Monday, September 13, 2010
Hall B (Convention Center)
Otoliths are calcium carbonate 'earstones’ common to all bony fish. By sampling discrete growth rings on the otolith, it is possible to reconstruct environmental histories of individual fish and link them to lifetime movements. However, the effect of physiology on otolith chemistry is poorly understood, with gonad development and growth rate suggested to play a role. Here, we present preliminary results from an aquarium-based study investigating the blood trace metal composition of non-migrating plaice over a full reproductive cycle, and examining how changes in blood chemistry are expressed in the growing otolith.For one year (June 2009-10) immature and mature plaice (Pleuronectes platessa) were held in a large seawater tank and blood sampled at monthly intervals. Significant temporal, size- and sex-related differences in growth rate, condition, gonadosomatic index, plasma total protein and trace metal concentrations were observed. Otoliths will be retrospectively sampled for trace metals and stable isotopic ratios by laser ablation ICP-MS and ion microprobe, respectively, and trends in blood and otolith chemistry will be examined alongside concomitant changes in physiological condition.The identification of a chemical signal uniquely attributable to reproduction could potentially be used to improve estimates of spawning stock biomass, an important parameter in stock assessment models.