74 NOTES ON A FISHING VOYAGE TO THE 



the water was remarked on ; the region had then eventually to be 

 abandoned, and the fishing voyage concluded at Iceland. In my 

 notes on the plaice the influence of temperature on the movements of 

 this species in other regions will be further indicated. 



The Plaice {PlenronecUs platcssa). 



This was by far the most abundant species met with, and is of 

 course the special object of the trawlers' exploitation of the region. 



Throughout the greater part of this voyage on the lloman, samples 

 of the catch were measured and examined. 



Methods of Obtaining and Measueing Samples. 



The method of obtaining and working through the samples was as 

 follows : As the contents of the trawl lay upon the deck, the crew 

 proceeded to gut the plaice and throw them one by one into the 

 " pound " on the side of the deck opposite to which the trawl had been 

 hauled, where they were eventually washed before being put below. 



Thus, by getting one or more of the men to put their gutted fish 

 as they picked them unselected from the deck into baskets, and by 

 taking as many baskets as it was possible to dispose of without 

 interfering with the regular routine of the ship, good samples could be 

 obtained. 



The gutting process consists of making an incision into the body 

 cavity, through which the viscera, with the exception of the reproduc- 

 tive organs, are extracted. Thus it was comparatively easy to make an 

 examination of the maturity of each individual fish. 



The international method of measurement was adopted (e.g. 39-39-9 

 car., recorded as 39 cm.), and the operation was carried out on a 

 portable measuring board, on the open deck in fine weather and under 

 the " whaleback," or roofed-in bow deck, when it was rough. 



On six occasions the whole catch of plaice was measured and 

 examined. The close agreement of the average sizes (p. 76) then 

 obtained, with those of smaller samples at other stations in the 

 vicinity, confirms the confidence in the value of the smaller samples. 



As each measurement was made and recorded the sex of the fish 

 was noted, together with the maturity. From these records (Table I) 

 it will be seen that the lengths of the smallest mature fishes were 24 

 and 35 cm. for male and female respectively, and the corresponding 

 largest immature 41 and 45 cm. The average size of the mature 

 males is 40-9 cm., and of the mature females 48-3 cm. 



The lengths of 113 fish (65 <? , 48 ? ) have been excluded from all 

 consideration, as in each of these casQS the tail had been more or less 



