Detection of the elusive Dwarf sperm whale (Kogia sima) using environmental DNA at Malpelo island (Eastern Pacific, Colombia).

Jean‐Baptiste Juhel,Virginie Marques,Tony Dejean,Sandra Bessudo,Régis Hocdé,Eilísh Richards,Nicolas Loiseau,Alice Valentini,Camille Albouy,Giomar H Borrero‐Pérez,Tom B Letessier,Stéphanie Manel,Andrea Polanco Fernández,Felipe Ladino,Florine Hadjadj,David Mouillot,Maria Mutis Martinezguerra,Loïc Pellissier,Laure Velez

doi:10.1002/ece3.7057

Abstract

Monitoring large marine mammals is challenging due to their low abundances in general, an ability to move over large distances and wide geographical range sizes.The distribution of the pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales is informed by relatively rare sightings, which does not permit accurate estimates of their distribution ranges. Hence, their conservation status has long remained Data Deficient (DD) in the Red list of the International Union for Conservation of Nature (IUCN), which prevent appropriate conservation measures.Environmental DNA (eDNA) metabarcoding uses DNA traces left by organisms in their environments to detect the presence of targeted taxon, and is here proved to be useful to increase our knowledge on the distribution of rare but emblematic megafauna.Retrieving eDNA from filtered surface water provides the first detection of the Dwarf sperm whale (Kogia sima) around the remote Malpelo island (Colombia).Environmental DNA collected during oceanic missions can generate better knowledge on rare but emblematic animals even in regions that are generally well sampled for other taxa.

Highlights

Marine mammals are among the most threatened vertebrates on earth with 37% of them being considered as endangered by the International Union for Conservation of Nature (IUCN) (e.g., Albouy et al, 2020)
Environmental DNA metabarcoding uses DNA traces left by organisms in their environments to detect the presence of targeted taxon, and is here proved to be useful to increase our knowledge on the distribution of rare but emblematic megafauna
Environmental DNA can detect and identify accurately the species, avoiding observer related errors in records. These results highlight the promises of eDNA as an alternative to standard monitoring methods for cetaceans, without requiring a close approach of a vessel

Summary

| INTRODUCTION

Marine mammals are among the most threatened vertebrates on earth with 37% of them being considered as endangered by the IUCN (e.g., Albouy et al, 2020). The pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales are porpoise-like shaped odontocetes smaller than 4 m (Plön, 2004) that are able to travel long distances (e.g., 255 nautical miles in 4 days, Scott et al, 2001) They occur worldwide in tropical and temperate waters including Colombia (Rice, 1998) and count 1,931 records (1,627 at the species level) of opportunistic sightings and strandings referenced in OBIS (Ocean Biogeographic Information System, www.obis.org, January 2020) and 2,503 records (2,223 at species level) in GBIF (Global Biodiversity Information Facility, www.gbif.org, for example, Mora-Pinto et al, 1995). We document the first detection of the uncommon Dwarf sperm whale (Kogia sima) around the remote Malpelo island (Colombia) using eDNA

| METHODS

Findings

| DISCUSSION