At Marion Reef, as well as encounters with graceful Manta Rays, this was a fantastic opportunity to swim with sea snakes. Sea snakes are even more maligned than sharks, crocodiles and the wealth of other ‘dangerous’ wildlife in tropical Australia but compared to their land-based cousins are surprisingly docile and approachable…even inquisitive, which both added an element of surprise and apprehension amongst most of our snorkellers and divers, many of whom had never encountered snakes, let alone at sea! They are truly remarkable animals. Unlike turtles, which have to come to land to lay their eggs, sea snakes never leave the ocean. These air-breathing reptiles spend their whole life feeding, breeding and even giving birth on reefs like Marion.

Of the 32 species of sea snake that occur in Australia (roughly two-thirds of the world’s types), several have not been seen for years and there has been a worrying loss of otherwise-unknown species across some entire reef systems. For a top predator that eats mostly fish, they occur at an extraordinary high density. In just two swims at Marion Reef, we encountered sea snakes at almost every rock bommie, three species in total, and in other parts of Australia millions of snakes can occur.

So, it is perhaps unsurprising that prawn trawling catches hundreds of thousands of animals across northern Australia and sea snakes are similarly threatened elsewhere in the world’s oceans. Although they are are caught less and less, due to the use of devices on fish nets, we don’t understand the true consequence of any loss now or in the past. Like sharks, sea snakes should be abundant top predators, crucial for reef health. Remove them, and the food chain becomes unstable, like a spinning top that runs out of energy and falls over. We have no way of ever knowing what the true consequence would be of losing such charismatic species. A healthy reef will have healthy numbers. Anything that affects how the ecosystem regulates itself, runs the risk of reducing resilience to other human influences, including climate change.

So give a thought to the turtle’s poor cousin, the “fundamentally unlovable”[1] but extremely important sea snakes.

1. Quote from Tony Courtney, FRDC Fish Magazine.