Documenting the effects of human-induced disturbance on a Weddell seal colony

• Main Author: Muller, Chris
• Format: Other/Unknown Material
• Language: English
• Published: 2001
• Subjects: Weddell; Leptonychotes wedelli; Weddell Seal
• Online Access: http://hdl.handle.net/10092/14271

The purpose of this study was to document the effects of human-induced disturbance on a Weddell seal (Leptonychotes wedelli) colony. The main disturbance source used was a group of two to twelve people moving thlvugh the colony, and approaching within 5m Of seals. Average measures of the activity level of the colony were obtained using the Instantaneous scan sampling method (Altman 74). The average activity rate Of the colony increased markedly in the presence of disturbance, with the pmportion of the population resting dropping from around 87% pre-disturbance to 36% during disturbance. An increasing proportion of active disturbance-response behaviours were recorded in the presence of the disturbance (eg. watching, looking up, or moving away). Data from controlled approaches to individual seals indicated that 10m is a more suitable maximum approach distance to seals than 5m, and reduces the cumulative percentage of population lesponse (or probability of disturbance) from around 60% to 17%. It may be possible to achieve "no disturbance" with an approach distance limit of 20m. Therefore it can be concluded that the seal colony was disturbed by the human activity, and this in a change of behaviour and of the average activity levels of the colony. Further study is required to confirm these trends, and to determine whether such disturbance would have a significant impact on the colony, or significant cumulative effects over time. The purpose of this study was to document the effects of human-induced disturbance on a Weddell seal (Leptonychotes wedelli) colony. The main disturbance source used was a group of two to twelve people moving thlvugh the colony, and approaching within 5m Of seals. Average measures of the activity level of the colony were obtained using the Instantaneous scan sampling method (Altman 74). The average activity rate Of the colony increased markedly in the presence of disturbance, with the pmportion of the population resting dropping from around 87% pre-disturbance to 36% during disturbance. An ...