Cetaceans Sightings During Research Cruises in Three Remote Atlantic British Overseas Territories

Stephanie M Martin,Marta Soeffker,Simon A Morley,Rhys Hobbs,Andy Schofield,Trevor Glass

doi:10.3389/fmars.2021.660152

Abstract

Marine mammal sightings were recorded during research cruises to three remote, mid-ocean British Overseas Territories in the South Atlantic and Southern Ocean. In March to April 2018 and 2019, the Exclusive Economic Zones (EEZs) of tropical St Helena and temperate Tristan da Cunha were surveyed. The sub-polar waters of South Georgia and the South Sandwich Islands (SGSSI) were surveyed in February to March 2019. At St Helena in 2018, five species were recorded during 11 sightings, and in 2019, four species, with one additional unidentified species, during seven sightings. Most of these sightings were of dolphin species, which are known to be resident around the Island and seamounts. In Tristan da Cunha in 2018, a total of five identified and one unidentified species were recorded during six sightings, half of which were associated with the Islands or seamounts. In 2019, due to rough weather, no sightings were recorded in the Tristan da Cunha waters. Around SGSSI, 162 sightings of 236 cetaceans were made in 2019, mostly of baleen whales, with seven species identified with certainty. Sightings around the southern South Sandwich Islands included beaked whales and large dolphins, whereas baleen whales dominated in the northern South Sandwich Islands. These results provide new data for rarely surveyed regions, helping to build a spatial picture of important areas for marine mammals, which will help inform marine spatial protection strategies.

Highlights

The remote British Overseas Territories in the South Atlantic (St Helena and Tristan da Cunha) and in the Southern Ocean (South Georgia and the South Sandwich Islands - SGSSI) span the global migration routes of cetaceans, from tropical breeding to polar feeding grounds (Figure 1)
The Blue Belt Programme further funded a survey of the South Sandwich Islands in austral autumn 2019
St Helena is tropical with one main Island (12–19◦S), while Tristan da Cunha is further south and spans the sub-tropical convergence (33–43◦S) with three main Islands in the northern group and Gough Island to the south

Summary

INTRODUCTION

The remote British Overseas Territories in the South Atlantic (St Helena and Tristan da Cunha) and in the Southern Ocean (South Georgia and the South Sandwich Islands - SGSSI) span the global migration routes of cetaceans, from tropical breeding to polar feeding grounds (Figure 1). The exclusive economic zones (EEZs) of these territories provide habitat for resident cetacean populations Due to their remoteness the lack of, or limited data, makes it difficult to assess cetacean populations within these territories and how they have changed since or recovered. The Blue Belt Programme further funded a survey of the South Sandwich Islands in austral autumn 2019 During these surveys, cetacean observations were conducted to provide up to date information on cetacean species within these three rarely surveyed Atlantic overseas territories with the aim that this new data will feed into marine spatial planning and management

MATERIALS AND METHODS

Survey Methods

RESULTS

DISCUSSION

DATA AVAILABILITY STATEMENT