evaluation of chemical shark repellents on demersal longlines eric m. stroud, july 17, 2006
DESCRIPTION
Chemical Characteristics Polar and short-chain Time-release matrix Stable at pH >7 Targets olfaction & gustation Short environmental fateTRANSCRIPT
Evaluation of Chemical Shark Repellents on Demersal Longlines
Eric M. Stroud, July 17, 2006
Requirements
Chemical characteristicsEffects on ElasmobranchsEffects on TeleostsDelivery SystemEnvironmental characteristicsCost
Chemical Characteristics
Polar and short-chainTime-release matrixStable at pH >7Targets olfaction &
gustationShort environmental fate
Chemical Characteristics
OO
OH
H
H
3-methylbutanal
(target=gustation)
(E)-2-butenoic acid
(target=olfaction)
ACTIVES
Chemical Characteristics
OO
OH
H
H
3-methylbutanal
(target=gustation)
(E)-2-butenoic acid
(target=olfaction)
ACTIVES
OH
O
OH
O
Chemical Characteristics
TIME-RELEASE MATRIX
Hydroxypropylmethylcelluose Diethylene glycol monoethyl ether
Chemical Characteristics
OO
OOH2+
OO
O
::
:
:
+ H:OH
H+ [NaI]
Possible stabilization mechanism via acetal formation
Effects on Elasmobranchs
Study the actives using tonic immobility
Study the actives in surrounding-cloud dispersion
3-Methylbutanal Effects
Average dose size to terminate tonic immobilityNeedle-thin jet released at least 5cm from nares, juveniles
0
200
400
600
800
1000
1200
1400
tiger N=1 nurse N=18 lemon N=13
MIC
ROLI
TERS
3-Methylbutanal Effects
Average dose size to terminate tonic immobilityCloud released at least 15cm from nares, adult sharks
0
1000
2000
3000
4000
5000
6000
7000
blacktip N=7 nurse N=6 lemon N=5 tiger N=4 blacknoseN=1
blue N=2
MIC
ROLI
TERS
3-Methylbutanal Effects
Average dose size to terminate tonic immobilityDirect oral dosage using micropipettor, juveniles
0
50
100
150
200
250
300
350
400
nurse N=5 lemon N=12
MIC
ROLI
TERS
(E)-2-Butenoic Acid Effects
Average dose size to terminate tonic immobilityCloud released at least 15cm from nares, juvs and adults
0
1000
2000
3000
4000
5000
6000
tiger N=3 blacknose N=1 lemon N=7 nurse N=7
MIC
ROLI
TERS
0:000:010:020:040:050:070:080:100:110:120:14
0:00
:00
48:0
0:00
96:0
0:00
144:
00:0
0
192:
00:0
0
240:
00:0
0
288:
00:0
0
Duration of attractant presentation (minutes)
Dura
tion
of p
asse
s at
sou
rce
(sec
onds
)
(E)-2-Butenoic Acid Effects
Test on >3m S. mokarran 400mL dose released
Effects on Teleosts
IATTC Achotines, Panama Feeding preference trials in
Thunnus albacares University of Miami, RSMAS
Feeding preference trials in Rachycentron canadum
South Bimini, Bahamas Melichthys niger, Balistes
ventula, Mojarra spp., Remora remora
Crabs!!!
Effects on Teleosts
T. Albacares Feeding preference tests at IATTC, Achotines, Panama
Effects on Teleosts
Cobia feeding preference tests at RSMAS
Delivery System
Muslin bags On gangion above
hook Close to hook
Direct injection Fill bait with gel
prior to rigging
Environmental Issues and Cost
Repellents are NOT cited in: Clean Water Act, Priority Pollutants, Section 307 Marine Pollutants, per 49CFR Parts 171 and 172 Toxic Release Inventory Chemical, per EPA 260-B-
01-001 Hazardous Substances (Superfund) BCF <100 for solvent
Additional Cost:
$1.05 / bait
Longlining Protocol
4 demersal lines Each line has 15 16/0
circle hooks LP Hook Event Timers Same type of bait 24 hour rebait periods Lines checked every 4
hours 15-30 treatments / 30-45
controls
Longlining Protocol
4 demersal lines Each line has 15 16/0
circle hooks LP Hook Event Timers Same type of bait 24 hour rebait periods Lines checked every 4
hours 15-30 treatments / 30-45
controls
Check current direction using fluorescein and a digital flowrate meter
Current in and out of lagoon, normal to lines
Preliminary Results
September 2005 Trials
0
1
2
3
4
5
6
7
Controls Treatments
Num
ber o
f sha
rks
capt
ured
40 hour soak time, 15 treatments/45 controls
No sharks captured on treatment line
Preliminary Results
November 2005 Trials
02468
1012141618
Controls Treatments
Num
ber o
f sha
rks
capt
ured
Gel was not replaced (Trying to determine longevity of the gel)
67 hour soak time, 15 treatments/45 controls
1 male lemon (TL=154cm) at 27:28
Preliminary Results
February 2006 Trials
01
23
Controls Treatments
Num
ber o
f sha
rks
capt
ured
Gel was replaced at 24 hour rebait marks
48 hour soak time, 30 treatments/30 controls
Tiger (TL=286cm) at 9:03 from rebait
Next Steps
CPUE is too lowChemistry and delivery OK
NOAA longline cruise – November ‘06Preference tests with one speciesFL bait company
Acknowledgements
Bimini Biological Field Station Dr. Samuel Gruber Steve Kessel, Tristan Guttridge, Grant Johnson, Katie Grudecki, Jo
Imhoff, and the crew NOAA – Pascagoula
Mark A. Grace Charles Bergmann
Vernon Scholey, IATTC RSMAS
Dr. Dan Benetti Patrick H. Rice
NOAA/NMFS JIMAR/PIFSC Yonat Swimmer Mike Musyl Chris Boggs Mark A. Grace Charles Bergmann