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More than 70% of the earth’s surface is covered by the ocean, hosting the vast majority of the world’s biodiversity. However, their exploration has always been limited by the difficulty of observation, both because of the physical and chemical properties of the water in which the marine species live and because of their three-dimensional movements. In fact, it is estimated that around 95% of the volume of the ocean has yet to be discovered .

The
Marine Strategy Framework Directive
requires European Union Member States to assess and monitor the environmental status of their marine waters. For this purpose, various functional groups, including cetaceans, are monitored and evaluated, the main method for their evaluation being the study of trends in their abundance.

Traditional methods, based on distance sampling using oceanographic vessels, are expensive and complex and depend on good environmental conditions for them to develop successfully, so they are widely spaced out over time, making it difficult to assess populations and highlighting the need to look for new alternatives. Thus, the development and improvement of observation and analysis techniques will be key to understanding the functioning of their ecosystems, as highlighted by the Spanish National Research Council (CSIC).

In this context, the project has sought to contribute to the improvement of monitoring programmes by developing two innovative methodologies in three areas of the North Atlantic demarcation: detection of DNA of these organisms in water (environmental DNA or eDNA) and use of remotely controlled aerial vehicles (drone) to estimate their presence and abundance.

The general objective of the project has been to contribute to the improvement of cetacean abundance monitoring programmes within the framework of the Marine Strategies.

The specific objectives were as follows:

• Design the sampling plan to be developed in the North Atlantic demarcation.
• Obtain water samples in two areas of the aforementioned demarcation for the determination of environmental DNA (eDNA).
• To obtain sighting data in two areas of the North Atlantic demarcation.
• To analyze the presence of environmental DNA (eDNA) of cetaceans in samples collected in the three areas of this demarcation.
• Analyze the sighting data collected in the three zones of the demarcation.
• Interpret the results of laboratory analyses and sighting data.
• Make proposals for methodological improvements and analyze their implications for marine policies.

• 6 samplings in different strategic points of the Vigo estuary for the collection of environmental DNA (eDNA).
• Planning of cetacean sighting surveys through the use of unmanned aerial vehicles (drones).
• Planning of the collection of data on cetacean sightings in the continental shelf area and the taking of water samples for the detection of eDNA during the PELACUS oceanographic campaign of the Spanish Institute of Oceanography (IEO). During the transects, mammals, seabirds, large pelagic fish, floating garbage, boats and fishing gear are recorded.
• Collection of water samples for eDNA analysis in the Vigo estuary in order to detect the three most abundant cetacean species in the sampled area: bottlenose dolphin(Tursiops truncatus), common dolphin(Delphinus delphis) and porpoise(Phocoena phocoena). The aim was also to test the potential of this technique as a complementary tool to visual detection methods for estimating the distribution of these marine mammals.
• Collection of water samples for eDNA analysis in the continental shelf area, specifically in northwestern and northern Spanish waters from the south of Galicia on the border with Portugal to the border with France.
• Sighting data collection in the coastal area of the Vigo estuary with drones.
• Collection of sightings data in order to study the distribution of top predators (those at the top of the food chain) on the continental shelf of the north and northwest of the Iberian Peninsula, as well as to analyze the factors affecting their distribution.
• Analysis of water samples for the detection of cetacean eDNA in the sampled areas.
• Analysis of sighting survey data in oceanic waters of the Spanish North Atlantic Demarcation in order to provide estimates of the population abundance of the most abundant cetacean species in European Atlantic waters, in the framework of the SCANS-IV campaign.
• Data analysis of the sightings recorded in the Spanish North Atlantic Demarcation within the framework of the IEO PELACUS campaign.
• Data analysis of the sightings recorded in the Vigo estuary with drones.
• Comparative study of the relationships between presences detected by sightings and those detected by eDNA analysis in the three areas of the North Atlantic Demarcation.
• Use of new technologies based on environmental DNA detection to correct false absences detected and estimates of sighting surveys from oceanographic vessels.
• Assessment and proposals for the use of drones to estimate the abundance and detect the presence of cetaceans in coastal areas.
• Review of the marine mammal monitoring programs of the Marine Strategies Framework Directive, as well as the methodologies used and the evaluation criteria, in order to develop proposals for improving the methodologies currently used in these programs.
• Dissemination and communication of the project in order to promote greater knowledge of cetaceans and the marine environment, as well as the methods used for their study and conservation: production of 3 articles in the digital press, participation in a radio interview, publication of content on social networks, preparation of leaflets, infographic posters and an informative video, publication of a scientific article and participation in two congresses of the Spanish Cetacean Society (SEC) and the European Cetacean Society (ECS).

Traditional methods for monitoring and assessing cetaceans are based on visual and acoustic sampling to study parameters such as distribution and abundance. These methods are carried out from oceanographic vessels or airplanes, which are often expensive, logistically complex and depend on good environmental conditions to be successful. For this reason, in recent years it has become evident that there is a need to look for new alternatives that contribute to the improvement of monitoring programs.

In this context, the project “New molecular and remote control technologies for the assessment of cetacean populations (NuTEC)” has tested the application of two innovative methodologies for the monitoring of cetacean populations in the north and northwest of the peninsula: environmental DNA analysis (eDNA) and the use of unmanned aerial vehicles (drones). In this sense, a protocol has been developed for the collection and analysis of eDNA with the aim of detecting marine mammals from the genetic fingerprint that remains in the water after their passage.

This methodology has made it possible to detect different species of dolphins (common, bottlenose, striped and gray dolphins, pilot whales and killer whales), whales (fin and minke whales) and even elusive species such as beaked whales and porpoises, providing complementary data to those found in visual surveys.

In this regard, the entity emphasizes that this analysis has limitations, as it does not allow for abundance estimates of the species detected. Thus, it is concluded that comparisons between eDNA detections and sightings in a given area are not possible since no direct relationship between them has been observed.

On the other hand, the use of drones for the aerial monitoring of cetaceans has shown great potential both for species identification and group size estimation, as well as for the study of their behavior and/or body condition, both through specific flights and programmed missions.

At the same time, various actions have been carried out aimed at promoting greater knowledge of cetaceans and the marine environment, as well as the methods used for their study and conservation, through educational resources of high graphic quality to reach the general public (such as leaflets, infographic posters and an informative video), in addition to other communications focused on the scientific field (presentation in two congresses, day of presentation of results and publication of a scientific article).

Ultimately, the project emphasizes the relevance of monitoring programs to both assess population status and manage anthropogenic threats to marine mammal populations.