This report describes marine mammals’ observations done by scientific observers on board the fishing vessel B/P Altamar. The fishing trip observed lasted from 8 April to 1 August 2021, the vessel targeted Patagonian toothfish Dissostichus eleginoides and the fishing area was located in sub-area 48.3 of CCAMLR, mainly around South Georgia Islands. Three different types of marine mammal sampling were carried out: “scheduled observations”, “unscheduled observations”, and “secondary observations”(also referred as opportunistic). For each sampling, the following data were recorded: type of observation, location from where on the vessel the observation was done, time, position (latitude and longitude) and type of maneuver (set, haul, sail) the vessel was doing at the beginning and end of the sampling. During the surveys, each sighting of a marine mammal was recorded as an observation event and the following data were collected: time of observation, species or lowest possible taxonomic level that could be identified, abundance (total number of individuals, or minimum and maximum possible), certainty of identification (certain, fairly certain, uncertain), approximate distance and position (angle) in relation to the vessel’s bow, behaviour (i.e. whether they were feeding and/or interacting with the vessel or fishing gear), and comments from the observation.
Scheduled observer surveys ("Scheduled obs") were carried out by the scientific observers every day when weather conditions permitted. In general, these surveys were carried out once a day around midday, from the high bridge of the B/P Altamar and for a period of approximately half an hour, regardless of whether marine mammals were detected or not. Unscheduled observations ("Unscheduled obs'') were made from different locations on the vessel (e.g., bridge, high bridge, bow, gangways, galley, etc.); and opportunistic observations of marine mammals ("Secondary obs'') were generally made from the navigation bridge while other scientific observation tasks were being carried out. Both unscheduled surveys and opportunistic observations were always initiated after the presence of marine mammals in the vicinity of the vessel was detected by a crew member. In the case of unscheduled surveys, the observation of marine mammals lasted for several minutes from the start of the survey, while opportunistic observations consisted of spot records of marine mammals for which the duration of the sightings was not recorded.