466 
Fishery Bulletin 106(4) 
Table 2 
Percent frequency of occurrence of prey categories determined from stomach contents of Greenland halibut ( Reinhardtius hip- 
poglossoides) caught on five individual bottom trawl surveys in August 2003-05, November 2003, and March 2004, and on the 
vertical longline survey in August 2005, and for all bottom trawls combined. 
Aug 
2003 
bottom 
trawl 
Nov 
2003 
bottom 
trawl 
Mar 
2004 
bottom 
trawl 
Aug 
2004 
bottom 
trawl 
Aug 
2005 
bottom 
trawl 
Aug 
2005 
vertical 
longline 
Combined 
bottom 
trawl 
Crustaceans 
Amphipods 
4.5 
5.4 
6.7 
7.1 
14.7 
22.2 
7.8 
Euphausiids 
0.0 
5.4 
0.7 
2.4 
0.0 
0.0 
1.1 
Shrimps 
28.8 
35.1 
15.3 
21.4 
36.0 
48.1 
24.6 
Undetermined 
3.0 
8.1 
24.7 
7.1 
13.3 
3.7 
14.9 
Cephalopods 
Gonatus fabricii 
37.9 
10.8 
20.0 
35.7 
58.7 
40.7 
34.6 
Rossia spp. 
0.0 
0.0 
1.3 
2.4 
1.3 
3.7 
1.1 
Undetermined 
1.5 
0.0 
4.7 
2.4 
4.0 
0.0 
3.5 
Fish 
Salmon 1 
0.0 
0.0 
0.0 
0.0 
1.3 
0.0 
0.3 
Herring 
18.2 
8.1 
36.0 
2.4 
5.3 
0.0 
20.0 
Blue whiting 
9.1 
5.4 
2.7 
14.3 
2.7 
0.0 
5.4 
Sebastes spp. 
3.0 
0.0 
0.7 
0.0 
0.0 
0.0 
0.8 
Other fish 
0.0 
5.4 
1.3 
4.8 
2.7 
0.0 
2.2 
Undetermined 
21.2 
32.4 
31.3 
14.3 
12.0 
3.7 
23.8 
Offal 
3.0 
0.0 
0.0 
4.8 
4.0 
0.0 
1.9 
Other 
3.0 
2.7 
1.3 
11.9 
1.3 
0.0 
1.8 
Number of stomachs examined 
327 
98 
378 
298 
— 
— 
198 
Stomachs with contents 
66 
37 
150 
42 
75 
370 
27 
Empty stomachs 
80% 
62% 
60% 
86% 
— 
— 
86% 
1 A Carlin dangler tag from a tagged salmon was found in one Greenland halibut stomach. 
10 - _ 
0 - 
J FMAMJ J ASOND 
Month 
Figure 9 
Seasonal variation in mean vertical activity (VA) for Greenland 
halibut ( Reinhardtius hippoglossoides) tagged with archival tags. 
For each month, the number of days of individual archival tag 
recordings where VA was greater than 5 (bold), 10 (regular), and 
15 m (dotted line) respectively, is given as a percentage of the 
total number of days recorded by all tags combined. 
During these acoustic surveys, most of the 
total backscatter was allocated to herring in 
the upper layer and blue whiting in the lower 
layer. As usual with these types of surveys, 
the allocation was based on visual recogni- 
tion of typical patterns, guided by data on 
target strength of individual echoes and catch 
composition from sporadic pelagic trawl hauls 
(mostly outside our extended survey area). 
Figure 11 shows how catches of redfish and 
gadoids on vertical longlines compare with the 
results from the acoustic surveys. The gadoids 
Atlantic cod ( Gadus morhua), saithe ( Polla - 
chius virens), and blue whiting were generally 
caught within the depth range of the lower 
acoustic layer, i.e. from 200 to 500 m. The 
low-target-strength species, the deepwater 
redfish (Sebastes mentella), was caught in the 
lower part of this layer and below, mostly from 
400 to 600 m depth. The bathymetric distribu- 
tion of Greenland halibut catches from pelagic 
longlines overlapped to a large extent with the 
distribution of the prey species redfish and 
blue whiting, much less with other gadoids, 
and not with herring. 
