Summer in the Cayman Islands is always a magical time for scuba divers and for any of our fishy friends who feed on the blooming clouds of fish we call silversides.
The seas are calm and the water is so warm you can dive all day without a wetsuit. For many divers the distinctive sight of silverside schools in the caves and caverns of Grand Cayman is one of the few encounters that will leave them lost for words.
Silverside schools are actually made up of several species of two-inch herring-like fish that mix together in large shoals for their protection. Schools protect their residents by providing more eyes on the lookout for danger, a dilution effect for individuals of safety in numbers and a confusion effect where it is difficult for a predator to pick out a target. This doesn’t stop the predators trying; silverside schools always attract a host of predators – tarpon, groupers, snappers and jacks are all keen to gorge themselves on this summer bounty.
Schools of silversides are enchanting to watch, pulsing in the rays of light, with the fish moving in unison as if they are a single creature. At peak times in Grand Cayman the schools can completely fill the caverns and gullies of dive sites like Grouper Grotto, Snapper Hole and Eden Rock, even overflowing across the top of the coral reef.
On these exceptional days, these dives are probably the best in the world, as divers not only descend beneath the waves, but then also on into another living liquid of millions of fish. As you scuba dive and fin forward, the silver school parts in front of you, then engulfs you in a bubble of clear saltwater, entirely and symmetrically encircled by fish. Suddenly a predator bolts through the mass, hoping to catch a straggler, momentarily scattering the silversides before they re-form into their sinuous mass. Cayman summers don’t get any better than this.
The exact spacing of individuals and the precise and unified movement are controlled mainly by eye contact, although the lateral line which can sense movement is also thought to be important. Interestingly, many protective shoals like those of silversides disperse at night and then re-group and return to the protected topography of the reefs at sunrise.
Every July, August and September in Grand Cayman, silversides can be witnessed at over 30 different dive sites on Grand Cayman. Sites with caverns are the most spectacular, with engulfing swarms that take over the whole dive site, such as:
Other Grand Cayman dives sites have pockets of silversides of different sizes at specific locations on dive sites, such as:
Pageant Beach Reef
Cheese Burger Reef
Royal Palm ledge
High Rock Drop-Off
Jack McKenney’s Canyon
Sand Hole / Lexau’s Legacy
Little more is known about this fish that is unnoticeable by itself, but unforgettable en-mass. The exact timing of and reason for their cycles is only just becoming understood and a realisation that an encounter at such a cross-roads in the food chain is a pure marvel. To be immersed in a bait-ball of life as tarpon, jacks and snappers dive-bomb to feed on this silver seafood buffet – divers call it a ‘silver rush’.