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Fish Talk: What are fish telling us about the condition of the Reef?

If coral reef fish could speak, what would they tell us about the health and condition of the Great Barrier Reef? Citizen science data could be the key to finding out.

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It appears that each individual reef has its own unique fish community structure. 

Fish are more vocal than you might think, and numerous studies have been published to prove it.

One thing that fish and humans have in common is that most of our communication (over 70 per cent) is non-verbal. So if we can understand the non-verbal cues that fish give us, perhaps we can find out more about the health of the reef.

It sounds simple but coral reefs are the most complex ecosystems on earth. The Great Barrier Reef supports more than 1500 species of fish, each with its own habitat requirements, its own behaviours and its own non-verbal language.

One thing we do know about fish is that they tend to move to a spot when conditions suit them and move out when conditions aren’t so great. A key to unlocking their secrets is noting who is home when we drop by for a visit and who is away on vacation.

When a reef system is healthy it supports a bigger population of fish and many different species. There will usually be a good mix of herbivorous, carnivorous, planktivorous and detritivorous fish.

A reduction in the number or variety of fish could be a warning that their reef habitat is under stress.

Greg Vinall, Chair of Wet Tropics Waterways, says the partnership has been keen to understand what fish are telling us about the condition of inshore and offshore reefs in our region.

“We’ve explored the reef fish data that has been collected over many years by citizen scientists,” he says.

“There are lots of these data sets, but those collected by citizen scientists contributing to the Reef Life Survey, GBRMP Eye on the Reef Tourism and Reef Check programs most closely matched our needs. And by the magic of high-powered computation and data analysis, we were able to visualise what the coral reef fish were telling us.”

Greg says that in many cases the data confirmed what was suspected, but there were also surprises.

“The data confirmed that communities of fish on our inshore reef systems are markedly different from those on the outer reefs. What surprised us was how quickly the fish communities also changed when we compared reefs from north to south, both inshore and offshore. It appears that each individual reef has its own unique fish community structure.

“It was also clear that despite hundreds of fish surveys being conducted over many years, each successive year produced species that hadn’t been recorded previously, which is once again a testament to the amazing diversity of the reef.”

The project lays the groundwork for future fish monitoring in terms of how, when and why citizen science fish data is collected and used.

This project is funded by the partnership between the Australian Government’s Reef Trust and Great Barrier Reef Foundation.

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