FISH OTOLITHS

 

 

Otoliths are inner ear structures in fish and they grow similarly to tree rings in that each ring represents a single year of the life of the fish. Our analysis with lasers can examine the changes in metal exposure throughout those years. Why does this matter? The otoliths can reveal:

  • temporal changes in metal exposure as salmon migrate from the ocean to their natal streams;

  • how the introduction of mine effluent has influenced metal concentrations in local fish populations;

  • the effectiveness of water treatment on aquatic ecosystems by comparing pre-treatment with post-treatment rings within the same otolith; and,

  • in old fish (>10 years), the state of water quality in an aquatic system from many years previous.

Fish otoliths can replace the need for fish tissue analysis typically required for aquatic monitoring programs, such as Environmental Effects Monitoring (EEM) in the mining industry. Single otoliths from fish >1 year old can provide multi-year data as compared to a single, short-term look of metal exposure obtained from the muscle. Multi-year fish harvesting programs for fish tissue analysis can be replaced with single-year otolith analyses. This results in not only cost-savings, but it negates the need for over-harvesting of fish for environmental monitoring programs. Grand perspectives can come from a microscopic viewpoint.