2013 bahamas cruise report

7/27/2019 2013 Bahamas Cruise Report

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Satellite tagging endangered sharks and

delineating shark nursery areas inside The

Bahamas Shark SanctuaryCruise Report.

DEMIAN D. CHAPMAN (PH.D.), MARK E. BOND, School of Marine & Atmospheric

Science, Stony Brook University.

TREVOR BACON, Moore Charitable Foundation.


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EXECUTIVE SUMMARYThe Commonwealth of The Bahamas recently enacted legislation that prohibits

commercial trade in sharks throughout the countrys Exclusive Economic Zone (EEZ). At a total

size of 629,293 square kilometers The Bahamas is now the single largest sanctuary for these

imperiled apex predators anywhere in the Atlantic Ocean.The Bahamas Shark Sanctuaryresearch cruise was conducted from May 4- June 12, 2013 and visited five major islands (Cat,

Nassau, Andros, Berry and Grand Bahama). Nearly 100 sharks were tagged as part of the cruise,

about a quarter of them with transmitters that enable us to track their movements remotely.

Twenty four oceanic whitetip (Carcharhinus longimanus) and one blue shark (Prionace glauca)

were fitted with pop-off satellite archival tags (PSAT) off Cat Island between May 4 and May

17. TV, radio, print and internet media outreach activities were conducted between May 19-25 in

Nassau, educating a very large Bahamian audience about The Bahamas Shark Sanctuary and

shark biology and conservation. Andros, the largest and one of the least populated Bahamian

Islands, was surveyed from May 26-June 2. We observed but were unable to catch a critically

endangered smalltooth sawfish (Pristis pectinata), confirming that the species still occurs at

Andros. We documented the presence of juvenile lemon (Negaprion brevirostris), blacktip

(Carcharhinus limbatus) and bull sharks (Carcharhinus leucas) off Andros, suggesting the island

serves as a nursery area for these species. We also observed large aggregations of mating nurse

sharks (Ginglymostoma cirratum) and located an aggregation of juvenile silky sharks

(Carcharhinus falciformis). The Berry Islands were surveyed from June 2-June 9, yielding

evidence of lemon shark nursery areas. Finally, Grand Bahama Island was surveyed from June

10-12. We found evidence of lemon, blacktip and bonnethead (Sphyrna tiburo) nursery areas on

this island. Overall, we found sharks and shark nursery areas to be common and widespread in

The Bahamas Shark Sanctuary and we tagged enough critically endangered oceanic whitetips to

conduct a comprehensive analysis of their movement patterns.We are now positioned to produce

peer-reviewed publications on the following subjects: (1) Migrations and breeding areas foroceanic whitetip sharks in the Western Atlantic (projected date of submission June 2014), (2)

Diving behavior of oceanic whitetip sharks (projected date of submission December 2013) and

(3) Homing sharks: local population structure of lemon sharks based on genomic analysis

(projected submission date March 2014). We will also make a detailed presentation to The

Bahamas Department of Fisheries by the end of 2013 in which we will disclose the locations of

potential shark nursery areas around the islands we surveyed.


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PROJECT RATIONALE & OBJECTIVES

The Commonwealth of The Bahamas recently enacted legislation that prohibits commercial trade

in sharks throughout the countrys Exclusive Economic Zone (EEZ). At a total size of 629,293 square

kilometers The Bahamas is now the single largest sanctuary for these imperiled apex predators anywhere

in the Atlantic Ocean. The effectiveness of The Bahamas Shark Sanctuary will hinge largely on whether

or not individual sharks spend significant amounts of time within its boundaries. Movement outside ofthese protected waters will expose them to potential capture in ongoing shark fisheries operating on the

high seas or the EEZs of other nations. Another key factor in determining the success of The Bahamas

Shark Sanctuary will be the availability of nursery habitat for sharks to breed within its borders. The final

ingredient for success will be education of the general public and regulatory agencies about the sanctuary,

so that it enjoys broad public support and is effectively enforced. We propose a research and educational

expedition within The Bahamas Shark Sanctuary that would bring these elements together. Our

overarching goal was three-fold: (1) to use pop-off satellite archival tags (PSATs) to track the movements

of three species of endangered sharks and sawfish (a close relative of sharks) in relation to sanctuary

boundaries; (2) survey shark nurseries to delineate important breeding habitat in the sanctuary; (3) raise

awareness among the general public and key regulatory agency (Department of Fisheries) about the

sanctuary and endangered sharks of The Bahamas.

CRUISE MAP

Figure 1:Red triangles locate stations visited during The Bahamas Shark Sanctuary research

cruise 2013 (May 4-June 12).


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CRUISE RESULTS

Objective 1: Satellite tagging sharks (oceanic whitetip, Carcharhinus longimanus, and great

hammerhead, Sphyrna lewini) and smalltooth sawfish (Pristis pectinata).

The oceanic whitetip shark, Carcharhinus longimanus, is among the most threatened of all of the

large epipelagic sharks. They are a large-bodied species, maturing at lengths of 170-190 cm1.

Very little is known about their reproduction1, but they have a delayed maturation, relatively

slow growth, long gestation time and infrequent breeding. This makes them keenly vulnerable to

overfishing. Oceanic whitetips have declined precipitously in the Northwest Atlantic and Pacific

basins, due largely to excessive longline landings2,3

. The fins of oceanic whitetips are highly

valued in Asia and made up 1.6-2.1% of the global shark fin trade in 20004. They are currently

listed as Critically Endangered in the Northwest Atlantic and Vulnerable globally by the

International Union for the Conservation of Nature. There is growing international interest in

oceanic whitetip conservation, including a recent listing under Appendix II of the Convention on

International Trade in Endangered Species (CITES) and efforts to reduce the catch of this species

by regional fisheries management organizations (e.g., the International Commission for the

Conservation of Atlantic Tuna; ICCAT). Many of these efforts are limited by a lack of scientific

information on the species.

Oceanic whitetips have a circumtropical, pelagic distribution but very little is known about their

migration patterns1. It is not known if they routinely move long distances throughout entire

ocean basins or spend substantial periods within the Exclusive Economic Zones (EEZ) of

particular countries. This is important in the Atlantic, as some countries operate extensive

longline fleets while others have banned longlines altogether. The safest place for oceanic

whitetips in the North Atlantic is likely the EEZ of The Bahamas, because longline fishing wasprohibited there in the mid-1990s and commercial harvesting of all sharks was recently banned

by the creation of a nationwide Shark Sanctuary. There is a clear need to investigate the

movements and habitat use of oceanic whitetips in the Atlantic in relation to relatively protected

areas, such as The Bahamas, and potential threats.

Pop-off satellite archival stags (PSATsMicrowave Telemetry, Maryland) have proven to be a

valuable tool for obtaining conservation-relevant data on the shark movements and habitat use5,6

. PSATs are externally attached to individuals and collect information on light, temperature

and depth during this deployment. They are pre-programmed to detach from the shark at a

specified time (usually a few months to a year), at which time they pop off and float to the

surface, where they transmit data summaries to the ARGOS satellite system. The pop-offlocation provides an end point to the track, akin to a conventional tag recapture. Light levels

recorded during the deployment can be used to reconstruct a track of the animal over time. In

2011 and 2012, our research team fitted 41 oceanic whitetips with PSATs off Cat Island in the

Bahamas, with the goal of learning more about how much time they spend within The Bahamas

Shark Sanctuary. Results from the first 12 tags applied to adult females show that some

individuals spend nearly the entire year in the sanctuary where others move long distances over


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several months before eventually returning after ~ 3 months. One third of the tagged sharks

moved north to an area between Cape Hatteras, NC, and Bermuda. Another third moved to an

area north of Puerto Rico. The goal of the 2013 cruise was to fit adult males and females known

to be gravid or non-gravid (based on an ultrasound examination or blood test) with PSATs as a

means to delineate the species mating and pupping areas in the Atlantic. We reason that gravid

females will migrate to the pupping areas, while non-gravid females and males will migrate tothe mating areas.

In 2013 at Cat Island we fit 24 oceanic whitetips with PSATs and 6 more were captured and fit

with ID tags. Four adult males, 2 gravid and 2 non-gravid females were among those fitted with

PSATs. All other PSAT sharks were adult females and blood tests are being carried out to

determine their reproductive status. Notably, the PSAT applied on this expedition brings us to 65

total, making this the third largest PSAT study for a marine animal in history. The PSATs are set

to detach from the sharks anytime from August 2013 through to April 2014. During fishing

operations for oceanic whitetips we also tagged Caribbean reefCarcharhinus perezi (N=2), tiger

Galeocerdo cuiver(N=1), bluePrionace glauca (N=1, including a PSAT) and silky (N=1)

sharks (Carcharhinus falciformis) and observed many more, including the only great

hammerhead (Sphyrna mokarran) observed during the cruise.Three oceanic whitetips were also fitted with accelerometer tags to study their short-term

movements and hunting behavior. One of these tags was recovered after a 4 day deployment and

revealed the depth, swimming speed and orientation of the shark every 5 seconds during the

track. Analysis of the recovered data is ongoing but there were several instances of vertical burst

swimming by the shark (i.e., launching itself upward in the water column from depth). This is

likely to be related to feeding, suggesting that these tags could provide useful information on the

hunting behavior of oceanic whitetips.At Andros we attempted to fit smalltooth sawfish (Pristis pectinata) with Smart Position OrTemperature Transmitting (SPOT) tags to enable almost real-time position and temperature data

to be transmitted to the Argos satellite whenever the tag breaks the surface of the water. Based

on what we know about the sawfishs movements and the type of habitat they inhabit the SPOT

tag was thought to be a useful tag to apply to them to help in delineating their movement

patterns. To locate sawfish, searches were conducted with 2 boats moving in a grid like pattern

parallel to one another, covering the shallow sand flat adjacent to the west coast of Andros.

Additionally aerial observation support was provided with the Flamingo Cay helicopter. One

smalltooth sawfish was located at Andros (24.43016 N; -78.23705W), however it evaded capture

by accessing water too shallow for the boats to follow. Estimated to be 2.45m (8ft) in length this

was still an interesting finding. Previous attempts to locate the smalltooth sawfish at this time ofyear have failed and due to their extremely low numbers in The Bahamas even observational

data is valuable. Interviews with some of the local bonefishing guides indicate the smalltooth

sawfish are more common in March/April around Andros and our collaborators at the National

Marine Fisheries Service (NMFS) are planning a new expedition to this site in 2014 to complete

this objective.


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Based on previous knowledge of the area and our understanding of what constitutes suitable

nursery habitat for sharks we set out to capture juvenile sharks at Andros, Berry and Grand

Bahama islands using custom shark-friendly longlines and rod and reel. Once hooked, the

shark was secured alongside the vessel while still in the water via a tail-rope. The data takenincluded three body length measurements, a fin-clip to provide DNA and the sharks sex. The

shark was then fitted with a National Marine Fisheries Service (NMFS) dart-tag to assist in a

regional mark-recapture study, the entire hook was removed and the shark was released.

Figure 3: Shark sightings (right) and captures (left) off Andros Island. Circles in right panel

indicate sightings of sharks color-coded by species (see inset key). Circles in left panel are color-

coded according to species and sized proportionately to the number of individuals sampled at

that location. The red star in the right panel shows the location where a lemon shark was fitted

with a PSAT tag.

Andros: Juvenile lemon sharks were common around Andros (Figure 3, Table 1). Twenty-six

individuals were captured and tagged, including two newborns (neonates). Other species that

were captured around Andros included two mature Caribbean reef sharks (Carcharhinus perezi)

and a mature female blacktip (Carcharhinus limbatus). Two juvenile silky sharks (Carcharhinus

falciformis) were caught further offshore. This species is listed as Vulnerable in the region(IUCN Red List) and could warrant additional protection in the near future. We also observed a

juvenile bull shark (Carcharhinus leucas), suggesting this species may breed at Andros as well.

Mating nurse shark (Ginglymostoma cirratum) pairs were also observed throughout western

Andros indicating this island serves as a mating ground for this species (Figure 3).


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Table 1. Male Female

Neonate 0 2

Juvenile 12 6

Subadult 2 4

Table 1: Lemon sharks captured at Andros by life stage and sex.

The Berry Islands: A total of 17 lemon sharks (Table 2) were caught at the Berry Islands

including two neonates (Figure 4). Sightings of juvenile lemon sharks throughout the islands

suggest it is a nursery area for this species similar to Andros (Figure 4).

Figure 4: Lemon sharks sighted (left) and captured (right) in the Berry islands.

Table 2: Lemon sharks captured at Berry Islands by life stage and sex.

Grand Bahama: Grand Bahama was the most densely populated island we visited on the cruise.

Nonetheless, juvenile sharks are common on the flats we surveyed on the northeast coast of the

island (Figure 5, Table 3). Juvenile lemon, blacktip and bonnethead sharks were all sighted and

captured at this site (Figure 5). The recreational dive site known as Tiger Beach was also

Table 2. Male Female

Neonate 1 1

Juvenile 4 2

Subadult 2 3

Adult 1 0


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Objective 3: Conduct outreach activities aimed at educating Bahamians about The Bahamas

Shark Sanctuary and sharks in general.

Participation of Bahamians in Cat Island research cruise: Two BESS scholars (Jesse

Courtemarche, Christina Roberts) joined us in the field in Cat Island during the first two weeksof the cruise. Both of them assisted directly in research activities and were educated about The

Bahamas Shark Sanctuary and shark biology (Figure 6).

BREEF eventat Stuart Coves: In conjunction with Stuart Coves and BREEF, Demian Chapman,

Amy Abercrombie, Christina Roberts (BESS scholar) and Mark Bond presented information on

sharks and the Shark Sanctuary to 35 Bahamian high school students and took them on an

afternoon snorkeling trip with reef fish and Caribbean reef sharks. This was a full day event that

included local media.Island FM Radio Interview: The Morning Boil show (Demian Chapman and BREEF). This

featured a 20-minute segment in prime time covering the significance of The Bahamas SharkSanctuary as well as talking about the objectives and initial results of the cruise.Guardian Radio Interview: The morning show with Dwight Strachan (Mark Bond and BREEF).

This interview covered why sharks and shark conservation are important, goals of the expedition

and Bahamian involvement in the work.Bahamas@Sunrise TV Interview: This was a 10-minute segment on same topics as above (Mark

Bond and BREEF).Print and web-based media coverage:

Bahamas Weeklyhttp://www.thebahamasweekly.com/publish/community/Bahamian_students_participate_in_Shar

k_Research_Expedition28407.shtmlThe Nassau Guardianhttp://www.thenassauguardian.com/index.php?option=com_content&view=article&id=39506:a-

once-in-a-lifetime-opportunity-&catid=36:education&Itemid=57BREEF staff use the presentation materials we developed during the course at teacher training

workshop. Most recently they did this in San Salvador (July 2013).Other: In conjunction with efforts to reach Bahamians we also strived to provide informationabout the cruise to a broader audience. This information was disseminated in a blog format

through the websites of Stony Brook Universitys School of Marine and Atmospheric Science

(SoMAS) and internationally recognized marine conservation author Carl Safinas Blue Ocean

Institute (BOI).

SoMAS:http://www.somas.stonybrook.edu/research/highlights/Chapman/index.html
http://www.somas.stonybrook.edu/research/highlights/Chapman/index.htmlhttp://www.somas.stonybrook.edu/research/highlights/Chapman/index.htmlhttp://www.somas.stonybrook.edu/research/highlights/Chapman/index.htmlhttp://www.somas.stonybrook.edu/research/highlights/Chapman/index.html


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Carl Safinas BOI:http://blueocean.org/2013/05/heads-up/?shared=email&msg=fail

Future outreach: We will make a detailed presentation to The Bahamas Department of Fisheries,

Department of Marine Resources and Department of Environment in November 2013. In these

meetings we will disclose the locations of potential shark nursery areas around the islands wesurveyed as well as bringing them up-to-date on our satellite tagging efforts. We will stress the

finding that many threatened and endangered sharks are flourishing in The Bahamas Shark

Sanctuary, validating their continued support for this approach and to persuade them to support

Figure 6: BESS scholar Jesse Courtemarche helping tag an oceanic whitetip at Cat Island.

efforts to develop similar legislation in other countries in the region.
http://blueocean.org/2013/05/heads-up/?shared=email&msg=failhttp://blueocean.org/2013/05/heads-up/?shared=email&msg=failhttp://blueocean.org/2013/05/heads-up/?shared=email&msg=failhttp://blueocean.org/2013/05/heads-up/?shared=email&msg=fail


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Publication plan

Results gathered during The Bahamas Shark Sanctuary cruise will be disseminated in peer-

reviewed scientific papers, accompanied by media releases. Key papers are listed below:

Migrations and breeding areas for oceanic whitetip sharks in the Western Atlantic (projected

date of submission June 2014). This paper will be based on all PSAT deployments made from2011-2013 and will delineate the movement patterns and infer the location of mating and

pupping areas inside and outside The Bahamas Shark Sanctuary.Diving behavior of oceanic whitetip sharks (projected date of submission December 2013). This

paper will use the combined PSAT and accelerometer data to elucidate the vertical migrations,

depth range and infer hunting behavior in oceanic whitetips.Local population structure of lemon sharks based on genomic analysis(projected submissiondate March 2014). This paper will use genetic information collected during the cruise and an

existing database that belongs to the Chapman laboratory to resolve the population structure of

lemon sharks in the western Atlantic ocean. Our main question is whether or not The Bahamasand perhaps each of its islands harbors a distinct lemon shark population. We will also use

genetic data to estimate the relative sizes of the breeding population at each of the islands we

visited.

Collaborators:

In conjunction with The School of Marine and Atmospheric Sciences (SoMAS) at Stony Brook

University and the Moore Charitable Foundation, The Cape Eleuthera Institute and Microwave

Telemetry also provided technical and logistical support throughout the cruise.

References

1Castro, JI. 2011. The Sharks of North American Waters. Oxford University Press, New York,

USA.

2Baum JK, Myers RA. 2004. Shifting baselines and the decline of pelagic sharks in the Gulf of

Mexico. Ecology Letters 7: 135145.

3Walsh WA, Clarke SC. 2011. Analyses of Catch Data for Oceanic Whitetip and Silky Sharks

reported by Fishery Observers in the Hawaii-based Longline Fishery in 19952010. WCPFC-

SC7-2011/EB-WP-03.

4Clarke SC, et al. 2006. Identification of shark species composition and proportion in the Hong

Kong shark fin market using molecular genetics and trade records. Conservation Biology 20:201-211.

5Bonfil R, et al. 2005. Transoceanic migration, spatial dynamics, and population linkages of

white sharks. Science 310 (5745): 100-103.

6Chapman DD, et al. 2007. Deep-diving and diel changes in vertical habitat use by Caribbean

reef sharks, Carcharhinus perezi. Marine Ecology Progress Series 344: 271275.


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7Howey-Jordan L, et al. 2013Complex movements, philopatry and expanded depth range of a

severely threatened pelagic shark, the oceanic whitetip (Carcharhinus longimanus) in the

western North Atlantic. PloS one, 8(2), e56588.

2013 bahamas cruise report

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