A global cline in a colour polymorphism suggests a limited contribution of gene flow towards the recovery of a heavily exploited marine mammal

Evaluating how populations are connected by migration is important for understanding species resilience because gene flow can facilitate recovery from demographic declines. We therefore investigated the extent to which migration may have contributed to the global recovery of the Antarctic fur seal (Arctocephalus gazella), a circumpolar distributed marine mammal that was brought to the brink of extinction by the sealing industry in the eighteenth and nineteenth centuries. It is widely believed that animals emigrating from South Georgia, where a relict population escaped sealing, contributed to the re-establishment of formerly occupied breeding colonies across the geographical range of the species. To investigate this, we interrogated a genetic polymorphism (S291F) in the melanocortin 1 receptor gene, which is responsible for a cream-coloured phenotype that is relatively abundant at South Georgia and which appears to have recently spread to localities as far afield as Marion Island in the sub-Antarctic Indian Ocean. By sequencing a short region of this gene in 1492 pups from eight breeding colonies, we showed that S291F frequency rapidly declines with increasing geographical distance from South Georgia, consistent with locally restricted gene flow from South Georgia mainly to the South Shetland Islands and Bouvetøya. The S291F allele was not detected farther afield, suggesting that although emigrants from South Georgia may have been locally important, they are unlikely to have played a major role in the recovery of geographically more distant populations

Animal-borne telemetry: An integral component of the ocean observing toolkit

Animal telemetry is a powerful tool for observing marine animals and the physical environments that they inhabit, from coastal and continental shelf ecosystems to polar seas and open oceans. Satellite-linked biologgers and networks of acoustic receivers allow animals to be reliably monitored over scales of tens of meters to thousands of kilometers, giving insight into their habitat use, home range size, the phenology of migratory patterns and the biotic and abiotic factors that drive their distributions. Furthermore, physical environmental variables can be collected using animals as autonomous sampling platforms, increasing spatial and temporal coverage of global oceanographic observation systems. The use of animal telemetry, therefore, has the capacity to provide measures from a suite of essential ocean variables (EOVs) for improved monitoring of Earth's oceans. Here we outline the design features of animal telemetry systems, describe current applications and their benefits and challenges, and discuss future directions. We describe new analytical techniques that improve our ability to not only quantify animal movements but to also provide a powerful framework for comparative studies across taxa. We discuss the application of animal telemetry and its capacity to collect biotic and abiotic data, how the data collected can be incorporated into ocean observing systems, and the role these data can play in improved ocean management

First record of a vagrant Commerson’s dolphin, Cephalorhynchus commersonii, at the southern African continental shelf

Commerson’s Dolphins Cephalorhynchus commersonii are distributed in two disjunct populations, one around southern South America and the other around the sub-Antarctic Kerguelen Islands. These populations have been shown to be morphologically and genetically distinct and movement between the two populations is unlikely. We report on the sighting of a single specimen over the South African continental shelf on 13 November 2004. To our knowledge this is the first record of this species in South African waters and such a vast distance (over 4000 km) from the known distribution limits.Keywords: Cephalorhynchus commersonii, vagrant, distribution, South Afric

Killer whale ecotypes: is there a global model?

Killer whales, Orcinus orca, are top predators occupying key ecological roles in a variety of ecosystems and are one of the most widely distributed mammals on the planet. In consequence, there has been significant interest in understanding their basic biology and ecology. Long-term studies of Northern Hemisphere killer whales, particularly in the eastern North Pacific (ENP), have identified three ecologically distinct communities or ecotypes in that region. The success of these prominent ENP studies has led to similar efforts at clarifying the role of killer whale ecology in other regions, including Antarctica. In the Southern Hemisphere, killer whales present a range of behavioural, social and morphological characteristics to biologists, who often interpret this as evidence to categorize individuals or groups, and draw general ecological conclusions about these super-predators. Morphologically distinct forms (Type A, B, C, and D) occur in the Southern Ocean and studies of these different forms are often presented in conjunction with evidence for specialised ecology and behaviours. Here we review current knowledge of killer whale ecology and ecotyping globally and present a synthesis of existing knowledge. In particular, we highlight the complexity of killer whale ecology in the Southern Hemisphere and examine this in the context of comparatively well-studied Northern Hemisphere populations. We suggest that assigning erroneous or prefatory ecotypic status in the Southern Hemisphere could be detrimental to subsequent killer whale studies, because unsubstantiated characteristics may be assumed as a result of such classification. On this basis, we also recommend that ecotypic status classification for Southern Ocean killer whale morphotypes be reserved until more evidence-based ecological and taxonomic data are obtained

Ecology of Moroteuthopsis longimana at the sub-Antarctic Prince Edward Islands, revealed through stable isotope analysis of squid beaks.

Understanding the underlying ecological factors that affect the distribution patterns of organisms is vital for their conservation. Cephalopods such as giant warty squids Moroteuthopsis longimana are important in the diets of marine predators, including grey-headed albatrosses Thalassarche chrysostoma, yet our understanding of their habitat and trophic ecology remains limited. We investigated the habitat and trophic niche utilised by M. longimana through the δ13C and δ15N profiles captured in their beaks. M. longimana beaks were collected around grey-headed albatross nests at the Prince Edward Islands during 2004 and 2013 (n = 40 beaks). The results showed distinctly Antarctic distributions (δ13C = -24.0 ± 1.0‰, mean ± SD) for M. longimana, consistent with albatrosses foraging at the Southwest Indian Ridge, as opposed to broader foraging zones utilised by albatrosses from Îles Crozet and Îles Kerguelen. Slightly lower δ15N values (5.4 ± 0.7‰) were found compared to other islands in the Indian Sector of the Southern Ocean, which may indicate more crustaceans in the squid diets. Sequential sampling along the lateral walls of individual beaks (n = 4) revealed ontogenetic shifts in δ13C and δ15N values, but individual variation in these shifts requires further investigation

Cephalopod diet of the Cape fur seal, Arctocephalus pusillus pusillus, along the Namibian coast: variation due to location

Scats of the Cape fur seal, Arctocephalus pusillus pusillus, were sampled at four mainland colonies, Cape Cross, Atlas Bay,Wolf Bay and Van Reenen Bay, along the Namibian coast over a period of eight years (1994–2001) to assess the diversity and spatial variability in the cephalopod component of the seal diet. Additional scat samples were collected from the Possession Island seal colony (1999–2000) to gain a broader perspective of spatial variation. A uniform and low diversity of cephalopods, only six species amongst all colonies, was identified, indicating that independently the scat sampling method is unsatisfactory for determining species diversity within the diet. Given the ease of scat collection, this method does, however, provide valuable insight into the variability of the most important species in the diet. Ommastrephids dominated the cephalopod component of the diet of seals from Atlas/Wolf Bay and Cape Cross, both in terms of wet mass and numbers. Sepia australis proved to be numerically the most important cephalopod in the diet of seals from Possession Island and Van Reenen Bay, while Octopus magnificus dominated at these colonies in terms of wet mass. Contrary to previous findings it is suggested that seals from Van Reenen Bay and Possession Island forage south of the upwelling cell at Lüderitz (in the southern Benguela ecosystem), while previous evidence of Atlas/Wolf Bay and Cape Cross seals foraging north of this upwelling cell (in the northern Benguela ecosystem) is supported. Prey specimen size differences, within species between colonies, were identified, but lack of cephalopod life history and movement data, and scat sampling biases preclude adequate explanation of these findings, indicating the necessity for further studies.Keywords: Arctocephalus pusillus pusillus, cephalopods, spatial variation, diet, scat samples, Namibi

Inshore occurrence of southern right whales (Eubalaena australis) at Subantarctic Marion Island

Opportunistic shore-based sightings of southern right whales Eubalaena australis for  Marion Island (46°54’S, 37°45’E) were documented at five different times between 1974 and 2009. Whales were sighted between May and September and exclusively on the eastern lee side of the Island. Notwithstanding some observer biases over this time frame, the species appears to be an infrequent visitor to the inshore marine environment of Marion Island.Key words: Eubalaena australis, Marion Island, shorebased sightings; Southern right  whale, vagrants