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Fishery Bulletin 106(4) 
Greenland halibut to study their pelagic distribution. 
A series of experiments with vertical longlines were de- 
signed to catch the species in the pelagic zone, and in- 
formation on individual depth trajectories were obtained 
from archival tags for comparisons with the vertical 
distribution of longline catches. In addition, stomach 
contents from concurrent bottom trawl hauls provided 
information on diet of Greenland halibut, length com- 
positions were obtained from demersal longlines and 
bottom trawl, and acoustic surveys gave insight into 
the pelagic distribution of some of the prey species. The 
study aims at describing the use of the pelagic zone by 
adult Greenland halibut in the Northeast Arctic, both 
in terms of temporal variability and through param- 
eters such as size, sex, and maturity. 
Materials and methods 
Data were mainly collected from dedicated surveys with 
hired commercial longline vessels within a limited area 
of the continental slope between northern Norway and 
Bear Island (the central study area. Fig. 1). The long- 
line vessels were used for pelagic fishing with vertical 
longlines, fishing with demersal longlines, and release 
of fish tagged with archival tags. Data were also col- 
lected from a number of additional surveys in the same 
or nearby areas and time periods. These additional sur- 
veys included bottom-trawl surveys for stomach contents 
analyses and length-frequency distributions, and trawl 
acoustic surveys for acoustic profiles. The additional 
surveys were not originally designed for this study, and 
data from these investigations were extracted for the 
extended survey area (Fig. 1). 
Vertical longlines 
Vertical longline experiments were conducted within 
the central study area during seven surveys in March, 
August, and November from 2003 through 2005 (Fig. 1). 
The main survey, with 73% of all the vertical longline 
settings, took place in August 2005. During the first 
six surveys the experiments were only a minor part of 
the total mission. These six were made partly to gather 
experience, and partly to establish a time series to be 
compared with the main survey. 
The vertical longline gear consisted of an anchor 
(25 kg minimum), a rope, a hooked longline, anoth- 
er rope and, finally, a buoy at the surface. A Mustad 
autoline system was used on all vessels. The hooked 
longline was 9 mm thick and had hooks of type Mus- 
tad EZ 12.0, ganglion length was approximately 50 
cm, and the spacing between hooks was 1.5 meters. To 
record the position and action of the vertical longline, 
archival tags (DST-milli, Star Oddi, Reykjavik, Iceland) 
were attached to the top and bottom of the hooked sec- 
tion, as well as over the anchor. Bait was a 1:1 ration 
of Atlantic mackerel (Scomber scombrus) and flying 
squid ( Todarodes sagittatus ) — the most common bait 
types used to target catch of Greenland halibut (Bjordal 
Figure 1 
Bathymetric map of both the central and expanded study 
area situated along the continental slope between Norway 
and Spitsbergen. Depths are in meters. The longline 
experiments, as well as release of Greenland halibut 
( Reinhardtius hippoglossoides) tagged with archival tags, 
were made within the central study area, whereas data 
from the acoustic surveys and bottom trawl surveys 
were gathered from the extended study area. Recapture 
positions of individuals with archival tags are marked 
with open circles. 
and Lpkkeborg, 1996). Bait size was approximately 
2.5 cm x 5 cm. 
The hooked section of the longline covered most of the 
water column, from 45 m below the surface to 20-150 m 
over the bottom. Longlines were rigged to ensure that 
the hooks did not touch the bottom, and the position 
of the anchor and the highest and lowest hooks were 
monitored by using archival tags. At bottom depths 
