— 7 — LATKH STAGES OF GADOIDS 



adopted. It will be seen that a very insigniticant number of fish of this size or age are 

 caught in the otter trawl, a number not sufficient to give a definite cusp upon the ordi- 

 nary curve. Group II and Group III, culminating respectively at about 35 and 52 centi- 

 metres, are clearly shown, and equally clearly indicate the fish that are now respectively 

 just two and three years old. Group IV is only slightly indicated, somewhere in the 

 neighbourhood of 70 centimetres, on the descending slope of the curve. 



The May (April to June) curve (fig. 2) happens to be based on a smaller number of 

 fish. We now see that the young Cod of group I, which we may take to be approxi- 

 mately 15 months old, form a sj'mmetrical curve as regards the small mesh catches, but 

 it is obvious that now a considerable number of the larger of them fail to pass through 

 the cod-end of the ordinary trawl, and accordingly form a small cusp upon the ordinary 

 curve. It is interesting to note how such a cusp, being constituted by a selection only 

 of this group of fishes, would give a misleading and exaggerated idea of their mean or 

 modal size, unless it were corrected, as it is in this case, by the more complete samples 

 supplied by the small mesh net. The increase of size of the I group is not very great 

 as compared with the February curve, the mean increase in size being only about one or 

 two centimetres. In like manner the II group shows us only a small increase in size of 2 

 or 3 centimetres. The III group is now very poorly represented upon the curve, and the 

 small number of older fishes up to 100 centimetres similarly fail to resolve themselves into 

 recognisable groups. 



In the July to September curve (fig. 3) the small mesh net has captured for us a 

 very small number, about 250 in all, of young Cod, and the modal size of these is about 

 12 centimetres. It is certain that at least the greater part of these do not belong to the 

 same annual group as those which the small mesh net captured for us in the spring 

 months. They are actually smaller by 2 or 3 centimetres than those captured three 

 months before, though the intervening three months are undoubtedly months of rapid 

 growth. I believe that we are now dealing with an 0-group, that is to say with fishes of 

 the immediately preceding winter spawning season, fishes that are somewhere about six to 

 eight months old. But I think it more than probable that here again we are dealing only 

 with an imperfect sample of the group, that our small mesh net is catching only the larger 

 individuals among them, and that the mean size of the U-group during the months in 

 question is smaller by some centimetres than this curve indicates. 



A very high and symmetrical cusp occurs at about 23 centimetres in the catch of 

 the ordinary trawl. This represents, I am convinced, the I group, the fishes of about 

 one and a half years old, which have increased in size no less than 6 or 7 centimetres 

 on the average, or say 272 inches in length within three months since the date of the 

 former curve. They have just reached a size when they are freely caught by the ordi- 

 nary cod-end. The II group, or fishes of about two and a half years old, are fairly well 

 represented, though they are evidently so far overshadowed by the larger individuals of 

 the very numerous preceding annual group that the cusp of their own proper curve is 

 not clearly indicated on the curve itself. It is by no means impossible to analyse the 

 curve, by proper means, so as to reveal the probable position of the cusp, but we may 

 take it provisionally to be somewhere about 43 or 44 centimetres. Group III is present 

 in small numbers, and the larger and older fish are still scantier than in the preceding 

 seasons. 



