A thousand leopards in the sea

by Rucha Karkarey and Vardhan Patankar

 

Aboard a tiny boat in the waters of the Lakshadweep, a group of researchers spotted something incredible…

Can you imagine seeing a thousand leopards in a forest patch, the size of a football field? As you make your way through the forest thicket, you are elated when you see your first leopard, peering down at you from the branches. You consider yourself very lucky if you see two more, but a thousand leopards at a time? Sounds impossible, right?

Not to us, because we have seen them with our own eyes; hundreds of them, all around us!! After all, they do not call it the ‘sea’ of possibility for nothing!

The forest we speak of is a coral reef from a remote atoll in the Lakshadweep archipelago and the ‘leopard’, a species of reef fish known as the squaretail grouper ( Plectropomus areolatus ).

A large, carnivorous fish, with black spots on its body, the grouper likes to hunt by ambushing its prey. It prefers to remain solitary, making it a formidable reef predator, just like leopards.

This grouper shows a unique mating behaviour, where several individuals gather at certain areas during certain times of the year, to reproduce. These gatherings are known as ‘spawning aggregations’. Spawning aggregations in some species like the squaretail grouper tend to occur at the very same locations, every year.

Curious observation

In 2011, we conducted a Lakshadweep-wide survey, when we observed an unbelievably high number of squaretail groupers at one particular site, on a remote little atoll. Their peculiar behaviour made us wonder if we could be amidst a grouper spawning aggregation?

We resolved to return to this site to investigate, at the same time, the following year.

We set out once again in 2012 aboard a tiny tuna boat called “Arakkal” to study the event. But we had to hope the timing, location and weather would work out in our favour. The first three days were not as successful as we imagined.Turn of the tides

Just as we were about to give up, a day before the new moon, the tide turned, so to speak. We returned to one of the sites and were stunned! The entire reef was carpeted with squaretail groupers!

We saw male groupers fighting each other to defend small territories and female groupers arriving in shoals of 200 to interact with the males. The entire incident unfurled in front of us like a 50-minute play, just like the literature had described!

We returned that night, completely overwhelmed by the days’ proceedings. Our colleague Ommni, a diver from Lakshadweep, aptly described our experience as ‘seeing a thousand leopards in the sea’.

Seizing the moment

In all our dives during this spawning, we saw over two thousands individuals! By the third day all signs of the aggregation had completely vanished from the site. It was sheer luck and a little bit of instinct that got us to the right place at the right time.

Spawning aggregations of fishes provide a lucrative opportunity for fishermen to obtain large catches of fish, with minimum effort. But fishing at such a time can take out a large proportion of the population in a matter days.

Beyond wondering at the spectacular sight of these massive gatherings of fish, we also need to think about their conservation.

 

Photo credit: Rucha Karkarey