Post on 14-Oct-2019
Сomparison of feeding ecology of chum salmon in the western part of Bering Sea and adjacent waters of Pacific Ocean
E.DulepovaLaboratory of Applied Biocenology,
TINRO -center
• To analyze annual and regional dynamics in feeding of different size groups of the fish.
Our objective wereOur objective were::
• To estimate the role of different plankton groups, particularly, gelatinous plankton in chum feeding over years.
• To estimate the place and role of chum in the trophic structure within ecosystem of the Bering Sea and adjacent waters
Structure of data
Suryes Seasons Years Regions
Bering Sea
Pacific waters of Kamchatka
Okhotsk Sea
Pacific waters ofKuril Islands
1986- 2002Summer-fall
Methods• Criterion Kolmogorov-Smirnov
(comparison of shares)• Cluster analysis
15
Differences in feeding of chum
smaller and larger than 40 sm
>40
<40
Undigested part
medusaectenophores
nekton
copepods
Feeding spectra of large chum salmon in the Bering Sea
1993, 1995
1992, 2002
ctenophores
medusae
nekton
Undigested part
Prey spectrum for chum salmon (> 40 sm)
130.00 140.00 150.00 160.00 170.00 180.00 190.00 200.00
40.00
50.00
60.00
nekton
ctenophores
130.00 140.00 150.00 160.00 170.00 180.00 190.00 200.00
40.00
50.00
60.00
nekton
Prey spectrum for chum salmon (< 40 sm)1995
Chum prey upon animals that belong to different trophic levels
• Euphausiids, copepods, tunicates - non-predatory zooplankton (II trophic level)
•Chaetognats –predatory zooplankton (III trophic level)
Amphipods-predatory zooplankton (III trophic level)
Pteropods -predatory and non-predatory zooplankton ( II, III trophic levels)Coelenterates, Ctenophores - predatory zooplankton (III trophic level)Pisces, squids - (IV trophic level
0
100
200
300
400
500
600
700
800
900
1000кал/г
A.digitale
N.crista
tus
Th. rasch
ii
P. pacifica
P.libellu
la
C.limacin
a
9
9,5
10
10,5
11
11,5
12
12,5
%
A.digitale N.cristatus Th. raschii P. Pacifica P.libellula
Gross caloric density (cal/g wet weight) for salmon prey organism
and
the estimated proportion of prey that is indigestible for salmon (Davis et al., 1998)
A. digitale
A. digitale
The dynamics of gelatinous plankton abundance in stomach contents of large
chum
0
10
20
30
40
50
1986 1987 1990 1992 1993 1995 2000 2002
CtenophoresMedusae
% 1987
1995
Chum salmon belonging to the different trophic levels in the Bering Sea
< 40 sm
15%
43%
42%III trophic level
IV trophic level
V trophic level
30%
45%
25%> 40 sm
Thank you.
Спасибо.