The largest living fish, whale sharks, may increasingly be using volcanic islands off the western coast of Europe as a new home as sea surface temperatures rise, researchers say. 
 
 This finding could shed light on how climate change might alter the behavior of fish globally, the scientists added. 
 
 The whale shark is a titan, known to reach up to 41.5 feet (12.65 meters) in length and 47,000 lbs. (21,500 kilograms) in weight, and some anecdotes suggest they can get even larger. Unlike predators such as great white sharks, whale sharks are gentle giants, using rows of their tiny teeth as a filter to strain out tiny creatures in the water for meals, just like the largest whales do. 
 
 "Whale sharks are the largest living fish, yet they are also very elusive," said lead study author Pedro Afonso, a marine and fisheries ecologist at the University of the Azores. 
 
 Whale sharks prefer warm tropical waters that are 79 to 86 degrees Fahrenheit (26.5 to 30 degrees Celsius). However, in recent years, fishermen have increasingly sighted these giant fish around the Azores Islands, nine volcanic isles in the central North Atlantic west of Portugal. These islands lie along the colder northern edge of the waters that whale sharks historically have preferred. [Image Gallery: Mysterious Lives of Whale Sharks] 
 
 To better understand why these gargantuan fish appear more often around the Azores, the scientists analyzed data on whale shark sightings gathered over 16 years, from 1998 to 2013, by observers on tuna fishing boats. Fishermen in the Azores have long detected tuna by looking for whale sharks, locally known as 'pintados' — Portuguese for "spotted," referring to the sharks' spotted skin. 
 
 "They know that a whale shark will almost always carry a school of tuna underneath it," Afonso told Live Science. (It remains a mystery as to why tuna accompany whale sharks, he added.) 
 
 Afonso noted "there was no way we would get to know anything about whale shark occurrences" without observers on these tuna fishing boats. The area in which the whale sharks are seen around the Azores "is 1 million square kilometers [386,000 square miles], easy," Afonso said. 
 
 The researchers used computer models to investigate the patterns of whale shark sightings over time and space, in relation to factors such as food, sea surface temperatures and seafloor features. The scientists found a sharp rise in whale shark sightings in the exceptionally warm year of 2008, and the giant fish became regular visitors to the region afterward. 
 
 The scientists also found that sea surface temperatures helped predict whale shark sightings. For example, higher water temperatures around the southernmost Azores Island of Santa Maria were associated with more sightings of the fish. Observers also spotted the sharks more often in areas with underwater hills and mountains; these seafloor features coincide with large amounts of photosynthetic organisms that feed the creatures that the whale sharks eat. 
 
 These findings are a window into what might happen as climate changes globally, the scientists said. "Large marine animals such as the whale shark can change their oceanic distributions depending on regional conditions," Afonso said. 
 
 Future research could investigate why whale sharks remain in this area during the summer. "Is it only the food around the seamounts, or something else — maybe the presence of other whale sharks to mate with?" Afonso said. 
 
 Afonso and his colleagues Niall McGinty and Miguel Machete detailed their findings online today (July 16) in the journal PLOS ONE. 
 
 Follow us @livescience, Facebook & Google+. Original article on Live Science. ||||| The reef manta ray, shown here, is among the world's largest fishes. Both it and the giant manta ray can grow several feet across. They are slow growing, however, typically giving birth to only one pup every two to three years. They are migratory and occur in small, highly fragmented populations that are sparsely distributed across the world’s tropics. Manta rays are captured in targeted fisheries and incidentally as bycatch. In addition, manta rays are used for human consumption, shark bait, and -- as for devil rays -- are increasingly sought for their gill rakers. "The international trade in shark and ray products, including fins, meat, and other body parts, is driving shark and ray fisheries around the world, and most of these are unmanaged or only minimally managed," said Dr. John Robinson, WCS's executive vice president for Conservation and Science. "Lack of controls on fisheries and international trade puts species at risk, but also jeopardizes sustainable fisheries, ecosystems, and food security." The Convention on International Trade in Endangered Species of Wild Fauna and Flora will meet in Thailand in March 2013. PHOTOS:Shark Teeth Weapons Reveal Surprises 
 
 Many rays, such as these, are also in peril. The Wildlife Conservation Society and over 35 government agencies and NGO partners at the congress additionally highlighted population loss problems associated with so-called "devil rays," which feed on planktonic crustaceans. Small schooling fishes become trapped on their specialized gill rakers. Rays are frequently captured in target fisheries and as bycatch across much of their range. One reason is that the gill rakers are dried and exported for the Asian medicinal market. 
 
 Scalloped hammerhead sharks are endangered all around the globe. This tropical species forms large migratory schools at certain times of the year. The aggregating behavior, distinct from that of other sharks, makes the shark particularly vulnerable to fishing. "We estimate that many millions of sharks are killed annually through both legal and illegal, unregulated and unreported fishing for the trade in fins, the prime ingredient in shark fin soup," said Dr. Rachel Graham, director of WCS's Gulf and Caribbean Sharks and Rays Program. "The high price for fins has caused the global shark fishery to expand far beyond what is sustainable. The need for international regulation and enforcement has never been greater." Shark Paradise Found 
 
 The oceanic whitetip shark is critically endangered in the Northwest and Central Atlantic Ocean. It's frequently sought after for its fins, used to make shark fin soup. Usually the rest of the dead or dying shark is then tossed back into the sea. Andrew Brierley, a University of St. Andrews marine ecologist, told Discovery News that when sharks like this die off, the deaths can cause a domino effect of other ecosystem losses. Shellfish, for example, may go into decline because they are consumed more by predators that the sharks would normally prey upon. "The trophic cascade brought about by the increasing demand for shark fin soup has not only left once economically valuable bivalve fisheries in crisis, but has precipitated an ecological and culinary bankruptcy," explained Brierley. 
 
 -- Five rays and sharks are receiving priority attention at this week's IUCN World Conservation Congress held in Jeju, Republic of Korea. The congress is the world's largest conservation event. One of the five sharks is the porbeagle, shown here. Porbeagles are vulnerable globally, and are classified as critically endangered in the Northeast Atlantic. Their low reproductive capacity combined with over-fishing has led to severe population declines over several parts of its range. "Sharks and rays have traveled the Earth for more than 400 million years," said Dr. Cristián Samper, president and CEO of the Wildlife Conservation Society and keynote speaker at the Jeju congress. "Yet, in only recent decades, many of these species have become threatened from overfishing and, in some instances, have disappeared entirely from major portions of their range." He added, "The potential loss of one of only two groups of the world's living fishes is a crisis the world community must take decisive action to address. We are calling for governments around the world to vigorously support CITES international trade regulations and strengthen fisheries management and protection measures for shark and ray species. We cannot continue to allow the destruction of these wonders of evolution." Manta Rays Fate Worse Than Sharks 
 
 Whale sharks are flocking to waters off of the Azore islands, a Portuguese archipelago in the North Atlantic Ocean, a new study has found. 
 
 Whale sharks tend to enjoy warmer temperatures, but even this species has been affected by climate change, according to the study, which is published in the latest issue of the journal PLoS ONE. 
 
 It appears to be a Goldilocks effect where the sharks prefer temperatures that aren’t too hot or too cold. Things must be just right — at least for the momen t– in the Azores, which is becoming whale shark central. 
 
 5 Sharks, Rays Needing Urgent Protection: Photos 
 
 Pedro Afonso of the University of the Azores and his colleagues wrote that the “occurrence of the whale shark in the wider Azores region increased drastically in 2008. Prior to this, and for a full decade, these large animals had only been sighted sporadically,” but the sharks keep coming. 
 
 Whale sharks, the world’s largest sharks, are slow-moving filter feeders known for their large mouths. They usually inhabit tropical and warm-temperate seas, preferring temperatures from 78.8 degrees Fahrenheit to 86 degrees. 
 
 In Portugal, the authors note that “whale sharks — local name ‘pintados’ — are known by Azorean fishermen to sometimes occur during the summer and associate with tuna, and have been used for a long time as an aid to locating and fishing the tuna schools.” 
 
 But the sharks have been coming even more often than that, to the point that "whale shark watching" tourism has become a growing business in the region. 
 
 The researchers analyzed a 16-year (1998-2013) observer data set from tuna fishermen around the region. They also used models to investigate the movement of the sharks in relation to factors such as food, sea surface temperature and seafloor features. 
 
 Photos: Shark Paradise Found 
 
 Since 2008, whale shark presence around the Azores has been steadily increasing, which appears to coincide with water temperature changes. 
 
 Usually the Azores fall into the colder side of the sharks’ preferred range, but water temperature rises at this location are proving to be a draw for sharks. Conversely, temperatures that are too hot or too cold in other spots are becoming less desirable for them. 
 
 The temperature increase in the Azores correlated with larger amounts of chlorophyll — a, a type of whale shark food. 
 
 The researchers also found that whale shark populations are higher in areas of increased seafloor slope and closer to seamounts. That’s because these regions tend to be richer in chlorophyll-a. 
 
 “Our findings underline the potential for an increase of the wider Azores region’s importance as an oceanic habitat for the whale shark in the North Atlantic in years of exceptionally high water temperature, and for a concomitant shift in the whale shark distribution within the Atlantic Ocean, as predicted by global modeling studies,” Afonso and his team concluded. 
 
 “In the future, such shifts need to be placed in the context of decadal and very long-term changes in this ocean.” 
 
 Photo: A whale shark. Credit: ThinkStock
– Those hoping to avoid the world's biggest sharks would do well to stay away from Portugal's Azore Islands. That's where whale sharks—the biggest fish in the sea—are making a new home, likely due to climate change, a study finds. The creatures have a very specific set of temperatures they can tolerate, ranging from 78.8 degrees to 86 degrees Fahrenheit, Discovery notes. The Azores are currently fulfilling the needs of the animals, which, LiveScience notes, can be up to 41.5 feet long and weigh a whopping 47,000 pounds. The temperatures around the Azores, off western Europe, appear to be linked to higher amounts of a favorite whale shark food: chlorophyll-a. Researchers in the area came to their shark population conclusions by assessing 16 years of data from tuna fishermen who've spotted the animals. Indeed, so many sharks have headed there that the region, previously in the northernmost part of the sharks' territory, is experiencing a boom in tourists' "whale shark watching." These tourists, it seems, needn't fear: Whale sharks are by no means ferocious, LiveScience points out. Great whites are a little scarier.