tiger shark

Shark Handling Techniques

Hi everyone, my name is Giancarlo Nunes and I’m the Research and Conservation manager for Fundacion Parke Nacional Aruba. I can be considered a jack of all trades for this trip since I’ve been lucky enough to receive training on several of these expeditions. What I mostly do though is assist in getting the shark safely secured to the boat by either handling the head or the tail of the shark.

What is the proper way to restrain a shark for tagging?

Once a shark is hooked to the line, the line is then used to carefully guide the shark to the side of the boat with it’s head facing towards the front of the boat. Another crew member then secures the shark’s tail to the back end of the boat using a rope which is thick enough to hold the shark but also soft enough to not cut the shark’s skin. At this moment the shark is considered secured and the science team can start with data collection. During data collection it is important for the shark handler to continuously assess the shark’s health. One of the most important things during the expedition is to make sure the sharks are strong and healthy so they can be released with no issues.

How do you tag a shark?

Photo credit: Sami Kattan / Beneath the Waves

There are several types of tags being used on this expedition and each one serves a different purpose. All the tags are attached either on the shark’s fin or at the base of the fin. Shark fins are made out of cartilage which is the same material human ears are made of. Tagging a shark can be compared to piercing a person’s ear. The tags don’t affect the shark’s survival much like earrings don’t affect a person’s daily activities.

What type of tags are used?
There are many types of shark tags and each have a different purpose. For this expedition we will be using the following three types.
1. Floy tags are used as an external visual marker for researchers and fishermen to know if a shark as been tagged for research purposes. Floy tags are shaped like uncooked spaghetti which is why they are also called spaghetti tags. Floy tags contain contact information of the organization which tagged the sharks.
2. PIT tags are small chips which are inserted under the skin via a needle at the base of the fin and can not be removed as easily as a Floy tag. Each PIT tag has a unique code which can be read using a portable scanner.
PIT tagging a shark is comparable to chipping a pet animal for identification purposes.
3. Satellite tags are work via GPS and are attached to the top of the shark’s fin. A signal is sent to orbital satellites whenever a tagged shark’s fin breaches the water’s surface which allows us to track it’s location. Knowing where sharks go allow us to discover areas important to their survival such feeding and breeding habitats.

Keep following us on DCNA’s website,  Facebook (Dutch Caribbean Nature Alliance), Instagram (dcnanature)  for daily updates!

 

Article published 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

The value of sharks

My name is Francois Mille, I am a Marine Park Ranger at STENAPA in Sint Eustatius.

Sint Eustatius is a small volcanic island, 21km2, that belongs to the Dutch Kingdom. It was incorporated into the Netherlands in October 2010. There are about 3’500 souls living there. It is a dormant stratovolcano. The second highest mountain of the Netherlands.

Stenapa stands for St Eustatius National Park Foundation.  We manage 3 protected area and a botanical garden, which correspond to 33km2. Bigger than the island itself!

My role in the expedition involves various tasks. In the morning I hopped on the Queen Beatrix 2, the support boat. I also help placing the line in the water to catch the sharks, including baiting the hook and attaching the hook line to the main one. I really like this part because we must put the line close to each other, so you have no break in between.  At the end of the day, I prepare the equipment for the next day. They need a good rinsing because they do not like salt water. For that task I am helped by Leslie Hickerson, she is from Nature Foundation St. Maarten, so we have a good chat while doing this. Then I help whoever need helps!

But yesterday was great because I got to go on Lady Rebecca to help tag the biggest female Tiger shark, and that was great!

Tiger shark (Galeocerdo cuvier) © Daniel Norwood

Sometimes people ask me how we could help the shark population.

  • First do not eat or buy any shark related product. Some country sells fins, meat, or liver oil from sharks.
  • Second, use less plastic. We use too much plastic, a part ends up in the ocean, and animal eat them, by mistake, confusing them with prey. Or worse, they get entangled in trash and drown.
  • Third, sharks have been on earth since before the first trees appeared. It is sad to think that humans are responsible for killing most of them. That humans are pushing some species to disappear completely. When humans catch sharks for their fins, they cut the fins from the sharks while they are alive and throw them back in the sea alive! Their death is horrible.

You might wonder why it is important to care about shark. If you have been watching Jaws, you might think we need to kill them all. But the reality is far from a Hollywood movie.

Sharks are very important because they are at the top of the food chain. Imagine a pyramid, they are on top, taking care of the large fish that are one step below them. Now, imagine no more sharks: those larger fish will not be hunted, therefore they will develop a lot, maybe a bit too much. Then one day those fishes would not get any food because they eat them all. So those will start to die as well. You will then end up with several steps of pyramid that would disappear completely. Before you know it, just like that all the fish are sick and dying, all the way to the plankton, and this can happen rapidly.

Sharks are important because as predator they will hunt the weak and the sick prey. They keep the marine ecosystem in balance.

A way to help shark is to create protected areas where you cannot harm them. The Yarari Marine Mammal and Shark Sanctuary was established by the Dutch government in 2015 to protect sharks in the Caribbean Netherlands.  This corresponds to the 3 following islands: Bonaire, Saba and Sint Eustatius. The purpose is to try to keep shark population steady as their numbers are on high decline.

You might be surprised but the more sharks there are, the more fish there will be.

Though we do not know everything about sharks, we do expeditions such as these. For example, we know that female tiger sharks cruise through the Saba Bank, but we do not know if they breed there.

And some fishermen with very large and long fish net catch shark by mistake. So it is important not to do that where sharks are protected.

It is important for those islands to protect the fish and it has an important economic impact.

But not only does the sanctuary protect sharks, but all the marine mammals in the area as there are dolphins and whales living there or just passing by during their migration.

 

Photos by: Daniel Norwood

 

Article included in Special Edition Bionews: Tiger Shark Expedition

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

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

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