Genetic Sex Determination of Free-Ranging Short-Finned Pilot Whales from Blow Samples

Abstract

Whale blow, the vapor exhaled during respiration of cetaceans, provides valuable genetic information to monitor health status and population dynamics. However, obtaining samples of sufficient quality and quantity remains a challenge, particularly for small odontocetes. Here, we developed both field and laboratory protocols optimized for the genetic analysis of blow samples of short-finned pilot whales (Globicephala macrorhynchus). Blow collection was performed from a small research vessel at a slow speed using a hand-held carbon fiber pole equipped with a sterile Petri dish. Determination of the sex was conducted using up to five PCRs of multiplexed markers from a classical methodology (SRY + ZFX/ZFY genes) and a novel protocol (SRY + FCB17) optimized for highly degraded, fragmented and/or scarce DNA. A total of 47 blow samples of free-ranging pilot whales off the Canary Islands were collected. The presence of DNA was confirmed in 98% of the blow samples, which were further processed resulting in 32 of them with positive genetic sex determination applying the novel methodology (70%), compared to only 8 (19%) with the classical method. Results confirmed the success of sampling, DNA extraction and sex determination using multiplexed markers in blow samples of odontocetes. This protocol represents an important management tool to conduct future non-invasive health assessments of small cetaceans in the wild.