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Whale Shark - Rhincodon typus
#16
6,000 Feet Under: Whale Sharks' Deepest Dives Detected

By Mindy Weisberger, Senior Writer | June 28, 2016 03:08pm ET

[Image: aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1h...AxLmpwZw==]
Marine ecologist Mark Erdmann swims with a tagged whale shark in Raja Ampat, Indonesia.
Credit: © Shawn Heinrichs

Known as the "gentle giants" of the shark family, whale sharks are the largest fish alive today. But there is much that scientists have yet to discover about their biology and habits.

And these massive fish recently revealed a big secret — they're capable of far deeper dives than previously suspected.

By using highly sophisticated fin-mounted satellite tags on whale sharks for the first time, scientists observed the deepest recorded dives by a whale shark — nearly 6,000 feet (1,800 meters), approximately the length of 27 football fields. 

Whale sharks (Rhincodon typus) live in warm and temperate waters around the world, and can grow to about 50 feet (15 m) in length. They are filter feeders, hoovering up not only plankton and fish eggs, but also small fish and squid. Sometimes their diet gets them into trouble with fishermen; when whale sharks swim too close to boats that are trawling for baitfish, they can get caught in the nets.

However, their tendency to tangle themselves up turned out to be a lucky break for a team of researchers in Indonesia.

Whale sharks had previously been difficult to tag with fin-mounted satellite tags — trackers used on a number of shark species that can transmit position, water depth and temperature — because the sharks are too big for divers to manipulate alongside a research boat in order to attach the devices.

But a team of scientists recently took a different approach — tagging sharks that had gotten trapped in fishing nets before they were released.





Down in the depths

Over 18 months, scientists tagged 16 whale sharks in southeast Indonesia's Cenderawasih Bay, collecting a wealth of data on the sharks' movements — including how deep they dove — results that greatly surprised the researchers.

Of the 16 tagged sharks, 10 were observed to dive more than 2,000 feet (625 m), according to Mark Erdmann, a coral reef ecologist and vice president of the Conservation International (CI) Asia-Pacific marine program, who led the tagging expeditions.

And two of the smaller sharks dove even deeper than that by about 4,000 feet (1,219 m), Erdmann wrote in a blog post on the CI website, though the researchers have yet to learn what exactly the sharks are doing in those depths.

"Are they diving for food, or for other reasons? It's still unclear," he said.

The tags have a two-year battery life, and the scientists are greatly anticipating what unexpected whale shark behaviors might still be revealed. Meanwhile, the tagged sharks' movements can be followed on the CI website, using a "whale shark tracker" tool going live later this week, part of an initiative to raise awareness and appreciation of these massive and mysterious marine creatures.

http://www.livescience.com/55216-deepest-diving-whale-sharks.html
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#17
First successful wild whale shark health assessments performed
The scientific milestone will expand the community's understanding of this endangered species


Date: August 17, 2017
Source: Georgia Aquarium

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Cenderawasih Bay whale shark.
Credit: Georgia Aquarium

For the first time ever, scientists successfully performed health assessments, including collecting blood and biological samples, taking measurements and attaching satellite tracking tags, to a population of wild whale sharks -- the world's largest fish, classified as "endangered" since 2016. The research advancement, which occurred in Indonesia's remote Cendrawasih Bay, has significant implications for unlocking the mysteries surrounding the overall health of whale sharks -- including the potential impacts of tourism on their health. These details can better inform future conservation policies to protect and encourage their population recovery.

"The data and biological samples we collected provide an invaluable snapshot into the lives and activities of a species we know relatively little about," said Alistair Dove, PhD, vice president of research and conservation at Georgia Aquarium. "As we begin decoding what we've collected from wild whale sharks, we become better positioned to protect them and educate the public about their importance."

Scientists wasted no time cataloguing the information and testing the samples, setting up a field laboratory on their research vessel. This testing continued at a laboratory at the State University of Papua (UNIPA) in Manokwari, the capital of Indonesia's West Papua Province. While at the school, researchers also presented to students and faculty about the results of the expedition and the techniques used to collect the samples.

This expedition is the result of an international collaboration between Georgia Aquarium, Conservation International (CI) and the Indonesian government that brings together critical skillsets from each of the partners. Georgia Aquarium experts, who care for whale sharks daily, brought to the expedition critical knowledge and proven techniques ensuring the welfare of the wild whale sharks while teams collected the biological samples. This was complimented by Conservation International's experience with local whale shark populations and strong relationships with the Indonesian government and local coastal communities, without which this expedition would not have been possible. Finally, the Indonesian Ministry of Marine Affairs and Fisheries (MMAF) and the Cendrawasih Bay National Park Authority hosted and permitted the expedition and will be integrating the findings into their local and national policies on whale shark conservation and tourism management.

Dr. Selvy Tebay, S.Pi., M.Si., Vice Rector IV of University of Papua (UNIPA) shared, "The involvement of UNIPA's scientists allows for an expansion of expertise within the West Papua Province. Local scientists studying whale shark migratory behaviors shared their knowledge with Conservation International and Georgia Aquarium, and have in turn received a more complete worldview of whale shark migratory patterns -- an important aspect of conserving a wide-ranging species. This will lead to practical and tangible conservation benefits for the species as well as wider marine tourism management within West Papua, which is a priority for the Indonesian Government."

The migratory species is constantly on the move, making it extremely difficult to perform health assessments or collect biological samples on free-swimming whale sharks. As luck would have it, the perfect opportunity came in the form of a unique interaction between fishers and whale sharks that occurs in Cendrawasih Bay.

Indonesian fishers in the area target schools of baitfish by suspending large nets beneath specialized bagan floating platforms and using bright lights at night to attract the baitfish above the nets -- which are quickly lifted in order to catch the entire school at once. This "free" meal is too good to pass up for whale sharks, which can be seen feeding on the baitfish around the bagans all year round. In the process, these animals can accidentally trap themselves in the nets. Fishers, who see whale sharks as a sign of good fortune, release them after clearing the nets of their catch.

In 2012, CI scientists repeatedly observed this peculiar situation, and in 2015 opportunistically deployed the world's first fin-mounted archival satellite tags on wild whale sharks prior to their release -- resulting in a wealth of movement data which has since helped to inform the management and conservation of the species in Indonesia.

"The unique situation in Cendrawasih Bay provides researchers unprecedented access to these massive animals. These health assessments are designed to provide important insights on whether whale shark ecotourism and research activities are having a significant impact on the sharks' welfare. This is critically important for us to understand, both to inform our tagging and research activities and especially for the Indonesian government to be able to sustainably manage whale shark ecotourism in a manner that benefits local coastal communities without negatively affecting the whale sharks." said Mark Erdmann, vice president of Asia-Pacific marine programs at Conservation International.

Ben G. Saroy, Head of Cendrawasih Bay National Park Authority, agreed, "Cendrawasih Bay, home to the biggest whale shark population in Indonesia, requires comprehensive information to manage this endangered species. The data gathered from this research will complement existing information and be used to strengthen conservation and tourism management policies within the bay -- which will ultimately bring benefits to the indigenous communities."

Andi Rusandi, Director of Marine Conservation and Biodiversity at MMAF, shared the importance of this study, "As we strive to develop whale shark ecotourism in Indonesia to benefit our local communities and these majestic animals themselves, it is important to highlight conservation. We have already published the Whale Shark Tourism Handbook as a guide, and the results of this study will further enrich our knowledge on the species. We greatly appreciate this support from our partners, and look forward to understanding these results and their recommendations in greater detail."

Over the course of the expedition, the team was able to successfully deploy seven additional fin-mounted satellite tags, each of which are expected to transmit valuable data on the shark's movements and diving behavior for up to two years.

Story Source: Georgia Aquarium. "First successful wild whale shark health assessments performed: The scientific milestone will expand the community's understanding of this endangered species." ScienceDaily. www.sciencedaily.com/releases/2017/08/170817110917.htm (accessed August 19, 2017). 
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#18
Tracking down the whale-shark highway

Date: August 30, 2017
Source: Monterey Bay Aquarium Research Institute
Summary:
Researchers recently discovered that whale sharks in the Eastern Tropical Pacific follow fronts -- the dynamic boundaries between warm and cold ocean waters.

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A whale shark near the Galapagos Islands being measured by a diver using laser photogrammetry.
Credit: © Jonathan Green/Galapagos Whale Shark Project

Did you know that August 30 is International Whale Shark Day? Whale sharks are the largest fishes on Earth, growing up to 18 meters (60 feet) long, but they feed mostly on tiny drifting animals such as copepods and, occasionally, small fish such as anchovies. To satisfy their immense appetites, whale sharks travel long distances to find dense swarms of prey.

MBARI biological oceanographer John Ryan recently worked with biologists who have been tracking whale sharks in the Eastern Tropical Pacific Ocean. They discovered that whale sharks in this area spend most of their time cruising along fronts -- the dynamic boundaries between warm and cold ocean waters. This study, recently published in the journal PLoS One, could help in the conservation of these endangered animals.

In 2011 and 2012, a team of researchers from Ecuador and England attached satellite tracking tags to 27 whale sharks at Darwin's Arch, a remote location about 200 kilometers (125 miles) northwest of the main Galapagos archipelago, and about two degrees north of the equator. This was the first time whale sharks had been tagged in the Eastern Tropical Pacific. The tagged sharks spent the next four to six months traveling east and west from this location across a 4,000-kilometer expanse of ocean, mostly staying between the equator and five degrees north latitude.

The researchers contacted Ryan to help them figure out how the whale-shark movements related to ocean conditions. This was a challenging task because ocean conditions are continually changing and whale sharks are always on the move.

Sea-surface temperatures, routinely measured by satellites, can reveal the oceanic features that whale sharks encounter during their large-scale movements. Ryan analyzed day-to-day changes in sea-surface temperature across the entire Eastern Tropical Pacific for the months when the whale sharks were being tracked. Because the Equatorial Pacific is often cloudy, Ryan used a combination of infrared and microwave radiation data from satellites (microwave radiation can pass through clouds).

When Ryan first looked at the whale-shark tracks in relation to the satellite data, he was struck by how consistent the tracks were. "The whale sharks could have ranged anywhere in the Eastern Tropical Pacific," he said, "but they were primarily following frontal boundaries between warm and cold water."

Extending across the Eastern Pacific is a distinct boundary between warm water north of the equator and colder water to the south. This boundary is called the North Pacific Equatorial Upwelling Front. Ryan's analysis showed that whale sharks followed this front as if it was an open-ocean highway. When the front moved north and south in huge wave-like meanders, the whale sharks followed these meanders like semi trucks negotiating a winding mountain road.

Darwin's Arch, the whale-shark tagging site, is located right in the middle of the equatorial front. This could explain why whale sharks are often seen in the area, but rarely hang around for very long.

Ryan pointed out that the equatorial front is an environmental transition zone. "To the north of this zone, the water is warm and stable but there's not a lot of productivity," he explained. "To the south the water has high productivity, but is much colder."

He continued, "Previous studies showed that plankton [small, drifting plants and animals] can accumulate in this transitional zone. So this zone may be a good place for whale sharks to find dense food patches, while not getting too chilled by cold water."

Ryan also discovered that, when whale sharks approached the coasts of Central and South America, they followed fronts in these areas as well. Though less extensive than the equatorial front, these coastal fronts also form at boundaries between cold, high-productivity water and warm, less productive water. Whale sharks appear to head for these "secondary highways" in January or February, when the equatorial front typically weakens or disappears.

In an interesting side note, almost all of the whale sharks tracked in this experiment appeared to be pregnant females. The one adult male that was tracked followed a similar path as the females. Two juvenile whale sharks that were tracked followed different paths, farther away from the equatorial front.

In 2016, whale sharks were declared an endangered species, their numbers threatened by shark finning, entanglement in fishing gear, and boat collisions. But one of the biggest challenges in whale-shark conservation is simply coming up with good population estimates. By demonstrating that whale sharks can be found along fronts, this study will make it easier for marine biologists to estimate how many of these gentle giants are out there riding the rolling waves of the whale-shark highways.

Story Source: Monterey Bay Aquarium Research Institute. "Tracking down the whale-shark highway." ScienceDaily. www.sciencedaily.com/releases/2017/08/170830155506.htm (accessed August 31, 2017).






Journal Reference:
John P. Ryan, Jonathan R. Green, Eduardo Espinoza, Alex R. Hearn. Association of whale sharks (Rhincodon typus) with thermo-biological frontal systems of the eastern tropical Pacific. PLOS ONE, 2017; 12 (8): e0182599 DOI: 10.1371/journal.pone.0182599

Abstract
Satellite tracking of 27 whale sharks in the eastern tropical Pacific, examined in relation to environmental data, indicates preferential occupancy of thermo-biological frontal systems. In these systems, thermal gradients are caused by wind-forced circulation and mixing, and biological gradients are caused by associated nutrient enrichment and enhanced primary productivity. Two of the frontal systems result from upwelling, driven by divergence in the current systems along the equator and the west coast of South America; the third results from wind jet dynamics off Central America. All whale sharks were tagged near Darwin Island, Galápagos, within the equatorial Pacific upwelling system. Occupancy of frontal habitat is pronounced in synoptic patterns of shark locations in relation to serpentine, temporally varying thermal fronts across a zonal expanse > 4000 km. 80% of shark positions in northern equatorial upwelling habitat and 100% of positions in eastern boundary upwelling habitat were located within the upwelling front. Analysis of equatorial shark locations relative to thermal gradients reveals occupancy of a transition point in environmental stability. Equatorial subsurface tag data show residence in shallow, warm (>22°C) water 94% of the time. Surface zonal current speeds for all equatorial tracking explain only 16% of the variance in shark zonal movement speeds, indicating that passive drifting is not a primary determinant of movement patterns. Movement from equatorial to eastern boundary frontal zones occurred during boreal winter, when equatorial upwelling weakens seasonally. Off Peru sharks tracked upwelling frontal positions within ~100–350 km from the coast. Off Central America, the largest tagged shark (12.8 m TL) occupied an oceanic front along the periphery of the Panama wind jet. Seasonal movement from waning equatorial upwelling to productive eastern boundary habitat is consistent with underlying trophic dynamics. Persistent shallow residence in thermo-biological frontal zones suggests the role of physical-biological interactions that concentrate food resources.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0182599 
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#19
New study, detailing 22-year-long global citizen science project sheds light on enigmatic endangered whale sharks

November 29, 2017
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A whale shark beneath a tour boat in the Philippines. Researchers are recording human encounters with the endangered animals in a photo-and-video identification library. Credit Duncan Murrell/Barcroft Media, via Getty Images

Vital scientific information about whale shark behavior, biology and ecology is being uncovered by an unlikely source - ecotourists and other citizens. Thanks to modern advancements in technology and the burgeoning field of "citizen science," new information about gregarious and mysterious whale sharks is being revealed in a study slated to publish on November 29 in BioScience.
Whale shark habitat spans the globe, making long-term research over wide geographic ranges a difficult challenge for whale shark researchers. To address this challenge, researchers harnessed modern technology, creating an online photo database called Wildbook for Whale Sharks and enlisted the help of ecotourists and citizens across the globe to upload any images of whale sharks they happened to see or encounter anywhere in the world. Photos of nearly 30,000 encounters representing 6,000 individually-identified sharks across 54 countries over 22 years has given scientists a rich data set to analyze and better understand the nature of this endangered species that has long been misunderstood and understudied.
Through this effort, researchers have now identified 20 whale shark aggregation sites globally, an increase from 13 identified prior to enlisting citizens in this scientific effort.
"This effort is increasing our knowledge of whale shark abundance and geographic range, trends in site fidelity and frequency," explained the study's lead author and Director of ECOCEAN Inc. Dr. Brad Norman. "That information is vital for prioritizing conservation areas for the species."
Analysis of the images provided data on sex-ratio bias, site fidelity and aggregation, hotspot sites, size and migration patterns of the animal—details that improve scientists' understanding of the species and help conservation efforts to protect them and their environment.
"Enlisting citizens to participate in science has helped us uncover several mysteries of the whale shark. We are piecing together a puzzle of both the ecology of this endangered species and the areas that are most critical to them," said Dr. Alistair Dove, Vice President of Research and Conservation at Georgia Aquarium, a co-author on the study.
The long-term observation project has provided enriched scientific knowledge of the species including:
  • Spot patterns in whale sharks are unique and long lasting, and provide a method of individual identification through photographs.

  • Some of the most populous hotspots of whale sharks include the Ningaloo Reef in Australia, the Atlantic coast of Mexico, Mozambique and the Philippines. Year-by-year observation of the population in these areas and lack of population in others suggests to researchers how illegal fishing and lack of conservation can impact aggregation.

  • There is a strong male bias at the majority of sites, showing an overall 66 percent male population globally.

  • For the most part, whale sharks aggregate around the same hotspots from year to year.

  • Few individual whale sharks move between countries.
Engaging citizen scientists in photo-identification of whale sharks tells scientists more than the nature of the species, but also identifies an association between ecotourism activities and how they may affect the appearance and return rate of whale sharks. It can also identify how areas of high fidelity are addressing conservation techniques, showing how those techniques may be applied on a larger scale. Finally, a broader analysis of the environmental variables in the aggregation sites can inform the long-term impacts of climate change in the movement of the whale sharks.
The study's authors encourage other directed research programs using citizen science to dedicate their efforts to photo-identification sampling at times and locations separate to regular tourism activities to encourage consistency and avoid data gaps.

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A whale shark in Indonesia. The bus-sized creatures feed on plankton. Credit Reinhard Dirscherl/ullstein bild, via Getty Images

https://phys.org/news/2017-11-year-long-global-citizen-science-enigmatic.html




Journal Reference:
Bradley M. Norman et al. Undersea Constellations: The Global Biology of an Endangered Marine Megavertebrate Further Informed through Citizen ScienceBioScience, bix127, https://doi.org/10.1093/biosci/bix127 Published: 29 November 2017

Abstract
The whale shark is an ideal flagship species for citizen science projects because of its charismatic nature, its size, and the associated ecotourism ventures focusing on the species at numerous coastal aggregation sites. An online database of whale shark encounters, identifying individuals on the basis of their unique skin patterning, captured almost 30,000 whale shark encounter reports from 1992 to 2014, with more than 6000 individuals identified from 54 countries. During this time, the number of known whale shark aggregation sites (hotspots) increased from 13 to 20. Examination of photo-identification data at a global scale revealed a skewed sex-ratio bias toward males (overall, more than 66%) and high site fidelity among individuals, with limited movements of sharks between neighboring countries but no records confirming large, ocean basin-scale migrations. Citizen science has been vital in amassing large spatial and temporal data sets to elucidate key aspects of whale shark life history and demographics and will continue to provide substantial long-term value.

https://academic.oup.com/bioscience/advance-article-abstract/doi/10.1093/biosci/bix127/4641655?redirectedFrom=fulltext 
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#20
Whale shark logs longest-recorded trans-Pacific migration

Date: April 26, 2018
Source: Smithsonian Tropical Research Institute
Summary:
A whale shark named Anne swam all the way across the Pacific from Coiba National Park in Panama to the Marianas Trench, setting a record as the longest-recorded migration.

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Whale sharks are filter feeders, eating plankton, fish eggs, krill, crab larvae as well as small squid and fish that enter their large mouths. They cannot digest plastic garbage.
Credit: Kevan Mantell

Little is known about the world's largest living fish, gentle giants reaching 12 meters (40 feet) in length. Researchers from the Smithsonian Tropical Research Institute (STRI) and colleagues tracked a female whale shark from the eastern Pacific to the western Indo-Pacific for 20,142 kilometers (more than 12,000 miles), the longest whale shark migration route ever recorded.

STRI marine biologist Héctor M. Guzmán tagged a female whale shark (Rhincodon typus) near Coiba Island in Panama, the largest island off of the coast of Central America, a National Park, World Heritage Site and marine protected area. His team named the shark Anne for conservationist Anne McEnany, president and CEO of the International Community Foundation (ICF). The multi-year project also tagged 45 additional sharks in Panama with sponsorship from Christy Walton's Candeo Fund at the ICF, along with STRI and Panama's science and technology bureau (SENACYT).

Guzmán estimated Anne's position based on signals from a Smart Position and Temperature (SPOT) tag tethered to the shark, received by the Advanced Research and Global Observation Satellite (ARGOS). The tag only communicates with the satellite when the shark swims near the surface. Anne remained in Panamanian waters for 116 days, then swam toward Clipperton Island (France), nearing Cocos Island (Costa Rica) en route to Darwin Island in the Galapagos (Ecuador), a site known to attract groups of sharks. 266 days after she was tagged, the signal disappeared, indicating that Anne was too deep to track. After 235 days of silence, transmissions began again, south of Hawaii. After a nine-day stay, she continued through the Marshall Islands until she arrived at the Marianas Trench, a canyon in the ocean floor near Guam in the Western Pacific where movie director James Cameron located the deepest point on the Earth's surface almost 11,000 meters (36,000 feet) below sea level.

Whale sharks dive to more than 1900 meters (6000 feet). But it is unknown what the animal was doing in this area.

"We have very little information about why whale sharks migrate," said Guzmán. "Are they searching for food, seeking breeding opportunities or driven by some other impulse?"

"Despite being the world's largest fish, it's amazing to me how little we know about this species," said Scott Eckert, co-author and biology professor at Principia College. "When I first began working on them, their taxonomy was debated, and it still wasn't clear how they reproduced."

Found in warm, tropical and sub-tropical waters, it is thought that about a quarter of whale sharks live primarily in the Atlantic, whereas about three-fourths live in the Indo-Pacific. Tourists are drawn to sites where 500 or more whale sharks gather: in Oman, Australia, Galapagos, Mexico, Mozambique and the Seychelles. Large groups are also reported from Taiwan, Southern China and the Gujarat coast of India.

Genetic studies show that whale sharks across the globe are closely related, indicating that they must travel long distances to mate. Whale sharks have been tracked for shorter distances along similar routes, but this report is the longest-recorded migration to date and the first evidence of a potential trans-Pacific route. Like Anne, other whale sharks appear to follow the North Equatorial Current for most of the distance. Large females can swim an average of 67 kilometers (about 40 miles) per day.

The whale shark is one of only three known filter-feeding sharks, feeding on plankton, fish eggs, krill, crab larvae as well as small squid and fish (and, accidentally, plastic, which they cannot digest). As such, they are not considered to be particularly dangerous, and tourism companies that offer the opportunity to swim very close to whale sharks are common near areas where they aggregate in large numbers. But their size also attracts fishing boats. They are sought after for their fins and meat, for their teeth (used for crafts and sold to tourists) and for cartilage and oil with purported medicinal value. Juvenile whale sharks often end up as bycatch in tuna and other fisheries.

Whale sharks were classified as endangered in 2016. During the past 75 years, it is estimated that nearly half of the world's whale sharks have disappeared. In many parts of the world, whale sharks have legal protection, but regulations are often not enforced. Guzman's data were used to design and draft local and regional policies for the protection of the species. Fishing, capture and sale of whale sharks are prohibited in Panama by Executive Decree No. 9, signed in 2009. In 2014, Panama's environmental authority passed an additional resolution regulating whale shark watching in Coiba National Park and the Isla Canales de Afuera marine reserve. The resolution includes a Whale Shark Watching Manual but unfortunately, tourism activities are not well organized and the authorities are not present to enforce the regulations.

"Whale sharks in Coiba have already changed their behavior to avoid the surface and tourists," Guzman said. "These studies are critical as we design international policy to protect transboundary species like the whale sharks and other highly migratory marine species."

Story Source: Smithsonian Tropical Research Institute. "Whale shark logs longest-recorded trans-Pacific migration." ScienceDaily. www.sciencedaily.com/releases/2018/04/180426180007.htm (accessed April 26, 2018).




Journal Reference:
Hector M. Guzman, Catalina G. Gomez, Alex Hearn, Scott A. Eckert. Longest recorded trans-Pacific migration of a whale shark (Rhincodon typus). Marine Biodiversity Records, 2018; 11 (1) DOI: 10.1186/s41200-018-0143-4

Abstract
Whale sharks (Rinchodon typus) are found in shallow coastal and deep waters of tropical and warm temperate seas. Population genetic studies indicate high connectivity among populations, and an Indo-Pacific meta-population has been suggested with potential migrations among some ocean basins. Here, we present the satellite track of a trans-Pacific migration of a female whale shark, which we tagged at Coiba Island (Panama), and which travelled over 20,000 km from the Tropical Eastern Pacific (Panama) to the western Indo-Pacific (Mariana Trench) in 841 d, primarily via the North Equatorial Current. This finding illustrates the migratory pathway between two ocean basins and potential passageway to reach the Philippine Sea into the South China Sea.
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#21
Madagascar emerges as whale shark hotspot

By Helen Briggs
BBC News
17 May 2018

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Whale sharks are the largest living fish

Large numbers of endangered whale sharks have been sighted in waters off Madagascar.

The first major scientific survey in the area shows there are far more of the huge fish than previously thought.

Eighty-five individuals were identified in a single season from photographs of their distinctive markings.

The coastal waters contain a huge diversity of marine life, including sharks, whales and turtles.

"No one thought there were that many [whale] sharks," said Stella Diamant of the Madagascar Whale Shark Project in Nosy Be, an island off the coast of Madagascar.

"They don't seem to be there all year round - they come back for the food."

Many stars

Whale sharks, which have unique spot patterns, are known locally as marokintana, meaning many stars.

The marine biologists uploaded photographs of the sharks' markings to a global database of sightings known as the Wildbook for Whale Shark.

They found no overlap with data collected from other feeding areas in the Indian Ocean, suggesting the whale sharks - all juveniles - had not migrated from Mozambique or other neighbouring areas.

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Satellite tags attached to the whale sharks to track their movements revealed that half of the tagged sharks visited a second hotspot off southern Madagascar, while five swam over to Mayotte and the Comoros islands.

"It was exciting to see that there is a second hotspot for the sharks in the area," said Diamant, who led the research project.

"Madagascar clearly provides an important seasonal habitat for these young whale sharks, so we need to ensure they are effectively protected in the country."

People travel to see and swim with these gigantic, harmless sharks as part of growing ecotourism industry on the island.

Researchers have drawn up a code of conduct to help protect the whale sharks from human interference.

"These sharks can be a major asset for the country," said co-author Dr Simon Pierce, principal scientist at the Marine Megafauna Foundation. "There's already a good marine ecotourism industry developing," he added.

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Stella Diamant (left) on the research boat

The whale shark, (Rhincodon typus), the world's largest fish, is classed as globally endangered on the RIUCN RedList.

Over the last decade, populations have declined dramatically globally, due to overfishing, accidental catches and boat strikes.

The vast majority of the fish are found in the Indo-Pacific, where numbers have declined by more than 50% over the last 75 years.

A smaller population found in the Atlantic is also in decline.

The research is reported in the journal, Endangered Species Research.

http://www.bbc.com/news/science-environment-44151782




Journal Reference:
Stella Diamant, Christoph A Rohner, Jeremy J Kiszka, et al. ‘Movements and habitat use of satellite-tagged whale sharks off western Madagascar’ is published on 17 May 2018


ABSTRACT: Whale sharks Rhincodon typus, the world’s largest fish, are routinely sighted off the northwest coast of Madagascar, particularly off the island of Nosy Be. Dedicated whale shark tourism has been developing in the area since 2011. During our first dedicated survey, from September to December 2016, we photo-identified 85 individual whale sharks ranging from 3.5 to 8 m in total length (all juveniles). None had been previously identified from surrounding countries. We tagged 8 sharks with tethered SPOT5 tags in October 2016, with tracking durations of 9 to 199 d. Kernel density plots showed that the main activity hotspot for tagged sharks was around the Nosy Be area. Three individuals were resighted back at Nosy Be in late 2017 after having lost their tags. A secondary hotspot was identified off Pointe d’Analalava, 180 km southeast of Nosy Be. Five sharks swam off the shelf into the northeastern Mozambique Channel, between Madagascar and Mayotte, and one of these continued to near the Comoros islands. Two sharks swam to southern Madagascar, with minimum track distances of 3414 and 4275 km. The species is presently unprotected in Madagascar, although a small proportion of the high-use area we identified in this study is encompassed within 2 marine protected areas adjacent to Nosy Be. Whale sharks are globally endangered and valuable to the local economy, so there is a clear rationale to identify and mitigate impacts on the sharks within the 2 hotspots identified here.

http://www.int-res.com/articles/esr2018/36/n036p049.pdf 
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#22
Secret to whale shark hotspots

Date: June 8, 2018
Source: University of York

[Image: 180608103330_1_900x600.jpg]
Gentle giants: Filter-feeding whale sharks do have around 3,000 tiny teeth, but are harmless to humans.
Credit: MWSRP

A study has uncovered the secret to why endangered whale sharks gather on mass at just a handful of locations around the world.

The new insights into the habits of the world's largest fish will help inform conservation efforts for this mysterious species, say the researchers.

Large groups of whale sharks congregate at only around 20 locations off the coasts of countries including Australia, Belize, the Maldives and Mexico. Why the sharks, which can reach more than 60 feet in length, choose these specific locations has long perplexed researchers and conservationists.

The new study, by researchers at the University of York in collaboration with the Maldives Whale Shark Research Programme (MWSRP), has found that the shark "aggregation sites" show many common characteristics -- they are all in areas of warm, shallow water in close proximity to a sharp sea-floor drop off into deep water.

The researchers suggest that these sites provide the ideal setting for the filter-feeding sharks to search for food in both deep water and the warm shallows, where they can bask near the surface and warm up their huge bodies.

Supervising author of the study, Dr Bryce Stewart from the Environment Department at the University of York, said: "Sharks are ectotherms, which means they depend on external sources of body heat. Because they may dive down to feed at depths of more than 1,900 metres, where the water temperature can be as cold as 4 degrees, they need somewhere close by to rest and get their body temperature back up.

"Steep slopes in the sea bed also cause an upwelling of sea currents that stimulate plankton and small crustaceans such as krill that the whale sharks feed on."

However, these perfectly contoured locations are not without their drawbacks due to human activity. Sharks swimming in shallow waters close to the surface are vulnerable to boat strikes caused by vessels ranging from large ships to tourist boats hoping to spot them.

Lead author of the paper Joshua Copping, who carried out the research while studying for a masters in Marine Environmental Management at the University of York, and is now working on a PhD at the University of Salford, said: "Individual whale sharks can be identified by their unique pattern of spots and stripes which allows researchers to follow specific sharks that visit these aggregation sites. That means we have a good idea of the rate and extent of injuries at each of these locations and sadly it's generally quite high."

Boat strikes, along with accidental trapping in fishing nets, and the targeted hunting of the species for their fins and meat, have contributed to an alarming decrease in global whale shark numbers in the past 75 years.

By highlighting what makes these areas important to the whale shark, the researchers hope this study will also highlight the importance of managing these areas carefully in order to minimise human impact on the shark's habitat and behaviour.

Dr Stewart added: "The more we know about the biology of whale sharks the more we can protect them and this research may help us to predict where whale sharks might move to as our climate changes.

"Not only do we have an ethical responsibility to conserve this miraculous animal for future generations, but they are also extremely valuable to local people on the coastlines where they gather, which are often in developing countries. While a whale shark can be worth as much as $250,000 USD dead, alive it can provide more than $2 Million USD over the course of its life span."

Co-author James Hancock from MWSRP added; "Whale sharks can travel huge distances around the globe and the existence of such a small number of known aggregation sites suggested there had to be something about the depth and shape of the underwater terrain in these areas that makes them appealing.

"It's very exciting to have narrowed down some of the key reasons why whale sharks choose these specific areas. However, the main focus of this research was on costal aggregations which are largely made up of young sharks -- exactly where the rest of the demographic hang out is still unclear."

Story Source: University of York. "Secret to whale shark hotspots." ScienceDaily. www.sciencedaily.com/releases/2018/06/180608103330.htm (accessed June 8, 2018).




Journal Reference:
Joshua P. Copping, Bryce D. Stewart, Colin J. McClean, James Hancock, Richard Rees. Does bathymetry drive coastal whale shark (Rhincodon typus) aggregations? PeerJ, 2018; 6: e4904 DOI: 10.7717/peerj.4904

Abstract
Background
The whale shark (Rhincodon typus) is known to aggregate in a number of coastal locations globally, however what causes these aggregations to form where they do is largely unknown. This study examines whether bathymetry is an important driver of coastal aggregation locations for R. typus through bathymetry’s effect on primary productivity and prey availability. This is a global study taking into account all coastal areas within R. typus’ range.
Methods
R. typus aggregation locations were identified through an extensive literature review. Global bathymetric data were compared at R. typus aggregation locations and a large random selection of non-aggregation areas. Generalised linear models were used to assess which bathymetric characteristic had the biggest influence on aggregation presence.
Results
Aggregation sites were significantly shallower than non-aggregation sites and in closer proximity to deep water (the mesopelagic zone) by two orders of magnitude. Slope at aggregation sites was significantly steeper than non-aggregation sites. These three bathymetric variables were shown to have the biggest association with aggregation sites, with up to 88% of deviation explained by the GLMs.
Discussion
The three key bathymetric characteristics similar at the aggregation sites are known to induce upwelling events, increase primary productivity and consequently attract numerous other filter feeding species. The location of aggregation sites in these key areas can be attributed to this increased prey availability, thought to be the main reason R. typus aggregations occur, extensively outlined in the literature. The proximity of aggregations to shallow areas such as reefs could also be an important factor why whale sharks thermoregulate after deep dives to feed. These findings increase our understanding of whale shark behaviour and may help guide the identification and conservation of further aggregation sites.

Full Study: https://peerj.com/articles/4904/ 
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#23
Novel approach studies whale shark ages the best way -- while they are swimming
New study reveals world's largest fish is larger and lives longer than previously thought


Date: July 18, 2018
Source: Nova Southeastern University

[Image: 180718104734_1_900x600.jpg]
This is a whale shark.
Credit: Guy Harvey Ocean Foundation

Already the world's largest shark species, male whale sharks can swim around the ocean for up to 130 years, according to a recently published study by scientists at Nova Southeastern University's (NSU) Guy Harvey Research Institute (GHRI) and collaborators from the Maldives Whale Shark Research Programme.

The research on whale shark aging growth dynamics, published in the Marine and Freshwater Research Journal, was conducted in the Republic of Maldives using a unique approach.

According to Cameron Perry, the first author of the scientific paper, and at the time a graduate student at NSU's GHRI, "What makes this a novel approach is that we took repeated noninvasive underwater measurements of live sharks over the course of a decade.

"Up to now, such aging and growth research has required obtaining vertebrae from dead whale sharks and counting growth rings, analogous to counting tree rings, to determine age. Our work shows that we can obtain age and growth information without relying on dead sharks captured in fisheries. That is a big deal."

According to the research study, "Comparing length-measurement methods and estimating growth parameters of free-swimming whale sharks (Rhincodon typus) near the South Ari Atoll, Maldives," taking repeated measurement of the same sharks over many years was possible because many of these sharks came back to the same place every one to two years, and individuals could be recognized by their unique spot patterns. The researchers then modeled their measurement results and found that:

male whale sharks can live as long as 130 years (that means some whale sharks swimming the world's oceans today were born when Grover Cleveland was President of the United States);
whale sharks may grow as large as 61.7 feet on average, which is longer and bigger than previously believed (nearly 17 feet longer than a school bus.)
"Growth and reproduction of whale sharks, which are endangered in many places, are poorly understood," said Mahmood Shivji, Ph.D., director of NSU's GHRI. "When you couple this lack of knowledge with the fact that whale shark products such as fins, meat and oil are highly valuable -- they are harvested in many countries -- one can quickly see the urgency in learning as much as possible in order to help save these majestic creatures."

Perry agreed.

"The more we learn about these animals, their growth dynamics, where they go, what areas may be their nurseries, it can lead to a better understanding of their life history, which is imperative to guide conservation efforts," he said.

Primarily funded by the Guy Harvey Ocean Foundation, NSU's GHRI works on initiatives and studies to provide the necessary information to better understand, conserve, monitor and effectively manage shark populations.

Story Source: Nova Southeastern University. "Novel approach studies whale shark ages the best way -- while they are swimming: New study reveals world's largest fish is larger and lives longer than previously thought." ScienceDaily. www.sciencedaily.com/releases/2018/07/180718104734.htm (accessed July 19, 2018).




Journal Reference:
Cameron T. Perry, Joana Figueiredo, Jeremy J. Vaudo, James Hancock, Richard Rees, Mahmood Shivji. Comparing length-measurement methods and estimating growth parameters of free-swimming whale sharks (Rhincodon typus) near the South Ari Atoll, Maldives. Marine and Freshwater Research, 2018; DOI: 10.1071/MF17393

Abstract
Whale sharks (Rhincodon typus) are an endangered species whose growth and reproductive biology are poorly understood. Given their conservation concern, estimating growth parameters, as traditionally derived from vertebral samples of dead animals, is challenging. We used a non-invasive approach to investigate growth parameters of whale sharks frequenting the South Ari Atoll, Maldives, by analysing repeat measurements of free-swimming sharks over a 10-year period. Total lengths of the sharks were estimated by three measurement methods. Visual estimates underestimated the sizes of large sharks, whereas laser and tape measurements yielded results that were similar to one another. The Maldives aggregation consisted of primarily male (91%) juvenile (total length = 3.16–8.00 m) sharks and sharks new to the area were significantly smaller than were returning sharks, which suggests that this site may constitute a secondary nursery ground. Estimates of von Bertalanffy (VBG) growth parameters for combined sexes (L∞ = 19.6 m, k = 0.021 year–1) were calculated from 186 encounters with 44 sharks. For males, VBG parameters (L∞ = 18.1 m, k = 0.023 year–1) were calculated from 177 encounters with 40 sharks and correspond to a male age at maturity of ~25 years and longevity of ~130 years. Differences between these estimates and those from other studies underscore the need for regional studies.

http://www.publish.csiro.au/mf/MF17393 
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#24
Satellite tracking reveals Philippine waters are important for endangered whale sharks

Date: July 24, 2018
Source: PeerJ

[Image: 180724110005_1_900x600.jpg]
A tagged juvenile whale shark swims through the waters of Panaon Island, Southern Leyte.
Credit: Gonzalo Araujo

A new scientific study published in PeerJ -- the Journal of Life and Environmental Sciences has tracked juvenile whale sharks across the Philippines emphasising the importance of the archipelago for the species. The study is the most complete tracking study of whale sharks in the country, with satellite tags deployed on different individuals in multiple sites.

The Philippines is an important hotspot for whale sharks and globally hosts the third largest known population of whale sharks. While the species has been protected in the Philippines since 1998, globally the species was uplisted in 2016 to 'endangered to extinction' in the IUCN Red List of Threatened Species due to a population decline of more than 50%, largely caused by continued exploitation in the Indo-Pacific. Particularly in South East Asia, concerns remain due to continued fishing in regional waters; understanding the movements of whale sharks in the Philippines is vital if we are to identify conservation priorities for the species.

By attaching Wildlife Computers SPOT5 satellite tags to whale sharks, researchers from Large Marine Vertebrates Research Institute Philippines (LAMAVE), Marine Megafauna Foundation (MMF) and Tubbataha Management Office (TMO) were able to follow the movements of juvenile whale sharks in near real-time to gain an insight into their behaviour. The tags work by communicating with passing ARGOS satellites, transmitting a location when the wet/dry sensor is triggered when a tagged whale shark breaks the surface. To aid transmission tags were tethered to a whale shark by a 1.8-meter line to ensure the tags broke the surface more frequently.

17 individual whale sharks were tagged in three different locations in the Philippines: Panaon Island (Southern Leyte), northern Mindanao (Misamis Oriental and Surigao del Norte) and Tubbataha Reefs Natural Park (Palawan). Tagging took place between April 2015 and April 2016. All tagged whale sharks were juveniles, ranging in size between 4.5 -- 7 meters and 73% of them were male.

In their paper, peer-reviewed and published in PeerJ -- the Journal of Life & Environmental Sciences, the researchers discovered that the tracks from the tags showed that all whale sharks stayed within the Philippines over the tracking period, emphasising the importance of the archipelago for the species. The longest track observed was from a whale shark originally tagged in Tubbataha Reefs Natural Park, which appeared to swim through the Sulu and Bohol Seas and into the Pacific, a journey accumulating over 2,500 km in length. While whale sharks are not known for their speed, results revealed that one individual whale shark was averaging 47km a day, further emphasising the species' mobile tendencies.

Lead author of the study, Gonzalo Araujo stresses that "this research highlights the high mobility of whale sharks, even juveniles, and the need for broader scale management and conservation plans for this endangered species."

Dedicated research by LAMAVE and citizen science has identified over 600 individuals in the Sulu and Bohol Seas, yet the proximity of this population to fisheries in the broader region (South China Sea) means it is vital to monitor this population as a whole to understand if this population is in recovery or continuing to decline. Identifying threats and mitigation strategies is a conservation priority for the species. LAMAVE continues to study whale sharks in five key areas in the Philippines, working with local and national governments as well as collaborating organisations to develop conservation strategies for this iconic species.

Story Source: PeerJ. "Satellite tracking reveals Philippine waters are important for endangered whale sharks." ScienceDaily. www.sciencedaily.com/releases/2018/07/180724110005.htm (accessed July 26, 2018).




Journal Reference:
Gonzalo Araujo, Christoph A. Rohner, Jessica Labaja, Segundo J. Conales, Sally J. Snow, Ryan Murray, Simon J. Pierce, Alessandro Ponzo. Satellite tracking of juvenile whale sharks in the Sulu and Bohol Seas, Philippines. PeerJ, 2018; 6: e5231 DOI: 10.7717/peerj.5231

Abstract
The whale shark Rhincodon typus was uplisted to ‘Endangered’ in the 2016 IUCN Red List due to >50% population decline, largely caused by continued exploitation in the Indo-Pacific. Though the Philippines protected the whale shark in 1998, concerns remain due to continued take in regional waters. In light of this, understanding the movements of whale sharks in the Philippines, one of the most important hotspots for the species, is vital. We tagged 17 juvenile whale sharks with towed SPOT5 tags from three general areas in the Sulu and Bohol Seas: Panaon Island in Southern Leyte, northern Mindanao, and Tubbataha Reefs Natural Park (TRNP). The sharks all remained in Philippine waters for the duration of tracking (6–126 days, mean 64). Individuals travelled 86–2,580 km (mean 887 km) at a mean horizontal speed of 15.5 ± 13.0 SD km day−1. Whale sharks tagged in Panaon Island and Mindanao remained close to shore but still spent significant time off the shelf (>200 m). Sharks tagged at TRNP spent most of their time offshore in the Sulu Sea. Three of twelve whale sharks tagged in the Bohol Sea moved through to the Sulu Sea, whilst two others moved east through the Surigao Strait to the eastern coast of Leyte. One individual tagged at TRNP moved to northern Palawan, and subsequently to the eastern coast of Mindanao in the Pacific Ocean. Based on inferred relationships with temperature histograms, whale sharks performed most deep dives (>200 m) during the night, in contrast to results from whale sharks elsewhere. While all sharks stayed in national waters, our results highlight the high mobility of juvenile whale sharks and demonstrate their connectivity across the Sulu and Bohol Seas, highlighting the importance of the area for this endangered species.

Full Study: https://peerj.com/articles/5231/
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#25
'Biological passport' to monitor Earth's largest fish

Whale sharks, the world's largest fish, roam less than previously thought

Date:  August 9, 2018
Source:  University of Southampton

[Image: 180809093435_1_900x600.jpg]
This is a whale shark in Mafia Island, Tanzania.
Credit: Copyright Clare Prebble, Marine Megafauna Foundation and University of Southampton

Whale sharks, the world's largest fish, roam less than previously thought. Local and regional actions are vital for the conservation of this globally endangered species moving forward, according to a new study by researchers from the Marine Megafauna Foundation, University of Southampton, and Sharkwatch Arabia. Their findings are published today in the journal Marine Ecology Progress Series.
Previously, genetic research indicated that whale sharks mixed within distinct populations in the Indo-Pacific and Atlantic Ocean, respectively. This new study used stable isotope analysis, a biochemical technique, to demonstrate that whale sharks feeding at three disparate sites in the Western Indian Ocean (Mozambique and Tanzania) and the Arabian Gulf (Qatar) rarely swim more than a few hundred kilometres north or south from these areas.
"Whale sharks are amazing swimmers, often moving over 10000 km each year, and they can dive to around 2000 meters in depth. Biochemical studies tell us more about where they go and what they do when they're out of our sight," said Dr Clare Prebble, who led the research as part of her PhD project at the University of Southampton.
The researchers used isotopes of nitrogen and carbon that have similar chemical properties, but vary in their atomic mass. Ratios between the heavier and lighter isotopes of these elements vary naturally across different habitats in the marine environment. For example, more of the heavier isotopes are found in near-shore environments than offshore. These ratios stay consistent as they are passed up through the food web, from tiny marine plants to top predators, and therefore provide a record of the animal's feeding and movement behaviours. Stable isotope analysis thereby provides a 'biological passport' for whale sharks.
Electronic tags are commonly used with marine animals to record their movements and diving behaviours. However, the challenge of keeping them attached to a large shark, while minimizing disturbance, has meant that only short-term deployments (weeks to months) have been possible. This study used tiny samples of skin tissue from wild, free-swimming whale sharks. These small pieces of skin, collected over 2-3 years at each location, were sufficient to reconstruct the sharks' movements and feeding preferences over the weeks and months prior to sampling.
Values of both carbon and nitrogen stable isotopes differentiated at each site. To complement the biochemical analysis, the researchers also took photographs of the natural markings on each whale shark to identify and track individuals over a 10-year timeframe. Every whale shark has a unique spot pattern, similar to a human fingerprint. The team recorded 4197 encounters with 1240 individual whale sharks within these three countries.
Only two sharks moved between sites, both swimming around 2000 km north from Mozambique to Tanzania. Taken together, these findings indicate that there are limited movements between these major aggregation sites over months to years. These results have implications for the conservation of this endangered species.
"The best data available suggests that more than half of the world's whale sharks have been killed since the 1980s. Although the Western Indian Ocean remains a global hotspot for the species, even the largest feeding areas only host a few hundred sharks. Our results show that we need to treat each site separately, and ensure good conservation management is in place, as the sharks may not re-populate if they're impacted by people's activities," Prebble added.
The study stresses the need to protect these filter-feeding sharks at the areas where they come together in numbers, particularly where human pressures are also present. Whale sharks are an incidental catch in coastal gillnets, which are frequently used in Mozambique and Tanzania. The Arabian Gulf is a huge oil shipping area where vessel strikes pose a major threat to the sharks when they are feeding near the surface.
"Whale sharks are fully capable of swimming across oceans, but it seems like the juveniles, at least, are choosing not to," commented Dr Simon Pierce, Principal Scientist at the Marine Megafauna Foundation and a co-author on this study. "They like coming back to the same sites each year to take advantage of predictable feeding opportunities. Looking on the bright side, that emphasises that local protection can have a major benefit for the recovery of this endangered species. The rewards can also be felt locally, with whale shark tourism now worth over $100 million each year around the world."
Earlier this year, colleagues reported that whale sharks regularly visit Madagascar to feed, which has led to a growing ecotourism industry between the months of September and December. To date, none of the sharks identified in Madagascar have been seen outside that country, further reinforcing the results from this new study.
Dr Clive Trueman from the University of Southampton concluded: "Interestingly, most sharks found at these feeding sites are juvenile males of less than nine meters. To truly assess how populations are globally structured and distributed, we need to learn more about where the sharks go once they reach adulthood. They may well move out of our sight to feed and breed in deeper offshore waters."


Story Source:
University of Southampton. "'Biological passport' to monitor Earth's largest fish: Whale sharks, the world's largest fish, roam less than previously thought." ScienceDaily. www.sciencedaily.com/releases/2018/08/180809093435.htm (accessed August 9, 2018).


Journal Reference:
  1. CEM Prebble, CA Rohner, SJ Pierce, DP Robinson, MY Jaidah, SS Bach, CN Trueman. Limited latitudinal ranging of juvenile whale sharks in the Western Indian Ocean suggests the existence of regional management units. Marine Ecology Progress Series, 2018; 601: 167 DOI: 10.3354/meps12667
ABSTRACT: 
Assessing the movements and connectivity of whale sharks Rhincodon typus through their range is difficult due to high individual mobility and limited knowledge of their behaviour following dispersal from coastal aggregation sites. Here, we use a large set of photo-identification and stable isotope data (δ15N and δ13C) to test the assumption that sharks frequenting aggregation sites in Mozambique, Tanzania, and Qatar are a mixed stock, as inferred by genetic data. Photo-identification revealed negligible connectivity among aggregation sites and none between the southern and central areas of the Western Indian Ocean (Mozambique and Tanzania) and the Arabian Gulf (Qatar). Sight-resight data indicated that shark movements at each site could be best represented by a model that included emigration, re-immigration, and some mortality or permanent emigration. Although there was high individual variation in the isotope profiles of sharks from each location, comparison with latitudinal isotope data suggests that sharks had shown site fidelity to within a few hundred kilometres of each study area over the period of isotopic integration. Given the Endangered status of whale sharks and regional differences in anthropogenic threat profiles, further studies—and conservation assessment efforts—should consider the possibility that whale shark subpopulations exist over smaller geographical scales than previously documented.

https://www.int-res.com/abstracts/meps/v601/p167-183/
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