1 ghent university, biology department, marine biology section ... · diet analysis stomach content...
TRANSCRIPT
Fulln
ess
inde
x
M a r i n e B i o l o g y
J Reubens,,*, M De Rijcke ̂S Degraer, 2, M Vincx11 Ghent University, Biology Department, Marine Biology Section, Krijgslaan 281, Sterre S8 9000 Ghent, Belgium
2 KBIN-MUMM, Gulledelle 100,1200 Brussels, Belgium
Objective: Unravel the diurnal behaviour of Atlantic cod (Gadus morhua L.) at windmill artificial reefs
Methodology: Acoustic telemetry in combination with catch statistics and diet analysis
Results:Acoustic telemetryFast fourier transformation revealed 2 peaks in activity :
Dominant peak at 12 h related to crepuscular movementsSecondary peak at 6 h related to tidal movements
Catch statisticsHighest catch rates were recorded close to sunrise and sunset Fish were collected during 8 sampling batches
il
600000
500000
400000
300000
oCl
200000
100000
0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96
Per iod (h)
Photo Karl Van Ginderdeuren
BatchSampling time
(UTC)CPUE
(ind h^fm 1 )BÍ 09:10-09:40 21.5B2 12:00-12:25 27B3 14:55 -15:30 21B4 17:55 -18:20 29.4B5 21:05-21:40 9.89B6 00:25-00:55 17.5B7 03:05 - 03:40 5.71B8 06:00-06:25 31.2
Diet analysisStomach content analysis revealed peak in stomach fullness close to sunrise and sunset
c -l
ooo
co■o
■o
c - jo
■o■o
B2 B3 B4 B5
Batch
B6 B7 BS
Stomach fullness at each sampling batch * indicate dusk and dawn
*
I A ALOOA w V
Observed prey species
> 0
JZOù
0)5001 OÙ ftOíuL.0iCl
40
20
nB1 B2
■ ■ iB3 B4
illB 5 B6 B7 B8
Batch
Other Items
Pisidia longicornis
Liocarcinus s pp.
I Jassa herdmani
Brachyura sp.
Actiniaria sp.
Average relative weight of dominant prey species in the stomachs of Atlantic cod
Conclusions:* Atlantic cod exhibited crepuscular movements related to feeding activity.
* Food availability and against currents may stimulate aggregation behaviour at thewindmill artificial reefs
C U
co
N ight Day Night
Current velocities
Conceptual representation of the diurnal activity patterns of Atlantic cod at the windmill artificial reefs. Atlantic cod are most active during twilight periods, followed by a smaller activity peak during periods of low current velocity.
^ [email protected], El Marine Biology Research Group, Krijgslaan 281 Sterre S8, 9000 Ghent, Belgium +32 9 264 85 17