Assessing reproductive status in elasmobranch fishes using steroid hormones extracted from skeletal muscle tissue.

B K Prohaska,J A Sulikowski,A C Brown,P C W Tsang,C R Wheeler,W B Driggers,E R Hoffmayer

doi:10.1093/conphys/cot028

Abstract

Elasmobranch fishes (sharks, skates, and rays) are particularly susceptible to anthropogenic threats, making a thorough understanding of their life history characteristics essential for proper management. Historically, elasmobranch reproductive data have been collected by lethal sampling, an approach that is problematic for threatened and endangered species. However, recent studies have demonstrated that non-lethal approaches can be as effective as lethal ones for assessment of the reproductive status of an animal. For example, plasma has been used to examine concentrations of steroid hormones. Additionally, skeletal muscle tissue, which can be obtained non-lethally and with minimal stress, can also be used to quantify concentrations of steroid hormones. Skeletal muscle progesterone, testosterone, and estradiol concentrations were determined to be statistically significant indicators of reproductive status in the oviparous Leucoraja erinacea, the yolk-dependent viviparous Squalus acanthias, and the yolk-sac placental viviparous Rhizoprionodon terraenovae. The results of the present study demonstrate that steroid hormones present in non-lethally harvested skeletal muscle tissue can be used as reliable indicators of reproductive status in elasmobranchs.

Highlights

The life history characteristics of many elasmobranchs, such as slow growth and late age at maturity, make these fishes susceptible to overexploitation (Dulvy et al, 2003)
R. terraenovae were captured by bottom longline in the northern Gulf of Mexico in an area centred around 88.812°W and 27.887°N, while S. acanthias were captured by bottom trawl and gill net in the US Northwest Atlantic in an area centred around 70.115°W and 42.471°N
The present study reported the successful detection of steroid hormones in the skeletal muscle of female R. terraenovae, L. erinacea, and S. acanthias during specific stages of their reproductive cycles

Summary

Introduction

The life history characteristics of many elasmobranchs, such as slow growth and late age at maturity, make these fishes susceptible to overexploitation (Dulvy et al, 2003). A comprehensive understanding of their life history characteristics is needed. Data on these characteristics are lacking for many species (Castro et al, 1999; Walker, 2004; Pinhal et al, 2008; IUCN, 2011). Essential life history characteristics needed for proper management include age/ size at maturity, gestation length, and reproductive cyclicity (Walker, 2004, 2005).

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Discussion

Conclusion