678 



Fishery Bulletin 97(3), 1999 



tributional overlap of the two spawning components 

 if the abundance of the southwestern component in- 

 creases. This overlap effect may be responsible for 

 the higher abundance at ages 2 and 3 of the strong 

 1978 year class on the U.S. side in spring (Fig. 8). 

 Note, however, that at ages 4 and older, abundance 

 shifts to being higher on the Canadian side of 5Zj,m. 



From the temporal and spatial patterns of distri- 

 bution, ratios of relative abundance with respect to 

 the ICJ line, net migration rates, and monthly land- 

 ings statistics, we can infer then that a seasonal 

 migration, probably associated with spawning behav- 

 ior, occurs in 5Zj,m. This migratory behavior may be 

 influenced by temperature conditions but, although 

 temperature data is collected during surveys, the 

 time range of this information is too limited to in- 

 vestigate the effect on migration timing. The west- 

 ward movement of haddock onto the bank into shal- 

 lower water probably begins around November and 

 reaches its greatest extent to the west during the 

 peak of spawning in March-April, after which the 

 return migration eastwards begins. Most haddock 

 have probably migrated eastward across the ICJ line 

 by July and by October; haddock are found far east 

 of the line preferring the deeper waters of the north- 

 east slopes of the bank. 



An understanding and appreciation of the distri- 

 bution and migration patterns on eastern Georges 

 Bank in relation to the ICJ line are important pre- 

 requisites for investigation of sustainable harvest 

 practices for this transboundary resource. The pat- 

 tern of migration described in our study does not al- 

 ter sustainable levels for the area as a whole but 

 because of the seasonal nature of exploitation by 

 Canada and the United States, this information can 

 provide guidance on the exploitable biomass avail- 

 able on each side during different seasons so that 

 consistent and equitable hai-vest rates can be deter- 

 mined. After establishment of the international 

 boundary, Canada and the United States have man- 

 aged the resources in their respective territories with 

 little attention to what was being done in adjacent 

 waters. Though it has been suggested that sustain- 

 able fisheries could be maintained through indepen- 

 dent management (Gavaris et al., 1993), it is likely 

 that the greatest potential would be achieved through 

 consistent management. Knowledge of temporal and 

 spatial distribution patterns can form the basis upon 

 which consistent management practices are explored. 



Acknowledgments 



We are grateful to the staff of the National Marine 

 Fisheries Service at the Northeast Fisheries Center, 



Woods Hole, Massachusetts, for their provision of 

 research survey and commercial landings data that 

 permitted the preparation of this manuscript. We also 

 thank especially Ralph Halliday and Russell Brown 

 for their valuable comments on an earlier version of 

 the manuscript and the two anonymous referees. 



Literature cited 



Beverton, R. J. H. and S. J. Holt. 



1957. On the dynamics of exploited fish populations. Fish. 

 Inve.st. Minist. Agnc. Fish. Food UK (series 2) 19, 533 p. 

 Bigelow, H. B., and W. C. Schroeder. 



1953. Fishes of the gulf of Maine. U.S. Fish Wildl. Serv. 

 Bull. 74, vol. 53, 577 p. 

 Clark, S. H., W. J. Overholtz, and R. C. Hennemuth. 



1982. Review and assessment of the Georges Bank and Gulf 

 of Maine haddock fishery. J. Northw. Atl. Fish. Sci. 3: 

 1-27. 

 Colton, J. B. 



1955. Spring and summer distribution of haddock on 

 Georges Bank. Special Scientific Report of the U.S. Fish 

 and Wildlife Service — Fisheries 156, 65 p. 

 Cook, R. D. 



1977. Detection of influential observation in linear reg- 

 ression. J. Statistical Society 74:169-174. 

 Gavaris, S. 



1980. Use of a multiplicative model to estimate catch rate 

 and effort from commercial data. Can. J. Fish. Aquat. Sci. 

 37:2272-2275. 

 Gavaris, S., and L. Van Eeckhaute. 



1990. Assessment of haddock on eastern Georges Bank. 

 Canadian Atlantic Fisheries Scientific Advisory Commit- 

 tee (CAFSAC) Res. Doc, 90/86, 37 p. 



1991. Assessment of haddock on eastern Georges Bank. 

 CAFSAC Res. Doc. 91/86, .30 p. 



1994. Assessment of haddock on eastern Georges Bank. 

 Canadian Dep. Fisheries and Oceans (DFOl Res. Doc. 94/ 

 31, 38 p. 



1995. Assessment of haddock on eastern Georges Bank. 

 DFO Res. Doc. 9.5/6, 36 p. 



1997. Assessment of haddock on eastern Georges Bank. 

 DFO Res. Doc. 97/54, 72 p. 

 Gavaris S., and L. Van Eeckhaute, M. I. Buzeta, and 

 J. Hunt. 



1993. Yield projections for the transboundary cod and had- 

 dock resources on eastern Georges Bank. Canadian Dep. 

 Fisheries and Oceans (DFO) Res. Doc. 93/71, 19 p. 

 Grosslein, M. D. 



1962. Haddock stocks in the ICNAF Convention Area. 

 International Commission for the Northwest Atlantic Fish- 

 eries (ICNAFi Redbook Part III: 124-131. 

 Halliday, R. G. 



1988. Use of seasonal spawning area closures in the man- 

 agement of haddock fisheries in the Northwest Atlantic. 

 Northwest Atlantic Fisheries Organization (NAFO) Sci. 

 Coun. Studies 12:27-36. 



Halliday, R. G., and A. T. Pinhorn. 



1990. The delimitation of fishing areas in the northwest 

 Atlantic. J. Northwest Atl. Fish. Sci. 10:1-51. 

 Lough, R. G., and G. R. Bolz. 



1989. The movement of cod and haddock larvae onto the 

 shoals of Georges Bank, J, Fish Biol, 35(suppl, A):71-79. 



