Salinity-linked growth in anguillid eels and the paradox of temperate-zone catadromy.

摘要: Temperate-zone anguillid eels use both saline (marine or brackish) and fresh waters during their continental phase, but of is paradoxical because on average these fishes grow more rapidly in than waters. Based data from whose habitat-residency histories had been determined by Sr:Ca otolithometry, superiority growth rates water much greater American Anguilla rostrata north-eastern North America (mean saline:fresh rate ratio 2.07) European anguilla, Japanese japonica shortfinned australis (range mean ratios 1.12-1.14). Data A. the Hudson Estuary, U.S.A., Prince Edward Island, Canada, were used to test adaptive explanations catadromous migrations. The hypothesis that lower mortality offsets faster was not supported loss (mortality + emigration ) did vary between zones Estuary. Hypotheses move escape larger evaluate habitat quality size age distributions. Catadromy temperate-zone increases diversity occupied habitats therefore lowers fitness variance caused environmental fluctuations. could be due natural selection for maximum geometric which sensitive variance. catadromy might also maladaptive, at least local areas, shifts over time selective pressures inability panmictic genetic systems adapt conditions.