Macquarie Island southern elephant seal capture-mark-recapture data

The Southern Ocean has been disproportionately affected by climate change and is therefore an ideal place to study the influence of changing environmental conditions on ecosystems. Changes in the demography of predator populations are indicators of broader shifts in food-web structure, but long-term data are required to study these effects. Southern elephant seals (Mirounga leonina) from Macquarie Island have consistently decreased in population size while all other major populations across the Southern Ocean have recently stabilised or are increasing. Two long-term mark-recapture studies (1956-1967 and 1993-2009) have monitored this population, which provides an opportunity to investigate demographic performance over a range of climatic conditions. This provides insights on individual vital rates of known-age seals from Macquarie Island over extensively long timeseries.

Methods
Between 1951–1965 and 1993–1999 weaned Southern Elephant Seals were captured and marked permanently by hot iron branding. Seals were recorded in regular re-sights varying from daily isthmus searches during the breeding season to ad-hoc sightings outside of active monitoring. Biological data from individual short-term scientific projects include information on the physical condition for a sub-set of pups and adult seals.