448 REPORT ON TRAWLING AND OTHER INVESTIGATIONS 



The apparatus employed during the Oitlioiia's work is described more 

 fully by Dr. Kyle in a separate paper.* It was a form of otter trawl 

 specially adapted to the Brixham grounds. For greater lightness the 

 twine employed was cotton, not manilla as in the ordinary otter trawl, 

 and the mesh throughout was graded as in the trawls of the Brixham 

 Mumble Bees, There has been no essential change in the structure of 

 the nets of the latter since Mr. Holt carried out his investigations ; and 

 as the mesh of the trawls used by him was of a similar character, the 

 present records are directly comparable with his, so far as regards the 

 proportions of large and small fish. The differences between the nets, 

 in regard to their total catching power, will be adverted to below in 

 the discussion of the results. 



The work at sea consisted in the enumeration and, with few excep- 

 tions, the measurement of all the fishes caught. During 1901 the 

 measurements were recorded to the nearest half -inch, but during 1902 

 to the nearest half-centimetre. Experiments with marked plaice were 

 also undertaken, as a means of studying the migrations of this fish. 



In the present report the original measurements have been converted 

 into inches, in order to facilitate comparison with Mr. Holt's results; 

 but in the case of the marked fishes the original records in centimetres 

 have been retained, owing to the greater convenience of this unit for 

 comparisons of a minuter character. 



The selection of the trawling stations was left entirely to Dr. Kyle, 

 who is also responsible for the accuracy of the identifications and 

 measurements, and for the general conduct of the work at sea. My 

 own part has been limited to the tabulation and analysis of the records, 

 and to the formulation of such conclusions as appeared to be substan- 

 tiated by the facts and to be relevant to the main questions before the 

 Devon Sea Fislieries Committee as to the advantage or disadvantage 

 to the fishery of the closure of the bays to trawlers. 



It will be convenient, before proceeding to details, to present a 

 summary showing the general characteristics of the three bays as 

 regards distribution and abundance of the chief kinds of fish. The 

 following table has been prepared from Dr. Kyle's records, and repre- 

 sents the sum of the Oithona's catches of each species throughout the 

 year, reduced to the average catch for one hour's fishing. This pro- 

 cedure is necessarily somewhat drastic, especially in the case of seasonal 

 migrants, and in the case of the less common forms it naturally reduces 

 the numbers in many instances to mere fractions. Where this fraction 

 exceeds 0'5 it has been treated as 1 ; in cases where it is less than 0*5 

 the })lus sign has been inserted in place of the fraction to indicate the 



* Kyle, "Fishing Nets, with Special Reference to the Otter-Tiawl," Juurn. M. B. A., 

 this number, p. r)G2. 



