The owners, skipper and crew of the Sealord fishing vessel Rehua have been helping scientists perform acoustic mapping during annual transits across the Tasman Sea.
Sounding out life in the ocean
Commercial fishers are helping marine scientists to map and monitor food supplies available to top order predators in the oceans around Australia.
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16 June 2010 | Updated 14 October 2011
Fishers provide vital link in ocean observing system
Skippers for Sealord NZ, Australian Longline, Austral Fisheries and Onwards Fishing are using their echo-sounders to record slices of life beneath their vessels while en route to fishing grounds across the Southern and Indian oceans and Tasman Sea.
A team of scientists led by Dr Rudy Kloser of the CSIRO Wealth from Oceans Flagship is studying the acoustic signals to understand how mid-water prey species such as small fish, squid, krill and jellyfish are distributed.
Mid-water prey (known collectively as micronekton), form the core of the ocean food web, transferring energy from primary producers at the ocean surface to top predators such as tunas, billfish, sharks, seals and seabirds.
The mass and distribution of micronekton reflects broad-scale patterns in the structure and function of the ocean, as well as the dynamics of marine ecosystems. But observations of micronekton in the Southern Hemisphere are sparse.
Samples of midwater prey species are collected to help scientists understand their different acoustic signals.
Acoustic mapping from fishing vessels provides rapid, cost effective sampling at a range of depths and locations, and at a fine level of detail (the water column is ‘measured’ every 20 metres).
The mapping will complement established observing systems such as physical sampling of ocean currents, surveys of ocean chemistry and biology (plankton and zooplankton), and electronic tagging and tracking of large marine fish and mammals.
The combined information will greatly enhance the capacity of marine scientists to monitor shifts in food availability over time, assisting in the monitoring and modelling of oceanography, ecosystems, fisheries and climate change, and in understanding the behaviour of top predators.
Acoustic backscatter (broad and and fine-scale) recorded on a transect across the Tasman Sea. Acoustic instruments on commercial fishing vessels are being used to map the distribution and abundance of mid-water prey in oceans surrounding Australia.
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