First Ultrasounds of Wild Manta Rays Worry Scientists


| LAST UPDATE 05/28/2023

By Stanley Wickens
manta ray conservation research
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Recently, scientists have made an exciting but worrying discovery. The world's first ultrasounds of wild manta rays have revealed some shocking news. Despite believing that reef manta rays were quite resilient, it turns out they are even more vulnerable than we had previously thought. However, the silver lining is that this information puts us in a better position to protect and save them.

Pregnant manta rays can have a wingspan of almost five feet - as wide as a park bench!? That's incredible, but it also poses a challenge for conservationists. Pregnancy only becomes visible after six months, which means it's difficult to identify and protect these vulnerable creatures during the early stages of pregnancy. Thankfully, a team of scientists led by Froman has developed new contactless ultrasound technology to identify early-stage pregnancy in reef mantas. With this innovative tool, researchers can now examine pregnant manta rays earlier in their 12.5-month gestation period and take proactive steps to ensure their survival. This marks the very first time such technology has been utilized for this purpose. The study, published in the Journal of Fish Biology, involved a total of 81 scans of 55 free-swimming reef mantas. However, the results were unexpected and concerning. Of the 21 scans that captured images of the uterus, only four of the seven pregnant females showed visual signs of pregnancy, leading to some alarming discoveries.

manta ray endangered species
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According to the study, only a fraction of the pregnant females showed visible signs of pregnancy, and an unexpectedly high number of females with large, developed uteri were found. This means that the number of mature females in the population has been seriously underestimated by scientists. In the Maldives, the population of around 4,000 reef mantas has more mature females than newborns, indicating that the species' fertility rate is lower than expected. This new insight shows that the population is even more vulnerable than previously believed. According to Froman, the situation calls for immediate action to protect this magnificent species.

This breakthrough technology is critical for protecting these magnificent animals, which are listed as vulnerable to extinction by the International Union for Conservation of Nature. With the Manta Trust leading the charge, scientists are analyzing more than a decade of photo data to uncover information about the population's survival rate, any trends over time and location, and which factors, such as tourism, fishing, and climate change, are having the most significant impacts. The results of this study are a wake-up call for conservationists and underscore the importance of understanding and protecting our planet's precious marine life.

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