FISHERY BULLETIN: VOL. 81, NO. 3 



Gulf of St. Lawrence exhibit the highest growth rate 

 and mature much earlier than fish from other areas. 

 Conversely, the population of Greenland halibut 

 from Baffin Bank exhibits the slowest growth rate, 

 and maturity is reached at a later age than those from 

 the Gulf of St. Lawrence. The initial growth rate of 

 the Labrador- eastern Newfoundland areas has been 

 shown to be very similar, occurring somewhere be- 

 tween those of the Baffin Bank and the Gulf of St. 

 Lawrence. However, the size and age at maturity de- 

 crease significantly from south to north, contrary to 

 the above theory. The reason for this may be ex- 

 plained if a northward spawning migration occurs. If 

 this is the case, then it would be expected that the 

 proportion of maturing individuals in catches at any 

 particular size up to 100% mature would be greater, 

 moving progressively northward. This would result in 

 a shifting of the maturity curve to the left going north 

 and subsequently producing lower values of M 50 . 

 This would further suggest that in the Labrador area 

 the value of M 50 for Saglek Bank may be in fact more 

 representative of the entire Labrador-eastern New- 

 foundland area. The value of M 50 for Saglek Bank 

 falls between that of the Gulf of St. Lawrence and 

 Baffin Bank data as does the initial growth rate. This 

 would then be in agreement with Aim's (1959) theory 

 of the relationship of maturity and initial growth 

 rate. 



Recent investigations by Chumakov (1982) also 

 found that the abundance of larger mature fish in- 

 creased moving northward. From tagging studies in 

 eastern Newfoundland, Chumakov (1982) found that 

 Greenland halibut migrated northward over long dis- 

 tances, from the southernmost parts of the area to the 

 spawning grounds located in Davis Strait. He also in- 

 dicated that having reached the spawning grounds, 

 mature fish would not return to the areas where they 

 had been dwelling before maturation. The propor- 

 tions of mature fish in the more southerly areas would 

 therefore be expected to be slowly moving south- 

 ward, as shown in the data presented here. Further- 

 more, Bowering (1982) also studied migrations of 

 Greenland halibut in the same area. For Greenland 

 halibut tagged in White Bay, Newfoundland, (Fig. 1) 

 the returns mostly came from deep waters along the 

 continental slope of Labrador to as far north as the 

 waters off Baffin Island near the known spawning 

 grounds. This further suggests a northward migra- 

 tion of prespawning Greenland halibut. 



LITERATURE CITED 



Alm, G. 



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1981. A review of biology and fisheries of roundnose grena- 

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