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Researchers working to help determine age of fish stocks
Date: Tuesday, 28 July 2009
Lee Higgins and Jan St Quintin have been using diamond tip saws to dissect fish ear bones for more than a decade, as part of critical research undertaken by the Department of Fisheries at its Hillarys laboratories.
Commercial and recreational fishers regularly donate fish frames, for use by the research team.
The otoliths (ear bones) are then removed and handed over to Lee and Jan.
Lee and Jan go through the process of cutting thin sections of the ear bones, which are then put on slides and examined under a microscope.
The image from the microscope is projected onto a computer screen so that the internal bands can be seen clearly. Each set of bands represents one year of growth.
By counting the bands, the age of the fishes can be determined, much like counting the growth rings in a tree trunk.
Lee has been working at the department for 14 years, and Jan since 1988, together with another team member Helen Mee.
Supervising scientist Dr Brett Molony said knowledge of the age of a fish is critical for assessing the health of the stock from where it comes.
“Age structures (how many fish of each age are in a population), size and age at maturity and how long fish live, all provide useful information for fisheries’ management,” Dr Molony said.
“This knowledge will help us determine if fish stocks are being exploited sustainably and to provide advice on strategies to manage these vulnerable stocks.”
This work also supports the tough new regulations for recreational fishing recently introduced, ongoing research into Western Australia's recreational fisheries, which has led to the recent introduction of measures to ensure its sustainability.
Research has already indicated that unless catch reductions were made, some of WA’s iconic fish species, such as dhufish, pink snapper and baldchin groper, remain threatened.
Commercial and recreational fishers regularly donate fish frames, for use by the research team.
The otoliths (ear bones) are then removed and handed over to Lee and Jan.
Lee and Jan go through the process of cutting thin sections of the ear bones, which are then put on slides and examined under a microscope.
The image from the microscope is projected onto a computer screen so that the internal bands can be seen clearly. Each set of bands represents one year of growth.
By counting the bands, the age of the fishes can be determined, much like counting the growth rings in a tree trunk.
Lee has been working at the department for 14 years, and Jan since 1988, together with another team member Helen Mee.
Supervising scientist Dr Brett Molony said knowledge of the age of a fish is critical for assessing the health of the stock from where it comes.
“Age structures (how many fish of each age are in a population), size and age at maturity and how long fish live, all provide useful information for fisheries’ management,” Dr Molony said.
“This knowledge will help us determine if fish stocks are being exploited sustainably and to provide advice on strategies to manage these vulnerable stocks.”
This work also supports the tough new regulations for recreational fishing recently introduced, ongoing research into Western Australia's recreational fisheries, which has led to the recent introduction of measures to ensure its sustainability.
Research has already indicated that unless catch reductions were made, some of WA’s iconic fish species, such as dhufish, pink snapper and baldchin groper, remain threatened.
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