Novel approach studies whale shark ages the best way -- while they are swimming

New study reveals world's largest fish is larger and lives longer than previously thought

Date:  July 18, 2018

Source:  Nova Southeastern University

Summary:

A new study of whale sharks, using a novel approach to gathering data, shows these endangered animals can live longer and grow larger than previously believed.

Already the world's largest shark species, male whale sharks can swim around the ocean for up to 130 years, according to a recently published study by scientists at Nova Southeastern University's (NSU) Guy Harvey Research Institute (GHRI) and collaborators from the Maldives Whale Shark Research Programme.

The research on whale shark aging growth dynamics, published in the Marine and Freshwater Research Journal, was conducted in the Republic of Maldives using a unique approach.

According to Cameron Perry, the first author of the scientific paper, and at the time a graduate student at NSU's GHRI, "What makes this a novel approach is that we took repeated noninvasive underwater measurements of live sharks over the course of a decade.

"Up to now, such aging and growth research has required obtaining vertebrae from dead whale sharks and counting growth rings, analogous to counting tree rings, to determine age. Our work shows that we can obtain age and growth information without relying on dead sharks captured in fisheries. That is a big deal."

According to the research study, "Comparing length-measurement methods and estimating growth parameters of free-swimming whale sharks (Rhincodon typus) near the South Ari Atoll, Maldives," taking repeated measurement of the same sharks over many years was possible because many of these sharks came back to the same place every one to two years, and individuals could be recognized by their unique spot patterns. The researchers then modeled their measurement results and found that:

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