Uncovering the Effects of Ship Noise on Pilot Whale Populations in Tenerife

by Marín, O., Arranz, P., Johnson, M. and Aguilar de Soto, N BIOECOMAC Lab, University of La Laguna

This news article is part of Issue 2 of our annual newsletter, which chronicles our research in 2022. To view more articles describing our research progress from our second year, read the newsletter in full here.

Above: Drone operated by Dr. Patricia Arranz during the development of the CETTUS project. In the Canaries, the UAVs were operated under a UAV Operator license (Register # 2020064914) and an Advanced Certificate of aircraft piloted by remote control (RPA20605OT and RPA20605OP) under the Spanish Aviation Safety and Security Agency (AESA). © Universidad de La Laguna.

We are excited to share with you the latest findings from our ongoing research at the BIOECOMAC lab at the University of La Laguna (ULL) in the Canary Islands, Spain. Over the past year, we have been utilizing cutting- edge techniques such as passive acoustic methods (PAM) and analyzing maritime traffic data to gain a deeper understanding of the sounds that are most harmful to cetaceans in the area. Additionally, we have been utilizing drone images to study short-finned pilot whale (Globicephala macrorhynchus) populations in the Teno- Rasca special area of conservation on the island of Tenerife. We are pleased to report that funding for this work has been successful. Fieldwork in 2022 was financed by SATURN while the 2021 field season was financed by complementary funds from other projects, such as the Office of Naval Research (ONR) from the U.S. and the LIFE Programme of the European Climate Infrastructure and Environment Executive Agency.

During the field seasons in 2021 and 2022, we tagged 17 pilot whales and collected over 100 hours of recordings. This data has allowed us to better understand the impact of ship noise on these populations and how it affects their behavior. The sampling tasks were performed south of the Teno-Rasca maritime strip, an area known for its steep bathymetry, which makes it ideal for observing pilot whales directly from a land-based observation station. This station, located on the mountain of Chayofita in Los Cristianos, enabled our research team to track groups of animals and make predictions about their movements. Furthermore, we used an Automatic Identification System (AIS) receptor to record maritime traffic in the area during tagging operations and for the duration of the time that a DTAG was affixed to a pilot whale. A visual survey of the boats was also carried out every 15 minutes to obtain a more complete understanding of the maritime traffic in the area and its potential impact on the pilot whale populations we are studying.

Above: Tagging maneuver on a pilot whale. The DTAG is attached to a tagging pole. © Universidad de La Laguna.

Our preliminary analysis of the data collected from the tags has revealed some interesting findings about the feeding cycles of these animals. The recordings include both diurnal and nocturnal feeding cycles. The mean time that the DTAGs remained on the pilot whales was 6.6 hours, with the tag remaining on one animal for as little as 1.2 hours and as long as 20.3 hours. These findings are aiding us in better understanding the behaviors and habits of these pilot whale populations and how they may be affected by anthropogenic stressors. In order to expand our understanding of anthropogenic disturbances, we are collaborating with Dr. Patricia Arranz to investigate the impact of these disturbances on the nutritional health of individual animals. To achieve this goal, we are utilizing a variety of techniques such as measuring the morphometrics, allometrics, and body condition of cetaceans in their natural habitats.

Recently, we have been utilizing unmanned aerial vehicles (UAVs) to study the body shape, allometric relationships, and body condition of free-ranging short-finned pilot whales. We have taken photographs of the dorsal and lateral sides of the whales, measuring their body length, width, and height. We have also classified the whales into three age classes based on their total body length (BL). We have collected data from 77 whales (mean ± SD), including 9 calves (2.37 m ± 0.118), 31 juveniles (2.90 m ± 0.183), and 37 adults (3.72 m ± 0.440). Our findings are providing us with a deeper understanding of the health status of these populations and the ways in which they may be vulnerable to anthropogenic stressors. This information is critical for the long-term monitoring and conservation of these species. Our study is providing insights into the morphometrics, allometrics and body condition of free- ranging short-finned pilot whales and how they can be used to assess and monitor the health of cetacean populations. This will help us to better understand the vulnerability of these species to potential anthropogenic stressors and contribute to the management and conservation of these species.

As we continue to gather data and analyze ourfindings,weareexcitedtosharemore of our progress and discoveries with you in the coming months. This research project is being conducted in collaboration with Dr. Patricia Arranz, Dr. Frederik Christiansen and Dr. Kate Sprogis. If you have any questions or would like to learn more about our research, please don’t hesitate to reach out to us. We look forward to keeping you updated on our progress and contributing to the conservation and management of these animals.