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PAPER
International Council for the
Exploration of the Sea
ICES CM 19951L:15
Biological Oceanography
Committee
ZOOPLANKTON INVESTIGATIONS OFF WEST GREENLAND, 1956-1984
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by
S.A. Pedersen and E.L.E. Smidt
Greenland Institute of Natural Resources
(former: Greenland Fisheries Research Institute),
Tagensvej 135, l.tv., DK-2200 Copenhagen N, Denmark
Abstract
The available data on the density and composition of zooplankton obtained in offshore
plankton surveys carried out annuaHy during 1956-1984, except in 1965 and 1967, in JuneJuly off West Greenland by the Danish Institute of Fisheries and Marine Research and the
Greenland Fisheries Research Institute have been analysed. The average densities have been
calculated and inter-annual changes in the densities and of the most important species
investigated. There was a decreasing trend in both the CPUEs of plankton volume and selected
species e.g. the eopepod, Ca/anus finmarchicus, as weH as a positive associations to sea
temperature measurements from the late 1950s and early 1960s to the 1970s. These trends
may be indicative for a decrease in the zooplankton productivity and ehanges in the eeosystem
food-web structure in the same time period. A very weak positive association between the
mean number of eod (Gadus morhua) larvae caught and the mean sea temperatures were
found. The failure of the 1982 year-class and the inability to relate the eatches of eod larvae
to subsequent recruitment were the main reasons that put the end to the zooplankton timeseries from off West Greenland in 1985.
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Introduction
In the prescnt century there have been major changes in thc abundance of commercially
important fish species in \Vest Greenland waters. Historically, Atlantic cod (Gadus morhua)
has been the most important commercial fish species in Greenland waters, with annual
international1<mdings peaking at levels between 400,000 and 500,000 tons in the early 1960s
(Fig. 1). In the late 1960s the annual landings showed a drastie decline. After 1970, the
recruitment to the \Vest Greenland cod stock has shown large variations and all important
year-classes in West Greenland waters have been of Icelandic origin (Buch et al. 1994,
Hovgard and \Vieland in press). After 1990 the Atlantic cod has been very sparse in West
Greenland waters (Anon. 1994). In the 1980s and 1990s the northern shrimp (Pandalus
borealis) has been the far most important fishery resource at West Greenland with annual
landing peaking at 87,000 tons in 1992 (Anon. 1995). The low productivity of the West
Greenland cod stock is assumed to be duc mainly to decreased and unfavourable water
temperature conditions for spawning, eggllarvae survival and to changes in thc whole
ecosystem productivity (food-web structtirc) (Hermann et al. 1965, Pcdersen 1994).
In thc North Atlantic analogous biologieal seasons occur at different times of the year in
different parts of the same aquatory, as if they moved together with the water of warm
currents and this phenomenon often determines the direction of the feeding migrations of
pelagic fishes (Pavshtiks 1968, 1972). Davis Strait resembles the other northem regions of the
Atlantic in many ways in its complex circulation, clearly defined frontal zones, and other
hydrologieal factores (pavshtiks l.c.). Seasonal and inter-annual variability in the
hydrographieal conditions and fauna of the upper ocean layer along \Vest Greenland is governed mainly by inflow of water from other parts of the North Atlantic (pavshtiks l.c., Lee
1968, Buch 1984, 1990, 1993). The surface layer (0-150 m) of the \Vest Greenland Current
is dominated by cold, relatively fresh Polar Water carried to the area by the East Greenland
Current, while the underlying layer (150-800 m) consists totally of water originating from the
warm, salty Irminger Current (Fig. 2). Mixing and heat diffusion between the two layers are
important factors for the temperature conditions whieh among other things are dependent on
the flow intensity. Years with a strong East Greenland Current will tend to show up as cold
ones and viee versa. A description of annual and inter-annual variation in the iee conditions
is given in Buch (1990).
The most recent general publication on zooplankton in \Vest Greenland waters, including a
protracted list of references is by Smidt (1979). Smidt (l.c.) presents results of zooplankton
sampling in inshore and coastal waters throughout the years 1950-66, mainly in the Nuuk
(Godthab) district.
From 1956 to 1984 aseries of offshore plankton surveys were carried out annually, except in
1965 and 1967, in June-July off \Vest Greenland by the Danish Institute of Fisheries and
Marine Research and the Greenland Fisheries Research Institute. Some of the main aims of
these surveys and zooplankton collections were: 1) to collect and possibly quantify fish egg
and larvae, especially of Atlantic cod, in order to get information on the strength of the new
year-classes, 2) to evaluate the amount of zooplankton and quality (species composition) as
food for the recruiting year-classes of fish, 3) to identify indicator species for different
hydrographieal conditions in the area, 4) to compare variations in the zooplankton by year and
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possibly to ideritify trends over the ycars in the species eomposition rind productivity. The
zooplankton data (invertebrates and fish eggs and larvae) have reeently been eompiled in a
database together with sea temperature and salinity measurements. The purpose of the present
paper is to give a deseription of the information in the zooplankton database and to present
results froin analyses of the zooplankton data (species eomposition, oeeurreriee, abundanee
indices) for variations, trends and associations with e.g. temperature. Of special interest is the
long-term variations or trend between the period before 1970 (1956-1970, relatively walm
pedod) and after 1970 (1970-1984, relativcly eold period).
Materials and methods
MethodS of samplirig
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By far most of the zooplankton, 1956-1984, was eollected on stations along three transects
[hydrographie areas/sections, (SI,S2 and S3)] off \Vest Greenland in June-July in conjunction
with collectioris of hydrography data from standard depths (Fig. 2-5). Zooplankton and sea
water temperature data from these transeets have been analyzed for annual variations.
Sampling was carried out with the RJV "Adolf Jensen" and "DANA". Tbc zooplankton
sampling gear used was a 2 m (diameter) stramin-ring-net with 1 mm mesh size. Tbc towing
speed was about 1.5 to 2.0 knots during the whole tow duration of about 30 min. During the
years two different hauling proeedures were employed. Before 1963, all hauls were horizontaHy, stratified with two nets on the same wire in three times 10 min. and with wire lengths
200, 150, 125 and 100, 50, 25 m for the two nets, respectivcly.
In 1963 (the NOR\VESTLANT survey), aH hauls were made obliquely with only one net
hauled from about 50 m depth to the stirface at 1.5 knots, wire length 225-0 m, duration
about 30 min.
In 1964 and 1966, stratificd hauls with two nets were again made, but in a11 the fo11owing
years, 1967-1984, hauls with only one net wcre made obliquely as in 1963.
Analysis of sampIes
In order to make the zooplankton sampies comparable haul by haul, between years, arid hence
by hauling method (stratified vs. oblique hauls) all figures in the present paper are caiculated
to 30 inin.· hauis. Tbe figures from the two nets in the stratified hauls (before 1963 and in
1964 and 1966) have been averaged. Because of soine extra hauling time a conversion faetor
of roughly 0.75 is used for the stratified hauls before 1963 and roughly 0.85 for hauls in the
years 1964 arid 1966. Only data from hauls with a ma'dmum wire length less than 251 m have
beeri included in the preserit paper. .
Calibration experiments pcrformed in 1984 with flO\vmeter attached to the opening of the 2
m stramin riet showed that a haul duration of 30 rriiri. at towirig speed 2 knots equals a filtered
volume of water of about 6125 m3 (Hovgard and Wieland in press).
The mcthod uscd for sorting and counting was first to pick out and eount the largcr animals
4
from the total sampie before taking an aliquot subsampie to identify and count the smaller and
more numerous animals. The plankton volume in ml is the displacement volume measured at
sea exclusive salps and schyphomedusae, adjusted to 30 min. haul . All other zooplankton data
presented in this paper are expressed in numbers per 30 min. hau!.
The zooplankton groups and specics sclected and analyzed in the paper are listed in Table 1.
Very small animals are not caught by the 1 mm mesh size in the ring net used, and many
sma1l development stages and sma1l species are therefore not included in the species list Table
1. For more complete lists of specics including also sma11 development stages and species see
J"rgensen et al. (1978a,b) and Smidt (1979). In some years not a11 sampIes were sorted for
invertebrates, aIthough sorted for fish eggs and larvae and in 1965 and 1967 there were no
sampling at a1l (Table 2).
Analysis of variance and associations
The zooplankton CPUE data (volume and numbers per 30 min. haul) showed non-normality
and were, therefore, analyzed for variations (effects of sampling section and year) using rank
tests. Kruskal-Wallis tests and two-way ANOVAs on ranked data were performed (Anon.
1985, NPARl\VAY, RANK and GLM p'rocedures).
Thc sea temperature and salinity at the sampling stations were calculated as simple means of
temperature and salinity measurements in the range 10-50 m (norma1ly the standard depths
10, 25, and SO m or 10, 20, 30, and SO m). Effects of sampling locations and year on the
mean temperature and salinity were analyzed by a two-way ANOVA. The number of
temperature, salinity and zooplankton observatioris (sampled stations with data) by section and
year are given in Table 2.
Associations between temperature, salinity and logarithmic transformed CPUE-values of
zooplankton [Ln (volume and animal numbers per 30 min. haul)+l] were investigated by
Persons product-moment correlations (Anon. 1985).
Results
Distribution of the zooplankton CPUEs (Fig. 5-27)
The zooplankton CPUE-values, June-July 1956-1984, show not surprisingly large
distributional variations, however, some general trends are apparent. Comparing the "white"
and "red" form of Aglantha digitale it appears that the "white" form becomes less abundant
in the northem survey area around Disko Island whereas the "red" form is found only in the
northem and westernmost sampies (Fig. 7 and Fig. 8). The copepods Calanus finmarchicus
and C. hyperboreus show aUke distribution and the largest quantities are taken at the
westernmost stations and in the Disko Bay (Fig. 9 and Fig. 10). Euchaeta (Pareuchaeta)
nonvegica is most abundant at the western and southern haul stations (Fig. 11). Comparisons
of the distributions of Limacina (Spiratella) lzelicüia and Limacina (Spiratella) retroversa
show a clear trend of thc former being more northeinly distributcd than thc lattcr (Fig. 15 and
Fig. 16). Clione limacina shows no c1ear distributional trends (Fig. 17). Shrimp Iarvae are
caught on most of thc sampling locations with a trend of the Iargest catches being taken in
the Disko bay (Fig. 19). Crab larvae are most abundant in hauls riear the coast and in the
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Disko Bay (Fig. 20). LarVae of Atlantie eod, Greenlarid halibut, long rough dab, arid catfishes
havc beeri eaught in highcst numbers in hauls from seetion S1, S2 and S3 (Fig. 21, Fi g. 22,
Fig. 26 and Fig. 27). The highest CPUE-values of redfish larvae havc been observed on thc
southern and southwestemmost haul stations (Fig. 23). Highest CPUE-values of sarideell<irvac
have bceri obserVcd over thc so-ealled fishing banks dosest to thc shore arid in thc Disko Bay
(Fig. 24). Capeliri larvae have been taken mainly in inshore hauls in the Godthäosfjord area
and just south of Disko island (Fig. 25).
Analysis Qf varianCe und associations
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Mea~ sea temperat~r~ (MTEMP) and salinity (MSAL):
,.
Tbc MTEMP and MSAL, shows large inter-annual.fluetuatioris (Fig. 28a,b). A tWo-way
ANOyA with scetiori and year as dass variables showed ci significant e.ffe~t. of year ori
~1TEMP (F=10.64, p<O.01), but no sigiIificant <:ifeet of sampling section (F=2.37, p=0.10).
A two-way ANOVA with section and year as dass variables. showed a significant effeets of
both year and seetion on MSAL (F=39.26, p<O.Ol and F=14.95, p<:O.Ol, respeetively). Scetiori
1 gcnerelly had thc highest inean salinity followed by seetion 2 und 3. MTEMP showed thc
highest association with MSAL (r=0.46, p<O.Ol, ri=540) followed by log. transforrned CPUEs
of the "white" forni Aglantha digitale (r=0.32, p<O.Ol, n=186). MSAL showed the highest
associatiori with MTEMP (r=0.46, p<O.Ol, n=540) followed by log. transformed CPUEs of
GonatUs fabricii (r=0.28, p<O.Ol, n=306), and Euphausiaeea (r=0.27, p<O.Ol, n=312).
Plankton volume (PLVOL):
A two-way ANOVA on the ranked PLVOL data with seetiori and year as dass variables
showed a significant dfeet of year (F=6.98, p<O.01), and seetion (F=2L58, p<0~01) (Fig. 30).
Tbc log. transformed PLVOL showed positive but weak associatioris to MTEMP (r=0.29,
p<O.Ol, n=446) with a trend of higher PLVOL in thc latc 19505 and early 19605 with mean
temperatures abovc 2° C. eompared to thc, 1970s and 1980s with more fltictuating meari
temperatures (I:'ig..30). The log. trarisfomled PLVOL showed the highest associations with log.
transformed CPUES of Aglantha digitale (r=0.84, p<O.Ol, n=315), Limacinti sp~ (r=0.52,
p<O.Ol, n=314), Gonatusfabricii (r=0.51, p<0.01, n=306), euphausids (r=0.50, p<:O.Ol, ri=314),
etenophores (r=0.49, p<O.01, n=262), Calanus Izyperboreu.s (r=0.47, p<O.01, n=271) and
negative associaiions with sandeellarvae (r=-0.26, p<O.Ol, n=532) and crab laivae (r=-0.19,
p<O.Ol, n=315).
AglantJui digitale (HAGLA="white" form and RAGLA="red" form):
A two-way ANOVA \\ith section and year as dass variables showed a significant effeet Qf
year on the ra~ked HAGLA data (F=10.07, p<O.01), but not on thc ranked RAGLA data
(F=1.35, p=0.17) (Fig. 29). For, both rankcd HAGLA and RAGLA data thc sampling scction
had a significant effcet (F=10.29, p<O.Ol and F=19.30, p<0.01, respeetively). LOg. transformed
iIAGLA was posiÜvely associated with MTEMP (r=0.32, p<0.01, n=186), whereas log.
RAGLA was negatively associated with MTEMP (r=-0.26, p<O.Ol, n=186). Tbe latter shows
that RAGLA is a eold water iridicator.
Caltinus jinniarchicus (indudes also C. glacialis) (CALFI):
A two-way' ANOVA on thc ranked CALFI data with scction and year as dass variables
shO\vcd a significant cffcet of scetion (F=12.27, p<O.Ol) aridyear (F=7.11~ P<O.Oi)(Fig. 31
and Fig. 32) LOg. CALFI showed thc highcst association with log. transformed CPUES of
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Chaetognatha (r=O.81, p<O.01, n=272), Calanus hyperboreus (r=O.73, p<O.01, n=273),
Euchaeta (Pareuchaetiz) nonvegica (r=O.68, p<O.01, n=268), and Euphausiacca (r=O.67,
p<O.01, n=272), but no significant association with MTEMP (r=-O.OO, p=O.96, n=230).
Calanus hyperboreus (CALHY):
A two-way ANOVA on the ranked CALHY data with section and year as dass variables
showed a significant effect of section (F=8.44, p<O.01) and year (F=9.73, p<O.01)(Fig. 31 and
Fig. 32) Log. CALHY showed thc highcst association with log. transform cd CPUEs of
Calanus jinmarchicus (r=O.73, p<O.01, n=273), Euphausiacea (r=O.69, p<O.01, n=272), and
Euclzaeta (Pareuchaeta) nonvegica (r=O.67, p<O.01, n=272), but no significant association
with MTEMP (r=-O.01, p=O.94, n=230).
..
Euchaeta (Pareuchaeta) nonvegica (EUCH):
A two-way ANOVA on thc rankcd EUCH data with scction and ycar as dass variables
showcd a significant cffect of section (F=5.39, p<O.01) and year (F=6.07, p<O.01) (Fig. 32)
Log. EUCH showed thc highest association with log. transformed CPUEs of Chactognatha
(r=O.68, p<O.01, n=277), Calanus jinmarclzicus (r=O.68, p<O.01, n=268), and Euphausiacca
(r=O.60, p<O.01, n=276), but no significant association with MTEMP (r=-O.01, p=O.82,
n=269).
Hypcriidac (HYPER):
A two-way ANOVA on the ranked HYPER data with section and year as dass variables
showcd a significant effcct of year (F=2.21, p<O.002), but not of section (F=3.10, p=O.05)(Fig.
32). Log. HYPER showed the highest association with log. transformed CPUEs of Euchaeta
(Pareuclzaeta) nonvegica (r=O.57, p<O.01, n=276), but no significant association with MTEMP
(r=-O.09, p=O.12, n=269).
Euphausiacea (EUPH):
.
A two-way ANOVA on the ranked EUPH data with section and year as dass variables
showcd a significant effect of section (F=9.28, p<O.01) and year (F=6.68, p=O.01)(Fig. 32).
Log. EUPH showed thc highest association with log. transformed CPUEs of Calanus
Izyperboreus (r=O.69, p<O.01, n=272), and Calanus jinmarclzicus (r=O.67, p<O.01, n=272). Log.
EUPH showed a weak positive association with MTEMP (r=O.22, p<O.01j n=268).
Chaetognatha(CHAE):
A two-way ANOVA on the ranked CHAE data with seetion and year as dass variables
showed a significant effect of section (F=7.36, p<O.01) and year (F=4.41, p=O.Ol)(Fig. 32).
Log. CHAE showed the highest association with log. transformed CPUEs of Calanus
jinmarcJzicus (r=O.81, p<O.01, n=272), Euclzaeta (Pareuclzaeta) nonvegica (r=O.68, p<O.01,
n=277), Calanus hyperboreus (r=O.67, p<O.Ol, n=272), and Euphausiacea (r=O.62, p<O.Ol,
n=315), but no significant association with MTEMP (r=-O.Ol, p=O.86, n=269).
Limacina (Spiratella) Izelicina (LIMH):
A two-way ANOVA on the ranked LIMH data with seetion and year as class variables
showcd a significant effect of section (F=17.76, p<O.Ol) and ycar (F=6.93, p<O.Ol)(Fig. 33).
Log. LIMH showed the highest association with log. transformed CPUES of Limacina
(Spiratella) retroversa (r=O.63, p<O.Ol, n=304), Calanus Izyperboreus (r=O.59, p<O.01, n=264),
and Hypcriidac (r=0.52, p<O.Ol, n=305), but no significant association with MTEMP (r=-O.06,
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p=0.35, n=258).
.
,
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Limacina (Spiratella) retroversa (LlMR):
A two-way ANOVA on the ranked LIMR data with seetion arid year as dass variables
showcd a significant cffcet of scetion (F=26.17, p<:O.Ol) arid year (F=7.22, p=O.Ol)(Fig. 33).
LOg. LlMR showed thc highest association. with log. transformed CPUEs of Limacina
(Spiratel/a) he/icina (r=0.63, p<O.Ol, n=304), Greenland . halibut larvae (ReirihardtiuS
hippog/ossoides) (r=0.60, p<O.01, n=304), juvenile squids (Gonatus fabricii) (r=0.60, p<O.Ol,
n=294), "white" form Ag/antha digitale (r=0.52; p=<O.01~ n=204), ~md depth. to bottom
(r=0.54, p<O.01, n=303). Log. LIMR showed a wcak positive association with MTEMP .
(r=0.15, p=0.02, n=257).
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Clione limacina (CLlO):
A two-way ANOVA on the rrinked CLIO data with seetion and year aS daSs variables showed
a signifieant cffeet of year (F=6.57, p<O.Ol) but not of seetion (F=0.91, p=0.40)(Fig. 33). Log.
. .
CLIO showed the highest association with log. transformcd CPUEs of Limqcina
(Spiratel/a) retroversa (r=0.50, p<O.Ol, n=304), and Limacina (Spiratella) heIicina (r=0.49,
p<:O.Ol, n=305), but rio significant associatiori with MTEMP (r=0.09, p=0.16, n=269).
Gonatus fabricii juv., (GONA):
A two-way ANOVA on the ranked GONA data with seetion and year as dass variables
showed a signifieant effeet of seetion (F=10.00, p<O.Ol) arid yeal' (F=5.42, p<O.Ol)(Fig. 33).
Log. GONA showed the highest association with log. transfoinied CPUEs of Limacina
(Spiratel/a) retroversa (r=0.60, p<O.Ol, n=294), Greenland halibut larvae (Reinhardtius
hippoglossoides) (r=0.56, p<o.oi, n=308), and depth to bottom (r=0.53, p<O.Ol, n=307). Log.
GONA showed a weak positive association with MTEMP (r=0.25, p=O.01, n=260).
Shrimp (Pandalus sp.), mainly Panda/zis borealis (SHR):
A two-way ANOVA on thc rankcd SHR data with scetion and year as dass, variables showed
a sigriificant cffcet of seetion (F=3.59, p=0.03) and ycar (F;=3.88, p<O.Ol)(Fig. 33). Log. SHR ,
showed thc highest association with log. transformed CPUEs of Ca/anus[ininarchicus (r=0.39,
p<O.Ol, n=264), Ca/anus hyperboreus (r=0.38, p<O.Ol, n=264), ~md Euphausiaeea (r=0.37,
p<O.Ol, n=307), but no significant association with MTEMP (r=O.OO, p=0.96, n=262).
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Crab (Zoea stage). Braehytira: Hyas sp. ,and Chiofwecetes sp.(CRAB):
A two-way ANOVA on the ranked CRAB data with seetion arid year as dass variables
showed a significant effeet of seetion (F=23.61, p<O.Ol) and year (F=5.05, p<O.Ol)(Fig. 33).
Log. CRAB showed the highest association with log. transfo~ed CPUEs of sarideel larvae
(Ammodytes sp.) (r=0.45, p<O.Ol, n=317), "white" forriiAglantha digitale (r=-0.29; p=<O.Ol,
n=209), arid depth to bottom (r=-0.24, p<O.Ol, n=316). Log. CRAB showed rio significant
association \vith MTEMP (r=-~.Ol, p=0:82, n=269).
Fish larvae:
Gadus inorhua (COD): '
A two-way ANOVA on the ranked eOD data with seeiion and year as dass variables showed
a signifieant cffeet of seetion (F=12.49, p<O.Ol), and )'car (F=5.07, p<O.Ol) (Fig. 34 and Fig.
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35). Log. COD showed the highest association with log. transformed CPUEs of long rough
dab larvae (Hippoglossiodes platessoides)(r=0.37, p=<O.01, n=540), "white" form Aglantha
digitale (r=0.37, p=<O.01, ri=209), rcdfish larvac (Sebastes sp.)(r=0.31, p=<O.Ol, n=S40),
Grccnland halibut larvac (Reinhardtius hippoglossoides) (r=0.30, p<O.01, n=540), Calanus
finmarcJzicus (r=0.26, p<O.01, n=273), and Calanus hyperboreus (r=0.24, p<o.oi, n=273). Log.
COD showcd a weak positive association with MTEMP (r=0.20, p=O.Ol, n=452).
Reinhardtius hippoglossoides (GHL):
A two-way ANOVA on the rankcd GHL dab with seetion and year as dass variables showed
a significant effcet of seetion (F=30.31, p<O.Ol), and year (F=2.5, p<O.Ol) (Fig. 35). Log.
GHL showed the highest association with log. transformed CPUEs of Limacina (Spiratella)
retroversa (r=0.60, p<O.Ol, n=304), juvenile squids (Gonatus jabricii) (r=0.56, p<O.Ol, n=308),
"white" form Aglantha digitale (r=0.52, p=<O.01, n=209), lang rough dab larvae (Hippoglossiodes platessoides)(r=0.51, p=<O.Ol, n=S40), plankton volume (r=0.46, p=<O.Ol, n=533),
Limacina (Spiratella) heUcina (r=0.43, p<O.Ol, n=305),. eatfish larvae (Anarhichas sp.)
(r=0.39,p<0.01, n=S40), and depth to bottom (r=0.36, p<O.01, n=538). Log. GHL showed a
weak positive association with MTEMP (r=0.13, p=0.006, n=452).
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Sebastes sp. (RED):
A two-way ANOVA on the ranked RED data with scetion and ycar as dass variables showcd
a significant cffcet of scetion (F=3.51, p=0.03), and ycar (F=5.16, p<O.01) (Fig. 35). Log.
RED showcd thc highcst association with log. transformcd CPUEs of eod larvac (Gadus
morhua )(r=0.31, p<O.01, n=S40), Calanus finmarchicus (r=0.30, p<O.01, n=273), Euphausiaeea
(r=0.29, p<O.Ol, n=316), Limacina (Spiratella) retroversa (r=0.27, p<O.Ol, n=304), Euchaeta
(Pareuchaeta) nonvegica(r=0.2S, p<O.Ol, n=277). Log. RED showcd no significant association with MTEMP (r=0.06, p=0.21, n=452).
J
Ammodytes sp. (SAND):
A two-way ANOVA on the ranked SAND data with seetion and year. as dass variables
showcd a significant cffcet of seetion (F=2S.44, p<O.Ol), and year (F=8.84, p<O.Ol) (Fig. 35).
Log. SAND showcd the highcst. association with log., transformcd CPUEs of Crab (Zoca
stage)(r=0.45, p<O.Ol, n=317), dcpth to bottoin (r=-0.35, p<O.Ol, n=538), "white" form
Aglantha digitale (r=-0.30, p<O.Ol, ri=209). juvenile squids (Gonatus jabricii) (r=-0.29,
p<O.Ol, n=308). Log SAND showcd a wcak ncgative association with MTEMP (r=-0.16,
p=0.0006, n=452).
Hippoglossiodes platessoides (PLA):
A two-way ANOVA on the ranked PLA data with seetion and ycar as dass variables showed
a significant cffcet of scetion (F=48.74, p<O.Ol). and year (F=4.33, p<:O.Ol) (Fig. 35). Log.
PLA showcd the highcst association with log. transformed CPUEs of Greenland halibut larvae
(Reinlzardtius hippoglossoides) (r=0.51, p<O.Ol, n=540), juvcnile squids (Gonatus jabricii)
(r=0.39, p<O.Ol, n=308), "white" form Aglantha digitale (r=0.39, p=<O.Ol, n=209), plankton
volumc (r=0.37, p=<O.01, n=533). and ead larvae (Gadus mo;hua) (r=0.37, p<O.Ol, n=540).
Log. PLA showed a weak positive association with MTEMP (r=0.15, p=0.002, n=452).
Anarlziclzas sp. (CATF):
A two-way ANOVA on the rankcd CATF data with scetion and year as dass variables
showed a signifieant cffcet of seetion (F=12.64. p<O.Ol), and ycar (F=2.62, p<O.Ol) (Fig. 35).
e
.
9
Log. CATF showed the highest association with log. transfoimed CPUEs of Limacina
(Spiratella) retroversa (r=OAO, p<0.01, n=304), Greenland halibut larVae (Re,inJuirdtius
hippoglossoides) (r=0.39, p<0.01"n=540), juvenile squids (Goriatus fabTicii) (r=0.38, p<0.01,
n=308), and Limacina., (Spiratella) hel~cina (r=0.35,' p<O.01; ri=305), but no significant
association with MTEMP (r=0.08, p=0.08, n=452).
Discussiori
General rem3rks on tbe sampling
There is lrirge seasorial and inter-annual variability in the abundance and patchiiiess formation
of zooplarikton off \Vest Greenland and this may causc difficulties in the interpretation of the
results of thc data comparisons between years. Howcvcr, by taking the same stations on a
particular section at approximately the same time each year and calculating the average density
for that section one should get a measure of each year's conditions arid the most marked
ch~inges taking place (Astth6rsson al. 1983). This has not completely been fulfilled dtiiing·
tbe\Vest Greenland zooplanktori surveys. BCfore 1968 the stations sampled were situated '
further offshore in section si arid S3 as~ompared to the stations after 1968 (Fig. 4a,b - only
some sclected years are presented). This may ,cause difficulties in thc interpretation of the
results of the data comparisons betWeen sampling years for, soine of thc species with high
CPUEs far offshore e.g. Calanus finmarchicus and, C. hyperbore'us (Fig. 9 and Fig. 10), but
not for others e.g. nortberri shrimp arid Greenland halibut (Fig. 19 arid Fig. 22).
et
Trends in species cOIl1positjon and productjvity
There was a decreasing trend in both the CPUEs of plankton volume ~d copcpods as weIl
as a positive association to sea temperature measurements from thelate 19505 and early 1960s
io tbe 1970s (Fig. 30 and Fig. 31). These trends may be indicative for a deciease in
zooplankton produciivity and changes in thc ecosystem food-web structure in thc same time
period. ,Similar dccreasing trend in CPUEs. of plankton volume and especially Calanus
finmarchicus have also been observed in riorthern Icelaridie waters in spring from the early
1960s .to 1970 (Astth6rsson et al. 1983, Stefansson and Jakohsson 1989). According to
Astth6rsSon et al. (l.e.) a reduced iriflux of Atlantcie water to thc areas llorth of Iceland
probably delayed the onset of the spring primary production and thus the zooplanktori
production. The same may have happcnd off \Vest Greenland duririg approxirriately thc same
tinie periocl.
Wami and cold ,vater inclicators
Boreal speeies (Calanus finmarc/zicus, Euchaeta (Pareuchaeta) nonvegica, Limacina
retrol1ersa) and Arctie forms (Ca/anus hyperboreus, C. glacialis, Metridia longa, Limacina
helicina) occur in tbc Davis Strait zooplankton dunng tbc greater part of tbc year (Pavshtiks
1968, 1972). ArcHe forms enter thc Davis Strait with thc cold Briffin Larid Current (Labrador
CurreIlt), and with the Bast Greenland Current (Fig. 2). Thc boreal species oecur throughout
the strait together with thc cold water forms from the Arctie; ihey overwiritcr in thc deep part
of the strait (Pavshtiks l.e.)~ In t~c daia presented in this paper no . reliablc diseriiniriation
behveen C. finmarchicus and C. glclcialis have been made, therefore, the C. finmarchicus data
10
may include an unknown number of C. giacialis. According to Pavshtiks (I.c.) C. jinmarchicus
and C. glacialis form the bulk of the Davis Strait zooplankton during the greater part of the
year and it is assumcd that sevcral populations of Calanus exist and spawn in this area.
Howevcr, the most abundant C. finmarchicus population is brought into thc Davis Strait with
the Irmingcr Current (Atlantic water) during spring (Pavshtiks I.c.). Spawning of C.
jinmarclzicus takes place from May to July both in thc Atlantic water of thc Irminger current
and in the \Vest Greenland coastal waters whereas C. glacialis is associated with cold water
in the Baffin Land Current and spawns iri the coastal waters of Canada (Pavshtiks l.c.).
Therefore, the C. finmarchicus data in this paper from section SI-S3 are assumed to include
only a relative1y small number of C. glacialis.
The "white" form of Aglantha occurs almost everywhere in the Davis Strait, but in decreasing
numbers the colder the water, and it is replaced by the "red" form in arctic waters (Bainbridge
and Corlett 1968). According to Smidt (1979) Limacina (Spiratella) retroversa is a warmwater species found only off southem \Vest Greenland whereas Limacina (Spiratella) helicina
is a cold water species found further to the north and with similar distribution as ariother cold
water species Clione limacina. These findings were also indicated by the prcsent study and
data analysis.
Monitoring ycar-class strcngth of fishes [rom larval surveys
The year-class strength (given at number at age 3) of Atlantic cod off \Vest Greenland has
been found to be positively correlated with the mean water temperature (surface to 45 m over
Fylla Bank in June) duririg the larval phase (Hermann et al. 1965, Hansen and Buch 1986).
Hansen and Buch (I.c.) also found ycar-class strength to be positive1y correlated with larval
abundance (mean number of cod larvae caught per 30 min. stramin net haui). However, they
conclude that although temperature and larval abundance off \Vest Greenland provide some
information on the size of cod year-classes better estimates of recruitment may be obtairied
from young fish surveys. In the present study we found a very weak positive associatiori
between the mean number of cod laivae caught and the mean sea temperature (Fig. 34). The
sea temperature, the drift of larvae by surface currcnts, and the stability of the water masses
(hydrographic fronts) are important oceanographic factors affecting recruitrrient to fish and
shellfish stocks in West Greenland waters as in waters elsewhere (Horsted et al. 1978, Buch
et ai. 1994, Stein and Llort 1994, Tande et ai. 1994, Rassmussen and Tande 1995, Munk et
ai. in prcss, Sinclair and Page 1995).
Recruitment success for fish and shellfish larvae depend on mainly two (controlling) biological
processes - predation and food availability (the right food in sufficient amount at the right
time). An assessment of the possible intensity of predation on fish larvae is difficult since Httle
is known of the relative importance of the various carnivorous species as predatörs of young
fish (Bainbridge and Corlett 1968). Coclenterates, especially Aglanta, together with
ctenophores, chaetognaths, and siphonophores are serious predators of fish larvae (Frascr
1961). Among other forms kriown to be voracious feeders on a wide vadety of zooplankton
are the hyperiid amphipods, adult Meganyctiphanes, Euchaeta, Tomopteris, and small
cephalopods (Bainbridge and Corlett I.c.). An other common camivorous specics in the North
Atlantic is Clione but this gastropod may be ci selective feeder in Spiratella (Bainbridge and
Corlctt 1968, after Bigclow 1924). Thc latter phcnomcnon is also indicated in the prcscnt
study by high associations between Clione limacina and both Limacina (Spiratella) retroversa
•
11
and Limacina (Spiratella) helicina. The fish larvae show both associations with potential food
spccies and prcdator species e.g. Greenland halibut larvae showed positive associations with
Limacina (Spiratella) retroversa, small squids (Gonatus fabricii), "white" formAglantha
digitale, long rough dab larvae (Hippoglossiodes platessoides), and Limacina (Spiratella)
helicina. Cod, redfish, Greenland halibut and long rough dao larvae showed relativdy high
associations with Calanus ftnmarchicus and this prey species may be of crucial importance
for the larvae survival (Bainbridge and McKay 1968). However, there is a need to establish
whether inter-annual variability in fish stock recruitment depends directly upon variations of
Ccila;züs produetivity (Miller 1995). High associations between 'predators and their prey inay
not be expcctcd to show up as high correlation cocfficients of CPUE survey datri, especially
not in cascs wcre the predators very Cffectively are grazing their prey. Similarly, the
corrclation coefficients of sea tcmperature, salinity and zooplankton CPUE data can be
difficult to interpret because the data are integrated over e.g. hydrographical fronts and patchy .
zooplankton distributions.
Attempts to monitor the strength of new year-classes of fish and shellfish already in tbe larval
phase, are. known from many areas, however,
with moderate success due to the many and
0
highly fluctuating variables (Cushing 1990, Adlandsvik and Sundby 1994, Sundby et aI. 1994,
Sinclair and Page 1995). According to Sinclair and Page (1995) thcre is a need for increased
consensus by the scientific community on which of the competirig hypotheses on population
regulation bcst capture the critical mechanisms. Prediction of the impacts of climate change
are dependent upon which hypothisis or hypotheses best capturc thc realistic dynamics for a
given population and time (Sinclair and Page l.c.).
In 1982, the relatively high mean number of cod larvae caught in the stramin net h~lUls on the
\Vest Greenland sampling sections SI-S3 indicated a good prospect for a large cod
recruitment, however, the 1982 year-class becaine poor. It has been assumcd that the failure
of thc 1982 year-class mainly was caused by the extremely low winter temperatures in West
Greenland during 1982-1984 (Buch 1990). Thc failure of thc 1982 ycar-class and the inability
to relate the catches of cod larvae to subsequent recruitment were the main reasoris that put
the end to the time-series and zooplankton collections off \Vest Greenland in 1985.
We hope the present pap~r will stimulate and add direction to future studies on pelagic
ecology, and critical recruitmerit mechanisms for fish and shellfish stocks in West Greenland
marine waters.
Acknowledgement
A large part of the work compiling the zooplankton database was made by E.L.B. Smidt and
H. Hovgard. Thanks to thc ICES Secretariat and J.R. Nielsen (Danish Fisheries Research
Institute) for help with the hydrographical data. Thanks also to S.Aa. Horsted for a critical
.
review of an earlier draft of this paper.
-'.
12
References
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Fraser, J.H. 1961. The oceanic and bathypelagic plankton of the Northeast Atlantic. Mar. Res.
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int. Comm. Northw. Atl. Fish. 6: 389-395.
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Jorgcnsen, K.F., Jensen, K., Andersen, O.N. and Pctcrsen, G.P. 1978b. A survey of
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Pavshtiks, E.A. 1968. The influence of currents upon seasonal fluctations in the plankton of
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14
Table 1.
List of species in the West Greenland zooplankton
sampies. X - indicate selected group or species induded
in the database, abbreviations given in brackets.
X Ctenophora (CTEN):
Beroe cucumis
Mertensia ovum
Hydromedusae :
Aglantha digitale (HAGLA="white" form and RAGIA="red"
X
form)(red individuals are cold water indicators)
Sarsia tubulosa
Sarsia princeps
Euphysa sp.
Bougainvillia superciliaris
Ratkea ocopunctata
Catablema vesicarium
Catablema multicirrata
Halitholus cirratus
Laodicea undulata
Staurophora mertensi
Ptychogena lactea
Halopsis ocellata
Oblia sp.
Aeginopsis laurentii
Scyphomedusae: (Discarded, not ind. in plankton volume)
Aurelia aurita
Aurelia limbata
Cyanea capillata
Periphylla periphylla
Siphonophora :
Physophora hydrostatica
Dimophyes arctica
Polychaeta
Tomopteris spp.
Autolytus sp.
Ostracoda
Concoecia elegans
Concoecia obtusata
15
Table 1.
continued.
X Copepoda (COP):
X
Calanus hyperboreus (cold water indicator)(CALHY)
X
Calanus finmarchicus (include also C. glacialis)(CALFI)
Euchaeta (Pareuchaeta) norwegica(EUCH)
X
Other species in total copepoda:
Pleuromamma robusta
Eucalanus elongatus
Rhincalanus nastutus
Euchirella rostrata
Centropages sp.
Metridia longa
Heterorhabdus norwegicus
X Hyperiidae (HYPER):
Parathemisto abyssorum .
Parathemisto gadicaudi
Parathemisto libellula
Hyperoche medusarum
Hyperia galba
Hyperia medusarum
Gammaridea
:
Gammarus willdtald and others
X Euphausiacea (EUPH):
Thysanoessa longicaudata
Thysanoessa inermis
Thysanoessa raschii
Meganyctiphanes norwegica
Mysidacea
Boreomysis nobilis
Pteropoda
X
X
X
Limacina (Spiratella) retroversa (LlMR)
Limacina (Spiratella) helicina (cold water indicator)(LIMH)
Clione limacina (eLlO)
X Chaetognatha (CHAE):
Eukrohnia hamata
Sagitta elegans
Sagitta maxima
16
Table 1.
continued.
Copelata
Oikopleura spp.
Fritillaria borealis
Pelagic bottom invertebrate laryae: Only bigger larvae were taken with the stramin net.
Smaller larvae were taken with microplankton and Hensen nets.
X
Decapod crustacean laryae:
Shrimp (Pandalus sp.), mainly Pandalus borealis (SHR).
Other shrimp larvae: Spirontocaris sp., Sabinea septemcarinata,
and Pontophilus norvegicus.
Crab (Zoea stage). Brachyura: Hyas sp. and Chionoecetes sp.
(CRAB)
.
X
Gastropoda
Veluntina veluntina
X
Cephalopoda :
Gonatus fabricii juv. (GONA)
Fish egg and laryae:
X
Gadus morhua (COD)
Anarhichas sp. (CATE)
X
X
Sebastes sp. (RED)
Reinhardtius hippoglossoides (GHL)
X
Ammodytes sp. (SAND)
X
Hippoglossiodes platessoides (PLA)
X
X
Mallotus villosus (CAP)
17
The number (station sampled) of temperature and zooplankton
observations by section and year.
Table 2.
MTEMP
M8AL
PLVOL
HAGLA
RAG LA
CALFI
CALHY
8ection
8ection
8ection
8ection
8ection
8ection
8ection
81 82 83 81 82 83 81 82 83 81 82 83 81 82 83 81 82 83 81 82 83
YEAR
56
57
58
59
60
61
62
63
64
66
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
N
N
N
3
4
4
5
4
4
5
5
6 7
1
6 20
5 7
5 7
4 5
6 8
5 5
8 8
6 4
5 5
5 5
6 6
6 6
4 6
6 6
7 6
3 4
5 4
2 5
3 4
5 3
(CONTlNUED)
N
N
N
N
N' N
7 '3 4 7 3 5 8
6 4 4 6 5 5 7
7 4 5 7 4 7 8
7 5 5 6 5 5 9
2 2 2
2
5 6 7 5 6 ,7 6
3 1
3
21 6 20 21 12 33 33
10 5 7 10 6 9 11
7 5 7 7 7 10 8
8 4 5 8 6 7 ,9
6 6 8 6 6 8 6
15 5 5 15 6 7 16
14 8 8 14 8 9 14
8 6 4 8 7 7 10
5 5 5 5 5 5 5
5 5 5 5 7 6 5
4 6 6 4 6 6 4
5 6 6 5 6 6 5
4 4 6 4 4 6 5
5 5 5 5 6 6 5
7 6 6
6
4
5 5 5 5
5 3
4
5 5 5 5
5 5
4 2 5 4 2 5 5
4 4
3 4
4 5 3 4 5 5 4
N
N
N
N
N
N
N
N
N
N
N
N
3
2
2
5
4
3
5
2
4
3
2
2
5
4
3
5
2
4
3
2
2
5
4
3
5
3
4
3
2
2
5
4
3
5
3
4
6
7
6
6
7
6
6
7
6
6
7
6
8
9
12 26 15 12 26 15
8 6 9 8 6 9 8
8 7 9 8 7 9 8
6
6
7
8
9
8
8
6
4
4
5
1
4
6
6
7
6
5
5
7
5
5
2
2
6
6
5
5
5
1
5
5
5
5
5
5
7
5
5
2
2
6
6
5
5
5
1
4
4
5
1
4
7
5
1
5
5
5
5
5
7
6
7
4
6
6
4
4
4
12
10
10
4
3
4
5
4
5
5
7
4
6
6
12
10
10
4
3
4
5
4
5
5
4
5
7
1
6
7
5
4
4
---------
18
Table 2.
continued.
EUPH
EUCH
HYPER
8ection
8ection
CHAE
8ection
LlMR
8ection
LlMH
8ection
CLlO
8ection
8ection
S1 82 83 81 82 83 81 82 83 81 S2 83 81 82 83 S1 82 83 S1 S2 S3
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
YEAR
56
57
58
59
60
61
62
63
64
66
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
3
2
2
5
4
3
2
3
4
3
2
2
5
4
3
5
3
4
3
2
2
5
4
3
5
3
4
3
2
2
5
4
3
5
3
4
3
2
2
5
4
3
5
3
3
3
2
2
5
4
3
5
3
4
3
2
2
5
4
3
5
3
4
6
7
5
6
7
6
6
7
6
6
7
6
5
7
6
5
7
6
6
7
6
12 26 15 12 26 15 12 26 15 12 26 15 12 26 15 12 26 15 12 26 15
6 9 8 6 9 8 6 '9 8 6 9 8 6 9 8 6 9 8 6 9 8
7 8 8 7 9 8 7 8 8 7 9 8 7 9 8 7 9 8 7 9 8
7
7
1
6
7
2
4
4
6
6
5
4
(CONTlNUED)
14
10
10
5
5
5
5
4
5
5
5
7
7
1
3
6
7
5
5
2
4
5
6
6
5
5
5
4
14
10
10
5
5
5
5
5
5
5
5
5
5
7
7
1
3
6
7
5
5
2
4
5
6
6
5
5
5
4
14
10
10
5
5
5
5
5
5
5
5
5
5
7
7
1
3
6
7
5
5
2
4
5
6
6
5
5
5
4
14
10
10
5
5
5
5
5
5
5
5
5
5
7
7
1
2
6
7
5
5
2
4
3
6
6
5
5
5
4
14
10
10
5
5
3
2
2
5
5
5
5
5
7
7
1
2
6
7
5
5
2
4
3
6
6
5
5
5
4
14
10
10
5
5
3
2
2
5
5
5
5
5
7
7
1
3
6
7
5
5
2
4
5
6
6
5
5
5
4
14
10
10
5
5
5
5
5
5
5
l::
5
19
Table 2.
continued.
5ection
5ection
5ection
5ection
Fish
larvae
CRAB
5HR
GONA
51 52 53 51 52 53 51 52 53 51 52 53
N
N
N
N
N
N
N
N
N
N
N
N
YEAR
56
57
58
59
60
61
62
63
64
66
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
3
2
2
5
4
3
5
3
4
3
2
2
5
4
3
5
3
4
3
2
2
5
4
3
5
3
4
6
7
6
6
7
6
6
7
6
12 26 15 12 26 15 12 26 15
6 9 8 6 9 8 6 9 8
7 10 8 7 9 8 7 9 8
14
7
1
3
6
7
5
5
2
4
7 10
5
5
5
5
5 5
6 5
6 5
5 5
5 5
5 5
4
7
7
1
3
6
7
5
5
6
6
5
5
5
2
5
14
10
10
5
5
5
5
5
5
5
5
5
5
7
7
1
3
6
7
5
5
6
6
5
5
5
2
4
5
4
14
10
10
5
5
5
5
5
5
5
5
5
5
3 5 8
5 5 7
4 7 8
5 6 9
2 2 2
6 7 6
1
3
13 33 34
6 9 11
7 10 8
6 7 9
6 8 6
6 7 16
8 9 14
7 7 10
5 5 5
7 6 5
6 6 5
6 6 5
4 6 5
6 6 5
7 6 6
5
5
2
4
5
5
5
5
5
5
5
4
5
4
20
500000
-
450000
-
f-
400000
-r-
350000
r-
f-
r-
300000
f-
250000
_r-
-
200000
150000
f-r-i-
100000
r0-
50000
h
o
Year
Fig.1. Nominal eateh in tons of Atlantic eod in Subarea 1, 1956-1994
(Data from Horstcd 1994).
73°
_0
Baffin Land and East Greenland
Currents
C' ••••• lrminger Current
· ..,
F19.....
West Greenland Current ••••
Subarctic Mixed Current .-.)
The currents around Greenland, and the locations of the three
hydrographie seetions off West Greenland (From Buch 1984)
(simplified after Kiicrich 1939, Hermann and Thomsen 1946).
21
70~
GREENLAND
(
I
I
~
52
t'1
.,,
./
Fig.3.
Map showing the major physiographie features (depths in m) off West
Greenland :ll1d loeations of the thrcc scetions 51, 52 and 53.
22
195
000
o
o
196
Fig. 4a.
Sampling position of hydrography and zooplankton data in June-July
by section and year.
23
197
1982
198
Fig. 4b.
o
Sampling position of hydrography and zooplankton data in lune-luly
by sectioll and year.
24
ro©
o
o
o
Plankton volume (30 min. hau)
June-July 1956-1984
go
5000 10 9300
o
+
Fig.5.
(45)
500 10 5000 (509)
50 10 500 (461)
t 10 50 (147)
0
(3)
o
o
0 0
o
cY
Plankton volume in ml per 30 min. stramin net haul a11 samples in
June-July, 1956-1984, off West Greenland. Frequency of occurrence
in brackets.
~--------------
25
+
0
o
e
©
o
e
.
o
@
e
Ctenofores
June-July 1956-1984
()3
(126)
02
(181)
©
o
01 (136)
+0
(85)
©
Fig.6.
Numbcr of Ctenoforcs per 30 min. stramin net haul a11 samples in
June-July, 1956-1984, off West Greenland. Frequency of occurrence
in brackets.
26
o
c
.g
o
J
J
©
White Aglantha
June-July 1956-1984
8o
5000 1016500
o
+
Fig.7.
(51)
o
1000 10 5000 (98) :
50 10 1000 (179)
110
50 (99)
0
(23)
Number of white AglantJza digitale per 30 min. stramin net haul all
samples in June-July, 1956-1984, off West Greenland. Frequency of
occurrence in brackets. Only stations sorted for red and white individUJls are presented.
27
o
o
;.~(§)
@O@
....,
+
o®
Red Aglantha
+
June-Ju~I956-1984
8o
1000104131
(21)
100 to 1000
20 to 100
(74)
(481
o
+
110
0
20
+
+
(5i)
(250)
+
Fig.8.
Number of red Aglantha digitale per 30 min. stramin net haul all
samp!es in lune-lu!y, 1956-1984, off \Vest Greenland. Frequenc)' of
occurrence in brackets. On!)' stations sorted for red and white individuals are presented.
28
o
o
+
e
@
o
o
i
CaJanus Iinmarchias
500000 101070000
(4)
50000 to 500000
(14)
o
o
+
Fig.9.
5000 to
500 to
110
0
o
o
June-July 1956-1984
~
o
50000 (47)
5000 (59)
500 (169)
(226)
o
o
o
o
• l,'.
o
0
'.
o
o
+
Number of Ca/anus finmarcllieus (C. g/acialis) per 30 min. stramin net
haul alt samples in June-July, 1956-1984, off West Greenland.
Frequcncy of occurrence in brackets.
29
,
@GD
~
~
©~0
Cl)
0
0
0
0
+
0
ci
i
0
0
+
+
0
Calanus hyperboreus
@)
June-July 1956-1984
~"""'. """" '"
50000 to 500000
0
0
+
0
0
0
0
(31)
0
5000 to 50000 (48)
500 to 5000 (67)
500 (197)
Ho
(175)
0
0
0
o
0
0
0
+
Fig. 10.
0
Number cf Ca/anus hyperboreus per 30 min. stramin net haul all
samples in lune-luly, 1956-1984, off West Greenland. Frequency of
occurrence in brackets.
30
+
+
+
+
+
+
+e
+
4-
,.
*+ ++~
...
+
~
o
e
+
o
\
o
Euchaeta
June-July 1956-1984
8o
10000 10 22000
o
o
+
+e +
o
(12)
o
5000 10 10000 (14)
100 10 5000 (74)
110 100 (110)
+
0
o
o
(311)
o
Fig. 11.
..
+ +
o
@
o
Number of Euchaeta (Pareuchaeta) norwegica per 30 min. stramin net
haul a11 samples in June-July, 1956-1984, off West Greenland.
Frequency of occurrence in brackets.
31
@
o
o
J
o
o
Hypenlds
June-July 1956-1984
~
o
.,.
20000 10 49650
(3)
5000 10 20000
(12)
1000 10 5000 (66)
300 10 1000 (49)
1 10 300 (440)
0 to
0 (47)
Fig. 12.
o
o
Number of hyperiids per 30 min. stramin net haul all samples in JuneJuly, 1956-1984, off West Greenland. Frequency of occurrence in
brackets.
32
0
+
0
+
EIl
e
~d)
+
eOoo\il
-'
.Euphausids
June-July 1956-1984
8o
1oooot091800
o
+
o
(161
1000 to 10000 (31)
100 to 1000 (60)
1 to 100 (261)
0
Fig. 13.
(223)
Number of euphausids per 30 min. stramin net haul all sampies in
June-July, 1956-1984, off West Greenland. Frequency of occurrence
in brackcts.
33
Chaetognatha
JunEhJuly 1950-1984
8o
SOOO 10 18600
o
+
o
(8)
500 10 5000
50 to
1 to
0
Fig. 14.
(72)
SOO (90)
SO (179)
(258)
Number oi Chaetognatha per 30 min. stramin net haul all sampies in
June-July) 1956-1984) off West Greenland. Frequcncy of occurrence
in brackets.
34
o
0
+
+
,
I
r
+
+
@
I
+
/e
'-'
+
+
~
'?
~(~
oe
e
0
Umacina (Spiratella) helicina
June-July 1956-1984
()5000 to 2Z32O
Ö
o
o
+
©
(14)
+
500 10 5000 (86)
50 10 500 (96)
110
50 (103)
0
(301)
o 0 0
o
0
+
I
Fig. 15.
+
0
Number of Limacilla (Spiratella) Izelicina per 30 min. stramin net haul
all samp!es in lune-lu!)', 1956-1984, off 'West Green!and. Frequency
of occurrence in brackets.
35
e
®
~
©
o@
I
0
0
Umacina (Spiratella) retreNersa
June-July 1958-1984
8o
50001031600
o
+
(23)
500 10 5000 (102)
5010 500 (117)
1 10
50 (134)
0
(224)
Fig. 16.
o
o
o
>.
o
Number of Limacina (Spiratella) retroversa per 30 min. stramin net
haul a11 samples in June-July, 1956-1984, off West Greenland.
Frequency of occurrence in brackcts.
36
oo@
~
o
o
Cliane limacina
June-July 1956-1984
n2000 10 4040
o
o
o
+
(1)
200 10 2000 (31)
20 10 200 (221)
I 10 20 (306)
0
(57) I
Fig. 17.
I
0
0
0
0
0
0
,
0
0
0
Number of CLione limacirza per 30 min. stramin net haul all samples in
June-July, 1956-1984, off West Greenland. Frequency of occurrence
in brackcts.
37
+
~
~
+
+
©
+
o
+
o
Gonatus fabricii
Jun~1956-1984
nSO tc 224
o
(24)
010:0 50 (102)
1:0 10 (170)
+ 0
(313)
o
o
o
Fig. 18.
o
Number of juvenile Gonatus fabricii per 30 min. stramin net haul all
sampies in Junc-July, 1956-1984, off West Greenland. Frequency of
occurrencc in brackets.
.--------------------
---------
----
38
e
e
e
0
0
0
0
0
cPC>
+
eOa:>g
l
I
I
I
I
•
0
(3l
e
-I
-+e
o
o
o
Northem shrimp laNae
June-July 1958-1984
8o
50001014700
o
+
o
(3)
1000 to 5000 (23)
50 to 1000 (182)
110
50 (281)
0
(117)
o
o
o
Fig. 19.
Number of shrimp larvae (mainly Northem shrimp) per 30 min. stramin
net haul all sampies in June-July, 1956-1984, off West Greenland.
Frequency of occurrcncc in brackcts.
39
0
+
+
o
o
o
®
o
'~6,~
'~iSlJ~)
l
l
~
+
+
EB
"-
e
l
~
+
+
el
o
o
Crab larvae (zoea stage)
June-July 1956-1984
()5ooo 10 52000
(17)
Ö
(47)
o
o
+
500 10 5000
1010
110
0
+
o
500 (190)
10 (13:3)
(230)
o
+
Fig. 20.
Number of crab larvae per 30 min. stramin net hau1 a11 sampIes in
June-July, 1956-1984, off West Greenland. Frequency of occurrence
in brackets.
40
s+
+
+
~
0
...
e
+a il4
e-"'~~
0
+
+
0
@
+
+
Atlantic cod larvae
June-July 1956-1984
8o
o
+
200 to 1890
(5)
2Oto 200
(41)
510
20 (116)
1 to
0
5 (357)
(696)
e
e
... +
...
0
......
...
0
+
+
Fig. 21.
+
Number of Atlantie eod larvae per 30 min. stramin net haul all samples
in June-July, 1956-1984, off West Greenland. Frequency of occurrence
in brackets.
-------1
41
++
+
+
+
Greenland haJibut larvae
June-JuJy 1956-1984
8o
10010416
o
+
o
(14)
5010100 (18)
1010 50 (130)
1 10 10 (337)
0
(716)
+
~
+
+
o
· ..,..,
F19........
+
...
...
...
Number of Greenland halibut larvae per 30 min. stramin net haul all
sampies in June-July, 1956-1984, off West Greenland. Frequency of
occurrence in brackets.
42
l
+.,.
+
+
+
+
+
e
.+
+
.:F+
...
+
+
Redfish larvae
June-July 1956-1984
()SOIO 182
(10)
Öl010 50
(36)
310 10 (46)
o 1 to 3 (61)
+ 0
(10621
o
Fig. 23.
+
+
+
o
Number of redfish larvae (Sebastes sp.) per 30 min. stramin net haul
all sampies in June-July, 1956-1984, off 'West Greenland. Frequency
of occurrencc in brackets.
43
~~
e
o
+
+
SandeeilaNae
June-JWy1956-1984
8o
1000 to 8120
o
+
(12)
100 to 1000 (44l
1010 100 (131)
110 10 (279)
0
(749)
+
I
+ +
+
...
...
+
+
Fig. 24.
Number of sandeel larvac per 30 min. stramin net haul all sampies in
June-luly, 1956-1984, off \Vest Greenland. Frequency of occurrence
in brackcts.
44
... +
+
-I-
-I-
...
-I-
...
...
+
~
... l
...
Capelin larvae
June-JuIy 1956-1984
8o
o
...
Fig.25.
100 10 730
(5)
1010100
310 10
110 3
(14)
(15)
(19)
(1153)
0
...
...
+
+
...
+
+
.
•
+
+
......
I
Number of capelin larvae per 30 min. stramin net haul all samples
in June-July, 1956-1984, off West Greenland. Frequency of occurrcnce in brackcts.
45
+
+
+
e
+
o
~
o
CO +
+
Leng rough dab (aNae
June-JUIy 1956-1984
()100 10 296
Ö
o
o
+
so 10100
e
+
+
(81
(20)
510 50 (1731
110 5 (221)
0
(781)
+ +
+
+
+
+
+
Fig. 26.
Number of long rough dab larvae per 30 min. stramin net haul all
samples in June-July, 1956-1984, off West Greenland. Frequency of
occurrence in brackets.
46
1-
-t-
+
e
+
Catfish larvae
June--JUIy 1956-1984
0151045
o
o
+
+
(2)
51020 (19)
1 to 5 (2551
0
...
-
(939)
...
Fig. 27.
+
+
o
+
+
+
.+
+
Number of catfish larvae per 30 min. stramin net haul aU samples in
June-July. 1956-1984. off West Greenland. Frequency of occurrence
in brackets.
47
5.00
a
4.50
,
4.00
""":'
U
L.- 3.50
...u
I
3.00
~
...
(;j
u
0.
0
2.50
E
~
2.00
c:
C':
u
..
··,.:
!
1.50
::E
1.00
,
0.50
0.00
+--""--1--1--1--1--+-__-+--+-'_--+------+-+-+--1--1
....................._+--+--+--1--1--...+--1
56 57 58 59 60 61 52 53 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84
Year
34,10
r--------;:=:::::====;:::;--------------,
b
~o-seclionsl
A
33,90
Section S2
--SeclionS3
........
_._------
-.g
33.70
-.q
.S
C':
u
0
33.50
"(;j
'"c:
,
'0
33,30
,
o
0
~\
'..! \
.
,
<l'. \
i:0-
.? .:
:.'.
:1' ...... ~/ ••~ :
·/\:,
..:-::,.!.A
.:
q
p
:i
\>'-q
.... .
P.
".11'
.
"
·0··4.....
:~ }'
'.Q
••••
0
I
\..
~ .~
.
.»
! f
:
.
:
,
:~.\
~
33,10
::E
32.90
32.70
32.50
1--0000""-
_I_-I--I--+-_1_-+--+-_------+--+-+-+--I--I..................._+--+-+--1----...o.-J
58~58~60~5253646566~6869MnnnN~~77M~80~8283M
Year
Fig..28. Mean sea temperatures (a) and salinities (b) of the 10-50 m layer
in June-luly by section and year.
-....
+
:;
«J
.c
LRAGLA
LHAGLA
9 ~----------------,
7~----------------"
8
6 ....\
7
o(')
a
6
•
4 \
a
\
,
...
5
3 \
a.
ci
c
c
4
2
Q)
«J
Q)
.§.
Cl
.3
a
5
C
E
\
a
a
a
a
2\--.---.--..---T-,.--..__....-..........-..----r---.~..__...,._._r'
56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Yeor
Seclion
~
SI.·.·. S2 -
Fig.29.
S3
\
\
•,
\
I
\
\
i
I
3
\
\
·L
o-l
j
a
\i !/:!
\,:
•
\! !
\!\~ I
.J../::,J.
56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Yeor
Seclion
~
SI
•._. 52 __ 53
Mean number of white (LHAGLA) and red (LRAGLA) Aglantha
digitale per 30 min. stramin net haul in June-July by sampling section
;md )'car.
48
·5,00
3000
4,50
5ection 51
2500
4,00
3,50
2000
3,00
•
-·2,50
1500
·2,00
1000
1,50
1,00
500
0,50
0,00
0
sJ
E
e
3,50
3,00
/
........
CL>
5ection 52
g
"<:;
4000
~
•
vv
•
3000
=>
Ci
:>
<3
·2,50 w
(l)
~
C""
"-'
- 2,00 -c
~
1,50
c
b
C-
E
2000
(l)
t-
1,00
1000
0,50
0,00
0
5ection 53
4,00
3000
3,50
2500
3,00
2,50
2000
•
2.00
1500
•
1,50
1000
1,00
500
0,50
o'
0,00
56 57 58 59 60 61 62 63 64 55 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84
Year
Fig. 30.
Mean plankton volume (mi) per 30 min. stramin net haul and mean
tempcrarUfc (thc 10-50 m Iaycr) in June-July by sampling section
and year.
49
20000
15000
10000
5000
0
250000
::::l
200000
CU
.c
c:
'E
150000
0
...
('t)
100000
Q)
C-
o
c:
c:
50000
CU
Q)
0
E
35000
30000
25000
•
20000
15000
10000
5000
,
0
56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
57 59 61 63 65 67 69 71 73 75 77 79 81 83
I0
Fig. 31.
Oth. cop.
~ Calfi
_
Calhy
_
Euch
Mean number of Calanus finmarchicus (include also C. glacialis)
(Calfi), Ca/anus hyperboreus(Calhy), Euchaeta· (Pareucllaeta)
norwegica(Euch) and other copepod species (Oth. cop.) per 30 min.
stramin net haul in June-July by sampling seetion and year.
50
LCALFI
13r---------------,
12 .
. ~
t
11 \ i
!
10 \ j
I
9 \f
:
I
V/i
~IH
6
5
·
i
'
.
}:
~
'
•
'E
:M ·\ ·
oCf)
5
i
/fi
i
i
!
d
f
;
i
4
i
3
c
c
i
i
1
Q)
E
-...
Cl
.5
o
1\
A
Seclion
G-8-<J
,
i
j
f
i
i
:
!
7\
5
r
A
.~
;
i
i
4
i '
!
i
i
•
!
D
3 \;
~
1'r--..,.-....,......-,--...........,..-...-,-~_....,..........,r__..__._,........,........,.....-T
......
56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Year
Section D-ü-O Sl •.•.• S2 - - S3
56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Year
Section o-e-o Sl ...... S2 - - S3
LCHAE
LEUPH
10r--------------~
o
\i
2
'8-
..... S2 __ 53
10r--------------.....,
8
......
51
LHYPER
9
i
o .J
I
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Year
Section 11-+-0 S1 .·.·.52 -- S3
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56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Year
Section
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Fig. 32.
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56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Yeor
Section G-8-<J SI.·..·• S2 - - S3
Mean number of Calanus finmarchicus (include also C. glacialis)
(LCALFI), Calanus hyperboreus (LCALHY), Euchaeta (Pareuchaeta)
norwegica(LEUCH), hyperiids (LHYPER), euphausids (LEUPH),
Chaetognatha (LCHAE) per 30 min. stramin net haul in June-July by
sampling section and year.
51
LUMH
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56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
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Fig. 33.
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56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
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56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Year
Section
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S3
Mean number of Limacina (Spiratella) helicina (LLIMH), Limacina
(Spiratella) retroversa (LLIMR), Clione limacina(LCLIO» GonatzLS
jabricii(LGONA), Shrimp (Pandalus sp.), mainly Pandalus borealis
(LSHR), Crab (LCRAB) per 30 min. stramin net haul in Junc-July by
sampling scction and ycar.
52
30 r--n--------------------------~
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25
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56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84
Year
Fig. 34.
Mean number of Atlantic cod larvae per 30 min. stramin net haul and
mean temperature (the 10-50 m layer) in June-July by sampling section
and year.
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56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Year
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Seetion lHHJ S1 ..... S2 - S3
56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Year
Sectien IH-O Sl •.•.• 52 --- S3
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56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
Year
SecHen
o-a-o
Sl
..... S2 -
S3
Mean number of Atlantic cod larvae (LCOD), Greenland halibut larvae
(LGHL), redfish larvae (LRED), sandeellarvae (LSA1~D), long rough
dab Iarvae (LPLA) and catfish larvae (LCATF) per 30 min. stramin net
haul in lune-luly by sampling scction and year.