GDEGEM workshop

1. A network for bottlenose dolphin photo-ID
monitoring along the French Mediterranean coast
Olivier Gimenez, Hélène Labach, Léa David, Maxime Barbier, Nathalie Di-Meglio,
Julie Jourdan, Marine Roul, Caroline Azzinari, Nicolas Tomasi, Nicolas Robert,
Frank Dhermain, Cathy Cesarini, Guido Gnone, Michela Bellingeri
Marseille, December 1-2, 2015
GDEGeM

2. The GDEGeM Project: Grand Dauphin Etude et
Gestion en Méditerranée
• A collaborative and multi-disciplinary project - H. Labach’s talk
• Launched and coordinated by GIS3M (Group of Scientific
Interest in Mediterranean Marine Mammals)
• 3-year project : February 2013-December 2015

3. Improve conservation of sub-population in
northwestern Mediterranean Sea
• Estimate abundance, identify key areas and movements
• Identify monitoring units
French Mediterranean MPAs
MPA
-­‐
ASPIM
MPA
–
Natura
2000
MPA
–
Na0onal
Park
MPA
–
Marine
Park

4. Monitoring protocol
• Photo-id campaigns during 2 years (all seasons!)
Gulf of Lion
Provence
Corsica

5. Monitoring protocol
• Photo-id campaigns during 2 years (all seasons!)
• Database through INTERCET - G. Gnone’s talk
Gulf of Lion
Provence
Corsica

6. Monitoring protocol
• Photo-id campaigns during 2 years (all seasons!)
• Database through INTERCET - G. Gnone’s talk
• Abundance estimation via capture-recapture (CR) methods
Gulf of Lion
Provence
Corsica

7. Distinguish what you see…

8. From what is actually out there

9. Imperfect detection and capture-recapture
Observation

10. Imperfect detection and capture-recapture
Observation Reality

11. Population of (unknown) size N

12. Take first sample n1

13. Tag captures
x
x
x
x
x
x
Comparison of catalogs
via INTERCET

14. Release captures

15. Take second sample n2

16. Take second sample n2
of which m2 are already marked (matching)

17. Do the maths
• Under some assumptions
Hence, an estimate of total abundance
boring…

18. Do the maths
• Under some assumptions
• Hence, an estimate of total abundance
boring…
with detection

19. Extension to ‘open’ populations
• Main assumption: demographic closure
• How to account for mortality?
• Rarely possible to track individuals from birth to death
• Number resightings decreases over
time if you’re dead
• There is information on survival in CR
data
• P. Couet’s talk

20. Extension to ‘open’ populations
• Use of open population CR models - mortality
• Estimate survival probability while accounting for detection < 1

21. Extension to ‘open’ populations
• Use of open population CR models - mortality
• Estimate survival probability while accounting for detection < 1
• Abundance estimate = observed counts corrected by detection
Observation Reality

22. Results

23. The sampling effort (is huge!) – 21 464 km
Gulf of Lion 12 859 Km Provence : 5 196 km Corsica : 3 409 km

24. The sampling effort (is huge!) – 21 464 km
Gulf of Lion 12 859 Km Provence : 5 196 km Corsica : 3 409 km

25. Some stats on the groups
© Sonia Gara_BREACH

26. Some stats on the groups
Number of
sightings
Group size
Mean (SD)
Group size
Min
Group size
Max
Gulf of Lion 92 16.6 (13.2) 1 51
Provence 18 15.7 (10.3) 1 54
Corsica 41 5.34 (4.53) 1 23
© Sonia Gara_BREACH

27. How many guys were spotted and photo-IDed?
Comparison of catalogs via INTERCET

28. How many guys were spotted and photo-IDed?
# pictures # photo-
IDs
# ind.
R L R & L
Gulf of
Lion
919 894 534 1280 834
Provence 227 207 174 260 147
Corsica 140 130 103 167 132

29. • 53 individuals sighted both in Provence and Gulf of Lion
• No exchange with Corsica
• 66% sighted only once
• 37 individuals seen ≥ 5 times
• Transience issue
Focus on continental coasts

30. Sightings and utilization distribution of residents
Individuals sighted ≥ 5 times

31. Capture-recapture results

32. Capture-recapture results
Gulf of
Lion
Proven-
ce
Corsica

33. Season-specific recapture estimates
Gulf of Lion
655 [385;1095]
Provence
91 [51;155]
Corsica
0.0
0.2
0.4
0.6
0.8
Su2013 Au2013 Wi2014 Sp2014 Su2014 Au2014 Wi2015
0.0
0.1
0.2
0.3
Su2013 Au2013 Wi2014 Sp2014 Su2014 Au2014 Wi2015
0.0
0.2
0.4
Su2013 Au2013 Wi2014 Sp2014 Su2014 Au2014 Wi2015

34. Season-specific abundance
Gulf of Lion
655 [385;1095]
Provence
91 [51;155]
20
30
40
50
Su2013 Au2013 Wi2014 Sp2014 Su2014 Au2014 Wi2015
250
500
750
Su2013 Au2013 Wi2014 Sp2014 Su2014 Au2014 Wi2015
Corsica
0
250
500
750
Su2013 Au2013 Wi2014 Sp2014 Su2014 Au2014 Wi2015

35. Abundance estimates
Gulf of Lion
655 [385;1095]
Provence
91 [51;155]
Corsica
149 [67;335]

36. Abundance estimates wrt sampling effort
Gulf of Lion
655 [385;1095]
Provence
91 [51;155]
Corsica
149 [67;335]

37. Total abundance
Gulf of Lion
655 [385;1095]
Provence
91 [51;155]
Corsica
149 [67;335]
Total
895 [661;1427]

38. Model assumptions?
• Demographic closure: survival < 100% for 2 out 3 regions
• Permanent marks: adults only by discarding badly marked
• Homogeneity in detection: heterogeneity doesn’t do better
• Homogeneity in survival: transience accoun-
ted for (Madon et al. 2013)
• How to reconcile our estimates with results
from aerial surveys? Cf. S. Laran’s talk
Madon, Garrigue, Pradel & Gimenez (2013). Marine Mammal Science, 29: 669–678

39. Perspectives
• Deal with bilateral photo-IDs for full data exploitation
Bonnici, Labach, David, Di-Méglio & Gimenez (in prep). Improved integration of bilateral photo-id data in mark-recapture analyses.
Iago Bonnici

40. Perspectives
• Use spatial information
L. Blanc

41. Perspectives
• Use spatial information and opportunistic data for increased precision
L. Blanc
REPCET, whale-watching tours, stranding, …;
How to deal with observer bias?

42. Perspectives
• Tremendous work by local structures: « Strength in unity »
• Use of abundance to inform management of the network of MPAs -
cf H. Labach’s & S. Laran talks
• GDEGeM reboot? Importance
of long-term monitoring programs!

43. Thank you