244 



Part III. — Sixteenth Anmrnl 'Re2iort 



The dab spawns botli iu iushoic and offshore waters. Its spawning 

 period lasts (Fulton, I.e.) from the end of February .to middle of July, 

 with the mean in April, May, and June. It may extend later, however, 

 for (Masterman, I.e.) its eggs have been obtained throughout July to the 

 end of August. 



The data correspond, for the earliest, obtained in April, must have l)een 

 spawned in February, six weeks before ; the latest, at the end of 

 September, must have been spawned in the beginning of the month. 

 This is of importance iu connection with its rate of growth. Mr. 

 Williamson,* taking the spawning period as from March Lo mid-June, 

 calculates that a dab grows to 60 or 70mm. in one year. Even on the 

 extended period this represents the average growth. A series of larger 

 forms have been given for each month in the year, except May, and it is 

 not difficult to trace approximately the rate of growth, but, as this has 

 been done by Williamson, and the conclusions are much the same, there 

 is no need to go into details. 



Turning to the pelagic forms, it has to be noted again that the larval 

 and early post-larval specimens are obtained from the midwater and 

 bottom nets; only once was a specimen 5mm. long taken on the surface 

 in company with others 12"5mm. in length. The later post-larval 

 stages are found on the surface, midAvater, and bottom. The offshore 

 distribution is noticeable in contrast with that of the i)laice. Professoi 

 M'Intosh,t in 1884, made a reference to the large number of immature 

 examples of the dab, from 2J to 6 ins., which were obtained from the 

 deep water 15 miles from St. Abb's Head, more especially during July 

 and August. Xo young plaice were found in their company, and he 

 concludes that the occurrence of such small specimens so far from land 

 would raise a doubt as to whether all the young forms have been reared 

 inshore. A large number of the young dabs of the same size were also 

 obtained in St. Andrews Bay, a mile or two from land, in about 4 to 6 

 fathoms of water. Close inshore the young dabs are not taken except off' 

 the rocks ; some few are taken at the mouth of the Eden. The distribu- 

 tion of the young dabs from 1 inch onward is thus extensive, and there 

 does not seem any need of supposing that any great migration of the 

 adults takes place. From the early post-larval stages the dab is near the 

 haunts of the adult. 



On the 16th to 19th May 1894, over 3000 young dabs, from 10 to 

 16mm., were obtained, 15 miles from land, in the surface net. It is 

 possible, considering the short period of incubation, that these specimens 

 were not far from where the eggs were spawned, and it is possible, also, 

 that they never migrate far from the spot where they were found. Some 

 of the specimens (30) were examined as to their food contents. Only 

 diatoms were found in their stomachs, and one or two were crammed full 

 with them. The diatoms were of three distinct species at least 

 (Coscinodiscus and others), but I have not been able to connect them 

 with the scheme of Professor Cleve. Crustacea were present in the 

 water, though none were found in the stomachs of the specimens 

 examined. A difference was noted between the deep-sea and tlie inshore 

 specimens (figs. 8, 9, 10). The deep-sea specimens were longer at each 

 stage during metamorphosis — thus, the eye was halfway at 15 to 16mm., 

 whereas, in the inshore forms, 14 to 15mm. was the rule. Black pigment 

 was very well marked along the base of the fins, etc., in deep-sea 

 specimens, and the lines along the myomeres were present. Though 

 present it is not so prominent in the inshore forms. 



* Rate of Growth of Certain Marine Fishes, llth S.F.B. Report, p. 265. 

 t Commission on Trawling, 1884, p. 361. 



