Social media and citizen science records are important for the management of rarely sighted whales

Social media content is increasingly being validated and used as a valuable source of data within conservation science. Metadata obtained from social networking sites (SNS) can supplement knowledge and data gaps in traditional ecological monitoring programs by increasing the spatiotemporal extent of sampling. Here we consider SNS in the context of rare and threatened species, which are difficult to monitor due to their often-inaccessible habitat, or elusive and unpredictable occurrences. We focus on a recovering large whale population, as charismatic megafauna often appear on SNS and are ideal for public outreach sightings data. Southern right whales (Eubalaena australis, SRW) were once abundant throughout New Zealand waters. However, following widespread population decline during whaling, no SRW was reported around the mainland for 35 years, with the remnant population persisting only in the remote subantarctic islands. By using sightings data from 2011 to 2021 in the New Zealand Department of Conservation's (DOC) Marine Mammal Database and supplementing with crowd-sourced sightings reports made on SNS (Facebook and iNaturalist), we present evidence that SRWs are continuing to recover slowly around the mainland compared to their subantarctic breeding grounds. All sightings' data were categorised based on confidence of accuracy, for example, accompanying genetic or photographic confirmation of species identity. Sightings remain rare with only 116 sightings from both DOC and SNS sources reported over the 11-year research period (2011-2021), hindering efforts to identify key habitats and implement conservation measures. SNS sightings increased the overall number and quality of sightings. Specifically, as SNS sightings were all accompanied by images permitting confident species ID, they increased the overall quality of the dataset and provided new information on the fine-scale movement and residency times of SRW. Although opportunistic data such as these have limitations, our work suggests that the recolonisation of SRWs around mainland New Zealand has not increased in the past decade. This could reflect historic loss of matrilineal knowledge of the mainland, or it could also be an artifact of very few whales, resulting in less social aggregations frequenting the region. Citizen science and the use of SNS data are important for the continued monitoring of the New Zealand SRW population, with SNS data creating further opportunities to monitor similarly rare and data deficient populations.

Automated summary

Social media content is increasingly being used as a valuable source of data in conservation science, particularly for monitoring rare and threatened species. The recovering population of Southern right whales around mainland New Zealand is slow, but sightings reports from social networking sites provide additional information.