Records of harbour porpoise (Phocoena phocoena) in the mouth of the Douro River (northern Portugal) with presence of an anomalous white individual

Abstract

Background: Harbour porpoise (Phocoena phocoena) is listed under the Annex II of the European Habitats Directive (Directive 92/43/CEE) and Member States are required to designate special areas of conservation to protect their populations. Although harbour porpoise distribution in the Iberian Peninsula has been described, the mouth of the Douro River was never reported as part of its range of distribution. Methods: Observations from a pier in the mouth of the Douro were carried out to monitor the presence of the harbour porpoises. A monthly measure of sightings per unit of effort was calculated. Information on the sightings, group sizes and records of the white individual is presented. Results: Twenty six surveys were performed resulting in 22 sightings with group size varying from one to three animals. The white individual was sighted 12 times and recorded both in photographs and video. July was the month with the lowest number of sightings per unit of effort (SPUE), while October had the highest SPUE. Conclusions: Evidences, such as the presence of an easily recognizable white individual and the reports from local sea-users suggest a degree of site fidelity from this group of harbour porpoises in the mouth of the Douro River. However, further studies are needed to support the effective management and conservation of this group.

A Scientometric Review on Leucism in Wild Dolphins

“…However, both juvenile and adults were reported in the 14 articles investigated herein. This corroborates several previous assessments in marine mammals, indicating evident survival and relative longevity of leucistic individuals (Forestell et al, 2001;Tonay et al, 2012;Robinson & Haskins, 2013;Gil et al, 2019), both male and females, in line with studies indicating no associations to negative consequences in a specific habitat for several species (Abreu et al, 2013;Kopaliani et al, 2017). For example, Antarctic fur seals (Arctocephalus gazella) from Bird Island, South Georgia, displaying hypopigmentation attributed to leucism were identified as homozygous for a nonsynonymous mutation within the MC1R gene.This results in the substitution of serine with phenylalanine at an evolutionarily highly conserved structural domain.…”

Defining a common language to assess external deformities in free‐ranging cetaceans

“…Reif et al 2009, Taylor et al 2021); anomalous pigmentation can indicate congenital conditions leading to individuals being more susceptible to environmental stressors (e.g. Alves et al 2017, Gil et al 2019); emaciation is indicative of malnutrition (e.g. Pettis et al 2017); epibionts may indicate immunosuppressed individuals that are more susceptible to parasites (e.g.…”

“…cuts, fin amputation) should, therefore, be included in standard photo‐ID procedures as identification tools. Previous studies have used these features to recognise individuals and track their life histories, providing information about residency (Gil et al 2019), movements (Urbán‐Ramirez et al 2004), and habitat use (Bradford et al 2011).…”

“…Externally detected conditions offer additional and important clues for the identification of free‐ranging individuals, particularly when there are persistent marks (e.g. due to amputation, anomalous pigmentation, or deep scars; Urbán‐Ramirez et al 2004, Nascimento et al 2008, Bradford et al 2011, Gil et al 2019).…”

Autonomous Deployment of Underwater Acoustic Monitoring Devices Using an Unmanned Aerial Vehicle: The Flying Hydrophone

“…Abundance and distribution can be determined using several methods with visual and acoustic techniques being the most common [21,22]. Visual observations of harbour porpoises are used to collect information on their presence and surface behaviour and are commonly carried out from planes [23,24], ships [18,[25][26][27], and in some cases, from land [28]. Acoustic-based surveys are dependent on the underwater vocalisations of the species of interest and can be achieved through passive acoustic monitoring.…”