457 
Pelagic behavior of adult Greenland halibut 
( Reinhardtius hippoglossoides ) 
Abstract — It is evident from several 
field experiments with vertical long- 
lines and archival tags, as well as 
concurrent studies of predator-prey 
relationships, that adult specimens 
of the deep-water flatfish Greenland 
halibut ( Reinhardtius hippoglossoi- 
des) make regular excursions several 
hundred meters through the water 
column. The distribution of longline 
catches within the water column is 
confined to a well-defined depth layer 
overlapping with the distribution of 
blue whiting ( Micromesistius poutas- 
sou), an important prey species, and 
depth recordings from archival tags 
overlap with Atlantic herring ( Clupea 
harengus ), the other major fish prey. 
The degree of pelagic use varies with 
fish size as well as seasons. Smaller 
individuals are found further off 
the bottom, and pelagic activity is 
greatest during early autumn. Inter- 
action with pelagic prey species can 
influence results from bottom trawl 
surveys. 
Manuscript submitted 19 February 2008. 
Manuscript accepted 1 July 2008. 
Fish. Bull. 106:457-470 (2008). 
The views and opinions expressed 
or implied in this article are those 
of the author and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Tone Vollen (contact author ) 1 - 2 
Ole T. Albert (equal authorship) 1 
Email address forT. Vollen: tone.vollen@imr.no 
1 Institute of Marine Research 
Sykehusveien 23, 
N-9019 Trornso, Norway 
Present address: Institute of Marine Research 
Sykehusveien 23, N-9019 
Tromsa, Norway 
2 Department of Aquatic Biosciences 
Norwegian College of Fishery Science 
University of Trornso 
N-9037 Trornso, Norway 
Greenland halibut ( Reinhardtius hip- 
poglossoides (Walbaum)) is a deep- 
water flatfish of high commercial 
value in the northernmost parts of 
the Atlantic and Pacific oceans. The 
absence of a swim bladder renders 
the species virtually invisible to echo 
sounders; therefore data from scien- 
tific and commercial fishing opera- 
tions conducted close to the seabed 
with trawls, long-lines, and gill nets 
are used for stock assessments (Bow- 
ering and Nedreaas, 2000). This 
practice may be surprising, given the 
general perception of Greenland hali- 
but as a more free-swimming species 
than other flatfishes (Merrett and 
Haedrich, 1997). If indeed the use 
of the pelagic zone by this species is 
extensive or frequent, results from 
bottom trawl surveys may be biased 
and less informative for use in assess- 
ments. This problem increases if the 
pelagic behavior varies over time or is 
unevenly distributed among sizes, the 
sexes, and maturity groups. 
The perception that Greenland hal- 
ibut may be a pelagically distributed 
species has primarily been based on 
assumptions, anecdotical information, 
and circumstantial evidence. Morpho- 
logical characters such as a stream- 
lined body shape, pigmentation of the 
blind side, and positioning of the left 
eye on the dorsal ridge of the head 
led de Groot (1970) to suggest that 
Greenland halibut behaves more like 
a roundfish. This has been supported 
by historical reports of specimens of 
Greenland halibut being caught in 
pelagic waters with hand lines and 
salmon drift nets (Christensen and 
Lear, 1977; Merret and Haedrich, 
1997). More recent documentation of 
pelagic use is scarce, particularly for 
adult specimens. 
Jprgensen (1997) reported that one- 
year-old Greenland halibut were com- 
monly found in pelagic trawls in West 
Greenland waters, and two-year-olds 
appeared much less frequently. Older 
individuals were virtually absent 
from pelagic trawls, even when they 
were captured in high abundance in 
bottom trawls. The author concluded, 
however, that these results may have 
been influenced by differences in the 
selectivity patterns of bottom and pe- 
lagic trawls. 
Although records are scarce, a sig- 
nificant portion of the diet of adult 
Greenland halibut consists of bathy- 
and mesopelagic fish, mollusks, and 
crustaceans such as redfish ( Sebastes 
spp.), blue whiting ( Micromesistius 
poutassou), cephalopods, shrimps, and 
euphausiids, as well as epipelagic spe- 
cies such as Atlantic herring (Clupea 
harengus) and capelin ( Mallotus villo- 
sus) (Bowering and Lilly, 1992; Dawe 
et al., 1998; Michalsen and Nedreaas, 
1998; Hovde et al., 2002; Solmunds- 
son, 2007). We therefore used the 
assumed feeding modus of pelagic 
