Genetic diversity and local population structure

Genetic sampling is conducted to investigate genetic diversity and local population structure. This represents the first genetic characterisation of Peale’s and Commerson’s dolphin population within the Falklands. The work will assess: the degree of genetic separation from conspecific populations in South America; the genetic diversity around the Falkland Islands, in comparison to other conspecific population and expectations for effective population size; the degree of interchange or isolation among local populations within the Falkland Islands to assess the scale of management units; and level of kinship across generations within groups to better understand population connectivity on an ecological time scale. Skin and blubber samples, collected with a small biopsy dart will be stored and archived to allow subsequent analysis for natural isotope ratios (C/N), pollutant contaminants, etc. in future associated research.

Method

The collection of genetic samples is a non-surgical technique involving the collection of a small sample of skin and blubber using a biopsy dart deployed during small-vessel surveys. The duration of the biopsy sampling is essentially instantaneous, as the dart strikes the animal and immediately recoils from the force of impact. Vessel approaches the dolphins slowly to reduce the potential for behavioural disturbance.

The biopsy dart is a small stainless-steel punch, with 5 mm of diameter and 7 mm of length fitted to a light-weight pole. The dart is used for dolphins riding the bow of the boat. A metal flange or stop, approximately 2 - 3 cm in diameter, prevents penetration of more than a centimetre or two into the skin and blubber and provides recoil to dislodge the dart on contact with the dolphin. The force of impact of the dart is adjusted by the positioning of the boat. The biopsy dart is cleaned and sterilised by flaming after each collection and immersed in 70% ethanol immediately before use.

Maria sampling an individual un Peale’s dolphin off New Island.

Ethic statement

To our knowledge, no injuries have been reported for a dolphin with the use of either the pole biopsy. The healing and long-term response to biopsy samples is described for bottlenose dolphins in New Zealand (Tezanos Pinto and Baker 2012). The remote biopsy system to collect genetic samples from dolphins (and whales) has been approved by the University of Auckland, New Zealand, Animal Ethics Committee and the Oregon State University, Institutional Animal Care and Use Committee (IACUC). The licence for the sampling of 60 Commerson’s’ and 60 Peale’s dolphins have been released by the Falkland Islands Government – FIG (Research Licence No: R04/ 2016).

Preliminary results

Biopsy collection was carried out by Professor Scott Baker and, after appropriate training, by the SAERI staff. Under terms of the initial research license, 120 samples were collected, 60 samples of Commerson’s dolphins in the three focal study areas, and 60 samples of Peale’s dolphins in Port Williams and Berta’s Beach in the East Falkland and New Island, Beaver Island, Weddell Island and Shallow Harbour in the West Falkland.

After obtaining the appropriate CITES permits from FIG, the samples were sent to the Hatfield Marine Science Center, Oregon State University, USA, on the 8th of April 2017.

Analyses will last six months and should began in May 2017. Stay tuned for more information.

Sample extracted by a Commerson’s’ dolphin in Port Howard and wound left on the right side of the body