Sometime in the last week of March this year, I was winding up work at one of our study sites in Kavaratti, Lakshadweep, when there was a sudden burst of yellow and black and I was left blinking, smack in the middle of this huge shoal of convict surgeonfish. Naturally, I just had to record them swimming and swooping as they fed; like one giant troupe of performers dancing on the reef; leaving an infectious energy in their wake. It was a pretty sight, a happy one, and although I didn’t realise it at the time, this experience was a really special one.  

Surgeonfish play an important role in the coral reef ecosystem. Much like gardeners pruning a garden and keeping it free from weeds, surgeonfish keep algae from taking over the reef. In recent years in Lakshadweep, however, convict surgeonfish numbers seem to have dropped, making happy encounters like this one quite infrequent. The reasons for this decline in numbers are unclear right now.

Dr. Rohan Arthur, who’s been working in Lakshadweep for over 20 years now, and heads our Oceans and Coasts Programme says convict surgeonfish used to be a common sight.

“It is difficult to measure an absence. There was a time when the convicts roamed free among the reefs of the Lakshadweep. Like a throng of escapees, their prison costumes still on, they would swim furiously, braving the giant swells so they could feed in the shallows. They played an important function then, these convicts, scrounging up every bit of turf they could find, keeping the reef clean for new coral to settle and grow. When species so common drop out of your view, it happens without you noticing. At least at first. It is a slow, gentle slip. Until one day you realise that something is missing from your peripheral vision and when you try to pinpoint what it is, you realise that the convicts are gone. Without them, the reef is a different place. You see them now, small straggling schools, in a lagoon you have not visited recently, or in shallow reefs you are only now discovering. And when you do, you wonder what else you have lost in your peripheral vision, and what these accumulating losses mean for the reef. Absences are difficult to measure. So we may never know.”

Seeing the convict surgeonfish has taken on a deeper meaning for me, beyond just seeing pretty fish on a dive. Are there other fish that are declining, and we haven’t started missing them yet? In hindsight, that one experience feels very bittersweet now. I wonder if I’ll see them again next season or the season after that, and if I don’t, what would that absence mean? On the other hand, I do hope to see those convict surgeonfish shoals again soon, and if I do, I wonder what that would mean.