PACIFIC HALIBUT FISHERIES 15 



SESSIONAL PAPER No. 38a 



mate maximum size, namely, 32 inches; the turbot (over 20 pounds) is more heavily 

 built than the plaice (up to 10 pounds. The halibut attains the length of 84 inches. 

 The interpretation of spawning marks on the scales is a very intricate problem and, 

 as McMurrich justly odserves, the course of events as deduced from the scale-mark- 

 ings must be regarded rather in the light of a tentative suggestion. It is, however, 

 quite possible that the Atlantic and Pacific halibut may mature at different ages. 

 According to J. T. Cunningham, there is a difference of about 4 inches between the 

 sizes of plaice at maturity in the English channel and in the North sea ; moreover all 

 individuals do not become mature at the same size in a given locality. 



The halibut industry of the Pacific coast presents the usual complications 

 attendant upon deep-sea fisheries elsewhere. The distribution of the halibut does not 

 conform to international boundaries, but is continuous from the gulf of Alaska to 

 cape Flattery. There is no evidence at present that the halibut performs extensive 

 north-and-south migrations, though there are abundant indications that it ascends in 

 schools, and also as individuals, into comparatively shallow water (about 15 fathoms) 

 near the shoreline, which is generally steep-to on the west coast, and descends into 

 deep water (about 150 fathoms) near or over the edge of the continental shelf. As 

 mentioned in part I, there are reasons for presuming in a general way that the hali- 

 but approaches the shore in pursuit of its food, and descends to the depths for the 

 purpose of spawning. Not only do the known habits of the halibut point in this direc- 

 tion, but the inference receives some support from the analogy of the spawning migra- 

 tions of the plaice off the coast of Great Britain. It has been established by the 

 recovery of marked fishes at the Plymouth laboratory " that a large proportion of the 

 plaice to be found in Start bay make a periodical migration to the offshore grounds 

 on the approach of winter. Dr. Kyle observed that the majority of the plaice recovered 

 offshore from January to April in this experiment were either spawning or spent. 

 After this spawning migration has taken place the smaller fishes tend to return again 

 to the bays. The largest fishes may either return to the bays, or may pass to the south 

 and west of Start point." [Walter Garstang: Report on Trawling and other Investi- 

 gations carried out in the Bays on the South East Coast of Devon during 1901 and 

 1902. Jour. Mar. Biol. Ass. U.K. (n.s.) VI. December, 1903, Plymouth.] 



It is obvious that the investigation of the natural history of the halibut in its 

 relation to the maintenance of the stock at its full strength cannot be confined within 

 territorial limits, and it is almost equally clear that if any restrictive measures were 

 to be proposed, they would have to be based upon international agreement. The 

 stock of the halibut is the object of persistent attack, to the exclusion of other fishes 

 captured incidentally, whose food value to the human race is not inferior, in order 

 to supply the demands of an artificial market. Under these conditions we have to 

 consider whether the stock of halibut will continue to stand the strain that is imposed 

 upon it. Practical fishermen are sometimes apt to be pessimistic in this regard 

 although the aggregate catches do not yet show any sign of diminution. Up to a 

 certain point the thinning out of the banks by the capture of surplus fishes must be 

 beneficial to the numbers and quality of those that remain. But this optimum 

 standard of fishing intensity is vague and cannot be defined otherwise than arbi- 

 trarily. Eecommendations to curtail the fishery are easily made but they would be 

 entirely ineffective unless there happened to be a clear case for the immediate enforce- 

 ment of rigid restrictions. The fact is that there is no such pressing call for drastic 

 action, and therefore this aspect of the question need not be discussed here. What 

 we are asked to do is to devise measures for the expansion, not for the limitation of 

 the industry. 



In order to throw some light upon the periodical movements of halibut, in the 

 absence of marking experiments or supplementary to such experiments if they could 

 be carried out, there is need for the accumulation of numerous properly authenticated 



