Mercury concentrations in 4 carcharhinid and 3 hammerhead sharks from coastal waters of the Northern Territory

Analysis of mercury in muscle tissue of four species of carcharhinid shark (genus Carcharhinus) and three species of hammerhead shark (genus Sphyrna) from coastal waters of the Northern Territoryhas indicated that each of the species studied accumulates relatively high concentrations of mercury.Maximum observed concentrations in all species except C. sorrah (Valenciennes) exceeded 1 • 5 mgkg-1. Concentrations greater than 4 mg kg-1 were recorded in C. amblyrhynchoides (Whitley), S. lewini(Griffith & Smith) and S. mokarran (Rtippell). Mercury concentration was highly dependent on sharksize and increased more or less exponentially with length. Apart from S. lewini and S. mokarran, there were significant differences between length-mercury relationships for males and females of eachspecies. At a given length, males tended to have accumulated higher concentrations of mercury thanfemales. With the exception of C. sorrah, weighted mean concentrations of mercury for each speciesexceeded the current National Health and Medical Research Council standard for mercury of0 - 5 mg kg-1. Implications of possible management based on mercury standards are considered usinginformation available for C. limbatus (Valenciennes) and C. sorrah. © CSIRO 1984.<p></p>