15 February 2011 - Deep-sea Lanternfish
Far beyond the sight of any land, deep in the Coral Sea, scientists have, for the first time in Australia, found and made collections from large schools of spawning lanternfish.
During the summer spawning season, off the north Queensland coast, large schools of tuna feast on aggregations of lanternfish, creating a feeding frenzy that can include a suite of oceanic predators like whale sharks, billfish and seabirds. Tuna in the Coral Sea have been known to feed on lanternfish for some decades, but only a few badly degraded specimens from the stomach contents of tuna have been available for study until now.
Lanternfish, or myctophids, characterised by their patterns of light organs that produce bioluminescence of blue-green light, are one of the most common types of fish in the open ocean, living in the deep sea to depths of 1000 m, with some 250 different species. They ascend from the dimly lit depths of their daytime habitat at 400-1000 m by ‘vertical migration' after sunset to the upper 200 m where food is more readily available. The fish were sampled recently by scientists of the Deep Ocean Australia Project using equipment aboard the Australian Institute of Marine Science research vessel, the RV Cape Ferguson, on an expedition led by Dr Mike Hall of AIMS and PhD researcher Adrian Flynn of the University of Queensland, who is studying lanternfish ecology and biogeography in eastern Australian waters. On the cruise, midwater trawl surveys in the Coral Sea confirmed that the lanternfish are in highly concentrated spawning aggregations of only one species, the Dana Lanternfish. Although this species of lanternfish is very common off New South Wales and Tasmania, there has been no record of them spawning in the colder southern waters.
One of the scientists on the cruise, Dr John Paxton from the Australian Museum, said the Dana Lanternfish, which grows to between 8-13 cm in length may prove to be a "keystone species" because of its importance to the lifecycle of two of the most important species of tuna on the east coast of Australia, and unknown other species, in the Coral Sea.
Dr Paxton said that to catch the lanternfish in a trawl, the research expedition was assisted and directed by radio communication from commercial tuna fishers to the tuna aggregations. Fishers had spoken previously of huge feeding and spawning aggregations of tuna and lanternfish stretching up to 10 nautical miles, which have also attracted numerous other predators including whale sharks, dolphins, and larger fishes, including sharks. The ‘boiling sea' phenomenon is only seen on rare occasions and rarely erupts directly at the surface. Although the phenomenon was not observed on this cruise, the scientists did find the aggregations below the surface and could sample these with equipment guided by echolocation detection.
Dr Paxton said the first collections from this significant feeding and spawning event raise many more questions that will require further systematic collections and research.
For further information contact:
Dr Mike Hall, AIMS Principal Research Scientist, (07) 4753 4308; 0407 553 408; firstname.lastname@example.org
Adrian Flynn, University of Queensland/CSIRO MAR, Research Associate - Melbourne Museum 0421 693 120; email@example.com
John Paxton, Senior Fellow, Ichthyology, Australian Museum; (02) 9320 6139
Wendy Ellery, AIMS Media Liaison, (07) 4753 4409; 0418 729 265; w