DOI: 10.15493/dea.mims.09022026
title: Behavioural responses of Cape fur seals Arctocephalus pusillus to swim-with-seal tourism activities in the Robberg Marine Protected Area in South Africa

description: Behavioural responses of Cape fur seals Arctocephalus pusillus to swim-with-seal tourism activities in the Robberg Marine Protected Area in South Africa
description: Behavioural changes are often regarded as a key indicator of the effect of human disturbances on animals, and responses are commonly used as indices of disturbances. Tourism is an increasingly common source of disturbance to wild animals, including marine mammals. Swim-with-seals (SWS) tourism is an emerging industry that has grown in countries such as New Zealand, Australia and South Africa. We studied behavioural impacts of SWS in the Robberg Marine Protected Area (Western Cape, South Africa) on the adjacent Cape fur seal Arctocephalus pusillus pusillus colony through a modified Before-After-Control- Impact (BACI) behavioural study designed for simultaneous observations of impact and control sites (site factor) and before, during and after SWS activities (phase factor). Elevated observations were carried out at distances from the sites using sequential photography of the colony to enumerate seals in different behavioural categories, allowing comparisons between sites and between phases, as well as investigations of interactive effects of site and phase. Swim-with-seal activity and associated boat approaches elicited behavioural responses in the colony, and models showed that characteristics of the SWS activity (e.g. distances of boat or swimmers) and environmental factors influenced responses. However, responses were mainly limited to increased alertness or minor positional shifts among a very small proportion of seals at the impact site, and overall, the impacts of SWS could be seen as minimal. Minimal impacts can be attributed to the guidelines to reduce disturbance adhered to by the operator, habituation of seals in the colony to SWS, or likely a combination of these.
description: Data were collected from a vantage point overlooking the seal colony between 10–27 November 2020, 03 April–28 September 2021, and 03-19 October 2021, between 09h00 and 16h00. Observations covered both impact and control sites. Data sources included sequences of photographs (taken at 10-minute intervals during defined “counting events” before, during, and after SWS activities), videography, and visual observations aided by binoculars. Coincident records included swimmer numbers, activity duration, and environmental conditions (air temperature, swell height/direction, sea temperature). Distances between boats, swimmers, seal rafts, and sites were measured using a Nikon Forestry Pro II Laser Rangefinder, with proxy rocks used to ensure measurement consistency. Images were captured with a Nikon D7000 camera and Tamron 150–600 mm lens and visual observations aided by Pentax 7x50 binoculars. Data are raw observational records, supplemented by operator-reported sea temperature. No material biological samples were collected. Quality control involved repeated measurements, consistency checks against proxy points, and standardised observation protocols by a team of three to four observers.