The Yongala`s Halo of Holes – Who`s Digging It?

The Yongala`s Halo of Holes – Who`s Digging It?

The Yongala’s Halo of Holes
– Who’s Digging It?
Tracking of Taeniura meyeni at the wreck of the Yongala
Thomas Stieglitz (1,2,3) and the tag team
Greg Suosaari, Ron Schroeder, Michelle Jonker, Giles Winstanley, Ian Banks, Gavin Coombes,
Erol Eriksson, Alain Lochard, Cary McLean, Barry Bennett, Owen O’Shea, Glenn Everson,
JP Hobbs, Olga Bondarenko, Naomi Gardiner, Kathleen Swalling & Andrew Chapman
with
Paul Crocombe (Adrenalin Dive) & Heather Batrick (Yongala Dive),
and A Hobday, J Semmens, C Simpfendorfer & M Heupel
(1) AIMS@JCU, Townsville
(2) School of Maths, Physics & IT, James Cook University, Townsville
(3) Australian Institute of Marine Science, Townsville
The Yongala’s Halo of Holes
14m
18m
22m
100 m
26m
30m
The Yongala’s Halo of Holes
•
•
•
non-random distribution of depressions
well-defined range from wreck
asymmetry in distribution & hole depth
14m
18m
22m
100 m
Who and why?
26m
30m
The Yongala’s Halo of Holes
•
•
•
•
non-random distribution of depressions
well-defined range from wreck
asymmetry in distribution & hole depth
the central mean is at the bow = a favourite spot to find rays
x
14m
18m
22m
100 m
26m
30m
Listening Stations
•
•
•
11 inline moorings (10 VR2 / 1V9P)
VR2 6m above seafloor
serviced by diving
Range tests – pre deployment
1.0
detection probability
0.8
11 22
0.6
0.4
0.2
00
350m - 400m detection limit (25kt)
0.0
50
100
150
200
250
300
distance (m)
350
400
450
100
100 200
200
Meters
Meters
33
44 55
Receiver Station Placement
11
22
99
66
33
55
permanently
moored tag
88
44
00
100
100 200
200
Meters
Meters
77
11
22
Range tests - continuous
99
66
33
55
88
PP 10
44
9
00
77
100
100 200
200
Meters
Meters
8
7
YB 6
YS 5
4
3
2
1
27/07
06/08
16/08
26/08
05/09
15/09
tags deployed
25/09
11
22
wind (km/h)
WL (m)
Range tests – continuous (24 h)
99
66
33
55
50
88
0
4
2
0
44
6
0.2
0.1
0
270m
5
0.2
0.1
0
300m
4
0.2
0.1
0
320m
3
0.2
0.1
0
420m
7
0.2
0.1
0
440m
8
0.2
0.1
0
620m
0.2
0.1
0
630m
27/07
06/08
16/08
26/08
05/09
77
100
100 200
200
Meters
Meters
2
00
15/09
tags deployed
25/09
11
22
wind (km/h)
WL (m)
Range tests – continuous (24 h)
99
66
33
55
50
88
6
0.2
0.1
0
5
0.2
0.1
0
4
0.2
0.1
0
3
0.2
0.1
0
7
0.2
0.1
0
8
0.2
0.1
0
2
0
4
2
0
0.2
0.1
0
44
00
77
100
100 200
200
Meters
Meters
270m
?
300m
06/08
16/08
26/08
05/09
420m
440m
620m
Interference by wreck?
Background noise or self-collision?
27/07
320m
630m
15/09
tags deployed
25/09
Range tests - mid deployment 1
1.0
11
22
detection probability
0.8
99
66
0.6
33
BB
SS 5
5
0.4
88
44
0.2
00
0.0
50
100
150
200
250
300
distance (m)
350
400
450
100
100 200
200
Meters
Meters
77
Range tests – mid deployment 2
1.0
11
22
detection probability
0.8
99
66
0.6
33
55
0.4
88
44
0.2
00
0.0
50
100
150
200
250
300
distance (m)
350
400
450
100
100 200
200
Meters
Meters
77
External tagging of Taeniura Meyeni
•
•
handspear with modified tip & stopper
speargun = overkill
•
originally targeted rays on seafloor; turns out in water column is better.
Photo: Giles Winstanley www.snaq.net
Detection Time Series
tag serial number
TM f
all receivers
2323
2324
TM f
2325
TM f
2326
TM f
2327
TM f
2328
moored
2329
TM f
2330
HF f
visual
2331
TM m
2332
8/9
15/9
22/9
29/9
6/10
13/10
date in 2007
20/10
27/10
3/11
10/11
Where do they go?
all receivers
tag serial number
2323
TM f
2324
TM f
2325
TM f
2326
TM f
2327
TM f
2328
moored
2329
TM f
2330
HF f
2331
TM m
2332
8/9
9/9
10/9
11/9
date in 2007
12/9
13/9
14/9
1
2
Red tag – female Sept
9
6
3
5
PP 10
8
9
4
0
8
100 200
Meters
7
YB 6
YS 5
4
3
2
1
09/09
11/09
13/09 15/09
17/09
19/09 21/09
23/09
25/09
27/09
7
1
2
Red tag – female Oct
9
6
3
5
PP 10
8
9
4
0
8
7
YB 6
YS 5
4
3
2
1
30/09
05/10
10/10
15/10
20/10
25/10
30/10
04/11
09/11
100 200
Meters
7
1
2
Red tag – female
9
6
3
PP 10
5
8
9
4
8
0
100 200
Meters
7
YB 6
YS 5
4
3
2
1
0
6
12
hour of day
18
24
7
1
2
Blue tag – female Oct
9
6
3
5
PP 10
8
9
4
0
8
7
YB 6
YS 5
4
3
2
1
30/09
05/10
10/10
15/10
20/10
25/10
30/10
04/11
09/11
100 200
Meters
7
1
2
Blue tag – female Oct
9
6
3
PP 10
5
8
9
4
8
0
100 200
Meters
7
YB 6
YS 5
4
3
2
1
0
6
12
18
24
7
1
2
Blotchy – male Oct
9
6
3
5
PP 10
8
9
4
0
8
7
YB 6
YS 5
4
3
2
1
30/09
05/10
10/10
15/10
20/10
25/10
30/10
04/11
09/11
100 200
Meters
7
1
2
Blotchy – male Oct
9
6
3
PP 10
5
8
9
4
8
0
100 200
Meters
7
YB 6
YS 5
4
3
2
1
0
6
12
18
24
7
Is depth of any use?
all tags, all receivers
-8
-10
-12
Depth(m)
-14
-16
-18
-20
-22
-24
-26
-28
6
18
Hour of Day
Is depth of any use?
all tags, all receivers
-8
-10
-12
Depth(m)
-14
-16
-18
-20
Yongala =
cleaning station
-22
-24
-26
-28
6
18
Hour of Day
Some lessons learnt…
•
•
Detection range appears to be significantly impacted by the wreck.
Ambient noise and / or self-collision of tag with reflected signal?
•
•
Rays do not appear to be permanent residents.
Acoustic data confirms visual observations of greater chance to find
rays at the wreck at night.
Yongala is a cleaning station (actually, two cleaning stations).
Diurnal pattern of movement.
•
•