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Fishery Bulletin 106(4) 
600- 
500- 
400- 
300- 
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0 - 
4000-1 
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4000 -i 
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2000 - 
□ VD>10 m 
□ 0.5<VD<1 0 m 
■ VD<0.5 m 
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Time of day 
Figure 7 
Diurnal variations in standardized vertical distance ( VD , in meters) traveled 
by Greenland halibut ( Reinhardtius hippoglossoides) tagged with archival 
tags, within each of three depth intervals. The different shaded bars rep- 
resent frequencies of high (>10 m), medium (0.5-10 m), and low (<0.5 m) 
VD, respectively. 
Prey composition 
The main prey categories found in Greenland halibut 
stomachs were crustaceans, cephalopods, and fish. These 
species all occurred in 35-47% of stomachs with con- 
tents (all trawl surveys combined, Table 2). Crustaceans 
were mainly shrimps (primarily Pasiphaea spp. and 
Pandalus borealis) and gammarid amphipods, whereas 
Gonatus fabricii was the predominant cephalopod. Her- 
ring and blue whiting were the most common fish prey. 
One stomach contained a fish tag that one month earlier 
had been attached to a 19-cm salmon ( Salmo salar), but 
whether this tag represents a direct or indirect foraging 
link between salmon and Greenland halibut, remains 
unknown (Rikardsen et ah, 2008). 
Of the three main categories of prey, Crustacea were 
a relatively stable contributor, whereas frequency of 
occurrence of cephalopods and fish varied between sur- 
veys (x 2 , df=4, P<0.01). This temporal variability was 
mainly due to three species or species groups. Gonatus 
fabricii was recorded more frequently in August than 
in March and November, whereas herring was most 
frequent in August 2003 and March 2004, and blue 
whiting in August 2003 and 2004. 
Figure 10 shows how the diet changed with the size 
of the predator. In terms of weight, the contribution 
of cephalopods, shrimps, and most other crustaceans 
decreased with increasing length of Greenland hali- 
but. On the other hand, the contribution of herring 
and most other fish increased with increasing preda- 
tor length. Eelpouts and flatfish were found only in 
Greenland halibut specimens larger than 65 cm, and 
redfish were eaten only by individuals larger than 
75 cm. 
