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Finding Land Fish in French Polynesia: The Mystical Mountains of Moorea

By: Georgina Cooke, Category: Science, Date: 19 Nov 2013

Our journey had a rocky start involving 5 airports, 7 busses and a ferry, so we arrived exhausted but relieved on the island of Moorea.

Finding Land Fish in French Polynesia #1

Georgina Cooke © Australian Museum

A blog series about the scientific field trip to French Polynesia led by Australian Museum Chadwick Biodiversity fellow Dr Georgina Cooke together with volunteer Samantha Goyen and Honours student Tom Summers from the University of New South Wales.

They have travelled to this tropical paradise to study remarkable fish that live out of water and hope to use this research to gain insight into why our fishy ancestors left the water 350 million years ago…

Moorea is a small, breathtakingly beautiful island surrounded by aquamarine water and dominated by lush tropical mountains capped in clouds. From first glance we knew this place would be perfect for our project. But we had little time to sit around and ponder the coconut palms… Work had to be done!

We are working on a group of blenny fish that has evolved very interesting amphibious behaviour. In fact, there are several species that actively avoid going in the water and these spend their days foraging and socialising on rocky outcrops! Amphibious blenny fish can be found on tropical islands throughout the Pacific and Indian Oceans, and this is why we are here in French Polynesia, to collect specimens.

It was day one and it was only minutes down the road from the research station CRIOBE that we found our first fish out of water, Alticus simplicirrus. Fish belonging to the genus Alticus are truly remarkable and can hop from rock to rock using an axial tail twisting motion that propels them with extreme accuracy. They are so agile that catching one is extremely difficult, but with a small fish net, a metal stick and plenty of patience you may just be in luck!

Slipping and sliding, we collected a few, photographed each one, and took tissue for DNA analysis. These fish were then preserved so that they can be deposited in the Australian Museum's collections.

It was then time to expand our search, and we went looking for tide pools where we hoped to find greater diversity in species and their amphibious behaviour. With only one main road on Moorea, we jumped in the car and headed clockwise. Coral sands stretched along the coastline, but luckily from a lookout we saw a rocky outcrop in the distance that appeared suitable for sampling.

With all our gear we clambered out there and to our utter excitement it was indeed filled with blennies. In small rock pools nearest the splash zone, amphibious blennys, Praealticus ceaseus, were hopping between pools to escape our clumsy nets while below were large tide pools replenished with flowing seawater where four different species of blenny darted like lightening from rock hole to rock hole. We knew we had our work cut out for us here!

For the next few days, Samantha and I spent hours squatting over small blenny holes and being outsmarted by the likes of Istiblennius lineatus, Istiblennius edentulus, Blenniella caudolineata, and Blenniella periopthalmus. Meanwhile Tom photographed every single fish caught.
Tomorrow we catch the Ferry to Papeete, and the adventure continues!