of ike Fishery Board for Scotland. 



241 



bottom in deep water. It is doubtful, also, whether these young animals 

 exercise discrimination in the choice of food, to such an extent, at any- 

 rate, that food is the determining factor for the inshore migration. The 

 currents in the ^N'orth Sea are not sulficient either, though they form the 

 most potent influence perhaps. 



In St. Andrews Bay, the Firth of Forth, and the Moray Firth there are 

 conflicting elements, which tend to nullify the oflshore currents. The 

 shallower water is more easily disturbed by any strong wind, and the 

 influence of the rivers has to be considered. Some consideration also 

 must be given to the configuration of the land. Thus, St. Andrews Bay 

 seems peculiarly adapted for the shoreward migration of the plaice. The 

 North Sea current, deflected slightly by the current from the Tay, 

 carries its burden of eggs and larvae along the southern shore. The 

 east winds are blowing, as a rule, during the months of April and May, 

 bringing the forms near the surface close into the land ; but it has been 

 noticed that the young plaice do not appear on the shore when the east 

 winds are prevalent. This year (1897), for example, they were late in 

 their appearance — about the middle of May. It is commonly said here 

 that the young plaice wait for a warm day on which to approach the 

 shore. Perhaps the concomitants of the warmth have more to do with 

 it. On the warm days the west winds are usually blowing, thus causing 

 a surface current seawards. There is reason to believe that these outward 

 surface currents are compensated for by bottom currents tending inward; 

 or, rather, that the North Sea currents, strengthened by the easterly 

 wind, continue their course even when the wind has gone round to the 

 Avest, and so bring the young plaice shoreward along the bottom, the 

 surface forms tending outward to the sea. 



The young plaice are first found on the shore in the beginning of May 

 as a rule. During the month of May they enter the harbour of St. 

 Andrews, and penetrate into the fresh-water burn which flows into it. 

 They were never found beyond tidal influence. Until the middle of 

 June, varying however, they are by themselves except for the larger 

 flounders of the former years. As already mentioned, they are all of the 

 same species ; the dab is not amongst them. For a little over a month 

 they monopolise the shallow water along the beach and the harbour, until 

 the young flounders appear, and then, within the space of a fortnight, all 

 the young plaice leave the harbour. The period when the young plaice 

 and flounder meet was for this year (1897) the last fortnight in June. 

 In 1887, however, it seems to have been the first fortnight, for the 

 data show that the plaice and flounder were got together on the 8th June 

 in the Kinness Burn, where it flows into the harbour. Dr. Petersen 

 remarks that he never met with quite young dabs in shallow water 

 or together with the fry of plaice and flounder ; also, that the young plaice 

 appear on the shore a little earlier in the year than the young flounder. 



About a hundred of these young plaice, from 8mm. to 16mm., 

 were examined to ascertain their food, but lack of time has pre- 

 vented me from going very far into this portion of the research. The 

 early post-larval pelagic forms contained young Annelid larvae, the ova of 

 some crustacean (Calanus probably), Evadne nordmanni, and in larger 

 specimens, 13mm., larval moUusks. The Annelids were mostly larval 

 nereids. A portion of a specimen resembling Autolytus was present in 

 one at 14mm. Amphipods (Gammarus) were present in several. When 

 the young plaice come into the pools and brackish water they seem to 

 live mostly on one single form, a copepod {Tachidius hrevicornis or 



