Through this action, an assessment of the Conservation Status of the bottlenose dolphin (Tursiops truncatus), Common dolphins (Delphinus delphis) and Loggerhead turtles (Caretta caretta) and their foraging, migration and reproduction habitats in waters around Malta will be carried out. Based on the EC Document “Guidelines for the establishment of the Natura 2000 network in the marine environment”, particularly Sections 4.3 and 4.4 which deal specifically with locating and assessing Annex II species and the rationale for the selection of sites for these species, this assessment will include a study of abundance, distribution and use of the habitat and their relation with the environmental and anthropic parameters that could affect them, as well as their level of residence and home range in the different areas.
An analysis of the oceanographic and anthropic parameters which are more likely to affect populations of dolphins will also be included. In addition, model-based estimates of abundance in coastal and offshore Maltese waters will be developed in order to provide a baseline for the follow-up of this action with a monitoring plan designed to analyse trends in conservation status.
The sampling procedures to be used in this action are based on those developed by the Spanish research group ALNITAK in the context of its “Alboran Sea cetacean, seabird and sea turtle monitoring programme” (1990-2012) and LIFE projects LIFE02NAT/E/8610 and LIFE07NAT/E/000732. This will allow comparative analysis and enhance NATURA 2000 networking.
The first part of this action will involve the processing of the data compilation of Action A1 in order to design the boat-based surveys and adjust timing and methodology. The visual and acoustic surveys will cover the entire project area, focusing on the locations identified through the maps described in Action A.2.
A grid of transects will be designed for the purposes of this action. The survey will cover these transects with a double look-out post for the visual survey and towing an acoustic array to detect and record cetacean clicks and whistles. The survey will be conducted with adequate sea state conditions with a maximum seastate of 3 (Douglas sea state scale).
The presence of cetaceans and turtles will be recorded, and sampling stations will be set to take oceanographic data such as sea surface temperature, salinity, depth and other anthropic data such as the maritime traffic, fisheries, etc. For the oceanographic data and in order to have a better picture of the oceanographic characteristics, satellite images of sea surface temperatures and chlorophyll concentrations from the satellites will be used.
The visual survey will provide information on the abundance and the distribution of cetaceans and marine turtles, whereas the acoustic data will be used to complement detection of cetaceans which are not spotted by the visual survey. This, together with the use of the double sighting platform should allow us to obtain the detectability function for the visual survey data analysis. The acoustic surveying has the additional benefit of detecting other species of cetaceans such as sperm-whales or beaked whales, which spend only very short periods at the surface and are therefore not easily observable through the visual survey.
Observers will combine unassisted vision with the use of 7x50mm binoculars. An angle marker and reticule will be used on each side of the platform to obtain the exact angle and distance of cetacean and sea turtle sighting. The general direction the animal is swimming towards will also be taken. The towed acoustic array will consist of two BENTHOS AQ4 elements in an oil-filled tube connected to the ship with a 200m Kevlar cable. The data generated by this hydrophone will be logged automatically into the laptop computers using the IFAW, LOGGER and PAMGUARD softwares.
When cetaceans are sighted, the vessel will approach them, following standard procedures and protocols for a correct approach that reduces harassment and disturbance. Such a close encounter will enable specific data on species, number of individuals, calves, behaviour, etc. to be collected. If possible and if seen of interest, the survey transect will be interrupted to obtain photo identification data using the RHIB.
Photo-Identification is a useful method to assess the level of residence of these populations in the areas considered. The process consists of taking pictures and identifying specific individuals using natural marks (scratches, notches, pigmentations, shapes, etc.) and cataloguing them to further compare them and determine which individuals have been “re-captured” where and when. The term “re-capture” is used when an individual that had been identified in a previous sighting is re-sighted. In this manner it is possible to determine whether specific animals use a specific area all year round (resident) or not (non-resident). Photo-identification is a very powerful tool for long-term monitoring programmes. In the context of this project however, while the development of photo-id catalogues and establishment of data collection and analysis protocols are expected, it is highly unlikely that there will be sufficient data for the application of mark recapture analysis.