DIVELOG JUNE 406

MARINE BIOLOGY WITH MIKE SCOTLAND - FISH IDENTIFICATION

This Hale’s Ornate wobbegong from Pimpernel Rock was deciding what to do with my photo model.

We know this courtesy of Dr Charlie Huveneers’ excellent research. Baby wobbies get smashed by larger predators such as cod, trout and wrasse. Few survive! Behaviour Wobbegongs can lie still for hours. They do swim and lay claim to their territory quite often. They will let you know that you are on their turf so that you make no mistake about who is boss. They have lightning fast reflexes. They do have a habit of biting and sometimes holding on for ages. Therefore, they are considered to be one of the most dangerous sharks because they can be easily underestimated. Wobbies are renowned for the ability to turn on their tails. Divers often have a large wobbegong swim close to them in an obvious show of dominance. They like to let you know that you are on their turf. Wobbegongs have a strong sense of personal space. It is fifty-one centimetres! They will reluctantly tolerate you at one metre. They will give you a warning at sixty centimetres. Once you get to fifty-one centimetres, they explode with a powerful threat display. I found this out when trying to photograph one, many years ago. I needed to get closer to get a better shot. I photographed the wobby at eighty, seventy, sixty and then fifty-one centimetres. On the final shot, the shark

lunged at my camera with a very clearly audible cough. I got a photo of a tunnel of death, twelve centimetres around and twenty centimetres deep. It was deep throat, wobby style. I have never heard the wobby cough again. As they say, once warned, twice shy. Scientific Research Charlie Huveneers studied Wobbegongs in 2007. He was involved in the elevation of the Pygmy Ornate wobby, O. ornatus and Hale’s Ornate wobby Orectolobus halei to a species level to separate them. That is, the Pygmy Ornate and the bigger Hale’s Ornate wobbegong were recognised as two distinct species. Before that, there was a lot of confusion and Pygmies were sometimes thought to be baby Hale’s Ornate wobbies. They are commercially fished using the “Trap and Line” method from 1991. Scientists recorded a dramatic drop in numbers within ten years. They were overfished like so many fish in our oceans and are now officially listed as vulnerable. Divers noticed wobbegong encounters became rare. Fortunately, they can reproduce rapidly. Charlie has identified through research that populations were in serious decline as part of fisheries management.

77

www.divelog.net.au

DIVE LOG Australasia #406 - June ‘24