First African Marine Mammal Colloquium, South Africa, May 2010

The African Marine Mammal Colloquium (AMMC) was initiated to provide a platform for increased collaboration and communication between researchers working on marine mammals in and around Africa. The first meeting of the AMMC was held at Kleinbaai, South Africa, in May 2010. Talks were presented by each of the 48 participants and a number of discussion groups were held. Several countries were represented but most presentations and discussions were centred on research within the host country. In all, 13 papers that were based on presentations at the AMMC were selected after peer-review to appear in a special issue of the African Journal of Marine Science. Its theme, ‘Conservation biology of marine mammals in the southern African subregion’, reflects both the geographical area represented in these papers and their common subject.http://www.tandfonline.com/loi/tams2

The seasonal haulout cycle of the declining southern elephant seal, Mirounga Leonina, population at Marion Island

Data recorded from annual tagging and regular tag resightings of southern elephant seals at Marion Island, permitted the investigation of temporal variation in the terrestrial haulout cycle of this species, and estimation of participation levels in the little understood resting haulout phase, that could be related to age, sex, and sexual status. Primigravid females moulted later, and were less inclined to rest, than nulligravid females of the same age, but moulted earlier than mature females, among which the mean moulting dates of respective age-classes were practically the same. It is proposed that earlier implantation among primigravid females, as a function of their returning to sea and regaining condition before parous females, resulted in the earlier mean breeding haulout date of primiparous females. The mean haulout dates of breeding and moulting males were negatively and postively correlated with ascending age, respectively. More than half of the surviving individuals of each immature age- and sex-class were observed to haul out to rest, with participation levels generally consistent from year to year, indicating chat the autumn-winter haulout represents more than simple random haulout events. It is suggested that elephant seals are faced with a trade-off between maximising their time spent foraging, and gaining valuable experience at terrestrial functioning, in their immature years.Dissertation (MSc (Zoology))--University of Pretoria, 2006.Zoology and Entomologyunrestricte

Intraspecific differences in the diet of Antarctic fur seals at Nyrøysa, Bouvetøya

Intraspecific differences in the diets of many species of pinnipeds are to be expected in view of the great differences in morphology, life history and foraging behaviour between the sexes of many species. We examined the diet of the Antarctic fur seal population at Bouvetøya, Southern Ocean to assess intersexual differences. This was made possible by the analysis of prey remains extracted from scats and regurgitations collected in areas used primarily by one or the other sex. The results indicate that both males and females feed primarily on Antarctic krill Euphausia superba with several species of fish and squid being taken, likely opportunistically given their prevalence. Significant differences were identified in the frequency of occurrence of otoliths in scats and the percentage numerical abundance of the major fish prey species in the diet. Adult males ate a smaller quantity of fish overall, but ate significantly more of the larger fish species. The greater diving capabilities of males and the fact that they are not limited in the extent of their foraging area by having to return regularly to feed dependant offspring may play a role in the differences found in the diets of males and females. Additionally, females might be more selective, favouring myctophids because they are richer in energy than krill. The absence of major differences in the diet between the sexes at this location is likely due to the high overall abundance of prey at Bouvetøya.This study was financed by the Norwegian Polar Institute (NPI) and the Norwegian Agency for Development Co-operation (NORAD). Further support was provided by the Mammal Research Institute of the University of Pretoria. We thank Bjørn Krafft, Ludvig Krag and Brian Flascas for their valuable assistance in the field. We are grateful to Bjørn Krafft, Iain Staniland and one anonymous reviewer for their comments and suggestions on the manuscript

Prey of the Antarctic fur seal Arctocephalus gazella at Marion Island

The prey of Antarctic fur seals, Arctocephalus gazella, was investigated through scat analysis at Marion Island from 1996 until 2000. A total of 25 different prey species were identified from scats, of which 21 were fish, 1 crustacean and 3 cephalopods. Fish were by far the main prey item, occurring in 96.1% of samples, followed by crustaceans (2.7%) and cephalopods (1.2%). Fishes from the family Myctophidae (Gymnoscopelus piabilis, Electrona carlsbergi, G. fraseri and E. subaspera) were the most abundant prey (97.2%) every year, while those from the families Notothenididae, Paralepididae, Notosudidae, Microstomatidae and Gempylidae were present in small numbers. G. piabilis, E. carlsbergi, E. subaspera and G. nicholsi contributed the most in terms of biomass to the diet. Significant seasonal differences existed in the diet when comparing summer and winter. G. piabilis, K. anderssoni, P. bolini and P. choriodon dominated in summer as opposed to E. carlsbergi, E. subaspera, G. fraseri and G. nicholsi that dominated in winter. The fish varied in size and mass, from the small K. anderssoni to the large Paranotothenia magellanica. Cephalopods and the crustacean Nauticaris marionis, in very low numbers and in winter, appeared in the scats, but not in all years of study. Unidentified penguin remains rarely turned up in scats