of the Fishery Board for Scotland. 



245 



averaging about 0*8 inch* and the other about 30 inch. The only instance 

 where the "0" and " 1" groups may justly be compared in these Tables is for 

 September 21st, when a difference is found = 2'896 inches. This figure is 

 therefore the only reliable indication of the growth for the first year 

 (September to September). 



My own experiments show (which has also been observed by Dr. 

 Petersen) that the growth of the plaice during the winter months, while 

 the water is cold, is very small indeed, and it is therefore reasonable to 

 expect that the "0" group, which can be followed in Table V. from May to 

 October, when it has an average size of about 2*239 inches in the end of 

 March or the beginning of April, will average about 2 -4 inches. But it 

 is then one year old, and constitutes the new " 1 " group. During the latter 

 part of April and the beginning of May the growth-rate is again increas- 

 ing, and it corresponds well to find that the " 1 " group at that time (May 

 12th) averaged about 2*619 inches, and on June 10th 2*982 inches. 



I have already explained why the records contained in Petersen's 

 Table V. (reproduced in Table V.) are not well qualified to illustrate the 

 various annual series living within the six-mile limit in the locality where 

 the fishing was made, and an attempt to outline all the series that are present 

 is dangerous, owing to the mode of fishing. Two groups, however, are 

 distinctly indicated, viz. : — (1) the "0" group, or under one year, as previ- 

 ously referred to; it ranges between J of an inch and 1| inches, and has an 

 average size of 1*117 inches. (2) The "1" group, or over one year, which 

 is confined to a range between 2 inches and 4| inches, must also be con- 

 sidered duly represented. The fishes comprised in it were captured at a 

 depth of 2J fathoms and below, and the fishing in deeper water shows 

 that another group exists there, merging towards the " 1 " group. [Column 

 5 represents (1) part of the "1" group — below i\ inches, (2) a "2" group — 

 between 4£ inches and 7 inches, and (3) part of a " 3 " group — above 1\ 

 inches. Column 6 contains chiefly the "3 " group — above 7 inches; it is, 

 however, apparently mixed with the "2" group]. This ''1" group, thefishes 

 of which were captured on July 8th 1893, and was identified by Petersen, 

 has an average size of 3*332 inches, and agrees with the results regarding 

 this group in May, June, September, and October (see Table VIII.). 



The more or less favourable conditions prevailing in different years will 

 no doubt have some influence on the growth of the plaice ; but there is 

 no evidence to show, and it must be considered very improbable, that 

 the effect of such variations will be so great as to efface the distinction 

 between similar groups in two successive years. With due care and 

 allowance for possible variations, it ought to be quite possible to supple- 

 ment the one year's records with those of the preceding. Petersen's 

 Table V. (second part) contains the result of eight hauls, made with an 

 eel-seine net between July 12th and 19th 1892. Of the two groups shown 

 in the record, the smallest one, the fishes in which range in size from 

 4| inches to 7 inches, is of great interest. No information is given in 

 regard to the depth of water, yet the group is so circumscribed as to 

 exclude any doubt as to its correctness ; it contains 447 fishes with an 

 average size of 5*818 inches, and can only be the annual series following 

 the " 1 " group already described as existing between 2 inches and 4 J inches 

 and having an average size of 3,332 inches. This "2" group is also 

 recognisable at other dates in 1892. In the records for September 27th 

 (same Table) the result of five hauls with an eel-seine shows the same 



* In the months of May and June post-larval plaice are still found in considerable 

 numbers, and the young plaice found on the shore are therefore the oldest (or largest) 

 of those hatched the same year. The average sizes calculated for these two groups are 

 therefore too large, and cannot be used in comparison with Group 1. 



