Bo|e; Intermingling and seasonal migrations of Reinhardtius hippoglossoides 



417 



The model run covered a total of eight years, which 

 was the maximum timi' recorded for time at liberty 

 of tagged (Greenland halibut at sea. The random walk 

 distribution was compared with the true recapture 

 distribution by means of a chi-square test. The true 

 recapture distribution was corrected for fishing effort 

 by using the frequency of recaptured halibut per unit 

 landing in a statistical square (smallest statistical 

 unit to assign landings), where landings were monthly 

 averages for the period 1993-97. By pooling landings 

 monthly for this 5-year period there were no zero val- 

 ues in the data set. Effort data were not available for 

 the inshore fishery; therefore landings data were used 

 instead. Previously landings data for these inshore 

 areas were found to correlate well with fishing effort 

 (Anonymous, 1998). 



Migration distances are given in kilometers ( 1 

 km=0.540 nautical mile). For all analyses, SAS statis- 

 tical (SAS, 1988) and Statistica (StatSoft, Inc., 2000) 

 software were used. 



Results 



A total of 7244 Greenland halibut were tagged from 

 1986 to 1998. By the end of 1998, 517 recaptured 

 Greenland halibut (7.1% of halibut released during the 

 entire period) were recovered (Table 1). The majority of 

 recaptured fish were reported within two years after 

 tagging, but some were reported as late as eight years 

 after tagging. In general, Greenland halibut tagged in 

 the fjords of northwestern Greenland (Ilulissat, Torsuk- 

 kattak, Uummannaq, and Upernavik) tended to remain 

 resident, whereas some Greenland halibut from the three 

 other tagging sites (East Greenland fjords. Southwest 

 Greenland fjords, and West Greenland offshore) displayed 

 migratory behavior. 



Prevailing migratory patterns 



An overview of the numbers of recaptured Greenland 

 halibut (adjusted for fishing activity for each release 

 site versus recapture area) is presented in Table 2. Most 

 recaptured Greenland halibut were found at their release 

 locality (especially at Ammassalik in East Greenland, in 

 the fjords of Cape Farewell, in Godthaab Fjord, Uum- 

 mannaq, and Upernavik in West Greenland), and 99% 

 of the recaptured halibut were taken within the release 

 area. For releases in the two neighboring fjords in north- 

 western Greenland, Ilulissat, and Torsukkattak, 10-14% 

 of recaptured Greenland halibut showed intermingling 

 between the two fjords. Limited intermingling was also 

 noted between Ilulissat and Uummannaq (<l-3%). Of 

 the 21 recaptured Greenland halibut from Davis Strait 

 and Baffin Bay, 96% and 77%, respectively, were caught 

 in the release area (values adjusted for fishing effort). Of 

 23 recaptured Greenland halibut in Ammassalik in East 

 Greenland, the vast majority (99%) were recaptured near 

 the tagging site; whereas single specimens (less than 

 1%) were recaptured in Denmark Strait and north of the 



Figure 2 



Migration pattern for long-distance migrants only. Numbers indicate 

 percentage of recaptured fish from difTerent tagging sites in Green- 

 land that were caught at fishing grounds shown by the arrows (north- 

 western Greenland Fjord Torsukkattak, off Newfoundland, west of 

 Iceland, and north of the Faroe Islands). 



Faroe Islands. Greenland halibut recovered from releases 

 in the fjords of southwestern Greenland (Cape Farewell 

 and Godthaab Fjord,) were mostly recaptured at the 

 release site (99%), whereas the remaining were captured 

 in Denmark Strait, except for a single specimen captured 

 off Newfoundland. The majority of released halibut from 

 the most comprehensive tagging effort in the fjords of 

 northwestern Greenland were recaptured at their tag- 

 ging site (approximately 90%). This observed fidelity to 

 tagging site was most pronounced in the northern areas 

 of the Qord systems at Uummannaq and Upernavik. No 

 released fish from the Qords of northwestern Greenland 

 were recaptured outside the area. Of the halibut released 

 in the offshore areas of western Greenland, i.e. Davis 

 Strait and Baffin Bay, most were recovered at their 

 release sites, but a few specimens were also recovered as 

 far as Denmark Strait and Newfoundland. Although only 

 four Greenland halibut were recaptured from Baffin Bay, 

 two of them were captured in the ^ord of northwestern 

 Greenland (Torsukkattak). Adjusted for fishing effort, 

 they accounted for 17% of recaptured Greenland halibut 

 from Baffin Bay. 



Long-distance migrants 



Twenty-three specimens were recovered at substantial 

 distances from their release sites (Fig. 2). Greenland hali- 

 but tagged in Godthaab Fjord and recaptured in Denmark 

 Strait (6 specimens) migrated an average of approximately 



