Whale sharks show an impressive ability to recover from injuries

A new study has revealed for the first time the rate at which the world’s largest fish, the endangered whale shark, can recover from its injuries The results revealed that lacerations and wounds, which increasingly occur through boat collisions, can heal within weeks, and researchers have found evidence On the regrowth of the partially removed dorsal fins.

This work was published in the journal Conservation Physiology, Comes at a critical time for large sharks, which can reach lengths of up to 18 meters. Other recent studies have shown that as its popularity increases in the wildlife tourism sector, so has interactions with humans and boat traffic. As a result, these sharks face an additional source of injury in addition to natural threats, and some of these gigantic creatures in the ocean show scars from boat collision. So far, very little is known about the impact of such injuries and how they can be recovered.

“These key findings provide us with an initial understanding of wound healing in this species,” says lead author Freya Womersley, a PhD student at the University of Southampton and based in the UK Marine Biology Society. “We wanted to determine if there was a way to determine what many researchers were witnessing through the anecdotal stories in this field, and therefore we came up with a technique to monitor and analyze injuries over time.”

Unique whale shark placemarks allow researchers around the world to identify individuals and monitor regional populations, using websites such as WildBook where people can upload pictures of their shark sightings. In this study, the research team examined images taken by citizen scientists, researchers, and the whale shark tourism industry at two locations in the Indian Ocean where sharks frequently congregate, and used these markers to standardize the images. This method allowed the team to compare images taken without specialized equipment over time and increase the amount of data available to evaluate and monitor how individual wounds have changed.

“Using our new method, we were able to determine that these sharks can heal from very serious injuries in time frames of weeks and months,” Freya says. “This means we now have a better understanding of injury and healing dynamics, which can be very important to conservation management.”

The study also highlighted the ability of whale sharks to regrow a partially amputated first dorsal fin, which, according to the authors’ knowledge, is the first time that this phenomenon has been scientifically reported on a shark. Also of interest, its unique spot markings have also been observed forming over previously infected spots, indicating that these fine markings are an important feature of this species and persist even after being damaged.

These healing abilities indicate that whale sharks may be resistant to impacts induced by humans, but the authors of this work indicate that there may be many other unrecognizable effects of injuries to these animals, such as decreased fitness and the ability to search for Food and behavior change so injuries must be prevented wherever possible. They also found variation in healing rates, with lacerations, typical of fan injuries, taking longer to heal than other types of wounds, highlighting the need for more research to determine the effect of environmental factors and more subtle individual factors on injury healing.

Careful management of whale shark population sites, which occur seasonally in a number of coastal areas around the world, is essential to ensuring that sharks are protected while spending time in areas of high human activity. If sharks experience injuries at these sites, such research can help local teams estimate the age of the injury and make assessments about where and how it occurred based on knowledge of whale shark movements and propensity to revert to the same locations.

Recent research has been published in Temperate nature It found that 71% of pelagic sharks have declined in the past 50 years, and highlighted the need for tighter protection for this important group of ocean dwellers.

Freya concludes, “Whale sharks are experiencing a decline in population globally due to a variety of threats as a result of human activity. Therefore, it is imperative to minimize the human impacts on whale sharks and protect the species that are most vulnerable, especially when they are Interactions between human and shark are high

“There is still a long way to go in understanding healing in whale sharks, and in shark species in general, but our team hopes that fundamental studies such as this one provide a crucial guide for management decision makers that can be used to protect the future from whale sharks.”


Notes to Editors

More data on wound recovery: The results of this study show that by the 25th day, the surface area of ​​the primary injury decreased by an average of 56% and the fastest healing cases showed a reduction in surface area of ​​50% in 4 days. All wounds reached a 90% area closure point by day 35. There were differences in the rate of healing based on wound type, with lacerations and wounds taking 50 and 22 days to reach 90% to heal, respectively.

Pictures can be downloaded here. Credit as per filename.

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