How long can fish live? If you’re like most, you might assume a fish’s life expectancy is fairly short. Our recent groundbreaking research on deepwater fish along the MesoAmerican Reef uncovered that certain deepwater fish species, like the cardinal snapper, can live for over 60 years – far beyond what was previously thought possible.
By employing the precision of bomb-radiocarbon dating, scientists have confirmed that the cardinal snapper – a commonly captured deepwater species – can surpass an astonishing 60 years of age. This remarkable discovery redefines our understanding of regional deepwater fish lifespans and provides a low-cost, scalable method to aid sustainable fishery management.
Why Longevity Matters
Understanding the age of fish is critical for effective fisheries management, especially for long-lived species that are often more vulnerable to overexploitation. Key findings from the study highlight the significance of this research:
- Unprecedented Lifespan: The cardinal snapper now holds a place among the longest-lived snappers ever documented in the western Atlantic Ocean.
- Increased Vulnerability: Species with extended lifespans typically exhibit slower population recovery rates, making them especially susceptible to unsustainable fishing practices.
- Affordable Age Estimation: Researchers have developed a cost-effective method to estimate fish age using the weight of otoliths (ear bones). This innovation allows managers, fishers, and researchers to rapidly determine the age structure of cardinal snappers using only a digital scale—making it accessible even in resource-limited settings.
What Is Bomb-Radiocarbon Dating?
The origins of bomb-radiocarbon dating trace back to a pivotal moment in human history.
Carbon-14 (¹⁴C) is a naturally occurring isotope of carbon, but its concentration in the atmosphere significantly increased during nuclear bomb tests in the 1950s and 1960s. This surge of carbon-14, known as the “bomb pulse,” spread globally and was absorbed by organisms in terrestrial and marine environments. As a result, it became incorporated into the calcium structures of marine life – including corals, mollusks, and fish – leaving a unique chemical signature that scientists use for dating purposes.
All animals on Earth have a ¹⁴C signature that correlates to when and where they were born. As ¹⁴C is incorporated into the biological tissues of animals, it acts like a timestamp. Because this isotope can be measured, and because ¹⁴C relative concentrations have not yet declined to pre-bomb levels, scientists can use this method to determine the age of animals, including fish.
A thin section of a cardinal 68-year-old cardinal snapper otolith with white circles denoting annual band pair formations.
Deep-Sea Challenges and Breakthroughs
Traditionally, fish age is determined by examining growth rings in otoliths, much like counting tree rings. The idea is that a pair of rings are formed in the otolith each year, correlating to fast and slow growth in summer and winter (or rainy and dry seasons), respectively. However, this approach relies on clearly defined seasonal growth patterns, which may be different in deepwater ecosystems. Deep-sea fishes do not encounter the same variations in temperature and food availability as their shallow-water counterparts.
To overcome this limitation, we turned to bomb-radiocarbon dating to validate the lifespan of the cardinal snapper, a deepwater species commonly captured in fisheries between 200 and 350 meters. Our results were astonishing: two cardinal snappers, captured in Belize (2015) and Honduras (2019), exhibited ¹⁴C levels below pre-bomb values. This confirms that these individuals were born before the nuclear tests of the mid-20th century, making them over 60 years old.
To determine how old a fish is using bomb radiocarbon dating, you extract the core of the otolith, which contains the calcified materials formed from seawater during the first year of the fish’s life.
A Low-Cost Solution for Sustainable Management
The study’s significance extends beyond validating age through advanced radiocarbon techniques. We discovered a strong correlation between otolith weight and fish age, enabling us to develop a straightforward equation for age estimation. By applying this equation along with an affordable digital scale and an otolith, fishery managers can quickly and cost-effectively determine the age of captured cardinal snappers in the study region.
This breakthrough is especially critical for fisheries in the MesoAmerican Reef region, where resources for expensive and labor-intensive studies are often limited. By equipping managers with tools to assess fish populations more accurately, this research paves the way for improved conservation and sustainable practices.
A Deeper Understanding, A Brighter Future
The validation of the cardinal snapper’s extraordinary longevity underscores the need for tailored management strategies to protect long-lived species. With innovative techniques that combine cutting-edge science and practical accessibility, our research opens a new chapter in sustainable fisheries management and in the protection of long-lived deepwater species, which often do not survive capture due to pressure changes.
By bridging the gap between scientific precision and on-the-ground application, this study offers hope for the future of deepwater fisheries, ensuring that ecosystems and the communities that depend on them can thrive for generations to come.