Data on cetacean occurrence collected during the project “Identification and initial assessment of cetacean groupings in coastal waters of the north-western Black Sea, Ukrainian sector” funded by ACCOBAMS 2016-2017

Study Extent

two coastal areas: (a) waters near the Dzharylgach (or Jarilgac in another transcription) Island, and particularly in the Dzharylgach Bay
(b) waters near the Danube delta
warm season (from April to October)

Sampling

The linear transect survey (LTS) were designed according to standard principles of distance sampling (Buckland, 2004; Buckland et al., 2001). The survey platform was the yacht 8.8 m long; two pairs of observers, equipped by binoculars (10x40 and 10x50), changed after 30 minutes, and a dedicated operator recorded the data. The survey was conducted under good weather conditions (sea state less than 2 points of the Beaufort scale, visibility more than 5 km, zero precipitation). Boat speed was on average 9.5 km/h, at maximum 11 km/h. The observer eye height was 2.5 m. Tracks and coordinates were recorded, using the GPS navigator Garmin eTrex 30. Protocols of effort and registrations were filled in during the surveys. Species, group size, distance and angle from the moving boat were recorded at each encounter. In addition, behaviour types were recorded: fast movement, normal movement, feeding, etc., as well as behaviour in relation to the boat: avoiding, attraction or neutral. Individual photo identification was conducted from small boats, with a dedicated person responsible for protocol and coordinate logging. Tracks and coordinates were recorded, using the GPS navigator Garmin eTrex 30. Protocols of effort and registrations were filled in during the surveys.

Method steps

1. LTS (Linear transect surveys) The linear transect survey (LTS) was designed according to standard principles of distance sampling (Buckland, 2004; Buckland et al., 2001). Density and abundance, cluster (group) density were estimated by analytical tools based on detection probability functions for distance sampling (Buckland et al., 2001), using Distance 7.0 software (Thomas et al., 2010). Photo identification. The basis of the method is the principle of individual identification with natural labels on the body and on the dorsal fin in particular (Würsig and Jefferson, 1990; Wilson et al., 1999; Urian et al., 2015).

1. Phocoena phocoena relicta
   common name: Harbour porpoise rank: subspecies
2. Tursiops truncatus ponticus
   common name: Bottlenose dolphin rank: subspecies
3. Delphinus delphis ponticus
   common name: Common dolphin rank: subspecies

This data set is focused on two coastal areas: (a) waters near the Dzharylgach (or Jarilgac in another transcription) Island, and particularly in the Dzharylgach Bay
(b) waters near the Danube delta