Abstract. Relative body size has long been recognized as a factor influencing reproductive success in fishes, but maternal age has only recently been considered. We monitored growth and starvation resistance in larvae from 20 female black rockfish (Sebastes melanops), ranging in age from five to 17 years. Larvae from the oldest females in our experiments had growth rates more than three times as fast and survived starvation more than twice as long as larvae from the youngest females. Female age was a far better predictor of larval performance than female size. The apparent underlying mechanism is a greater provisioning of larvae with energy-rich triacylglycerol (TAG) lipids as female age increases. The volume of the oil globule (composed primarily of TAG) present in larvae at parturition increases with maternal age and is correlated with subsequent growth and survival. These results suggest that progeny from older females can survive under a broader range of environmental conditions compared to progeny from younger females. Age truncation commonly induced by fisheries may, therefore, have severe consequences for long-term sustainability of fish populations.
Nephrops norvegicus (L.) from fishing grounds on the west coast of Scotland has been found to harbour infection by a species of parasitic dinoflagellate. Chromosome morphology and ultrastructural features suggest that the parasite is a member of the botanical order Syndiniales, possibly related to Hematodinium perezi Chatton & Poisson 1931. Cells invading the haemal spaces, however, show no signs of flagella. Mode of transmission IS not yet known, and a flagellate spore stage has not been identified. Infection appears to be fatal to its host, the main cause of death possibly being disruption of gas transport and tissue anoxia caused by the proliferation of large numbers of dinoflagellate cells in the haemolymph. Severe infection has an adverse effect on meat quality that has provoked comment from fisherman and processors. Affected lobsters have been found at all west coast sites surveyed, with peak infection rates reaching 70 % of trawled samples. Infection occurrence shows marked seasonality coincident with the annual moult perlod of N. norvegicus. An increased prevalence of infection has been observed recently in some areas.
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