[mcmurrich] SCALE-MARKINGS OF THE HALIBUT 39 



Mcintosh* indicate that the ova of the Halibut are probably pelagic, 

 but so far as I am aware they have never been taken in plankton collec- 

 tions, or, at all events, have not yet been identified. And this is all 

 the more remarkable, since the ova have a diameter of over 3 mm. 

 and would therefore be conspicuous objects in a plankton collection. 

 No such ova were taken in collections that I made in September last 

 in the vicinity of the banks, off Rose Spit at the northern end of the 

 Queen Charlotte Islands and off the West Coast of Vancouver Island, 

 but these collections were limited in number and were possibly 

 made at an unfavourable time of the year. The more extensive 

 collections made in European waters, have, however, failed to 

 reveal them and the problem of the habitat of the Halibut ova is 

 still an open one. 



Secondly, definite information as to the spawning season of the 

 Halibut is highly desirable. The information on this point obtained 

 from fishermen is too varied to have any great value, nor do the scales 

 that I have examined give certain information, although it is possible 

 that the study of a greater number may throw some light on the ques- 

 tion. In the perfect scales that I studied, the nucleus was surrounded 

 by a band of verj^ narrow lines, which probably indicate a winter's 

 growth, the conclusion being that the fish from which the scales were 

 taken were spawned either in the late fall or early winter. The number 

 of cases is, however, too small to allow of this evidence being taken as 

 conclusive and as applying to all fish. Nor do the spawning marks 

 upon the scales give the desired information, since, as has been pointed 

 out, they do not affect a portion of a single year's growth but include 

 that of several years. It would seem that the ripening of the Halibut 

 ova is a gradual process and that the spawning is not a matter of a few 

 days or even weeks, but is prolonged over, it may be, several years. 

 But here again the number of fish yielding satisfactory scales was too 

 small to allow of deductions as to possible seasonal variations in the 

 spawning periods. The fact that the spawning periods are of long 

 duration may, however, be an explanation of the discrepant state- 

 ments of fishermen already referred to. The study of scales from a 

 long seies of fish, combined with the examination of the reproductive 

 organs of adult fish at all seasons of the year is necessary for the solution 

 of this part of the problem. 



Finally, reference may again be made to the desirability of definite 

 information as to the habits of the young Halibut from the time they 

 are hatched until maturity supervenes in their eighth year. Do the 

 young fish frequent the banks in company with the adults and, if not, 

 what are their habits? This is a most important question, especially 



*W. C. McIntosh. — Ann. and Mag. Nat. Hist, 1892. 



