FISHES OF THE GULF OF MAINE 



479 



bands in search of food as haddock do; but the available evidence as to their 

 migrations is so contradictory and so complicated by the local effects of hard fishing 

 that it is not worth while to attempt any discussion of it here, except to point out 

 that of old when halibut were still plentiful in the inner parts of the Gulf some of 

 them worked inshore and into shoal water in summer, to descend again to greater 

 depths for the winter, while others remained in deep water throughout the j^ear. 



The rate of growth of so large a fish is an interesting subject, and fortunately 

 Jespersen's ^' study of the otoliths of over 2,000 fish of all sizes caught about Ice- 

 land has thrown considerable light upon it, his conclusions being that the average 

 relationship between age and size is as follows: 



Age 



One year.,.. 

 Two years.. 

 Three years. 

 Four years.. 

 Five years.. 



Average 

 length 



Iiiches 

 3.9 

 9.1 

 13 



18.5 

 22.4 



Eitremes 

 of length 



iTiches 

 3. 1 to 5. 9 

 7. 1 to 12. 6 

 8. 3 to 18. 9 

 11. 8 to 24. 4 

 16. 1 to 28 



Age 



Six years 



Seven years. 

 Eight years. 

 Nine years.. 

 Ten years... 



Average 

 length 



Inches 

 25.6 

 27.6 

 29.1 

 33.9 

 37.4 



Extremes 

 of length 



Inchea 

 20. 9 to 34. 3 

 21. 7 to 40. 9 

 22. 8 to 40. 6 

 26. 8 to 42. 1 

 29. 5 to 55. 5 



Females averaged somewhat longer and heavier than males of the same age, 

 and the fact that the oldest was a fish of 20 years, 683^ inches long, suggests that 

 the monsters of 400 pounds and more, and upward of 7 feet long, which are 

 occasionally caught, may be half a century old, always assuming about the same 

 rate of growth for the Gulf of Maine halibut as for those caught about Iceland. 

 Probably the halibut does not reach sexual maturity until 9 or 10 years old. Ac- 

 cording to Thompson (Report of the Commissioner of Fisheries, Province of 

 British Columbia, 1914 (1915), pp. 76-99) Pacific halibut grow at approximately 

 the same rate for the first few years, more slowly after about the eighth year, but 

 with wide differences in the rate of growth on different banks, probably reflecting 

 differences in the food supply. 



Breeding habits. — -Very little is known about the breeding habits or early fife 

 of the halibut. It is believed to spawn in February in European and Icelandic 

 waters, judging from the state of development of the ovaries. Halibut continue 

 breeding throughout the summer off the American coast, for fishermen have fre- 

 quently reported ripe fish, both male and female, in April, May, June, July, August, 

 and early September at various localities from Georges Bank to the Grand Banks;" 

 while the fact that part of the eggs in the ovaries of a fish examined on Banquereau 

 by representatives of the Bureau of Fisheries on September 13, 1878, were ripe 

 while others were still immature is evidence that individual halibut spawn over a 

 considerable period. The pelagic larval and post larval stages had been found 

 only over great depths, a fact which has led European students generally to beheve 

 that the halibut spawns outside the 500-fathom line; but Cox (Contributions to 

 Canadian Biology, New Series, Vol. I, No. 21, 1924, pp. 409-412) has recently 



51 Meddelelser fra Eommissionen for Haviinders0gelser, Serie: Fiskerl, Bind V, No. 5, 1917. 

 " Goode (et al., 1884) mentions many reports to this eSect. 



102274—251 31 



