Ecology of Manta Rays

Transcription

1 Ecology of Manta Rays Kelly Newton, Don Croll, Kevin Weng, Felipe Galvan, John O Sullivan Sullivan, Ellen Freund, Heidi Dewar Alejandro Acevedo, Bernie Tershy

2 Trophically Simple Top Predators

3 Linked to oceanography

4 Fin whales in the Gulf of California

5 Fin whale tagging & tracking -Time-depth recorders Dive profile description -Echosounders Vertical density of krill Loreto La Paz

6 Depth (m) Fin Whales Krill Schools Day Night Day Night Depth (m) Frequency Foraging Dives Frequency Krill Aggregations

7 Isla El Pardito

8

9

10 Small Scale Artisanal Fisheries Gulf of California i

11 Small Scale Artisanal Fisheries Gulf of California Il Isla San Jose El Pardito Isla San Francisquito

12 Spine-tail Devil Ray Mobula japanica Near Threatened (IUCN 2006) Large size (3m Disk Width) Large maturity (2m DW) Low Fecundity Highly Migratory

13

14 x El Pardito

15 Depth (m) Manta Rays Day Night Percent Time (%) Depth (m) Krill Schools Day Night Percent of Krill Schools

16 Spine-tail Devil Ray Mobula japanica Last & Stevens 1994

17 Monterey Bay Aquarium Husbandry Group Habitat t preferences Movement patterns link to oceanography Fisheries i issues & conservation implications

18 Rodeo Technique

19 Pop-up Archival Tags 10 Males 3 Females Mean Disc Length: 93 cm Tag Deployments: 1076 days totalt days (mean SD) Max: 188 days

20 Habitat Preferences Time at Depth Time at Temperature <0 > Depth (m m) re (C) Temperatu >750 < Proportion of time Waters shallower than 50m Proportion of time Temperature ºC

21

22 Movement Patterns June July August September

23 June July August September

24 -3 Averag e Euphausia acea indiv m Krill Abundance Feb April July Oct IMECOCAL Cruise Data 2004 Lines From Lavaniegos et al. 2006

25 Loggerhead Sea Turtles Peckham et al 2007 Manta Rays Blue Whales Etnoyer et al 2006 Yellowfin Tuna Schaefer et al 2007

26 June July August September Schaefer et al. 2007

27 Yellowfin Tuna Purse Seine Fishery F/V Hanna: Mexico

28 Total YFT Total YFT Metric tons M IATTC 2008

29 2008 Yellowfin Tuna Purse Seine Distributions IATTC 7-10

30 2008 Purse Seine Fishery 186,000 mt Yellowfin Tuna 45.5% in Mexico Bycatch: Rays (Mobulidae & Dasyatidae) - 48 mt (33 NOA sets) ~ 500 animals

31 Conservation Implications Vulnerable to small artisanal fisheries & large purse seine tuna fishery Prohibited to catch: November 2005

32 Mobula japanica Last & Stevens 1994

33 Mobula japanica Last & Stevens 1994

34

35 Conservation Implications Worldwide Purse Seine Fisheries Western Indian Ocean: 425 per year Also fisheries in Indonesia, New Zealand, India, Sri Lanka, & Thailand Reduce bycatch of Manta Rays Need to know movement patterns, fisheries i mortality, population structure, and population biology

36 Population Genetics Mobula japanica Questions that cannot be resolved Mobula munkiana using tagging data: Stock structure Implications of migration Integration of long-term trends

37 Population Genetics Research Questions 1. What are the relationships within the family Mobulidae?

38 Manta Rays?

39 Population Genetics Research Questions 1. What are the relationships within the family Mobulidae? 2. Spatial scale and connectivity of genetically defined populations (aka genetic stocks) of manta rays in the tropical Pacific?

40 Approach: Sampling Sea of Cortez

41 Family Mobulidae Mobula japanica M. munkiana M. thurstoni M. tarapacana Manta birostris M. mobular M. eregoodootenkee M. hypostoma M. rochebrunei M. kuhlii

42 Family Mobulidae Baja California Mobulids Mobula japanica M. munkiana M. thurstoni M. tarapacana Manta birostris M. mobular M. eregoodootenkee M. hypostoma M. rochebrunei M. kuhlii

43 Mobula munkiana Near Threatened (IUCN 2006) Small size (110cm Disk Width) Smaller maturity (97 cm DW) Form large schools Low Fecundity Migratory (?)

44 Mobula munkiana Last & Stevens 1994

45 Mobula munkiana

46 Mobula munkiana 2007: 2 1 male: 29 days 1 female: 66 days 2008: 6 2 males 4 females days ~400 tracking days 2009: NONE 2010: 3 awaiting results!

47 japanica vs. munkiana Solitary Diet: Krill Pelagic Shallow > 50 m Majority left GOC Schools Diet: Krill & Mysids Coastal Shallow > 50 m All stayed within GOC

48 = pop up location Isla El Pardito

49 2009 Field Season Mobula thurstoni Near Threatened (IUCN 2006) Medium size (180cm Disk Width) Short head & cephalic lobes Form small schools Low Fecundity Migratory (?)

50 Mobula thurstoni Last & Stevens 1994

51 2009 Field Season Mobula thurstoni 4 PAT Tags - 3 Males -1 Female

52 = pop up location Isla El Pardito

53 2010 Field Season Mobula thurstoni 7 PAT & MiniPAT Tags -1 Male -6 Females -Pregnant

54 = pop up location Isla El Pardito

55 Family Mobulidae Baja California Mobulids Mobula japanica M. munkiana M. thurstoni M. tarapacana Manta birostris M. mobular M. eregoodootenkee M. hypostoma M. rochebrunei M. kuhlii

56 Family Mobulidae IUCN Red List Mobula japanica M. munkiana M. thurstoni M. tarapacana Manta birostris M. mobular M. eregoodootenkee M. hypostoma M. rochebrunei M. kuhlii

57 Manta Ray Research References: Elasmobranch 4,872 Mobulidae - 46 ISI Web of Knowledge

58 2006 Collaboration with Monterey Bay Aquarium Husbandry Group

59

60

61

62

63

64

65

66

67

68 Moby May 13, 2006 December 29, 2007

69

70 Future Work... Potential captures in Pacific to decrease transport time Assist with work in Bahia de Los Angeles Mobula japanica movements publication Comparison publication Continue genetics research

71 Acknowledgements Cuevas Family, Isla El Pardito Monterey Bay Aquarium National Geographic Society Field crew: CICIMAR students, family, friends Dana Wingfield & Dave Foley (SST satellite images)

72

73