Long-term sustainability of South Africa's boat-based whale-watching (BBWW) industry requires any desired growth to be achieved within sustainable parameters. Given that advertising is often the ...first point of exposure for potential tourists, transparency regarding permit regulations that support sustainable tourism and manage tourist expectations is important. To assess transparency, textual information and photographic content from 17 South African government permitted BBWW company websites were analysed. Regulation-related information in textual content was low across all websites (5-28% of sentences extracted); 91% of photographs containing whales, and 55% containing dolphins, appeared non-compliant for distance of vessel to animal. These results demonstrate that misleading advertising may result in tourist expectations that conflict with legal requirements for a sustainable industry and can place operators under pressure to provide the experiences as advertised. Solutions to address this problem and promote ecological sustainability in the industry include clearer advertising guidelines in permit regulations, standardised resources supplied to industry for advertising and tourist education, and greater awareness of advertising effects and how to positively promote regulations in website content.
The scale dependence of locomotor factors has long been studied in comparative biomechanics, but remains poorly understood for animals at the upper extremes of body size. Rorqual baleen whales ...include the largest animals, but we lack basic kinematic data about their movements and behavior below the ocean surface. Here, we combined morphometrics from aerial drone photogrammetry, whale-borne inertial sensing tag data and hydrodynamic modeling to study the locomotion of five rorqual species. We quantified changes in tail oscillatory frequency and cruising speed for individual whales spanning a threefold variation in body length, corresponding to an order of magnitude variation in estimated body mass. Our results showed that oscillatory frequency decreases with body length (∝length
) while cruising speed remains roughly invariant (∝length
) at 2 m s
We compared these measured results for oscillatory frequency against simplified models of an oscillating cantilever beam (∝length
) and an optimized oscillating Strouhal vortex generator (∝length
). The difference between our length-scaling exponent and the simplified models suggests that animals are often swimming non-optimally in order to feed or perform other routine behaviors. Cruising speed aligned more closely with an estimate of the optimal speed required to minimize the energetic cost of swimming (∝length
). Our results are among the first to elucidate the relationships between both oscillatory frequency and cruising speed and body size for free-swimming animals at the largest scale.
In 2016, South Africa became the first African country to draft Marine Spatial Planning (MSP) legislation. The underlying legal framework supports the achievement of ecological, social and economic ...objectives, but a national policy to grow the oceans economy provides a challenge for ecosystem-based approaches to MSP. During the 2018 International Marine Conservation Congress in Borneo, we convened a special session to discuss particular challenges that will likely apply to any developing country seeking to increase profits from existing, or proposed, marine activities. Here we present six inter-disciplinary research projects that support ecosystem-based approaches to MSP in South Africa, by addressing the following key challenges: (1) measuring ecosystem condition; (2) modelling impacts of climate change on food webs and fisheries; (3) managing fisheries with an ecosystem approach; (4) using dynamic ocean management to resolve conflicts between fisheries and threatened species; (5) managing conflicting objectives in a growing marine tourism industry; and (6) developing scenarios for alternative management strategies in complex marine social-ecological systems.
The Indian Ocean humpback dolphin (
Sousa plumbea
) is “endangered” with likely less than 500 animals remaining in South African waters. Established in 2016, the SouSA Consortium is a formalised ...network of scientists and conservationists to combine knowledge and research efforts, and make coordinated decisions with the aim of conserving the species. The first collaborative project collated available photo-identification data in an attempt to refine a national population estimate and investigate movements between research sites. This work was able to identify 250 uniquely marked individuals, with the population divided into the south-coast (Agulhas bioregion) and east-coast (Natal bioregion) populations. Environmental factors almost certainly play a role in the declining numbers of the species in South African waters. However, individual threats and solutions are challenging to identify as the South African marine environment is undergoing significant natural and anthropogenic changes with major shifts in the distribution and numbers of some prey, competitor and predator species. Therefore, we believe that a continued investigation of potential contributing factors and their interaction will take too long, inevitably resulting in another case of documenting extinction. With this in mind, we present the results of a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis in an effort to help us identify the next steps to take toward the conservation of humpback dolphins in South African waters. We unanimously conclude that no single cause for the rapid decline of humpback dolphins in South African waters can be identified, and that the cumulative effects of multiple stressors, which are difficult to pinpoint and mitigate, are impacting population numbers. While highlighting the need for continued research, we suggest a shift toward more action-focused conservation efforts, the first concrete steps being the development of a Conservation Management Plan with input from other stakeholders.
Morphological abnormalities in wild animals can be indicators of the underlying health of a population and may be determined through routine photographic surveys. Here, we assess unusual rostrum ...conditions in Indian Ocean humpback dolphins (Sousa plumbea) inhabiting South African coastal waters to understand the rate of prevalence of abnormal rostrums and formulate hypotheses on potential causes. Photographic data were collated from systematic boat surveys and opportunistic sightings, obtained between April 1998 and March 2021 in various regions along the South African coast. Overall, 31 unique individuals were found with abnormal rostrum conditions, varying from slight misalignments to severe wounds and/or aberrant morphologies. In most cases, injuries were likely caused by natural events during the animal's life history such as interactions with sharks and/or reef‐associated hunting strategies. Mark–recapture data indicated that individuals had survived with these injuries for up to 10 years. This study reports the highest incidence of rostrum abnormalities in the species. As numbers reflect only those that have survived their injuries, they are considered a minimum estimate. A better understanding of the cause(s) of these injuries is important given the endangered status of this species.
This study highlights the highest incidence of rostrum abnormalities identified for the species, but numbers presumably only reflect those that have survived their injuries and are, therefore, a minimum estimate for these animals. A better understanding of the cause(s) of these injuries is deemed important to be considered when revisiting the endangered status of this species.
The Indian Ocean humpback dolphin was recently uplisted to ‘Endangered’ in the recent South African National Red List assessment. Abundance estimates are available from a number of localized study ...sites, but knowledge of movement patterns and population linkage between these sites is poor. A national research collaboration, the SouSA project, was established in 2016 to address this key knowledge gap. Twenty identification catalogues collected between 2000 and 2016 in 13 different locations were collated and compared.
Photographs of 526 humpback dolphins (all catalogues and photos) were reduced to 337 individuals from 12 locations after data selection. Of these, 90 matches were found for 61 individuals over multiple sites, resulting in 247 uniquely, well‐marked humpback dolphins identified in South Africa.
Movements were observed along most of the coastline studied. Ranging distances had a median value of 120 km and varied from 30 km up to 500 km. Long‐term site fidelity was also evident in the data. Dolphins ranging along the south coast of South Africa seem to form one single population at the western end of the species' global range.
Current available photo‐identification data suggested national abundance may be well below previous estimates of 1000 individuals, with numbers possibly closer to 500. Bearing in mind the poor conservation status of the species in the country, the development of a national Biodiversity Management Plan aimed at ensuring the long‐term survival of the species in South Africa is strongly recommended. At the same time, increased research efforts are essential, particularly to allow for an in‐depth assessment of population numbers and drivers of changes therein.
The present study clearly indicates the importance of scientific collaboration when investigating highly mobile and endangered species.
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