The status and natural history of pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales off Southern Africa

For the present study 106 strandings of Kogia breviceps and 85 strandings of K. sima along the South African coastline between 1880 and 1995 were analysed in order to examine the age and growth, male and female reproduction, diet, stranding patterns, and population genetic structure of both species. Length and weight at birth were about 120cm and 53kg for K. breviceps and about 103cm and 14kg for K. sima. Von Bertalanffy growth curves were fitted to the data and indicated that physical maturity was reached at around 15 years in both sexes of K. breviceps and at 13 years in female and 15 years in male K. sima. Asymptotic length was reached at 306.0 and 286.1cm in female and male K. breviceps and 249.14 and 263.75cm in female and male K. sima, respectively. Maximum ages were16 years for male K. breviceps and 23 years for females and 17 years for male K. sima and 22 years for females. Reversed sexual size dimorphism was suggested for K. breviceps, while in K. sima males were larger than females. Attainment of sexual maturity in males occurred at between 2.5 and 5 years of age in K. breviceps and 2.6 and 3 years in K. sima, corresponding to 241-242cm and 197cm body length, respectively. The maximum combined testis weight comprised 1.04% and 2.00% for K. breviceps and K. sima, respectively, and a polygynous mating system with a roving male strategy was proposed for both species. The sperm morphology for both Kogia species was described and is characterised by 20-25 spherical mitochondria arranged in rows around the midpiece. Attainment of sexual maturity in females occurred at 5 years in both Kogia species, and at 262cm and 215cm body length in K. breviceps and K. sima, respectively. The ovulation rates were 0.9 and 0.7 per year for K. breviceps and K. sima, respectively. In K. breviceps conceptions occurred from April to September and births from March to August, while in K. sima both conceptions and births occurred from December to March. Annual reproduction and a post-partum oestrus was suggested for both Kogia species. The diet of K. breviceps comprised 50 different cephalopod species from 22 families and 17 other prey species, while K. sima fed on 32 cephalopod species from 17 families and six others. Although niche overlap indices between the two species and between groups within each species were high, some differences in diet could be determined, which allow these two sympatrically occurring species to share the same ecological niche off the coast of Southern Africa. An analysis of the stranding patterns revealed that K. sima has a closer affinity to the Agulhas current and to higher water temperatures than K. breviceps, which is supported by differences in the size of the appendages between the two species. The population genetic analysis revealed a high haplotype and nucleotide diversity for K. breviceps in the Southern hemisphere, but a lack of significant phylogeographic structure, indicating substantial gene flow among populations and inhibiting genetic differentiation of local populations, although the South African population was somewhat isolated from others in the Southern Hemisphere. In contrast the data on the phylogeographic structure of K. sima were somewhat restrictive as the majority of the samples originated from South Africa. Nevertheless, both nucleotide and haplotype diversities were markedly lower than in K. breviceps and more similar to those for other small cetacean populations, suggesting a smaller population size for K. sima than for K. breviceps. Although both Kogia species belong to the medium to larger-sized odontocetes their life histories are located near the fast end of the slow-fast continuum of life histories of marine mammals, indicating high mortality rates. The “false-gill” marking and the ability to squirt ink are thought to reflect adaptations to predator mimicry and avoidance

Morphology and Ultrastructure of the Amazon River Dolphin (<i>Inia geoffrensis</i>) Spermatozoa

The spermatozoa from seven adult Amazon river dolphins (Inia geoffrensis, CETACEA: INIIDAE) were analyzed by light and electron microscopy. The spermatozoa showed an elongated ellipsoid shaped head and a long tail with a well distinguishable midpiece. The head spermatozoa have a smooth surface like other odontocetes examined, with the exception of the Delphinidae family. The mean dimensions of the spermatozoa were within the range already reported for other cetaceans. The spermatozoa midpiece, as in other cetaceans, showed a random pattern of mitochondria, different from that described for other mammals. Further studies of sperm morphology of a wider spectrum of cetacean families could help to better understand the reproductive biology of these animals and the intergeneric and intrageneric relationships among them, as well as, among other mammals. Anat Rec, 300:1519–1523, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc

Spatiotemporal trends in cetacean strandings and response in the southwestern Indian Ocean : 2000–2020

On behalf of SIF, we would like to thank the Seychelles partners (Alphonse Foundation, Desroches Foundation, Island Conservation Society, Farquhar Foundation, Seychelles Islands Foundation, Silhouette Foundation) for providing financial support to acquire and grant use of their data. Collection of data in Reunion was funded by DEAL Reunion and Region-Reunion.The south-western Indian Ocean (SWIO) is a region of global importance for marine mammal biodiversity, but our understanding of most of the species and populations found there is still rudimentary. The Indian Ocean Network for Cetacean Research (IndoCet) was formed in 2014 and is dedicated to the research of all cetacean species across the SWIO. Since 2019, there have been efforts to create a regional network for coordinated response to stranding events as well as training and capacity building in the SWIO region. The present analysis represents a first investigation of stranding data collected by various members and collaborators within the IndoCet network, covering over 14,800km of coastline belonging to nine countries/territories. Between 2000–2020, there were 397 stranding events, representing 1,232 individual animals, 17 genera and 27 species, belonging to six families: four balaenopterids, one balaenid, one physeterid, two kogiids, six ziphiids and 14 delphinids. Seven mass strandings were recorded: two were composed of three to 20 individuals and five composed of > 20 individuals. Spatial analysis of stranding events indicated that local spatio-temporal clusters (excessive number of events in time and geographic space) were present in all countries/territories, except for the Comoros. The only significant cluster was detected on the southwest coast of Mauritius, just west of the village of Souillac. The SWIO region predominantly comprises relatively poor countries/territories, but imminent Ocean Economy developments are prevalent throughout the region. This study highlights the importance of establishing baselines upon which any future potential impact from anthropogenic developments in the region can be measured.Peer reviewe

Forschungsberichte aus der Biologischen Station zu Plön.

Mode of access: Internet

GET WITH THE BEAT! THE REGULATION OF UNDERWATER NOISE IN SOUTH AFRICA

Anthropogenic noise in the oceans, including from shipping and seismic surveys, is of concern as it often adversely impacts marine life and biodiversity. It is considered to be the number-one ocean pollutant today. The authors review major international legal instruments regarding underwater noise as a marine pollutant and examine them in the South African context. The authors find, inter alia, that a distinction between substance-based pollution (such as chemical pollution) and energy-based pollution (such as noise) is currently lacking. It is also found that very little literature is available on the impacts of shipping and seismic noise on small fish, turtles and cetaceans, a state of affairs that calls for a precautionary approach. It is recommended: (1) South African legal instruments that regulate underwater noise should be revised and aligned with international legal frameworks; (2) more scientific research should be conducted on the cumulative impacts of shipping and seismic surveys on the South African marine environment; and (3) the public participation process should be effectively monitored to ensure full compliance with the requirement to consult all affected and interested persons. Doing so would have wider implications for developments in the western Indian Ocean region regarding shipping, port construction and seismic explorations

Common dolphin Delphinus delphis occurrence off the Wild Coast of South Africa

Despite their typical large group sizes, limited research exists on the occurrence of common dolphins Delphinus delphis because of the pelagic, offshore nature of this species and the lack of barriers to their movement in this environment. The main purpose of our study was to investigate the occurrence of common dolphins off the Wild Coast of South Africa (western Indian Ocean) and whether spatiotemporal and environmental conditions affected their encounter rate, relative abundance and mean group size. The annual sardine run in this region, during austral winter (May to July), is considered a main driver of dolphin occurrence; however, our boat-based surveys over the period 2014–2016 indicated that common dolphins occur and feed in this area outside of this time-frame. In terms of environmental factors, the largest group (~1 250 animals) was found in the deepest waters. Additionally, at Hluleka, dolphins were observed primarily feeding, which could suggest that this coastal area is highly&nbsp; productive. As common dolphin distribution is thought to be correlated with prey distribution, our findings suggest that sufficient prey exists along the Wild Coast both during and outside the annual sardine run to sustain large groups of the dolphins and that their presence in the area is not solely a function of the sardine run. Keywords: boat-based survey, encounter rate, feeding behaviour, group size, relative abundance, sardine ru

Underwater Chatter for the Win: A First Assessment of Underwater Soundscapes in Two Bays along the Eastern Cape Coast of South Africa

In 2014, the South African government launched ‘Operation Phakisa’ under which port developments play a significant role in supporting ocean economic growth. These developments will likely increase vessel traffic to and from South African ports, making it imperative to monitor for changes in underwater sound budgets with potential negative effects on marine life. However, no soundscape studies have been conducted around South Africa, resulting in an absence of baseline measurements. This study provides a first description of the underwater soundscape in St. Francis Bay and Algoa Bay, Eastern Cape. Soundscape measurements identified major soundscape contributors, temporal patterns in broadband sound levels, and underlying environmental drivers. Applicability of modelled vessel noise and wind noise maps to predict large-scale spatial variation in sound budgets was assessed. Our study shows that sounds from biological sources and wind dominated at all recording sites, with fish choruses driving temporal patterns as a function of time of year and position of the sun. Sound from vessels was present at all sites but most notable in long-term spectral levels measured in Algoa Bay. Sound propagation models predicted a further increase in the contribution of vessel noise towards shipping lanes and east Algoa Bay. Our study provides a building block to monitor for shifts in sound budgets and temporal patterns in these two bays under a developing ocean economy. Furthermore, our study raises concerns that vessel noise is likely a significant contributor in shallow waters elsewhere along the South African coast where vessel density is known to be higher (i.e., Durban and Cape Town)

Underwater Chatter for the Win: A First Assessment of Underwater Soundscapes in Two Bays along the Eastern Cape Coast of South Africa

In 2014, the South African government launched &lsquo;Operation Phakisa&rsquo; under which port developments play a significant role in supporting ocean economic growth. These developments will likely increase vessel traffic to and from South African ports, making it imperative to monitor for changes in underwater sound budgets with potential negative effects on marine life. However, no soundscape studies have been conducted around South Africa, resulting in an absence of baseline measurements. This study provides a first description of the underwater soundscape in St. Francis Bay and Algoa Bay, Eastern Cape. Soundscape measurements identified major soundscape contributors, temporal patterns in broadband sound levels, and underlying environmental drivers. Applicability of modelled vessel noise and wind noise maps to predict large-scale spatial variation in sound budgets was assessed. Our study shows that sounds from biological sources and wind dominated at all recording sites, with fish choruses driving temporal patterns as a function of time of year and position of the sun. Sound from vessels was present at all sites but most notable in long-term spectral levels measured in Algoa Bay. Sound propagation models predicted a further increase in the contribution of vessel noise towards shipping lanes and east Algoa Bay. Our study provides a building block to monitor for shifts in sound budgets and temporal patterns in these two bays under a developing ocean economy. Furthermore, our study raises concerns that vessel noise is likely a significant contributor in shallow waters elsewhere along the South African coast where vessel density is known to be higher (i.e., Durban and Cape Town)