The earbones, or 'otoliths', help fish to detect movement and to orient
themselves in the water. Otoliths set down annual growth rings that can
be measured and counted to estimate the age and growth rates of fish.
"Otoliths can form the basis of new techniques for modelling fish
growth, productivity and distribution in future environments," said Dr
John Morrongiello of CSIRO's Wealth from Oceans Flagship, lead author of
a paper published online in Nature Climate Change November 28. "They
are widely used to support fishery stock assessments, and are beginning
to be used to measure and predict ecological responses to ocean warming
and climate change. "Any change identified in growth and age
maturity, especially of commercially-important species, clearly has
implications for forecasting future stock states and the sustainable
management of fisheries." Dr Ron Thresher, CSIRO Marine and Atmospheric Research "Millions
of otoliths are archived in research laboratories and museums
worldwide, and many fish species live for decades and some, such as
orange roughy, live for up to 150 years. "Their otoliths record
variations in growth rates that reflect environmental conditions.
Longer-lived fish and older samples take us back as far as the 1800s." The
paper, co-authored by Dr Ron Thresher and Dr David Smith of CSIRO,
builds on earlier research by Dr Thresher that identified the potential
of using fish 'hard parts', (such as otoliths), and deep ocean corals to
understand environmental change. It outlines a framework in which
Australian research institutions can analyse hard parts and assess past
and future impacts on a range of species. In the next research
phase, scientists at CSIRO, the Australian Institute of Marine Science
and the University of Adelaide will study selected species of commercial
interest, including tiger flathead, black bream, blue gropers,
barramundi and tropical snappers. "We will use otoliths to
investigate the environmental drivers of fish growth for many species
around Australia," Dr Morrongiello said. "This will allow us to
generate a continental-scale evaluation of climate change impacts on
Australia's fishes and help to guide the conservation and management of
our aquatic environments into the future." Dr Thresher said there
had already been extensive use of hard part archives from corals to
reflect on climate variability, such as El Niño events, and to
reconstruct environmental histories. "Any change identified in
growth and age maturity, especially of commercially-important species,
clearly has implications for forecasting future stock states and the
sustainable management of fisheries," Dr Thresher said. "A better
ability to predict such change will greatly enhance our ability to
forecast, manage and adapt to the impacts of climate change in marine
and freshwater systems."
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