I've dived in S'pore waters thousands of times. The Bedok jetty honeycomb ray is more significant than we think.

Soft truths to keep Singapore from stalling.

Mothership | August 17, 2020, 08:59 AM

PERSPECTIVES: An 80kg honeycomb ray was recently caught at the Bedok jetty, creating much hullabaloo among anglers and non-anglers.

Debby Ng writes about how a honeycomb ray of that size is important to this vulnerable species. Ng hopes that these interesting facts will interest and engage more people to find out more about the marine life in Singapore and make an informed choice as they undertake activities in the future.

Ng is a scuba diver, biologist, and writer who has been blogging about Singapore’s marine life for 17 years.

This post originally appeared on the Hantu Blog, a platform for Ng's non-profit dive group to reach out to members of the public.


By Debby Ng

Singapore shores never cease to amaze me. Whether I am exploring the reefs through SCUBA diving, or on foot during intertidal walks, every experience leaves me looking forward to the next trip.

My first encounters with wild fish in Singapore began when I was eight years old, and involved wading through the forest streams of Nee Soon with my father in the 1980s. I stopped exploring streams when we left the kampung, but continued visiting our forests for walks and birdwatching.

It would take another two decades before I discovered the amazing coral reefs of Singapore when I took my first dive at Pulau Hantu, an island just 9km southwest of VivoCity. Since then, I have dived in Singapore thousands of times, and have seen sharks, turtles and walking fish, but had never encountered a ray like the one caught at Bedok jetty.

Therefore, when I first encountered the news about the large ray, I was amazed and excited to learn that such a magnificent animal could be found so close to our shores.

https://mothership.sg/2020/07/giant-stingray-bedok-jetty

It is however not surprising that the rays exist in Singapore waters – our reefs are full of hundreds if not thousands of marine animals. It would be impossible for me to meet every one of them.

The writer, Debby Ng, poses with a filefish at Singapore's Pulau Hantu Credit: JeemeeGoh/Hantu Blog

False-clown anemonefish make their home in a purple-coloured Magnificent anemone Credit: Debby Ng/Hantu Blog

Tigertail seahorse at Pulau Hantu, Credit: Debby Ng/Hantu Blog

This catch was described as the second-largest catch from Bedok jetty, and the largest haul by a “shorewrangler” this year. According to various blogposts, the ray had a wingspan that measured around two to three meters and weighed somewhere around 70 to 100 kg. The one found at Bedok jetty was reported to be around 80kg.

Photo by Raj Bharathi via Facebook.

The websites that reported the catch had focused on the three to four hours that Uncle Alo, a “shorewrangler”, took to haul the ray out of the water.

They also taught us that Uncle Alo had been fishing for many decades and I imagined he would have many good stories to share of the variety of marine animals he had encountered through his years of angling in Singapore.

However, little was shared about the marine animals in Singapore, or this ray that was caught which I was disappointed about. That led me to write this post so that we can at least learn something about these animals that call Singapore shores home.

It takes 12 months to give birth to a honeycomb ray

Friends from the science community, Kelvin Lim and Zeehan Jaafar, helped me identify that it was a honeycomb ray (Himantura undulata).

Mother honeycomb rays carry their young for 12 months before giving birth to them live. This long gestation takes a toll on the mom. The ray embryo first grows on nutrients supplied from a yolk within its mother's uterus. After the yolks are used up, the mother produces milk that the embryo absorbs, which enables it to grow even bigger.

Why would a ray do this? Why not lay them as eggs like bamboo sharks and be done with it?

This long and energy-demanding pregnancy for the young to grow to that size is an important part of the rays' survival strategy. The babies of honeycomb rays can be born quite “big” as compared to other marine creatures. A honeycomb ray baby is about the size of both your palms put together (around 21-28cm). That means they are born too big for most other fishes on the reef to eat them.

12 months is about the same gestation period as a horse, a camel, and a donkey. If you think of camels, horses, and donkeys, the young are born pretty capable. They are big, and they can run. Of course, they could still get hunted and eaten by a predator, but if they can run, they’ve got a good chance at life. Similar for the honeycomb rays, the bigger they are born, the better a chance they have to survive. In this case, to survive from the sharks which are their main predator.

Spending such a long time inside the mom to get so big, however, means that they can’t have many siblings. Honeycomb ray moms only give birth to around three to five pups after a 12-month gestation.

Which brings us to our second part.

Honeycomb rays are vulnerable, but not because they are tasty

Honeycomb rays are vulnerable because they are long-lived, have few young, and are slow to sexually mature.

Of the three to five pups that are born after a year-long pregnancy, only one might survive. That’s OK if mom lives a long time. Think of mice and elephants – Mice have short lives, give birth often and have many young each time. Elephants take a frustratingly long time to grow and have few young in their lifetime. But their long lives help make up for their long and slow reproduction. Honeycomb rays are more like elephants than they are like mice in this sense.

Honeycomb rays take four to five years to reach sexual maturity. That’s eight to 10 times longer than cats and dogs that are sexually mature at around six months.

When honeycomb rays are born, they wander the shallow sea in search of small fishes, crabs, molluscs, worms, shrimps, and sea jellies while avoiding getting eaten by anything that is bigger than themselves (there are a lot of animals in the sea larger than a young honeycomb ray). They have to do this for half a decade before they are able to reproduce.

After years of wandering and evading the dangers of the shallow sea, if it is still alive and has managed to find enough food to grow well and sexually mature, it will then find a mate. If the mating is successful, a female honeycomb ray will get pregnant and have pups a year later.

This is why a honeycomb ray can be hard to come by, especially so these days when they face other threats too.

The ray caught at Bedok jetty likely to be a nine-year-old female

If the ray caught at Bedok jetty measured 120cm in diameter, it could have been at least nine years old.

Nine years may seem a long time for a wild animal, but these rays are known to live for at least a quarter of a century in the wild. At nine years old, the ray would have been sexually mature for around four years only. If the ray was a female, she could have had four litters at the most, or none at the very least.

One of the first things I noticed when I saw this photo of the ray upside down was that it was a female, but I wasn’t really confident because the photo wasn’t really good. I felt a bit more confident after looking at the photo below that was photographed from the rear.

Photo by Nicholas Chiam via Facebook.

Male honeycomb rays would have stout claspers, which seem to be absent in this ray from these two photos. Females are precious to any population, because they give birth to the next generation. Especially if the species is slow to sexually mature, have few young, and is long-lived.

Surviving for nine years is a great feat for an animal that lives in the shallow seas of the Pacific and Indian Ocean.

Point map showing records of honeycomb rays as reported by countries.

Honeycomb rays may have a large distribution, but this distribution also overlaps with some of the most threatened coastlines in the world that are being reclaimed, dredged, developed and trawled. Honeycomb rays are a common bycatch in shallow sea trawling.

Any ray that has managed to overcome the challenges of living in these shallow seas deserves a eulogy – hence this blogpost.

This is the story of every honeycomb ray that was ever caught and landed.

Importance of learning more about marine life

It’s wonderful to know and learn that there are such beautiful animals that live in our waters.

Fishers and photographers can contribute to our knowledge of Singapore’s marine life by sharing their stories and experiences.

Blue-spotted fantail rays are commonly sighted by divers in Singapore's reefs Credit: Debby Ng/Hantu Blog

A delicate porcelain crab on a soft coral Credit: Debby Ng/Hantu Blog

Six-banded angelfish are just one of a hundred different kinds of colour reef fish that call Singapore reefs home Credit: Debby Ng/Hantu Blog

They can also play an active role in protecting our marine life by being selective about where they fish and what they catch, and by using suitable tools and methods if practicing catch and release.

By protecting our reefs, we can ensure suitable habitat for these animals to hide when they are young, feed so that they may live, and live long enough so that they can mature, have young, and continue to provide joy, excitement, and awe for fishers and non-fishers alike.

News about this catch have made many people excited about fishing and marine life in Singapore. Although we only have a few photographs of this fishing event, we can learn fascinating stories about the beauty and wonder of our murky waters if we try to ask some questions.

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Have an interesting perspective to share or a commentary to contribute? Write to us at [email protected]

Top photo courtesy of Debby Ng and by Raj Bharathi via Facebook