Researchers found that a lungfish who arrived at the Steinhart Aquarium in San Francisco, Calif., in the 1930s could actually be up to 101 years old – older than any other living fish in an aquarium in the world.
According to the University of California Museum of Paleontology, lungfish (also known as Dipnoi) are creatures with a fossil record history dating back to the Permian period and earlier.
Methuselah, the Australian lungfish who lives at Steinhart, arrived in California via a Matson Navigation Company liner in November 1938 with 231 other fishes. To reveal her age, researchers conducted a “cutting edge” DNA analysis, said a Monday press release from the California Academy of Sciences.
They determined that she is at least 92 years old, and could be up to 101 years old, older than the Steinhart Aquarium itself. It celebrates its 100th anniversary this year.
When she arrived at the aquarium, there was no way to determine how old Methuselah was, according to Charles Delbeek, curator of aquarium projects. Over the past decades, she has become famous for her longevity and for her “charming personality,” and her love of belly rubs, according to the museum.
“Methuselah is an important ambassador for her species, helping to educate and stoke curiosity in visitors from all over the world,” said Delbeek. “But her impact goes beyond delighting guests at the aquarium: Making our living collection available to researchers across the world helps further our understanding of biodiversity and what species need to survive and thrive.”
Along with Methuselah, two lungfish in their 50s were also included in the study, led by Dr. Ben Mayne of CSIRO and Dr. David T. Roberts of Seqwater. Another 30 lungfish from six other institutions in the U.S. and Australia were also sampled to create a catalog of living lungfish. With this catalog, researchers hope to improve the accuracy of DNA-based age estimates for the fish.
“Estimating ages for such long lived and ancient fish is notoriously difficult and technically challenging, and has traditionally relied on more invasive and sometimes lethal aging methods such as examining otoliths, or earbones, and whole scale removal,” said the California Academy of Sciences.
Now, researchers have developed a new method that needs only a tiny fin clip that does not harm the lungfish or risk their health.
Mayne and Roberts published a paper on the development of the method in June 2021 in Molecular Ecology Resources. They intend to publish the full study findings later this year. With the method, scientists have been able to predict a maximum age clock for Australian lungfish for the first time since they were discovered in 1870, Mayne said.
“Accurately knowing the ages of fish in a population, including the maximum age, is vital for their management,” he explained. “This tells us just how long a species can survive and reproduce in the wild, which is critical for modeling population viability and reproductive potential for a species. It is a rare and valuable opportunity for researchers to access exceptionally long-lived fish such as Methuselah kept in the care of California Academy of Sciences, as it helps us understand maximum longevity of a species under ideal care conditions.”