Southern right whales are monitored annually at Head of Bight and Fowlers Bay aggregation grounds through daily cliff based and vessel based population census. Daily population census is completed for all individuals in the aggregation area throughout the study period to monitor whale numbers by population class, spatial and temporal use patterns, calf production and behaviour. Cliff based census at Head of Bight is conducted by scanning the study area with the naked eye and binoculars from 16 cliff top vantage points, between 33m and 53m high. Observers move from west to east along the 15km study site, recording the location, population class, direction of travel and behaviour of whales.
Vessel based census at Fowlers Bay is done by scanning the bay area for whales from the vessel bridge using the naked eye and binoculars. On sighting of a whale, the vessel is positioned closer to the whale and the location, population class and behaviour of whales is recorded.
Understanding population trends aids in the early detection of changes to the population. Population trend data is also fundamental for population modelling of recovery, which is reliant on long term and unbroken data collection. Up to 172 individuals including 67 calves are sighted at the study site annually (max count 2011). Long term abundance data shows triennial peaks representing cohort structured breeding cycles. Annual monitoring is required to assess the recovery of each cohort independently. This long term study has been completed annually at Head of Bight since 1991 to current date.