Food Habits of Key Groundfish Species in the Eastern Bering Sea Slope Region

120 Pages·2000·2.3 MB·English

NOAA Technical Memorandum NMFS-AFSC-67
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National Oceanic and Atmospheric Administration
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.S.U TNEMTRAPED FOECREMMOC
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D. James Baker, Under Secretary and Administrator
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National Technical Information Service
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iii
ABSTRACT
The eastern Bering Sea continental slope region contains many groundfish species that
are important to the Bering Sea ecosystem. Several studies have described the food habits
of these species in the eastern Bering Sea shelf region, however few studies have been
conducted for the slope region. Consequently, the food habits of the major groundfish in
this region are poorly understood. The focus of this study was to identify the trophic
snoitcaretni fo eyellaw kcollop argarehT( ,)ammargoclahc cificaP docsudaG(
macrocephalus), Greenland turbot (Reinhardtius hippoglossoides), arrowtooth flounder
(Atheresthes stomias), and flathead sole (Hippoglossoides elassodon) in the slope region
of the eastern Bering Sea. Stomach contents of 1,089 walleye pollock, 311 Pacific cod,
455 Greenland halibut, 282 arrowtooth flounder, and 366 flathead sole were examined.
The general diet of each species is described and dietary variation due to predator size,
depth, season, and latitude within the slope region are examined. Walleye pollock are
known to be the most important prey fish in the eastern Bering Sea shelf region. In the
slope region, species from the families Bathylagidae and Myctophidae were found, in
addition to pollock, to be important forage fish of groundfish predators
V
CONTENTS
ABSTRACT................................................................... iii
INTRODUCTION............................................................................................. 1
METHODS........................................................................ 5
STLUSER 11.......... .D.N.A........................ ...N.O.I.S.S.U.C.S.I.D...........................
eyellaW kcolloP
Result............................................................... ll
Discussion . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.. 1
eyellaW kcolloP nacSataD
Results............................................................................................ 36
Discussion......................................................................36
cificaPdoC
Results................................................................. 38
Discussion.....................................................................................................53
Greenland Turbot
Results............................................................56
Discussion............................................................................ 67
Flathead Sole
Results........................................................................ 71
.......................................................................................................noissucsiD 48
Arrowtooth Flounder
Result s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Discussion . .................................................... .95
YRATEIDSNOSIRAPMOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
SUMMARY.................................................................................................... 106
.....................................................................................................SNOITATIC 801
NOITCUDORTNI
The eastern Bering Sea supports one of the largest groundfish populations of the
world’s oceans, which in turn supports a multi-million dollar commercial fishery Species
hcus sa eyellaw kcollop argarehT( ;)ammargoclahc cificaP doc sudaG(;)sulahpecorcam
Pacific halibut (Hippoglossus stenolepis); and king (Paralithodes spp.); Tanner
(Chionoecetes bairdi); and snow crabs (Chionoecetes opilio) are important components of
the eastern Bering Sea ecosystem which is managed by state, federal, and international
seirehsif tnemeganam .snoitazinagro nI tnecer ,sraey sreganam evah neeb gnivom drawota
multi-species management approach that requires a more thorough understanding of the
scimanyd fo smetsysoce naht dah neeb ylsuoiverp .nwonk enO fo eht yeksretemarap
needed for successful multi-species management is an accurate estimate of the natural
mortality pressure exerted on a particular species by other species in the system.
Understanding predator-prey relationships is a complex, yet crucial aspect of the natural
mortality rates of a population. Quite a body of work has been generated around the food
habits of key groundfish predators in the eastern Bering Sea continental shelf where the
majority of the groundfish populations are found, and researchers are beginning to look at
the multi-species interactions that occur between fish, marine mammals, and birds,
However, little work has been done to determine the food habits of these important
groundfish species over the eastern Bering Sea continental slope region,
The eastern Bering Sea continental slope region (Fig. 1) is the area which links the
eastern Bering Sea continental shelf (<200 m) to the Aleutian basin (>2,000 m); however,
most of the important groundfish populations are found between 200 and 500 m. The area
coveredb yt hec ontinentals lopei ss mallr elativet ot hes helfr egiond uet oi tss teepness.
Groundfish populations in the eastern Bering Sea slope region are also small relative to
those on the eastern Bering Sea shelf but do represent an important component of the
ecosystem. Walleye pollock, Pacific cod, Greenland turbot (Reinhardtius