Surprising Sharks and Shipwrecks Saving Seas

In the popular and now iconic 1975 movie Jaws, directed by Steven Spielberg, a great white shark attacks swimmers during one summer in the fictional beach town of Amity Island, New York. Because of the film, many people came to fear great whites—with good reason. Great whites are arguably the largest predatory sharks in the world, with the most fatal attacks on humans. Such dangerous and formidable animals can be tough to imagine as small newborns. That’s particularly difficult with great white sharks because no one has ever seen a very young one in the wild—that is, until now.

But there’s even more surprising shark news. While about 99.9% of fish and shark species are cold-blooded, it’s just been discovered that basking sharks are a one-in-a-thousand exception.

The underwater environment is also making conservation news. Scientists have recently discovered that 50,000 shipwrecks around coastlines in the United Kingdom are protecting the seabed and species that live near the wrecks in areas still open to bottom-trawling. And California is showing us that Marine Protected Areas (MPAs)—and the ecotourists who go to experience them—truly do promote species diversity and protect habitats. That’s good news as we and the rest of the world try to reach 30 x 30 targets.

Shark sighting: great white being born

Known online as “themalibuartist,” wildlife filmmaker Carlos Gauna has spent thousands of hours filming sharks around the world. His videos of them swimming close to beachgoers have millions of views. But on July 9, 2023, near Santa Barbara on California’s Central Coast, he and University of California, Riverside, biology doctoral student Phillip Sternes captured something on his drone camera that thrilled even him. It looked like a shark pup but was unlike anything he’d ever seen before.

Great white sharks, called “white sharks” by scientists, are gray on top and white on the bottom. But the approximately five-foot-long shark Gauna spotted was pure white. After enlarging his images and watching them in slow motion, he realized the white layer was being shed from the body as it was swimming. Gauna interpreted it as a newborn white shark shedding its embryonic layer.

Gauna’s and Sternes’ observations were documented in a paper published in the science journal Environmental Biology of Fishes on January 29, 2024. Having seen a live newborn white shark is significant: it could help solve the longstanding mystery of great white birthing habits. No one has ever been able to pinpoint where they are born; nor has anyone before seen a newborn great white shark alive.

Though the paper’s authors acknowledge it is possible that the white film the shark shed could have been caused by a skin condition, the duo do not believe this to be the case. And even if it was, that, too, would be monumental because no such condition has ever been reported for these sharks.

For many reasons, though, Gauna and Sternes believe what they saw was, in fact, a newborn great white. First, great white females give birth to live pups. While in utero, the embryonic sharks feed on unfertilized eggs for protein. The mothers offer additional nourishment to the growing shark pups with a “milk” secreted in the uterus. Sternes stated that he thinks what they saw was the baby shedding the intrauterine milk. A second reason is the presence of large, likely-pregnant great whites in that location. Gauna had observed them there in previous years and in the weeks leading up to the observation. On that day, one of the sharks dove down; and not long afterwards, the small white shark appeared. Thirdly, the shark’s size and shape are indicative of a newborn. The animal was rounded, short and thin, denoting it was only hours old or one day old at most.

Many scholars believe that great whites are born far out at sea. That this pup was filmed so close to shore—roughly 1,000 feet from the beach—is highly significant because its age means it was likely born in shallow waters.

The International Union for Conservation of Nature (IUCN) lists the great white shark as vulnerable with a decreasing population trend. While further research is needed to confirm whether these waters near Santa Barbara, California, are a great white breeding ground, lawmakers should be encouraged to start preparations to protect them in order to ensure that white sharks continue to thrive.

Shark shock: basking shark is warm-blooded

Approximately 99.9% of fish and shark species are cold-blooded, meaning that their body tissues generally match the temperature of the water they swim in. However, researchers have just discovered that the basking shark is an extremely rare exception. Instead, these sharks keep the core regions of their bodies warmer than the water, as do the most athletic swimmers in the sea, such as great white sharks, mako sharks and tuna.

The latter examples are called “regional endotherms” and are all fast swimming, apex predators at the top of the food chain. Scientists have long reasoned that their ability to keep warm helped with their athletic, predatory lifestyle, and that evolution had shaped their physiology to match their requirements.

However, now an international team of researchers, led by those from Trinity College Dublin, has shown that gentle, plankton-feeding basking sharks are also regional endotherms despite having very different lifestyles than white sharks and tuna. The researchers note that it’s much like suddenly finding that cows have wings.

To make the discovery—the results of which were published in the international journal Endangered Species Research on July 20, 2023—the team first undertook dissections of dead basking sharks that washed up on shores in Ireland and the United Kingdom. They found that the sharks have cruise-swimming muscles located deep inside their bodies as seen in white sharks and tuna; whereas in most fish, this “red” muscle is found toward the outside of the animals. They also learned that instead of “spongy” hearts, basking sharks have strong, muscular hearts (typical of regional endotherm species) that probably help generate high blood pressures and flows.

Next, the team designed a new, low-impact tagging method to record the body temperatures of free-swimming basking sharks off the coast of County Cork, Ireland. Researchers were able get within 26 feet of the basking sharks to safely deploy the tags just under their skins. The tags recorded muscle temperatures for up to 12 hours before they automatically detached from the animals and were collected by the scientists. These tags revealed that basking shark muscles are consistently elevated above water temperatures and to almost exactly the same extent as their regional endotherm, predatory cousins.

This surprising discovery has implications for conservation, as well as raises a multitude of ecological and evolutionary questions. Endangered basking sharks, the second biggest fish in the world, gained legal protection in Irish waters just last year, with the species having undergone significant population declines throughout the northeastern Atlantic in the last century. However, they still face many challenges: regional endotherms are thought to use more energy, so they may respond differently to current ocean warming than other fish species. More work will be needed to decipher how these new findings regarding basking sharks might change previous assumptions about their metabolism or potential distribution shifts during this climate crisis, a focus for marine biologists as our planet and its seas continue to warm.

Shipwreck sanctuary: marine life finds refuge

Around the United Kingdom’s coastline, an estimated 50,000 shipwrecks can be found, some having been on the seabed for more than a century. They serve as a deterrent to fishers who use bottom-trawling to secure their catches. As a result, while many areas under heavy fishing pressure have been damaged significantly, the seabed in and around shipwrecks remains largely unblemished—and acts as a hidden refuge for corals, fish and other marine species. These are the findings of a new study that was published in the journal Marine Ecology and conducted by scientists from England’s University of Plymouth and the Blue Marine Foundation.

The researchers conducted their study—the first to demonstrate the increased ecological importance of shipwrecks in areas of heavy fishing pressure—around five shipwrecks off the Berwickshire, Scotland, coast that are thought to have sunk in the late 19th and early 20th centuries. They gathered video footage of the shipwrecks, the surrounding 165-foot radius and control locations almost 500 feet from the wreck sites. They discovered that the average density of marine life in areas still open to trawling was 240% greater within wreck sites than in sites actively being used for bottom-trawling. In parts of the seabed within a 165-foot radius of the wrecks, the difference was even greater with the density of marine life 340% greater than in the control sites. Conversely, in sites closed to trawling, the abundance was 149% greater than on wrecks and 85% greater than on the seabed within a 165-foot radius of the wrecks.

The researchers conclude that their study demonstrates the importance of factoring shipwreck sites into future conservation plans, along with the benefits of Marine Protected Areas. While the United Kingdom has made significant strides in protecting the marine environment, they state, there is still much to be done to reach the goal of having 30% of ocean waters protected by 2030. If the world is to get close to that, detailed evidence about what makes our oceans so special and about any existing initiatives that are working well will be essential. This study builds on previous work in that regard and highlights a past human activity that is truly having a positive impact on the seabed today.

Scuba spillover: benefits of MPAs for ecotourism

As the world works to make good on its 30 x 30 commitments, University of California, Santa Barbara, researchers at the Marine Science Institute are looking at the impact of Marine Protected Areas on the recreational scuba diving industry in California’s Northern Channel Islands. This study’s focus on the sport—an important sector of the Southern California marine ecotourism industry—is unique. Ecotourism is among the largest sectors in the ocean economy, constituting about 50% of all global tourism, equal to $4.6 trillion, according to the study’s authors. Yet it is an understudied benefit of MPAs.

To conduct their study, the Marine Science Institute researchers analyzed patterns from millions of Automatic Identification Systems (AIS)—onboard vessel broadcast systems that share high-resolution vessel locations and behavioral information—and data from for-hire scuba diving vessels. They then identified vessel behaviors linked to nonextractive ecotourism activities (such as underwater wildlife-viewing or photography) versus recreational lobster fishing, and compared the location of these activities within MPAs, on MPA borders or outside of MPAs.

They found that from 2016 to 2022, dive vessels engaged in ecotourism prefer MPAs and that dive vessels primarily conducting recreational lobster fishing prefer MPA border zones. Specifically, a high proportion of the most popular ecotourism dive sites (38%) were located in MPAs, a large proportion of the total number of unique ecotourism dive events (45%) were conducted within MPAs, and vessels engaged in ecotourism diving exhibited a high selection of MPAs.

Meanwhile, scuba diving vessel behavior in the lobster scenario, in which vessels were largely engaged in recreational lobster fishing, showed quite different patterns. The majority of the lobster fishing dive events (78%) occurred outside of the MPAs, but these dive vessels exhibited preferential selection for the buffer zones around the MPAs.

Of owner/operator survey respondents, 83% said they noticed that hunting (lobster fishing or spearfishing) was better near an MPA due to the so-called “spillover effect,” where species are so abundant and productive in an MPA that they spill over into surrounding areas. That effect is partly what attracts divers to these MPAs.

The biggest draws, however, were giant sea bass, playful sea lions and underwater cathedrals of undulating kelp forests. The dive captains stated that the MPAs of the Northern Channel Islands—Anacapa, San Miguel, Santa Cruz and Santa Rosa—enabled more of these experiences for their clientele.

Past considerations about the establishment of new MPAs or changes to existing MPA management have tended to focus on engagement with fishers (large- and small-scale) and evaluations of how this management tool affects fishing. But ocean tourism is a fast-growing sector in the blue economic portfolios of large and small coastal communities. It’s important to understand, say the researchers, that Marine Protected Areas not only act as a critical resource to fishers but also to those that place significant value in experiencing and exploring the “Galapagos of North America” with masks and fins. And as most of these MPAs are around only 20 years old, the benefits they bring will only increase as these protected areas mature.

Shark scientists: new generations

In a 2022 interview, Academy Award-winning filmmaker Steven Spielberg said he “truly regrets” how the bloodthirsty portrayal of great white sharks in his film Jaws contributed to a sharp decline in the animals’ populations. In the years following the film’s release, thousands began to hunt sharks for sport, and the number of large sharks in the waters east of North America declined by about 50%. According to the IUCN, more than one-third of all shark species and about 75% of oceanic shark species are faced with the threat of extinction.

Luckily, however, the fear of sharks that the movie Jaws initially inspired was soon replaced by fascination, which continues to this day. It inspired a generation of shark scientists, and we now know that there are many more kinds of sharks than we were aware of in 1974.

We’ve also learned that sharks are more interesting than we ever imagined, shipwrecks can find new life as sanctuaries and scuba divers can help us save the planet’s seas.

Here’s to finding your true places and natural habitats,

Candy