Underwater Television Survey Marine Mammal Observer Report RV Tom Crean 13 – 23 August 2022

Abstract

The Underwater Television Survey (UWTV) on the Porcupine Bank took place from the 13th to the 23rd of August, 2022 on board the Marine Institute’s R.V. Tom Crean. The research survey covered an area on the Porcupine Bank Nephrops grounds. A marine mammal dedicated survey was carried out by an observer on board following a standard single platform line-transect methodology aiming to collect relative abundance and distribution of marine mammals in the area of interest. The marine mammal survey was conducted during 8 days. The total amount of time the marine mammal observer spent on effort was 64 hours, 1 minute and 1 second. Environmental conditions varied between survey days. Visibility was overall good, with most time spent on effort under visibility 5 (i.e. from 16 to 20 km) accounting for 32.13% and visibility 6 (i.e. >20 km), accounting for 28.44% of the time. On the other hand, sea state conditions were not favourable, since most of the effort was carried out under sea state 5 (45.62% of the time). Swell height was recorded as higher than 2 m during most of the time spent on effort (62.75% of the total time). Marine mammal survey effort was carried out during all days while traveling, with the exception of the 19/08/2022, when effort had to be interrupted due to adverse weather conditions. A total of 10 sightings of marine mammal species were recorded over the course of the survey, with common dolphins accounting for 60% of these sightings.