Whale sharks, the largest fish species in the ocean, are critically endangered largely due to the impacts of human activity. Sadly, almost 80% of these majestic animals are marked by injuries that could have easily been avoided. The International Union for Conservation of Nature (IUCN) has listed them as endangered on its Red List of Threatened Species. During the last ¾ century, their populations have declined by more than half globally. The state of play in the Indo-Pacific region is sobering. At one point during that same period, the decline was as much as 63%.
The Bird’s Head Seascape off Indonesian West Papua, where things really couldn’t be worse. Recent research conducted by the Oceanic Society and others has shown that 62% of whale sharks are scarred and injured from human contact. These results highlight the critical importance of swift and effective conservation action to save these climate threatened marine creatures.
The Impact of Human Activity
Whale sharks have distinctive patterns of white spots and stripes, much like our fingerprints, that researchers can use to identify individuals. Yet, these magnificent animals now too often turn up with wounds directly linked to human actions.
Recent research found that an astounding 80.6% of whale sharks in the Bird’s Head Seascape exhibit scars. The vast majority of these injuries are directly attributable to human behavior. These such as non-life-threatening skin lesions usually caused by friction against hard surfaces like traditional fishing platforms called bagans or from boat collisions.
Severe injuries (lacerations, blunt force trauma) were recorded on 17.7% of whale sharks observed. The severity and frequency of such injuries is evidence enough that urgent reforms are needed to rectify fishing practice and marine tourism enterprise. Passing this resolution will protect marine wildlife from more unnecessary disruptions.
“We found that scars and injuries were mainly from anthropogenic causes, such as collisions with ‘bagans’—traditional fishing platforms with lift nets—and whale shark-watching tour boats,” – Edy Setyawan
The Life Cycle and Behavior of Whale Sharks
Whale sharks don’t reach sexual maturity until around 30 years of age, making recovery efforts for their rapidly declining populations all the more challenging. Having a clearer picture of how they behave will be key for developing effective conservation strategies.
The findings confirm that juvenile male whale sharks prefer shallow waters filled with plankton. In comparison, adult females prefer more oceanic depths, where they dive for krill and schooling fish. From habitat selection to understanding the threats they may face, the ability to track these movements opens a world of knowledge to us.
“Previous studies from around the world have shown that adult whale sharks, especially females, prefer the deep ocean where they feed on prey like krill and schooling fish, while the younger males stay closer to shore in shallow, plankton-rich waters that help them grow quickly,” – Mochamad Iqbal Herwata Putra
Tracking data from satellite telemetry indicates that adult whale sharks often utilize deep-sea features such as canyons and seamounts. That makes it all the more imperative that we protect these habitats in order to ensure their continued existence.
Conservation Efforts and Future Directions
In light of the dropping whale shark populations, scientists and conservationists alike are calling for swift action. They call on Congress to work with state and local governments to ensure protective measures are in place.
Mark Erdmann highlighted ongoing efforts, stating that regulatory changes could significantly reduce scarring among whale sharks in the region.
“We aim to work with the management authorities of the marine protected areas to develop regulations to require slight modifications to the bagans, including the removal of any sharp edges from boat outriggers and net frames. We believe those changes will greatly reduce scarring of [whale sharks] in the region,” – Mark Erdmann
Indeed, research has documented high residency and resighting rates for whale sharks in places such as Cenderawasih Bay and Triton Bay (Kaimana). It calls attention to the whale sharks’ importance as conservation treasures for local communities.
“Whale sharks in Cenderawasih Bay and Triton Bay (Kaimana) had high rates of residency and resighting, indicating that they should be viewed as valuable tourism assets for local communities and governments,” – Mark Erdmann