Researchers Catch Oldest Tropical Reef Fish Known to Science - Smithsonian Magazine

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Australian researchers have found what is thought to be the oldest tropical reef fish ever caught. The fish in question is an 81-year-old midnight snapper caught off the coast of Western Australia, reports Graham Readfearn for the Guardian.

Scientists caught the record-breaking fish at Rowley Shoals in 2016 while conducting a study on how rising ocean temperatures and human exploitation have impacted the longevity and growth of coral reef fishes. The study was published last month in the journal Coral Reefs.

The midnight snapper broke the previous record by a whopping 20 years, reports Sara Spary for CNN. The study also turned up another super-old fish that narrowly missed the number one spot: a 79-year-old red bass, which was also caught at Rowley Shoals.

“Until now, the oldest fish that we’ve found in shallow, tropical waters have been around 60 years old,” says Brett Taylor, a fish biologist at the Australian Institute of Marine Science who led the study, in a statement. “We've identified two different species here that are becoming octogenarians, and probably older.”

Taylor adds that recording the changes in length and age among fishes at different latitudes will help scientists understand how they’re responding to the warming water temperatures caused by climate change.

The study collected red bass, midnight snapper, and black and white snapper from four spots along the coast of Western Australia, as well as the protected Chagos Archipelago in the central Indian Ocean, reports Chris Baynes for the Independent.

Researchers found a total of 11 fish that were more than 60 years old. The team was able to accurately age the fish by measuring the growth rings on small bones inside their ears called otoliths. Each ring on the fishes’ otoliths correspond to a year of growth and can be used much like tree rings to determine their bearer’s age.

Taylor tells the Guardian that though the species featured in the study aren’t targeted by commercial or recreational fishers, their relatives are. “A lot of these snapper species that are commercially harvested are 40, 50 and 60 years old that people are buying. There’s a serious history to some of these,” he says.

While CNN, the Guardian and the Independent all cited major historical events, such as World War II, that were subsumed by the lifespan of these long-lived fish, rising ocean temperatures wrought by human-caused climate change may be the most significant changes seen by the octogenarian snapper.

“We talk about climate change being something in the future, but these 80-year-old fish saw a tremendous uptake of temperature [in the ocean] in their life spans,” Taylor tells the Guardian. “The main point is to understand how temperature affects growth and the lifespans of these species. By 2100, I don’t think we will have any more 80-year-old midnight snappers. These locations will warm to a point that based on current models it will have an impact on their biology.”

As for the current holder of the record for oldest fish in the sea, it’s the Greenland shark. A 2016 study examining these cold-water sharks’ eyes found one female estimated to be nearly 400 years old—good enough to hold the record for the oldest known vertebrate not just under the sea but anywhere on the planet.

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