Integrating acoustic and genetic methods to understand cetacean presence and distribution

The "Sphyrna Odyssey 2019-2020" mission combined passive acoustic monitoring and environmental DNA (eDNA) to monitor marine mammals in the Mediterranean, focusing on areas impacted by heavy marine traffic. Sphyrna autonomous vessels, equipped with hydrophones, provided real-time detection of vocalizing species [1], while eDNA sampling from surface waters captured genetic traces over larger spatial areas, including busy shipping lanes [4]. Acoustic monitoring provided real-time data on vocalizing species, while eDNA detected species even in the absence of vocalizations, though factors like ocean currents and DNA degradation influenced results [3]. Both methods identified eight cetacean species, revealing higher densities along continental slopes, submarine canyons, and areas with significant shipping traffic. This study highlights the value of integrating acoustic and genetic methods to understand cetacean presence and distribution, crucial for conservation in high-impact regions [2].

[1] Glotin, H., Spong, P., Symonds, H., Roger, V., Balestriero, R., Ferrari, M., ... & Dakin, T. (2018)  Deep learning for ethoacoustical mapping: application to a single Cachalot long term recording on joint observatories in Vancouver Island. The Journal of the Acoustical Society of America, 144(3), 1776-1777.

[2] Glotin H., Thellier N., Best P., Poupard M., Ferrari M., Vieira S., Giés V., ... Sarano F., Benveniste J., Gaillard S., de Varenne F. (2020) Sphyrna-Odyssey 2019-20, Découvertes Etho-acoustiques de Chasses Collaboratives de Cachalots en Abysse & Impacts en Mer du COVID19, http://sabiod.org/pub/SO1.pdf, 197p, Univ. de Toulon, CNRS

[3] Collins, R. A., Wangensteen, O. S., O’Gorman, E. J., Mariani, S., Sims, D. W., & Genner, M. J. (2018). Persistence of environmental DNA in marine systems. Communications Biology, 1(1), 185.

[4] Ficetola, G. F., Miaud, C., Pompanon, F., & Taberlet, P. (2008). Species detection using environmental DNA from water samples. Biology letters, 4(4), 423-425.