Mercury elimination by a top predator, Esox lucius

Area of Science:

• Environmental Science
• Ecotoxicology
• Fisheries Science

Background:

• Top piscivorous fish are valuable food sources but accumulate high levels of methylmercury (MMHg).
• Understanding MMHg elimination rates in these predators is crucial for human health risk assessment.
• Limited quantitative data exists on MMHg elimination kinetics in wild top predator fish.

Purpose of the Study:

• To quantify methylmercury (MMHg) elimination rates in northern pike (Esox lucius).
• To assess the persistence of accumulated MMHg in muscle tissue over time.
• To compare field-derived elimination rates with existing predictive models.

Main Methods:

• Northern pike naturally exposed to isotope-enriched MMHg were transferred to a mercury-free lake.
• Non-lethal muscle biopsies were collected over approximately 7 years.
• Isotope-enriched total mercury (THg) concentrations in muscle tissue were analyzed.

Main Results:

• Isotope-enriched THg persisted in pike muscle tissue throughout the 7-year study.
• THg burdens initially increased, then declined to 65% of original levels over 200 days, before plateauing.
• Estimated muscle THg half-life was 3.3 years, significantly slower than current model predictions.

Conclusions:

• Methylmercury elimination from northern pike muscle is a slow process.
• Current models may underestimate MMHg persistence in top predatory fish.
• Long-term field studies are needed to refine MMHg kinetic models for contaminated fisheries recovery.