Citizen science in shark and ray research and conservation: strengths, opportunities, considerations and pitfalls

Citizen science programs are growing around the world in number, diversity, and prominence, and they are arguably now accepted as a mainstream scientific methodology (Dickinson et al., 2012; Silvertown, 2009). Modern citizen science programs range from observation-based programs, such as recording local sightings of specific species or phenomena, to global efforts to collect "big data," such as the National Aeronautics and Space Administration (NASA) program Global Learning and Observations to Benefit the Environment (GLOBE), where citizen scientists from around the world use a smartphone app to photograph clouds and record data on mosquitoes. In the fields of biology and ecology, citizen scientists are collecting data on changes in species distributions, pollution, invasive species, threatened species, disease, phenology, biodiversity, habitats, and landscapes and are making tangible conservation contributions (Bonney et al., 2009, 2014; Dickinson et al., 2010; Edgar et al., 2017; Robinson et al., 2015; Silvertown, 2009). In situations where citizen science participants are numerous and widely distributed, these initiatives can help professional scientists greatly expand their spatial and temporal sampling capability, and thus the scope and scale of research questions they can address. In terms of biodiversity monitoring alone, citizen science programs have been estimated to include 1.5 million volunteers that contribute over $2.5 billion worth of in-kind contributions to biodiversity science every year (Theobald et al., 2015)