Don’t Hold Your Breath: Limited DNA Capture Using Non-Invasive Blow Sampling for Small Cetaceans

Document: Article
Abstract: Non-invasive conservation strategies currently used to monitor small cetaceans in the United Kingdom mainly focus on photo identification of individuals as a method to generate estimates of population status. With increasing anthropogenic pressures in the form of renewable energy developments, fishing, and tourism, there is a need for molecular techniques to more accurately measure population structure and health status of free-ranging cetaceans. Previous non-invasive DNA sampling has consisted of faecal, skin, or exhaled breath (blow) sampling. To date, blow sampling has been implemented primarily with an emphasis on microbial information, and field applications of this methodology have primarily targeted large mysticete cetaceans. In this study, we attempted to optimise an existing blow sampling protocol to enhance field sample collection and DNA recovery for both Tursiops truncatus and Delphinus delphis. Following previous recommendations, we streamlined the sampling approach to reduce the occurrence of avoidance behaviour and improve the precision for individual targeting. Overall, we collected 37 blow samples from T. truncatus (n = 7) and D. delphis (n = 30). Cetacean mtDNA was successfully extracted from one D. delphis sample, which is the first reported DNA detection of a small free-ranging cetacean from blow to our knowledge. Herein, we highlight the difficulty obtaining DNA from wild cetacean blow samples, despite improved collection success, and the uncertainty of determining the effects of storage on sample degradation prior to DNA extraction. We suggest future studies to improve DNA detectability through the use of robust preservatives such as an ethanol-sodium acetate solution. While promising, further optimisation is required to employ blow sampling as a conservation tool for estimates of respiratory microbial loads and individual identification for the purposes of genotype capture-recapture of small cetaceans.
Key Words: DNA, non-invasive, conservation, conservation genetics, Tursiops truncatus, Delphinus delphis
Page Numbers: 32-41

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