58 KEPOKT OF THE COUNCIL. 



Nearly 410,000 fishes have been measured under these conditions 

 since the beginning of the investigations, as shown in detail in the 

 following table : — 



Plaice. Haddock. Others. Totals. 

 1902-6 Voyages I-LXXV 90,463 26,705 181,660 ... 298,828 



1906-7 Voyages LXXVI-XC 17,151 20,535 71,633 ... 109,319 



Totals 107,614 47,240 253,293 ... 408,147 



In order to supplement the Huxley's measurements of plaice during 

 the spawning season, and to compare her results with those of com- 

 mercial trawlers during this season, a voyage on a Lowestoft smack was 

 made by a member of the staff in February last, and the entire catch 

 of plaice (2,631 fish) was measured and examined. During January 

 and February two members of the staff also measured and examined 

 19 samples of plaice, amounting to 8,208 fish, from smacks in Lowes- 

 toft market. 



Marking Experiments. — During the past year 2,053 marked plaice 

 have been set free, as compared with 2,041* during the previous twelve 

 months (1905-6). Of the latter fish 522 have been reported as recap- 

 tured by May 31st, 1907, i.e. 25-6 per cent of the total liberated, as 

 compared with 23-9 per cent reported last year for the 5,115 marked 

 plaice previously liberated. 



The correspondence of these percentages renders it highly probable 

 that under similar experimental conditions the percentage of recaptures 

 of marked plaice affords a reliable factor for estimating the intensity 

 of fishing in a particular area under modern conditions, and for 

 measuring differences in this respect in different regions. 



The annual percentage of marked fish returned has been found to 

 vary with the size of the fish, increasing regularly from less than 

 10 per cent for plaice marked at less than 20 cm. (8 inches) in length 

 to a maximum which lies between 30 per cent and 45 per cent in the 

 case of plaice marked at 30-39 cm. (12-15 inches) in length. Above 

 this size the percentage again decreases, a result which appears from 

 other data to be partly indicative of natural mortality. 



In this connection it is not without interest that during the spawning 

 season of the plaice the males have been caught in relatively greater 

 numbers than the females, not only among the marked fish, but also 

 in the ordinary course of the trawling experiments in spawning areas. 



The transplantation experiments to the Dogger Bank, which were 

 again carried out in the spring of 1906, have shown nearly the same 

 rapid growth of plaice which was so marked a result of the experiments 



*This total was given in last year's report as 2,042, owing to accidental inclusion of a 

 marked dab. 



