

 two bays. 



Of these differences two explanations alone appear to me to be 

 possible. They may be due in each case (1) to a difference in the 

 ages of the fish caught in the two bays; (2) to a difference in their 

 rate of growth.* As for the first of these explanations, it is difficult 

 to see why there should be a larger proportion of older fish in Start 

 Bay than in Teignmouth Bay ; and with regard to the second, I am 

 unable to point to any causes to which a difference in the rate of 

 growth might be ascribed. Whichever explanation is adopted, a 

 striking difference between the two bays, in respect of the most im- 

 portant fish they contain, appears to be indicated — a difference which 

 is the more remarkable in that the bays in question are not more than 

 15 miles apart, and open into the same sea. Whether such a difference 

 is constant throughout the year I am not yet in a position to say ; 

 but that it held good from October to December of this year there 

 is no reason to doubt. Further, though it would be out of place in this 

 preliminary paper to enter into further details, I may, perhaps, add 

 that while the differences in the mid-lengths of plaice and dabs for 



• The possible influence of diO'erenccs in the depths at which hauls were taken in the 

 two bays has not been overlooked ; but a comparison of the soundings taken does not 

 appear to favour such an exi)lanatiou of the dilTereuces between their respective populations. 



