Seals are often present in the vicinity of fishing vessels off our coast, both those operating inshore (<100m deep) and further offshore (>100m), where they either forage naturally and/or learn to scavenge catches. During operational interactions seals often disturb fish aggregations or cause damage to fishing gear and catches, and they themselves sometimes become entangled or are deliberately killed. Although the impact of these interactions were previously thought to be negligible in terms of the overall cost to the South African fishing industry and the total Cape fur seal population size (the bulk of which occurs on the West Coast), this has not been tested at the local fishery/population level on the south coast. Combining previous estimates and unpublished data of direct seal mortality in this area due to trawling and squid jigging operations alone, it is likely to be at least 30% of the south coast population with a strong bias toward adult males. These estimates do not even take into account indirect seal mortality from entanglement in lost or discarded fishing gear (or plastics) that litter our ocean. Unfortunately this information is now outdated, limiting our understanding of the demography of the affected population. In addition, it has been suggested that some seals specialize exclusively in scavenging fish from nets and lines, or unwanted catches that are discarded from fishing vessels. Unfortunately this has not yet been examined and the lack of updated scientific information on the extent of such behaviour hampers the development of effective management measures. Between 2017 – 2019 we collected  diet samples from shot seals that washed ashore, and those that drowned in trawl nets. We also spent a lot of time onboard squid fishing vessels, demersal trawlers and mid-water trawlers to collect updated observational data on the impact of interaction events on these important industries. All data and samples are stored with our research collaborator at the Port Elizabeth Museum, where we have started processing samples. The data will go a long way in future analyses aimed at potential specialist behaviour in perceived problem individuals that feed in association with commercial fishing operations along the south coast.

Credit: Danielle Conry