240 



Part III. — SixiePMth Annual Report 



^rasterman,* in his review of the work of the Garland^ 1890-96, 

 gives the spawning period of the plaice as extending from the beginning 

 of February to almost the end of May. Fulton {loc. cit., p. 370) gives 

 from the middle of January to middle of May, with the maximum in 

 early March. Allowing a little over twenty days for the period of 

 incubation, the first appearance of the larval and early post-larval forms 

 should be in the end of February and beginning of March. Their 

 absence during this period can only be accounted for by the lack of data, 

 for, at their first occurrence, April 3rd, 1893, to the east of May 

 Island, they reach the length of 12mm., which shows that the eggs from 

 which these earliest specimens M'ere hatched must have been spawned 

 some 50 dayst before — that is, in the earlier part of February. The 

 maximum spawning period is in March, and this accounts for the profusion 

 of young post-larval forms in May, two months afterwards. The great 

 majority of the specimens come from St. Andrews Bay and the Firth of 

 Forth — the eggs from which these were hatched coming from off the 

 coast of Kincardineshire (Fulton, Z.c, p. 374). So far as the few 

 specimens from the north coasts, Aberdeenshire and Moray Firth, 

 indicate anything, one may judge that the spawning season is the same 

 for the whole East Coast. 



As to the later limit of the spawning period, the examples obtained 

 point to the conclusion that, for some years, the spawning period is con- 

 tinued into June, and perhaps later. Thus, the record for the year 1888 

 is remarkable, examples being obtained in August, September, and 

 November. Holt (I.e.) mentions that some plaice spawn during 

 August. 



The majority of the specimens come from midwater and bottom, yet a 

 great number are present near the surface, and these, the larger specimens, 

 up to 14mm. The smaller specimens, from 6 to 8mm., are not present 

 anywhere on the surface, but are numerous in the midwater and bottom 

 nets. Little reliance can be placed on the lack of specimens, but it seems 

 as if the eggs, on floating shoreward, gradually sink, the specific gravity 

 of the water becoming less, until the larva? are in midwater. This is 

 more clearly seen in the region of the Moray Firth. The young post- 

 larval forms migrate of their own accord in search of food, or are drifted 

 by the midwater currents in which they find themselves, either to the 

 surface or bottom. This is the stage in which the mode of life of these 

 young flat-fish is least known. It is reasonable, however, to conclude 

 that when in a large moving body of water they swim equally in all 

 directions, darting about after the organisms they feed upon, and thus, in 

 the main, are subject to the influence of the current. 



Whatever be the mode of operations, the next stage finds the larger 

 post-larval specimens close inshore, and shortly afterwards in the rock- 

 pools. Although a large number of the small plaice are found inshore, it 

 IS possible that they are only a portion of the total. There is only 

 negative evidence to show that these young forms must come into shallow 

 water. Mr. Holt obtained his specimens from moderate depths, from 1 to 

 32 fathoms; the majority at less than nine fathoms. Plaice of 1 inch in 

 length were obtained between 5 and 9 fathoms. 



As to the specimens which come into inshore waters, one simple reason 

 for their appearance there is that they seek the food which is necessary 

 for them at this stage. This does not seem a sufficient reason, because 

 the plaice, as shown above, may undergo metamorphosis, and sink to the 



* 15tliS.F.B. Report, ]). 219. 

 i' I>anuevig, loc. cit. 



