Recolonisation of the Robberg Peninsula (Plettenberg Bay, South Africa) by Cape fur seals

Abstract

The Cape fur seal Arctocephalus pusillus pusillus colony at Robberg Peninsula, Plettenberg Bay, on the south-east coast of South Africa, was driven to extinction by indiscriminate harvesting by the late 1800s. Seals only began to recolonise this site in the 1990s. This study describes the recolonisation process from 2000 to 2009, exploring both within-and between-year count data of seals using the site. Counts increased over the study period from <300 animals to >3 100. Generalised linear models indicated the importance of year and month in explaining variability in the counts. Withinyear variability in the counts decreased over the study period, which may be related to an increasing proportion of resident (as opposed to transient) seals in the colony. However, the colony is currently still in a transition phase with a low ratio of breeding to non-breeding animals, based on the low numbers of pups born in the colony (currently still <100 per year). The influx of seals to the Robberg area may be associated with shifts in prey availability at the ecosystem level. The colony benefits from the protection afforded by the reserve status of the Robberg Peninsula and the existence of a marine protected area adjacent to it. However, human interference associated with fishing and/or ecotourism on the peninsula may inhibit development into a substantial breeding colony. Potential interventions for the conservation and management of this colony are discussed.

Physiological stress responses to natural variation in predation risk: evidence from white sharks and seals

“…) and established colonies in the study region do not exhibit significant monthly or seasonal fluctuations in population size or density (Huisamen et al. ). The only period during which the islands exhibit relatively large changes in seal density is during the breeding season (December); however, we did not collect fecal samples at this time to avoid disturbing breeding animals.…”

Spatio‐temporal shifts of the dynamic Cape fur seal population in southern Africa, based on aerial censuses (1972–2009)

“…2011), and monitoring the breeding status of colonies that currently have nonbreeding status ( e.g. , Huisamen et al . 2011).…”

“…Continued range-wide censusing of the population is recommended; this should include search effort in remote locations for new haul-outs that could develop into breeding colonies , and monitoring the breeding status of colonies that currently have nonbreeding status (e.g., Huisamen et al 2011). Interesting potential avenues for further research include comparisons of reproductive performance, phonological and behavioral attributes between the "leading edge" of the population and locations at higher latitudes.…”

Estimates of abundance and change in abundance of the Indo-Pacific bottlenose dolphins (Tursiops aduncus) along the south coast of South Africa

“…An important change in Plettenberg Bay since the 2002-2003 study of T. aduncus is the growing resident Cape fur seal colony ( Arctocephalus pusillus pusillus ) on the Robberg Peninsula [47]. This could cause direct competition for prey resources with T. aduncus including for species such as: piggy ( Pomadasys olivaceum) , squid (Loligo vulgaris reynaudii) , cuttlefish (Sepia spp .…”