Oceanographers commandeer trawler to locate lost seaglider

THE fishing trawler Shoalhaven on the weekend had one its more unusual catches – a free-swimming scientific probe or “seaglider”.

University of NSW oceanographic researchers teamed up with the local trawler to recover the wayward seaglider that lost power and was caught in strong currents off the Far South Coast of NSW.

The remotely operated seaglider named “Dory” was launched off Yamba on May 30 and had been drifting south in the East Australian Current recording ocean conditions along the way.

It was named in honour of the colourful character in the movie “Finding Nemo” that did so much to publicise the previously little understood ocean current.

There was a bit of panic when the glider’s battery reached a critical point after 52 days shutting down its science bay and necessitating the rescue but the good news that all the data is uploaded via satellite on daily basis and so none was lost.

It is the same glider that featured on the front page of the Narooma News in the first week of June after it was recovered off Narooma by the researchers on board a local charter boat.

Back then it had drifted down for 65 days collecting valuable data.

The scientists this time had to travel a lot further as the glider this time around was more than 100 nautical miles offshore and without power.

UNSW researchers Dr Amandine Schaeffer and Stuart Milburn from NSW-IMOS (Integrated Marine Observing System) called in the services of the 70-foot trawler Shoalhaven, normally based in Bermagui.

They steamed out of Ulladulla on Friday afternoon and using GPS tracking located “Dory” floating on the surface out beyond the shelf early on Saturday morning.

“It was just rescued before she took off east in the tail of a warm core eddy,” Mr Milburn said.

“It was a great effort from the crew of the Shoalhaven, who were very professional mariners.”

Senior lecturer and research associate at the School of Mathematics and Statistics - Sydney Institute of Marine Science, UNSW Dr Moninya Roughan said there had been a bit of a panic, as the glider was out of battery and the ocean currents have been strong in the wrong direction, compounded by last week’s big winds and swell.

The remotely-operated “seaglider” rode the East Australian Current (EAC) all the way down from the coast from Yamba, collecting and transmitting data along the way to oceanographic scientists and the whole world.

The free-swimming but unpowered, torpedo-shaped glider has internal weights and wings that can be controlled remotely to manoeuvre it up and down and in out of currents.

It can dive to depths of 1000m, taking readings including salinity, temperature, pressure, dissolved oxygen and chlorophyll-a.

Oceanographer Dr Robin Robertson from the University of NSW at Canberra said the research was part of ongoing studies into eddies and the separation of the East Australian Current from the coast, as well as internal tides and waves along the NSW coast, and conditions in some of the offshore marine parks in NSW.

As part of the same program, IMOS (Integrated Marine Observing System) also has two oceanographic moorings that monitor ocean temperatures deployed off Montague Island, Narooma for the past two years.

The moorings monitor in-situ temperature throughout the water column in an important temperate environment of the NSW coast and are serviced regularly by the NSW-IMOS moorings team aboard local fisherman’s Les Mueller's boat, Janelle.

Dr Roberston said Dr Chaojiao Sun from the Centre for Marine and Atmospheric Research CSIRO/Perth has predicted from her models that the EAC will be strengthened and extend further south in the future.

“By 2050, the zone that it generally split off the coast is expected to split off the coast further south, but still north of Narooma,” Dr Robertson told the Narooma News previously.

The data collected by the seaglider is available live and free off the Australian National Facility for Ocean Gliders (ANFOG) website and is broadcast whenever the gliders are in the water for the public to view.

The “Dory” seaglider’s path was visible until the battery died at http://www2.sese.uwa.edu.au/~hollings/anfog/

Dory will now be on display at the Sydney Institute of Marine Science stall at the Sydney International Boat Show this coming weekend.

Other good links to check out are:

http://www.imos.org.au/

http://www.oceanography.unsw.edu.au/moorings.html

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