Whale Shark Populations Mysteriously Decline, Here’s Why According to Study

A new study on whale sharks says that one of the species from the group becomes a victim of oceanic 'roadkill.' According to the paper, the species were specified as the popular spotted fish, which grows to a whopping 40 feet or more.

Despite being large, the spotted fish becomes a victim of human-induced activities throughout the seas. One of the main factors that cut their population is simply the travel of massive ships larger than them across the widest water bodies of the planet.

The latest marine biological research emphasized that the international shipping industry inflicts the ocean's biodiversity and even affects some of our time's largest and most endangered species.

Unknown Reason Behind Reduction of Whale Sharks in Earth's Oceans

INDONESIA-WILDLIFE-MARINE-WHALE SHARK — A youth stands on a a whale shark towed by fishermen along the coast of Surabaya in eastern Java island on October 22, 2013, to be sold to prospective buyers after getting entangled in a fishing net. Listed as vulnerable by the International Union for Conservation of Nature (IUCN) and banned for fishing by some countries, the species continues to be hunted in some parts of Asia. JUNI KRISWANTO/AFP via Getty Images

Throughout the decades in aquatic environment research, experts were always baffled regarding the unusual decline of whale shark populations around our planet. According to a report from the 12th Meeting of the Conference of the Parties (CoP12) to the Convention on Migratory Species (CMS), spotted fish has reduced by 50 percent in the last 75 years due to unknown reasons.

Researchers from 50 various institutions have teamed up to identify the possible cause of this decline. Among their interests were the scheduled trips of the ships and movements of the sharks across various oceans. The study's main goal is to point out the potential links between industrial activities and the receding population of the species.

The data were collected from tagged sharks between 2005 to 2019. This information included movements of approximately 300 whale sharks that inhabit waters of the Atlantic, Indian, and Pacific oceans, Gizmodo reports.

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Results show that the paths of the shipping vessels indeed coincide with the pattern of shark movements across these environments. The records presented that 90 percent of the animal's pathways are near the course of these marine vessels. Moreover, most of the transmissions from these tags tend to end in regions where the vehicle traffic is high.

Shark Tags Reveal Shipping Lines Kill Creatures in Their Natural Paths

The University of Southampton and Marine Biomedical Association specialist David Sims, who also served as author of the research, explained in a EurekAlert report that some of the tags that their team tracked showed whale sharks falling down the depths of the oceans and to the seafloor after visiting areas of shipping lanes.

These results where the sharks end up hundreds of meters below the waters are definitive evidence of lethal strikes that the species incur, Sims continued.

Unfortunately, we do not even know these experiences they face around the globe and could not give preventive measures to ease the issue, the expert said.

Other factors that push the huge sharks to their extinction are slow swimmers and are likely to travel near the surface. The absence of whale sharks in the ocean could heavily affect the natural balance of marine ecology, as these creatures feed on microscopic zooplankton responsible for algae blooms.

The study was published in the journal PNAS, titled "Global collision-risk hotspots of marine traffic and the world's largest fish, the whale shark."