‘Broken Jaw’ Mystery: Research Helps Save Humpback Dolphin

Marine biologist Shanan Atkins, who leads a project to study the endangered humpback dolphin at Richards Bay, shared information about research into how the rostra (jaw) of the endangered humpback dolphin in the Indian Ocean can be damaged and broken.

Habitat degradation, pollution, predators, ship propellers, shark nets, climate change, disease and many other issues make their lives constantly threatened.

Found humpback dolphins with damaged jaws

At the same time, some of these dolphins appear to have an exceptional ability to cope with the disability of a mutilated or severely damaged podium.

Working with colleagues from the SouSA consortium, a group that studies Indian Ocean humpback dolphins. (Sousa Plumbea) along the coastline of South Africa – for years they have photographed and documented such injuries.

“The characteristic ascent pattern of humpback dolphins provides many opportunities to observe their growth,” Atkins was quoted as saying in Zulu Watcher.

“Usually, the rostrum comes first, then the head, a quick breath, then arching the back, exposing the dorsal fin, and it disappears under the water, leaving only two expanding circular ripples as the only sign that it was there.”

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Researchers Collaborate on Coastal Research

The researchers were puzzled when they noticed anomalies in the dolphin’s snout, and the investigation revealed that colleagues in other study areas along the coast had documented similar sightings.

They decided to work together to describe the phenomenon, find out its extent, and study information about the survival of individuals.

“Ten researchers from seven institutions collaborated to collect and share photographs of dolphins taken in seven areas: False Bay, Gunsbay, Struisbay, St. Sebastian’s Bay, Mossel Bay, Plettenberg Bay and Richards Bay,” Atkins said.

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Jaw anomalies pose ‘serious consequences’ for dolphins

“They found that 11% of those surveyed had signs of an abnormal face.

“In total, 19 out of 31 people had visibly broken jaw bones, nine had abnormal shapes (such as crooked or damaged jaws), two had minor injuries, and one had a line problem.

“Some of these anomalies would likely have serious implications for dolphins, which need intact jaws/rosters to catch the fish they eat,” Atkins explained.

“In addition, the jaws are important for echolocation – for transmitting sound and receiving echoes. Therefore, damaged rostra potentially make it difficult for the dolphin to perceive its environment and to find and catch fish.

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Unexpected Finds and the White Tip Case

“We were surprised to find that many of the dolphins documented in the study survived despite these sometimes severe abnormalities,” Atkins said.

“Four people were followed for ten years with injuries and one more for seven years, with the most detailed data coming from Richards Bay.

“Since the beginning of our project in 1998, we have regularly seen White Tip with her calf Junior. By April 1999, Junior was independent and White Tip had a child, Spike.

“In October 1999, we noticed that something was wrong with the White Top podium, but it was not until February 2000 that we were able to photographically confirm that her upper jaw was severely fractured.

humpback dolphins rosta rostrum broken jaws
A badly damaged stand of a dolphin from Richards Bay named White Top. Photo: Brett Atkins/Zululand Observer

“We continued to see her and Spike frequently until July 2001, when they disappeared for almost a year. Imagine how happy we were to see her in June 2002 with a new calf!

“Unfortunately, we didn’t see them again until November 2002, when they were both deadly entangled in shark nets.

“This female not only survived the disability, but even bred—successfully raised a calf and gave birth to three more years after the injury,” Atkins said.

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Possible Causes of the Broken Jaw Phenomenon in Humpback Dolphins

The reason for these abnormalities in humpback dolphins is unclear, but possible causes include long and thin jaw shapes (cranial morphology), hunting strategies, defense mechanisms, aggression from predators and other dolphins, and exposure to pollutants.

“Humpback dolphins may be more susceptible to injury due to their longer rosters, and their hunting behavior can lead to collisions or getting stuck: they have been observed in an upright position, head down over reefs, probing crevices and crevices with their long rosters, snapping lateral movement heads of any stone fish that appeared,” Atkins explained.

“They could defend themselves, for example, from sharks or other dolphins. It is possible that a particularly high load from chemical pollution may also affect their bone density and make them more prone to abnormalities.

“These anomalies may be indicators of poor public health.

Efforts to develop conservation strategies

“Researchers are currently collaborating with the International Union for Conservation of Nature (IUCN) conservation planners to conduct threat analysis and engage stakeholders to develop conservation strategies for the endangered Indian Ocean humpback dolphin at this southern edge of its range.” says Atkins. concluded.

Edited by Cornelia le Roux.

This article originally appeared in the Zululand Observer and has been republished with permission. Read original article Here.