1. Hook locations in sea turtles where and why? Michelle Sims Duke University

2. Overview 2) Where are turtles hooked? - general overview with 2004-2007 data 3) What may influence the hooking location ? - bait, hook characteristics, turtle species/length 4) Ways to explore data - keep data separate by port and fishery - combine data - advantages and information required 1) Definitions - hook locations, ports, fisheries

3. Definitions Hook locations: External (Head, Neck, flippers, axilla, tail, shell) Lower jaw Jaw commissure Upper jaw Tongue Swallowed Fisheries: Surface: Tuna, Mahi and Shark Port: Given codes: 102, 104, 105, 106, 108, 109, 110

4. Where are turtles hooked? “Good” hookings ? “Bad” hookings ?

7. J hooks

8. What may influence the hooking location? Hook characteristics - type (e.g. C), size (e.g. 16), ring, offset Gear characteristics - bait (e.g. squid vs fish), mainline material ( ? ), distance between hooks ( ? ), hook depth ( ? ) Turtle characteristics - Species, size

9. What may influence the hooking location? Hook characteristics - type (e.g. C), size (e.g. 16), ring, offset

10. Available information on hooks and bait type: Old forms:  Hook type - C or J  Size of C hook (e.g. C16)  Species of bait used on line Extra information from new forms:  Size and shaft angle of J  Presence of ring on J and C  Offset size  Manufacturer  % of each species of bait used on line

11. Options for exploration  Keep data separate by port and fishery

12. Options for exploration  Keep data separate by port and fishery All examples - looking at probability that hook is swallowed

13. Mahi fishery - port 104 Used data from lines with 100% squid Data from 2005-2006 (old forms) Compare hooking locations in C15, C16 to J Number of hookings Hook typePercentage swallowed Difference in % swallowed (vs J) 53J15.1% 94C1522.3%No 92C165.4%Yes * Based on two sample Z-Test of proportions (vs J), one-sided, alpha=0.05 % of swallowed J hooks is significantly higher than C16 hooks

14. Tuna fishery – port 105 Used data from lines with 100% squid Years 2004-2006 (from old forms) Compare hooking locations in C16 vs J Number of hookings Hook typePercentage swallowed Difference in % swallowed (vs J) 94J45.7% 50C1638%No * Based on two sample Z-Test of proportions (vs J), one-sided, alpha=0.05 % of swallowed J hooks is NOT significantly higher than C16 hooks

15. Questions 1) Why differences in J vs C16 effects between ports ? Small sample size ? Differences in size of J or C16 hooks ? 2) Why differences in % swallowed between ports even with same bait and same hook ? Other gear or hook characteristics ?

16. Available information on hooks and bait type: Old forms:  Hook type - C or J  Size of C hook (e.g. C16)  Species of bait used on line Extra information from new forms:  Size and shaft angle of J  Presence of ring on J and C  Offset size  % of each species of bait used on line

17. Effect of ring on hooking location

18. Year 2007 (from new form) Only use data from lines with >90% fish Compare hooking locations by - Hook type and size - c15, c16, J (all angled) - Presence of ring Tuna fishery – port 110 Ring:YESNO C15114 C16719 J*4816 * On new form - Js with ring called “J8”. Js with no ring called “J” 90 Number swallowed 00 0 1 Number of turtles : ~20 % 0 %

19. Year 2007 (from new form) Only use data from lines with >90% fish Compare hooking locations by - Hook type and size - c15, c16, J (all angled) - Presence of ring Tuna fishery – port 110 Ring:YESNO C15114 C16719 J*4816 90 Number swallowed 00 0 1 Number of turtles : *Based on randomisation test No difference in % J hooks swallowed (p=0.06*)

20. Mahi fishery – port 110 Analysis 1 : Data from new forms Data from lines with 100% fish Compare hooking locations in C13, C14 and C15 Number of hookings Hook typePercentage swallowed Difference in % swallowed (vs C13) 30C133.3% 29C1413.8%No 61C150%No * Based on two sample Z-Test of proportions (vs J), one-sided, alpha=0.05 % of swallowed C13 hooks is NOT significantly higher than C14 or C15 hooks

21. Mahi fishery – port 110 Analysis 2 : Data from new forms Data from all lines with bait information Compare differences in swallow rates using: - % fish on line (0% if all squid) - C13, C14 and C15 hooks Based on logistic regression with hook type and % fish on line as covariates. One-sided z test, alpha = 0.05 No difference in swallow rates among C hook sizes Increase in % fish on line drop in % of hooks swallowed

22. Conclusions  Evidence of bait effect  Ring may increase rate of hooked turtles swallowing hook ?  Limitations: Small sample within a port x fishery to explore further

23.  Combining data from ports and/or fisheries - meta-analysis - increase understanding of factors influencing location - more comparisons (e.g. ring x hook size x bait type) Requires complete information on hooks and gear - gear information and hook type - old and new forms - more information about hooks - new form Options for exploration  Keep data separate by port and fishery

24. Questions for each port: Can you provide more information about and J and C hooks for years when old forms were used ? e.g. ring, offset, shaft angle and size of J

25. For each target fishery, is the size of J hooks similar : 1) A mong years ? 2) To other target fisheries within your port ? 3)To the same fishery in other ports ? 4)To other target fisheries in other ports ? Questions for each port:

26. For each target fishery, is the size of J hooks similar : 1) A mong years ? 2) To other target fisheries within your port ? 3)To the same fishery in other ports ? 4)To other target fisheries in other ports ? Questions for each port:

27. What may influence the hooking location? Hook characteristics - type (e.g. C), size (e.g. 16), ring, offset Gear characteristics - bait (e.g. squid vs fish), mainline material ( ? ), distance between hooks ( ? ), hook depth ( ? ) Turtle characteristics - Species, size

28. Hooked locations by species Olive Ridley Green / Black UnknownLogger- head HawksbillLeatherback External436 (23%) 151 (28%) 10754 Lower jaw724 (38%) 179 (33%) 25770 Jaw commissure 78 (4%) 28 (5%) 5420 Swallowed325 (17%) 54 (10%) 4890 Tongue129 (7%) 60 (11%) 1400 Upper jaw199 (11%) 67 (13%) 31050 Total = 1891 539 76 30 28 4

29. Unknown Olive Ridley Logger- head Green/ Black Leather- back Hawksbill ? ? ? Turtle lengths x species

30. Turtle lengths x port - all years 2004-2007

31. Turtle lengths x field office - data from 2007

32. C12 C13 C14 C15 C16 C18 J J2 J38 J8 102 mahi 0 0 3 0 0 0 1 0 0 0 102 shark 0 0 0 0 1 0 0 0 0 0 104 tuna 0 0 0 27 64 0 43 0 0 0 104 mahi 0 0 0 281 381 0 134 61 0 0 104 shark 0 0 0 70 80 0 31 5 0 0 105 tuna 0 0 0 0 84 2 131 0 10 0 105 mahi 27 14 15 19 0 0 42 0 0 0 105 shark 0 0 0 0 1 0 0 0 5 0 106 mahi 0 0 22 24 0 0 17 0 0 0 108 mahi 0 0 11 5 4 0 17 0 0 0 108 shark 0 0 0 0 8 0 5 0 0 0 109 mahi 0 2 6 4 0 0 20 0 0 0 109 shark 0 0 0 0 3 0 1 0 0 0 110 tuna 0 0 16 26 50 0 88 0 0 79 110 mahi 0 70 359 233 24 0 6 0 0 0 110 shark 0 0 0 0 3 0 1 0 0 0

33. Comparison of tuna fishery in office 105 and mahi in office 104