"Toki", a light low-cost video system for seabed research: performance and precision of Tehuelche scallop (Aequipecten tehuelchus) survey estimates in San José Gulf, Argentina

Abstract

Studies of benthic abundance and biodiversity are essential for fisheries management and environmental impact assessments. In the case of commercial species, such as Tehuelche scallop (Aequipecten tehuelchus), accurate information on the stocks and their densities is crucial. The standard survey method used to estimate abundance of Tehuelche scallops in San José Gulf, Argentina Patagonia, based on visual counts obtained by divers is labor-intensive and limited to diving depths. This study introduces a light low-cost video remote system, named "Toki", for monitoring scallop beds from small boats. Toki consists of a steel pyramidal structure that houses two cameras, capable of capturing georeferenced high-definition images. The performance of Toki for estimating the density and size composition of scallops was evaluated. The results demonstrate that Toki provides efficient and accurate density estimates, with variations that can be attributed to observer experience and environmental factors such as bottom algal cover. The size frequency distributions obtained from Toki aligned well with those from hand collection, which allows such measurement for beds beyond diveable depths. Toki offers advantages in terms of spatial coverage and permanent data records. While there are some limitations, such as processing time for image analysis, future developments based on artificial intelligence can overcome these challenges. Toki has the potential to improve the monitoring of scallop beds and data collection.