“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

The monitoring of benthic biomass and biodiversity is essential for fisheries management and environmental impact assessments. In the case of commercial species, such as Tehuelche scallop (Aequipecten tehuelchus), accurate information on stock density and distribution is key for regulating the harvest. The standard survey method used to estimate abundance of Tehuelche scallops in San José Gulf, Argentine 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 estimation errors that vary with observer experience and environmental factors such as bottom algal cover. The size frequency distribution obtained from Toki aligned well with that of hand-collected samples, making it possible to obtain size-composition information for beds beyond diveable depths. Toki offers advantages in terms of spatial coverage, simple survey logistics and permanent data records. While there are some limitations, such as processing time for image analysis, future developments based on artificial intelligence may overcome these challenges. Toki has the potential to improve the regular monitoring of scallop beds.