AGE, GROWTH, AND SEXUAL MATURITY OF GREENLAND 



HALIBUT, REINHARDTIUS HIPPOGLOSSOIDES (WALBAUM), 



IN THE CANADIAN NORTHWEST ATLANTIC 



W. R. BOWERING 1 



ABSTRACT 



Age composition of Greenland halibut, Reinhardtius hippoglossoides , in the eastern area ranged up to 14 

 years for males and up to 18 years for females; most fish, however, were less than 10 years old, with a pre- 

 dominance of older fish in the more northerly areas. In the Gulf of St. Lawrence, males beyond age 9 and 

 females beyond age 1 2 were completely absent from the catch. It is not fully clear if this is the result of emigra- 

 tion of older fish from the area or mortality due to early maturity. The empirical growth curves for all areas 

 show females growing faster than the males, particularly in the older ages, while the mean size at age indicates 

 little difference up to ages 8-12. Statistical treatment of back-calculated growth curves up to age 5 indicated 

 no difference between males and females. No statistical difference was found in the growth rate of fish of the 

 Labrador and eastern Newfoundland areas. Fish from the Gulf of St. Lawrence exhibited the fastest growth 

 rate and fish from Baffin Bank the slowest throughout the range. 



Onset of maturity of female Greenland halibut from the Gulf of St, Lawrence occurred at a much smaller size 

 and over a more narrow range of sizes than in other more northerly areas. In the Labrador- eastern Newfound- 

 land area the onset of maturity occurred at smaller sizes, moving progressively northward. Since the growth 

 rates of fish throughout this area are similar, this shift of the maturity curves is believed to be a result of ma- 

 ture fish migrating towards the spawning ground. The Baffin Bank maturity curve, on the other hand, is 

 similar to that of Nain Bank in the mid-Labrador area. However, since Baffin Bank is so near the presumed 

 spawning ground and heavily influenced by the cold polar current, most maturing fish are likely to be in deep 

 warmer water outside the fishable range; consequently, the curve may be biased to the right. These infer- 

 ences are supported by other investigations, particularly migration studies. 



Greenland halibut, Reinhardtius hippoglossoides, are 

 found in both the North Atlantic and North Pacific 

 Oceans but absent from intervening Arctic waters 

 (Hubbs and Wilimovsky 1964; Atkinson et al. 1981). 

 Based on meristic and morphometric characters, 

 Hubbs and Wilimovsky (1964) concluded that there 

 is one species found in both oceans, not two as pre- 

 viously suggested (Andriyashev 1954). In the north- 

 west Atlantic, Greenland halibut are widely dis- 

 tributed along the west Greenland coast and in the 

 Davis Strait and are reported as far north as Smith 

 Sound (lat. 78°N) by Smidt (1969) and Templeman 

 (1973). In the Canadian far north they are found in 

 abundance in the Baffin Island area (Templeman 

 1973; Bowering 1978b, 1979a) and in the Hudson 

 Strait to Ungava Bay (Dunbar and Hildebrand 1952). 

 They are most prevalent in deeper waters from 

 northern Labrador to the deeper waters of the 

 northern Grand Bank (Templeman 1973; Bowering 

 1977, 1978c, 1979b, 1980b; Bowering and Brodie 

 1981) with small numbers recorded in the vicinity of 



'Department of Fisheries and Oceans, Fisheries Research Branch, 

 P.O. Box 5667, St. John's, Newfoundland, Canada A1C 5X1. 



the Flemish Cap (Bowering and Baird 1980). Green- 

 land halibut are found incidentally on St. Pierre Bank 

 with a small localized concentration located in For- 

 tune Bay (Bowering 1978a). Recent investigations 

 (Bowering 1979c, 1980a, 1981) have shown that 

 Greenland halibut have now become commercially 

 abundant in this area with very little occurrence on 

 the Scotian Shelf. The most southerly occurrence is 

 Georges Bank where 20 specimens were reported 

 caught (Schroeder 1955). 



According to Smidt (1969), the main spawning for 

 Greenland halibut in the northwest Atlantic occurs 

 during winter in the Davis Strait area (lat. 67°N) at 

 depths of 600-1,000 m. From here the young are 

 believed to be carried by currents to west Greenland 

 and eastern Canada where they colonize the banks 

 and slopes of the continental shelf. Spawning also oc- 

 curs in the Gulf of St. Lawrence in the Laurentian 

 Channel, southwest of St. Georges Bay, during winter- 

 time (Templeman 1973K 



The commercial fishery for Greenland halibut in the 

 Canadian northwest Atlantic is one of the most im- 

 portant groundfish fisheries in the region with land- 

 ings averaging over 60,000 t annually during the last 

 few years. It is of prime importance to such countries 



Manuscript accepted December 1982. 

 FISHERY BULLETIN: VOL. 81, NO. 3, 1983. 



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