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Dec

TropWATER researchers can see through murky waters

TropWATER Researchers recently published the results of a fish survey that delivered more than they’d bargained for…

The study, funded by the Mohammed bin Zayed Species Conservation Fund, originally set out to search for endangered freshwater sawfish (Pristis pristis) and to document the estuarine fish community of a remote river on eastern Cape York. The use of underwater video cameras was hindered by poor water clarity that made identification of some fish difficult. But not all was lost. Through collaboration with Professor Paulo Drews Jr. from Universidade Federal do Rio Grande in Brazil, image enhancement techniques were applied to clips where species identification was difficult. These clips were then reviewed by co-authors to determine the effectiveness of each enhancement technique. It was found that two of the three techniques applied to the video clips yielded higher identification confidence than the raw footage (examples below). The study was recently published in Pacific Conservation Biology.

Examples of various image enhancement techniques applied to the same video clip. The raw footage is presented in the top left corner.

Researchers used a combination of survey techniques including baited and unbaited cameras. The cameras recorded many types of fish as well as stingrays, mud crabs and the apex predator of tropical estuaries; the estuarine crocodile. In fact, one of our baited cameras lived to tell the tale of its encounter with large estuarine crocodile …

A large estuarine crocodile swims by to inspect a baited underwater camera.

See the full clip here.

Published paper: Donaldson, J. A., Drews, P., Bradley, M., Morgan, D. L., Baker, R., & Ebner, B. C. Countering low visibility in video survey of an estuarine fish assemblage. Pacific Conservation Biology (Online early) https://doi.org/10.1071/PC19019

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