The crabeater seal as a candidate species for climate change monitoring and the CCAMLR Ecosystem Monitoring Program (CEMP): East Antarctica monitoring program

The management of commercial harvesting of Antarctic marine living resources, following the 'ecosystem approach' of the CAMLR Convention, necessitates considering the impacts on both target and dependent species. The CCAMLR Ecosystem Monitoring Program (CEMP), established in 1989, aims to detect significant changes in key marine ecosystem components and differentiate between those caused by commercial harvesting and environmental variability. While many krill-dependent predators are monitored, the crabeater seal (Lobodon carcinophagus) has been largely excluded due to its challenging habitat. However, its significant reliance on krill and its sea ice habitat makes it an important species to consider. The French polar program ASSET now includes a focus on the foraging ecology of crabeater seals, aiming to document the krill-crabeater seal system and understand future krill populations and their predators in East Antarctica. A successful pilot study in 2024 around the Shackleton Ice Shelf, Bowman Island, and Vincennes Bay provided valuable data on seal distribution and foraging ecology. The seals were equipped with high-resolution accelerometers to record prey interactions and diving behavior, which will help uncover seasonal shifts in foraging areas therefore krill distribution under sea ice. The goal is to implement functional trait estimations for krill-crabeater seal interactions using microsonar tags, ultimately enabling predictions of krill distribution based on seal behavior. Accurate isotopic analysis will detail the krill contribution to the seal diet (ice krill, Euphausia crystallorophias versus Antarctic krill, Euphausia superba), especially between movements on and off the continental shelf. The work in Area 58 presents a unique opportunity to monitor krill-dependent populations in the absence of fishing pressure, aligning with CEMP's objectives. It also highlights the urgent need to understand how climate-induced changes, such as sea ice decline, impact the Antarctic marine ecosystem. Integrating historical tracking data across different regions will facilitate the creation of essential habitat maps, aiding in the assessment of human activity impacts and management measures. This paper discusses the feasibility of including the crabeater seal as a candidate species in the CEMP program using tracking and diving data. It also highlights the importance of baseline data and tool for management and emphasizes the need for a collaborative project to compile historical tracking and dive data for krill predators. Understanding the foraging zones and spatial or temporal overlaps among krill predators is crucial for detecting long-term trends and the effectiveness of management measures.