LAUSR

Patterns of mother-embryo fractionation of 13 C and 15 N were assessed for their predictability across three species of batoids caught as bycatch in south-eastern Australia. Stable isotope analysis of 24 mothers and their litters revealed that isotope ratios of embryos were significantly different from their corresponding mothers, and that the scale and direction of the difference varied within and across species. The range of variation across species was 3.5‰ for ẟ13 C and 4‰ for ẟ15 N, equivalent to a difference in trophic level. In one species (Urolophus paucimaculatus) litters could be significantly enriched or depleted in 13 C and 15 N relative to their mothers' isotope signatures. These results suggest that patterns of mother-embryo isotope fractionation vary within and between species and that these patterns may not be explained by developmental mode alone. Contrasting patterns of fractionation between and within species makes it difficult to adjust mother-embryo fractionation with broad-scale correction factors. This article is protected by copyright. All rights reserved.