Van Eeckhaute et a\: Movements of Melanogrammus aeglefinus determined from a population model 



675 



Age I 

 Ages 2,3 

 Ages 4-8 



1985 



1986 



1987 



1988 



1989 



1990 



1991 



1992 1993 1994 



Figure 10 



Net migration rates (expressed as annual rates) across the ICJ line for 6-month tmie periods 

 for 5Zj,m haddock. These rates show that from April to September, net haddock migration 

 was towards the east resulting in almost all haddock in 5Zj,m residing on the Canadian side 

 in the fall. There was then a migration westward and across the ICJ line from October to 

 March, a migration associated with spawning activities. 



Discussion 



Observations regarding haddock spatial distribution 

 on Georges Bank during an earlier period (Colton, 

 1955) and for two dominant year classes more re- 

 cently (Overholtz, 1985) have indicated that adult 

 haddock are more abundant off the bank in deeper 

 waters during the fall but are found on the bank in 

 shallower waters during the spring. Colton (1955) 

 reported that during spring, the greatest concentra- 

 tions of larger haddock occur in water less than 110 m 

 and presumed this was related to spawning activi- 

 ties. Migration from shallower water in spring to 

 deeper water in the fall appears to occur by the end 

 of July. Colton (1955i reported that few haddock of 

 any age were found between 110 m and 165 m dur- 

 ing the July-August surveys undertaken in 1949 and 

 1950. Older haddock, age 5+, could be found in wa- 

 ters deeper than 165 m in unit areas 5Zg,h and j. 

 Overholtz (1985) also suggested that survey distri- 

 butions of age-2 haddock indicated a movement by 

 summer to deeper water in relation to the shallower 

 depths generally occupied in spring, Colton (1955) 

 and Overholtz (1985) reported some segregation of 

 ages as fish moved into deeper water, i.e. older fish 

 occupied deeper water than did younger fish, but 



Colton ( 1955 1 observed that in spring there appeared 

 to be less segregation of age groups. 



Although we observed two distinct distribution 

 patterns over time within 5Zj,m, our analysis indi- 

 cates that the depth-related patterns described above 

 were persistent. The 1963-71 distribution pattern 

 will be discussed more fully later in this section. 

 Patterns observed from 1972 to recent times show 

 that adult haddock in 5Zj,m were broadly dispersed 

 over the bank during the spring period, their distri- 

 bution extending westward of the ICJ line especially 

 along the southern flank of Georges Bank. The NMFS 

 strata with the highest densities in the spring were 

 the Canadian portions of 21 and 16 which have a 

 depth range from 56 to 110 m. The ratios of relative 

 abundance, especially those from the DFO survey, 

 clearly show that the majority of age-2-(- haddock 

 occupied waters within the Canadian jurisdiction at 

 that time. Both NMFS and DFO spring surveys ex- 

 hibit similar distribution patterns with similar ar- 

 eas of concentration. During the fall, haddock distri- 

 bution shifted to the east onto the deeper bank slopes 

 and few haddock remained on the U.S. side of the 

 ICJ line. The ratios of relative abundance indicate 

 that virtually all age l-i- haddock within 5Zj,m are 

 on the Canadian side of the ICJ line in the fall. 



