Sightings of marine mammals in New Zealand waters by government fisheries observers

The Department of Conservation administers the New Zealand Marine Mammal Database, which contains sightings of marine mammals that are reported by the public, researchers, and permit holders for marine mammal viewing, and also contains records of marine mammal strandings. Data in this database may be used to monitor marine mammal populations and to provide information of species distributions.

At‑sea sightings of marine mammals are recorded by government fisheries observers on‑board commercial fishing vessels, as part of two main programmes started in 2009. One programme is aimed at monitoring groups of marine mammals in inshore fisheries, with frequent counts of different pods recorded on handheld electronic devices (Nomad devices). The other programme is aimed at monitoring the abundance of seabirds around fishing vessels, and these counts are entered on paper forms; however, ad‑hoc sightings of marine mammals have also been recorded. In addition, marine mammals caught as bycatch in commercial fisheries have also been recorded on non‑fish bycatch forms since 1990.

To date, these data from fisheries observers have not been integrated into the New Zealand Marine Mammal Database, prompting the current project. Its overall aim was to prepare these data for inclusion in the New Zealand Marine Mammals Database, including the development of an online application that allows data to be queried and visualised.

The final dataset of sightings from observers included 13 815 unique sighting events of a total of 105 817 animals, of 32 taxa. The latter included 26 species or sub‑species, while the remaining the remaining taxa were groups of species. Summarising these data, there were 9 812 sightings of 29 553 individual pinnipeds (4 species), 3 591 sightings of 75 182 individual dolphins (13 species and sub‑species), and 412 sightings of 1 082 individual whales (9 species).

At the time of this project, there were 21 507 sightings of marine mammals in the New Zealand Marine Mammal Database, representing 57 different taxa. Sightings from government fisheries observers, therefore, represent a significant addition to the database.