Sharks

Uncovering the mystery of tiger shark reproduction in the eastern Caribbean

Much of the lives of the most iconic shark species – including the tiger shark – remains a secret, even to shark researchers. This is because these large sharks are capable of migrating thousands of miles across oceans in a single year. One of the most unsolved mystery of sharks’ lives is where adult females go during their pregnancy. Discovering the habitats that are important during this life stage will be critical for creating conservation protections for mother sharks and their developing pups.

Tiger sharks are wide-ranging marine predators that can carry around 10-80 (yes, up to 80!) pups within their womb while pregnant. Finally, after about 15 months in the womb, the mother tiger shark will give birth to the live pups that are around 75 cm long. While we know this basic information about tiger shark reproduction, we have yet to uncover many of the breeding grounds, gestation grounds, and pupping grounds for this migratory species. Discovering this information will require the use of novel technologies, and that’s where our research comes into play.

My name is Brooke Anderson and I am a PhD student at Arizona State University studying sharks, their movements, and their movements relate to reproduction. I am lucky to be a part of this team of researchers trying to figure out if and how pregnant tiger sharks are using the Yarari Sanctuary and the wider Caribbean.

To help solve this mystery, we must first set out to the Saba Bank and do some fishing. Once we catch a large female tiger shark, we will secure her along the research vessel and take several size measurements to confirm that she is healthy and mature. Female tiger sharks mature at a whopping 3 meters in length! We can also examine her for fresh bite marks on her fins or body, which indicates that she had recently mated and could be pregnant.

After we collect this information on her maturity, we will rotate her upside down in the water to initiate tonic immobility. Tonic immobility is a natural reflex in sharks that induces a trance-like state of inactivity. This trance-like state help keeps the shark calm and still for the next part of the workup where my expertise comes into play. I will be able to use a portable ultrasound (from E.I. Medical Imaging) – just like we could use on a human – to get a look inside the shark’s womb for hidden pups. If she is pregnant, we will see on the ultrasound many miniature tiger sharks inside their mother’s womb! We can even use the ultrasound to take measurements and determine the size of the pups – this helps us to estimate how far along in her pregnancy that the mother tiger shark is.

Image of a tiger shark embryo as seen on the portable ultrasound.

Next, we can attach a satellite tag to the mother tiger shark to track where she goes throughout her pregnancy in near real time. This will allow us to determine the extent that the Yarari Sanctuary, Saba Bank, and the surrounding eastern Caribbean are used as important habitats for pregnant tiger sharks for the very first time. With this information, we can help assess the effectiveness of current conservation and management strategies for this near-threatened and ecologically important species. Stay tuned to see if we were able to find pregnant tiger sharks and where they might be headed on their journey to motherhood.

Keep following us on DCNA’s website,  Facebook (Dutch Caribbean Nature Alliance), Instagram (dcnanature)  for updates about the Pregnant Tiger Shark Expedition!

 

Article included in the Special Edition BioNews: Tiger Shark Expedition

Date
2021
Data type
Media
Theme
Education and outreach
Research and monitoring
Geographic location
Saba
Saba bank

Importance of Yarari Sanctuary for Minke Whale

A new collaborative study provides new insight into how two species of minke whales utilize the Caribbean and neighboring Atlantic waters throughout their life cycle. The findings add further conservation value and significance to the relatively new Yarari marine sanctuary of the Netherlands. By combining scientific, citizen science and public information, this study provides key information which will help guide conservation efforts moving forward.

Minke whales are the smallest of the “great whales” and can be found in waters world-wide. There are actually two different species of Minke whale, the common minke whale, or northern minke whale (Balaenoptera acutorostrata) and the Antarctic minke whale, or southern minke whale (Balaenoptera bonaerensis).

Yarari Sanctuary

Minke whales are known to migrate over long distances, with both species using the warm waters of the Caribbean to breed and calf during the winter months. Within the Caribbean, there are a number of marine protected areas, such as the Yarari Marine Mammal and Shark Sanctuary, which includes the territorial waters around Bonaire, Saba, and St. Eustatius. In addition to providing vital protection of the marine ecosystem, the Yarari Sanctuary is used to help focus research for greater insight into the life cycles and migration patterns of both resident and migratory species. Understanding how these species travel during the year and use Caribbean waters is critical in designing effective conservation plans in the future.

New Study

A recent study brought together a wide array of researchers and conservation groups including the Institute of Environmental Sciences from Leiden University and the Aruba Marine Mammal Foundation. This study reviewed literature, citizen science and scientific records to compile spatial and temporal data for both species of minke whales. The goal of the study was to learn more about how these species use the Wider Caribbean Area throughout their life cycles.

In total, 130 records were collected, most of which were from scientific studies (100) and the rest from citizen science (30). Minke whales are notoriously inquisitive, frequently approaching boats, which makes them the perfect species to be spotted by citizen scientists. Improvements in civilian camera equipment, and increased initiatives to record and share biodiversity observations on social networks and public databases have led to a recent surge in citizen science reports for all species.

Findings

Photo credit: Hans Verdaat

This study was able to integrate scattered species records to provide new insights that point to the importance of the Yarari Sanctuary which lies in the center of an Eastern Caribbean wintering area for the common minke whale and thus add conservation value and significance to this relatively new marine sanctuary of the Netherlands. These new insights are in large part thanks to two previous studies conducted by Wageningen University & Research together with the Saba Bank Managing Unit and were generously funded by the Ministry of Agriculture, Nature and Food Quality (LNV). These latter results were aligned with similar studies and were found to be consistent with large-scale seasonal migration routes of the Minke whales.

Interestingly, this study highlighted that although it was previously believed that only the northern minke whale used the Gulf of Mexico, there were confirmed stranding incidents involving both species. Furthermore, the fact that there were strandings of minke whales throughout the year suggested that some whales stay year-round within the Gulf.

Report your Sightings

Every sighting can provide useful data that can contribute to the understanding needed to protect these species. Help further conservation efforts by reporting your (minke) whale (or other species) sightings and photos on the website Observation.org or download the free app (iPhone (iObs) & Android (ObsMapp)). These tools are available in over 40 languages and can be used by biologists, citizens and tourists alike.

For more information you can find the full report on the Dutch Caribbean Biodiversity Database by clicking the button below.

https://www.dcbd.nl/document/spatial-temporal-distribution-minke-whales-...

 

Article published in BioNews 46

 

Date
2021
Data type
Media
Theme
Education and outreach
Research and monitoring
Geographic location
Aruba
Bonaire
Curacao
Saba
Saba bank
St. Eustatius
St. Maarten
Author

Unraveling the Mysteries of the Saba Bank: DCNA Tiger Shark Expedition 2021

July 31st – August 7th, 2021 – For the first time on the Saba Bank, an expedition team was able to successfully assess the shark diversity by attaching five satellite tags and confirming pregnancy stages by ultrasound of two species of sharks. This research advancement resulted in assessing 56 sharks, including 16 Tiger sharks with one confirmed early-stage pregnancy, and the first tagged male in the region. These details inform us that the Saba Bank’s important role in the shark populations of the North-Eastern and wider Caribbean Region have yet to be unlocked. This information is crucial to better protect sharks within the Dutch Caribbean’s Yarari Marine Mammal and Shark Sanctuary as well as beyond.

Dutch Caribbean Nature Alliance (DCNA) along with the Protected Area Management Organizations of the Dutch Caribbean: Saba Conservation Foundation (SCF)Nature Foundation St. Maarten (NFSXM), St. Eustatius National Parks (STENAPA)STINAPA Bonaire, the Aruba National Parks Foundation (FPNA), the Dutch Caribbean Nature Alliance (DCNA) and World Wildlife Fund for Nature- The Netherlands (WWF-NL) led a team on the Saba Bank in collaboration with Arizona State University, University of Groningen, Beneath the Waves and funded by the Biodiversity Fund of the World Wildlife Fund for Nature- The Netherlands (WWF-NL) .

This week-long ocean research expedition aimed to understand the stages of the reproductive cycle of tiger sharks on the Saba Bank. Tadzio Bervoets, Director of DCNA and expedition leader adds “It is critical to collect the data necessary to advance the conservation actions for species of sharks in the Caribbean Region and with the data collected over the last week we have been able to get a clear picture of the important role the Saba Bank plays”. This expedition built upon previous research and expertise from collaborating scientists.

Throughout the week, the team was able to deploy five satellite tags on the dorsal fin of tiger sharks which will allow tracking of the animals over an extended period of time. The ultrasounds which were taken using high technology imagery to determine the maturity and pregnancy stage supported by Brooke Anderson, Ph.D. candidate of Dr. James Sulikowski’s Lab, Arizona State University show that the Saba Bank is a reproductive area for IUCN Near Threatened listed species tiger and the IUCN endangered listed Caribbean Reef Shark. One of the female tiger sharks was confirmed with an early stage pregnancy and boasted a total length of 251cm. This multidisciplinary research approach is necessary for taking the first steps in understanding the reproductive life cycle for the species in the region.

One of the mysteries which resulted was the first tagged male on the Saba Bank sized at 306 cm and later named Maestro Angelo. While it is common to find females, it was surprising to encounter male tiger sharks during the research. Due to the lack of research done previously on these sharks on the Saba Bank, it became evident as to why there is a need to emphasize the importance and need for scientific research into these species.

Expeditions brought forward by the protected area management organizations, such as this one, support the necessary research needed for data-driven management solutions. These results will be used to help steer future research activities, inform local governments on the significant impact these species and their habitats have on ecotourism, and ultimately strengthen conservation policies. Ayumi Kuramae, Saba Bank Management Unit Officer shared the importance of this study, “Through previous tagging expeditions it was clear that the tiger sharks tagged on the Saba Bank can travel as far south as Grenada, crossing many nations’ borders. This shows the importance of protecting the species not only in our waters, but region wide. Seeing male and female tiger sharks together of different life stages, shows us that protection of these species in our water is vital since we may be protecting the future generation of tiger sharks in the region. A decrease in the number of sharks can affect the overall fish stocks which leads to a disturbed natural balance in the sea. Saba, for example, highly depends on fisheries and dive tourism as part of the local economy which also relies on a healthy fish stocks. Thus, understanding the role of these apex predators is extremely important”.

After gazetting, the Yarari Marine Mammal and Shark Sanctuary will encompass the exclusive economic zone waters of the Saba Bank along with Saba, Bonaire and Statia. This sanctuary has the intention to provide a safe place for these animals, but without supportive data and knowledge, it is difficult to ensure they receive the appropriate protection measures. In order to survive, tiger sharks may use the Saba Bank as a key habitat for different stages of their life cycle but are known to travel to other regions during different life stages, making them a transboundary species. This expedition will help identify where larger, multi-national marine protected areas across the Caribbean should be to protect these species during their whole life cycle.

About Dutch Caribbean Nature Alliance

The Dutch Caribbean Nature Alliance (DCNA) is a non-profit organization created to protect the natural environment and to promote sustainable management of natural resources on the six Dutch Caribbean islands. DCNA was created to help consolidate knowledge and help bridge funding gaps for conservation within the Dutch Caribbean.

For more information on the Pregnant Tiger Shark Expedition, check DCNA’s Facebook, Instagram or DCNA’s website (https://dcnanature.org/news/) or contact projects@dcnanature.org

Photo credit © Daniel Norwood (all rights reserved)

Photo credit © Daniel Norwood (all rights reserved)

 

Articles published in BioNews 46  and Special Edition BioNews: Tiger Shark Expedition

Date
2021
Data type
Media
Theme
Education and outreach
Research and monitoring
Geographic location
Saba
Saba bank
Author

Expedition on the Saba Bank to Enhance Tiger Shark Protection

Starting August 1, 2021 a team of researchers will spend a week on the Saba Bank investigating the life-cycle of tiger sharks. Researchers will investigate the migration routes, where and when tiger sharks breed so they can protect them better within the Dutch Caribbean’s Yarari Marine Mammal and Shark Sanctuary as well as beyond. In this expedition members from the Saba Conservation Foundation (SCF)Nature Foundation St. Maarten (NFSXM), St. Eustatius National Parks (STENAPA)STINAPA Bonaire, the Aruba National Parks Foundation (FPNA), the Dutch Caribbean Nature Alliance (DCNA) and World Wildlife Fund for Nature the Netherlands (WWF-NL) will participate.

© Sami Kattan

In 2016, the Saba Conservation Foundation, Nature Foundation St. Maarten, and Sharks for Kids  partnered together as part of DCNA’s Save our Sharks Project funded by the Dutch National Postcode Lottery. Since then, satellite tagging of tiger sharks has been conducted on the Saba Bank and around Sint Maarten. Through this research we now know that tiger sharks in Dutch waters travel throughout the Caribbean basin, with most of these tagged sharks being sexually mature females. During the upcoming expedition the researchers aim to not only tag and track more tiger sharks to further investigate the life cycle, but they will also measure if and how large the pups inside pregnant tiger sharks are. This will help to determine if the Saba Bank is in fact a breeding ground for tiger sharks, one of the main goals of the expedition.

Tiger Shark. © Jarrett Corke WWF-Canada

The other objective is to see where these transboundary sharks migrate to in order to better understand the importance of the Yarari Marine Mammal and Shark Sanctuary and protect other geographical areas. The Yarari Sanctuary was established on September 1, 2015 and aims to protect marine mammals, sharks, and rays throughout the waters of Bonaire, Saba, and since September 2018, St. Eustatius. Collaboration between not only the six Dutch Caribbean islands but countries across the wider Caribbean as a whole is necessary in order to protect and conserve these essential species and ecosystems. Therefore the Caribbean Shark Coalition was recently formed to collaborate better in the entire Greater Caribbean region.

Celebrated on July 28 each year, World Nature Conservation Day acknowledges that a healthy environment is the foundation for a stable and healthy society. This includes a healthy ocean which, undoubtedly, depends on sharks. Sharks are large top predators that serve a critical role in maintaining balance in the marine ecosystem. Sharks help keep their prey population healthy by eating the weak while also affecting their prey’s distribution. In healthy oceans, sharks help to maintain stable fish stocks and healthy coral reefs and seagrass beds, which is important for the fisheries and the economy of the islands.

The Tiger Shark research expedition is coordinated by the DCNA and generously funded by WWF-NL through the Biodiversity Funds and the Dutch National Postcode Lottery. For more information on the Pregnant Tiger Shark Expedition, follow the participating organizations on Facebook, Instagram or DCNA’s website(https://dcnanature.org/news/).

 

Article published in BioNews 45 and Special Edition BioNews: Tiger Shark Expedition

Date
2021
Data type
Media
Theme
Education and outreach
Research and monitoring
Geographic location
Saba
Saba bank
Author

Caribbean Shark Coalition Launched to Promote Training, Impact, and Collaboration around shark protections in the Greater Caribbean Region

The Dutch Caribbean Nature Alliance (DCNA) and  Beneath the Waves (BTW) have launched the Caribbean Shark Coalition (CSC), an innovative, new platform to bring key stakeholders, researchers, governments and funders together to better collaborate and scale the impacts of science and policy within the entire Greater Caribbean region.

© Sami Kattan/Beneath the Waves

Represented are over 45 new members from NGOs, governments, and local businesses from 24 countries, which have formally joined the CSC to build capacity around research, policy, and education efforts for these threatened species in the region.

The Caribbean plays a key role in advancing the global target of protecting 30% of the worlds’ ocean by 2030. Under this vision, the CSC has three primary goals, which will be carried out through collaborative work and CSC-member projects. Firstly, the CSC will foster collaboration in shark and ray research, policy, and capacity building for conservation among stakeholders, and provide opportunities for knowledge transfer and data synthesis. The CSC will also seek to explore ways in which transboundary protections can be made to better safeguard the long-term health of shark and ray populations. Finally, the CSC aims to promote a sustainable future for these species as well as the human livelihoods who depend on them, by engaging local businesses, stakeholders, and private sector corporations.

“This is a historic moment for marine conservation efforts in the Caribbean,” says Tadzio Bervoets, Director of DNCA and a founding team member at the CSC. “We have been calling for transboundary marine protections in these waters, as we know that these apex predators are connecting ecosystems, reefs, fisheries, and nutrients across Exclusive Economic Zones. The CSC will help us to find and address critical knowledge gaps around sharks and rays in the region, and support collaborative research projects.”

Dr. Austin Gallagher, Chief Scientist of Beneath the Waves, shares, “Over the years we’ve had so many stakeholders from throughout the region express their interest in getting engaged in basic research or education around sharks, but a lack of resources or technical or operational expertise limited them from taking action.

He adds, “We hope The Coalition can play a role in creating that friendly, open, and supportive community those voices have been looking for.”

CSC members represent a collection of experts from NGOs, local communities, intergovernmental organizations and governments, academia, and policy institutes, and local businesses, working together to advance the study and conservation of sharks and rays found in the waters of the Greater Caribbean. The CSC will provide cross-disciplinary training, region-wide assessments, and will issue grants to CSC-member projects. The CSC will represent the interests and goals of members and, more broadly, sharks and ray species of the Caribbean at the UN (UNEP-CEP and the Regional Activity Center for the SPAW Protocols of the Cartagena Convention), IUCN-Caribbean, CITES, CMS, CBD, and other international gatherings.

For information visit www.caribbeansharks.co

 

Published in BioNews 43

Date
2021
Data type
Media
Theme
Education and outreach
Research and monitoring
Geographic location
Aruba
Bonaire
Saba
Saba bank
St. Eustatius
St. Maarten
Author

Sharks found with dangerously high levels of heavy metals in The Caribbean

In a new study, researchers from the non-profit research institute Beneath the Waves (BTW) documented and revealed alarmingly high levels of 12 heavy metals, including mercury, in the muscle tissues of large reef and tiger sharks sampled throughout The Bahamas. Published in Scientific Reports, the new findings carry important implications for human health in the Greater Caribbean region, where sharks are occasionally consumed by humans, even though strictly prohibited around several island such as in the Yarari Sanctuary (Bonaire, Saba, St. Eustatius) and around St. Maarten.

Over the last century, human activities have rapidly accelerated the influx of metals and metalloids entering the marine environment, posing potential risks to biodiversity and food security. Evaluating muscle tissues of 36 individual sharks from six species, the results from this study provide the first account of metal concentrations in sharks sampled in The Bahamas, a relatively pristine marine ecosystem where sharks live risk-free in a large marine protected area. Sharks are not commonly consumed by humans in The Bahamas.

As apex predators, sharks naturally bioaccumulate toxins in their bodies from eating other species of fish. While the impacts on shark health remain unknown, the concentrations of metals quantified as present in the study were determined to exceed the levels that are considered toxic for human consumption. The study also found that reef sharks, the more resident species, had higher mercury levels than tiger sharks, and that reef sharks’ mercury levels increased as they matured and grew larger.

Understanding how sharks are affected by humans is critical for ongoing conservation efforts of these ecologically and economically important species,” says Dr. Oliver Shipley, the study’s lead author, Research Associate at Beneath the Waves and postdoctoral researcher at The University of New Mexico. “Working in areas such as The Bahamas where shark abundance is relatively stable and healthy due to effective long-term protection, is important for us to be able to establish these baseline studies. If the levels are high in The Bahamas, imagine what they could be in other parts of the world where sustainability and environmental conservation are not a priority.

“This work underscores the benefits of the Bahamas shark sanctuary for conducting important baseline studies on the health of our marine resources,” says Eric Carey, Executive Director of Bahamas National Trust.  “It also highlights the need for sustained conservation efforts of sharks regionally, which are important to the Bahamian economy and reef health,” he added.

While the researchers in the study identified the need for future studies to understand the pathways for how these metals ultimately enter into the marine food web, the human health risks of ingesting heavy metals by consuming Caribbean sharks species are clear.

“Shark fisheries are not very prevalent in most of the Greater Caribbean region, but eating sharks can be culturally important to some nations,” says study co-author Dr. Austin Gallagher, Chief Scientist at Beneath the Waves and co-founder of The Caribbean Shark Coalition. “Yet with a strong demand for shark products worldwide, this is another piece of evidence to steer people away from consuming sharks,” he adds.

“Humans and oceans are intricately connected, and this work highlights the notion that science can and should guide decisions that improve ocean and human health.”

 

# # #

To download an open-access PDF of the full research paper, please visit: www.nature.com/articles/s41598-020-79973-w

Shipley ON, Lee CS, Fisher NS, Sternlicht JK, Kattan S, Staaterman ER, Hammerschlag N, Gallagher AJ (2021) Metal concentrations in coastal sharks from The Bahamas with a focus on the Caribbean Reef shark. Scientific Reports

About Beneath the Waves

Founded in 2013, Beneath the Waves is an ocean NGO using cutting-edge science to advance scientific discovery and catalyze ocean policy, with a focus on threatened species and marine protected areas.

www.beneaththewaves.org

Article included in BioNews 41

 

Date
2021
Data type
Media
Theme
Education and outreach
Research and monitoring

Metal concentrations in coastal sharks from The Bahamas with a focus on the Caribbean Reef shark

Over the last century anthropogenic activities have rapidly increased the influx of metals and metalloids entering the marine environment, which can bioaccumulate and biomagnify in marine top consumers. This may elicit sublethal effects on target organisms, having broad implications for human seafood consumers. We provide the first assessment of metal (Cd, Pb, Cr, Mn, Co, Cu, Zn, As, Ag, and THg) and metalloid (As) concentrations in the muscle tissue of coastal sharks from The Bahamas. A total of 36 individual sharks from six species were evaluated, spanning two regions/study areas, with a focus on the Caribbean reef shark (Carcharhinus perezi), and to a lesser extent the tiger shark (Galeocerdo cuvier). This is due their high relative abundance and ecological significance throughout coastal Bahamian and regional ecosystems. Caribbean reef sharks exhibited some of the highest metal concentrations compared to five other species, and peaks in the concentrations of Pb, Cr, Cu were observed as individuals reached sexual maturity. Observations were attributed to foraging on larger, more piscivorous prey, high longevity, as well a potential slowing rate of growth. We observed correlations between some metals, which are challenging to interpret but may be attributed to trophic level and ambient metal conditions. Our results provide the first account of metal concentrations in Bahamian sharks, suggesting individuals exhibit high concentrations which may potentially cause sublethal effects. Finally, these findings underscore the potential toxicity of shark meat and have significant implications for human consumers.

 

Referenced in BioNews Article https://dcnanature.org/sharks-toxins/

Date
2021
Data type
Scientific article
Theme
Research and monitoring

Voorlopige Lijst van Pelagisch voorkomende Vissoorten rond Curaçao en Bonaire

List of pelagic fishes found around Bonaire and Curacao, including scientific, English, Spanish and Papiamento names. Published by the Agriculure, Husbandry and Fisheries Service of Curacao, as Agrinoticia, Piská – No.1

Date
1979
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Curacao
Author

50 Tiger Shark Facts

Facts About Tiger Sharks

We are going to present before you some interesting facts about tiger sharks. It is one of the most feared sharks in the ocean. People are afraid of it. The name "tiger" also adds to that reputation of its being a dangerous animal. Let us learn some interesting info about it.

Date
2016
Data type
Other resources
Theme
Education and outreach
Research and monitoring

Ocean acidi cation and global warming impair shark hunting behaviour and growth

Alterations in predation pressure can have large e ects on trophically-structured systems. Modi cation of predator behaviour via ocean warming has been assessed by laboratory experimentation and metabolic theory. However, the in uence of ocean acidi cation with ocean warming remains largely unexplored for mesopredators, including experimental assessments that incorporate key components of the assemblages in which animals naturally live. We employ a combination of long-term laboratory and mesocosm experiments containing natural prey and habitat to assess how warming and acidi cation a ect the development, growth, and hunting behaviour in sharks. Although embryonic development was faster due to temperature, elevated temperature and CO2 had detrimental e ects on sharks by not only increasing energetic demands, but also by decreasing metabolic e ciency and reducing their ability to locate food through olfaction. The combination of these e ects led to considerable reductions in growth rates of sharks held in natural mesocosms with elevated CO2, either alone or in combination with higher temperature. Our results suggest a more complex reality for predators, where ocean acidi cation reduces their ability to e ectively hunt and exert strong top-down control over food webs. 

Date
2015
Data type
Scientific article
Theme
Research and monitoring
Document