Browsing by Author "Cooper, John"

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    Exploring South Africa’s southern frontier: A 20-year vision for polar research through the South African National Antarctic Programme
    (CrossMark, 2017-06) Ansorge, Isabelle J; Skelton, Paul; Bekker, Annie; de Bruyn, P J Nico; Butterworth, Doug S; Cilliers, Pierre; Cooper, John; Cowan, Don A; Dorrington, Rosemary; Fawcett, Sarah; Fietz, Susanne; Findlay, Ken P; Froneman, P William; Grantham, Geoff H; Greve, Michelle; Hedding, David; Hofmeyr, G J Greg; Kosch, Michael; le Roux, Peter; Lucas, Mike; MacHutcho, Keith; Meiklejohn, Ian; Nel, Werner; Pistorius, Pierre; Ryan, Peter; Stander, Johan; Swart, Sebastiaan; Treasure, Anne; Vichi, Marcello; Jansen van Vuuren, Bettine
    Antarctica, the sub-Antarctic islands and surrounding Southern Ocean are regarded as one of the planet’s last remaining wildernesses, ‘insulated from threat by [their] remoteness and protection under the Antarctic Treaty System’1 . Antarctica encompasses some of the coldest, windiest and driest habitats on earth. Within the Southern Ocean, sub-Antarctic islands are found between the Sub-Antarctic Front to the north and the Polar Front to the south. Lying in a transition zone between warmer subtropical and cooler Antarctic waters, these islands are important sentinels from which to study climate change.2 A growing body of evidence3,4 now suggests that climatically driven changes in the latitudinal boundaries of these two fronts define the islands’ short- and long-term atmospheric and oceanic circulation patterns. Consequently, sub-Antarctic islands and their associated terrestrial and marine ecosystems offer ideal natural laboratories for studying ecosystem response to change.5 For example, a recent study6 indicates that the shift in the geographical position of the oceanic fronts has disrupted inshore marine ecosystems, with a possible impact on top predators. Importantly, biotic responses are variable as indicated by different population trends of these top predators.7,8 When studied collectively, these variations in species’ demographic patterns point to complex spatial and temporal changes within the broader sub-Antarctic ecosystem, and invite further examination of the interplay between extrinsic and intrinsic drivers.
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    From both sides: dire demographic consequences of carnivorous mice and longlining for the critical endangered Tristan albatrosses on Gough Island
    (2009) Wanless, Ross M; Ryan, Peter G; Altwegg, Res; Angel, Andrea; Cooper, John; Cuthbert, Richard; Hilton, Geoff M
    The IUCN recently uplisted the Tristan albatross (Diomedea dabbenena) to Critically Endangered. Here we present new data indicating negative population trends on Gough Island arising from low adult survival (∼91%, ascribed to accidental mortality on fishing gear) and low breeding success (averaging 32%, due to mouse predation). Fledgling production from 1979 to 2007 and numbers of incubating adults from 1956 to 2007 have both decreased by ∼1% p.a. Consecutive annual counts of incubating adults and a population model permit the first reliable estimates of the Tristan albatross population, presently 5400 breeding adults and 11,300 birds in all age- and stage-classes. Population models explore scenarios of likely demographic trends using combinations of hypothetical best-case estimates vs. observed estimates for two key parameters: adult survival and breeding success. These scenarios highlight the relative benefits to the species of eradicating mice or mitigating bycatch. The model scenario using observed estimates predicts annual growth rate at −2.85%. Adult survival rates have probably decreased in recent years, concomitant with increased longline fishing effort, which might explain the discrepancy between counts and modelled trends. Negative trends cannot be reversed by improving breeding success alone, and adult survival must exceed an improbable 97% to balance the current chick production. A worst-case scenario including a fixed number of adult deaths annually predicted a catastrophic 4.2% p.a. decrease and extinction in ∼30 years. Population growth was most sensitive to adult survival, but even using an adult survival estimate without fishery mortality, current breeding success is insufficient to maintain the population. These findings do not support the ‘compensatory mitigation of bycatch’ model (offsetting bycatch impacts by eradicating invasive species), and the impacts of both fishery mortality and mouse predation must be addressed to improve the conservation status of the Critically Endangered Tristan albatross.
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    Impacts of the introduced house mouse on the seabirds of Gough Island
    (2007) Wanless, Ross M; Cooper, John
    Introduced house mice Mus musculus on Gough Island were suspected of widespread predation of Atlantic Petrel Pterodroma incerta and Tristan Albatross Diomedia dabbenena chicks in 2000/01. Video cameras recorded six fatal attacks by mice on live, healthy Atlantic Petrel chicks in 2004. Crude estimates of annual breeding success were 47%, 7% and 7% in 2003, 2004 and 2006, respectively. Mouse attacks were responsible for most chick failures. Mice were largely responsible for high numbers of Tristan Albatross chick failures in 2004-2006. Total failures were significantly related to total attempts but breeding success and total attempts were not correlated. There was little spatio-temporal consistency in total failures or breeding success. No environmental or biological variables examined explained the pattern. Proximity to a failed nest was a significant predictor of failure, suggesting a localised effect possibly due to a few predatory mice. Fledgling production has decreased by 1% annually since 1979-1982. Annual adult Tristan Albatross survival and breeding success averages are extremely low (91% and 32%, respectively) and modelled population growth using these parameters was - 2.85% p.a. Either parameter will drive decreases so reversing negative trends requires improving both.
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    Seabird mortality from longline fishing in the Meditarranean Sea and Macaronesian waters: A review and a way forward
    (Consejo Superior de Investigaciones Científicas, 2003) Cooper, John; Baccetti, Nicola; Belda, Eduardo J; Borg, John J; Oro, Daniel; Papaconstantinou, Costas; Sánchez, Antonio
    A country-by-country review of seabird mortality from longline fishing in the Mediterranean Sea and in Macaronesian waters shows a paucity of data. Of 12 Mediterranean countries known to undertake longlining, seabird mortality is only reported for six: France, Greece, Italy, Malta, Spain and Tunisia. Seabird mortality from longlining has been reported from the Azores (Portugal) but not from the other Macaronesian Islands. Only for one country, Spain, is information on the levels of mortality available, suggesting that 4-6% of the local breeding population of Cory´s shearwater Calonectris diomedea may be killed annually, a level considered unsustainable for the long-term persistence of colonies. Cory´s shearwater is the most commonly affected species, although a number of Larus gull species are also being caught. There is insufficient knowledge to conclude whether any seabird species is at conservation risk within the region, but concern is expressed for Cory´s shearwater. It is recommended that Mediterranean and Macaronesian countries conduct assessments of their longline fisheries and seabird mortality in terms of the Food and Agriculture Organization´s International Plan of Action - Seabirds. Regional fishery organisations, such as ICCAT and GFCM, should commence the collection of seabird mortality data. A longline action plan for the affected seabird species should be produced.
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    The Swift Tern Sterna bergii in Southern Africa : growth and movement
    (2006) Le Roux, Janine; Underhill, Les; Cooper, John
    Inlcudes bibliographical references.