Evaluation of Chemical Shark Repellents on Demersal Longlines

1. Evaluation of Chemical Shark Repellents on Demersal Longlines Eric M. Stroud, July 17, 2006

2. Requirements • Chemical characteristics • Effects on Elasmobranchs • Effects on Teleosts • Delivery System • Environmental characteristics • Cost

3. Chemical Characteristics • Polar and short-chain • Time-release matrix • Stable at pH >7 • Targets olfaction & gustation • Short environmental fate

4. Chemical Characteristics ACTIVES 3-methylbutanal (target=gustation) (E)-2-butenoic acid (target=olfaction)

5. Chemical Characteristics ACTIVES 3-methylbutanal (target=gustation) (E)-2-butenoic acid (target=olfaction)

6. Chemical Characteristics TIME-RELEASE MATRIX Hydroxypropylmethylcelluose Diethylene glycol monoethyl ether

7. Chemical Characteristics : : : + : H+ [NaI] + H:OH Possible stabilization mechanism via acetal formation

8. Effects on Elasmobranchs • Study the actives using tonic immobility • Study the actives in surrounding-cloud dispersion

9. 3-Methylbutanal Effects Average dose size to terminate tonic immobility Needle-thin jet released at least 5cm from nares, juveniles

10. 3-Methylbutanal Effects Average dose size to terminate tonic immobility Cloud released at least 15cm from nares, adult sharks

11. 3-Methylbutanal Effects Average dose size to terminate tonic immobility Direct oral dosage using micropipettor, juveniles

12. (E)-2-Butenoic Acid Effects Average dose size to terminate tonic immobility Cloud released at least 15cm from nares, juvs and adults

13. (E)-2-Butenoic Acid Effects 400mL dose released Test on >3m S. mokarran

15. 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!!!

16. Effects on Teleosts T. Albacares Feeding preference tests at IATTC, Achotines, Panama

17. Effects on Teleosts Cobia feeding preference tests at RSMAS

18. Delivery System • Muslin bags • On gangion above hook • Close to hook • Direct injection • Fill bait with gel prior to rigging

19. 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

20. 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

21. 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

23. Current in and out of lagoon, normal to lines Check current direction using fluorescein and a digital flowrate meter

24. Preliminary Results No sharks captured on treatment line 40 hour soak time, 15 treatments/45 controls

25. Preliminary Results 1 male lemon (TL=154cm) at 27:28 Gel was not replaced (Trying to determine longevity of the gel) 67 hour soak time, 15 treatments/45 controls

26. Preliminary Results Tiger (TL=286cm) at 9:03 from rebait Gel was replaced at 24 hour rebait marks 48 hour soak time, 30 treatments/30 controls

27. Next Steps • CPUE is too low • Chemistry and delivery OK • NOAA longline cruise – November ‘06 • Preference tests with one species • FL bait company

28. 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