Fish ear bones – ‘time capsules’ of river health
Niche is pleased to announce that we now offer archaeological fish otolith analysis as part of our specialist heritage management services to support our growing client base.
Dr Morgan Disspain, senior heritage consultant and expert in archaeological fish otolith analysis, has recently joined our team in northern NSW.
Morgan has more than 10 years of professional experience in cultural heritage management and archaeological research. She has published extensively – and received numerous awards – for her research on the analysis of archaeological fish remains.
What are fish otoliths?
Fish otoliths are hard, calcium carbonate structures that help with a fish’s balance and hearing and are located in the head of all bony fish, directly behind the brain. Otoliths are frequently recovered from archaeological sites.
“They hold a wealth of unique information within their makeup,” explains Morgan.
“Different fish species have otoliths of different shapes and sizes, and an otolith’s internal structure has seasonal growth rings, similar to those of a tree,” she continues.
“Features of otoliths can be used to identify the species, size, age, growth rate and season of death of an individual fish.”
What can we learn from fish otolith analysis?
Analysis of the oxygen isotope values of fish otoliths can provide information on the temperature of the water in which the fish lived, while studying concentrations of trace elements such as barium can indicate the salinity levels of the water.
Being organic, otoliths can also be radiocarbon dated, and information gained from such analyses can address broad and often key archaeological issues.
Otolith studies frequently contribute to answering questions focusing on changes in fish population structures, including examining impacts of intense human predation, environmental change and habitat destruction.
When this data is compared with modern records, changes in fish populations and environmental conditions can be assessed. Services include:
• Species identification
• Fish size estimation
• Fish age at death determination
• Season of death
• Trace elemental analyses
• Isotope analysis
For examples of the outcomes of Dr Disspain’s fascinating research, see her recent article in The Conversation.
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