The monitoring of wildlife and broodstock health through endocrine assessments is critical to understanding reproduction and stress. However, collection of traditional blood samples can be difficult and the sampling process can alter the hormone profile. Therefore, NIST works with stakeholders to develop measurement techniques for the quantitation of hormones in non-traditional and less invasive matrices for the monitoring of wildlife health and reproductive yields of broodstock.
The use of matrices other than blood for endocrine assessment is a common necessity when working with species that are difficult to sample. Because hormones are often present in other tissues, matrices that are more easily collected in the field or from species where blood collection is difficult are often preferred. A reduction in the time to sampling or remote sampling have the added advantage of not inducing a measurable stress response, meaning that the sample collected is a baseline representation of that animal’s stress and reproductive profile. However, reliable measurement techniques must be developed to ensure accurate measurement using these matrices with poorly known matrix interferences. Therefore, NIST works with stakeholders to develop measurement techniques that allow for endocrine assessment using alternative matrices.
Blubber for the Environmental Assessment of Contaminants and Steroids (BEAConS): Working with partners at the Marine Mammal Foundation and NOAA, who is tasked with monitoring marine mammal health under the Marine Mammal Protection Act of 1972, NIST has developed new methods for the remote monitoring of steroid hormones and contaminants in blubber to assess population dynamics and reproductive health status of marine mammal stocks. From a remotely sampled dart biopsy of blubber (approximately 1 g in mass) the sex, reproductive status, stress status, and organic contaminant loads can be determined for a free ranging cetacean. This remote collection greatly reduces the manpower needed and the stress induced by blood collection for health and population assessments. NIST scientists have developed new mass spectrometry methods for the measurement of steroid hormones pathways in blubber using liquid chromatography tandem mass spectrometry and can pair this analysis with existing methods for persistent organic pollutants in blubber. This methodology increases the amount of information from one relatively simple sample collection, which can help stakeholders investigate endocrine disruption of free-ranging species or assess reproductive success or stress status pre and post disruptive events.
Fish Mucus for Selection of Broodstock: Atlantic salmon commercial yields in the US have dropped in production more than 35% since 2000 due, in part, to decreased embryo survival rates. Reduced embryo survival is due to gamete quality which can be influenced by endocrine status of adult salmon. Currently, the Atlantic salmon endocrine profile has not been measured with respect to their reproductive fitness. Using a combination of untargeted metabolomics and a more targeted steroidomics, NIST is working to develop methods to identify biomarkers of fertility in Atlantic salmon using skin mucus, a less-invasive matrix that is known to contain reproductive hormones and other metabolites. By working with stakeholders, NIST will help to identify better biomarkers of fish fertility to aid in the identification of high-yield broodstock and increase production of this important food source.