Sauer W.H.H.,Rhodes University |
Potts W.,Rhodes University |
Raberinary D.,Aberdeen Center |
Anderson J.,Regional Coastal Management Programme of the Indian Ocean Countries |
Perrine M.J.S.,Fisheries Research and Training Unit
African Journal of Marine Science | Year: 2011
The annual catch of octopus in the Rodrigues Lagoon, located east/north-east of Mauritius, has dropped by almost half since 1994. This has prompted concern over the resource and has initiated an assessment of the current status of the stock. The limited available biological information suggests that the main pulse of recruitment into the lagoon occurs in the first few months of the year, but that exact timing varies between years and additional staggered recruitment may occur throughout the year. Size frequency information suggests that the brooding period may be variable and extended, with a main peak between October and January. Catch-and-effort data were also limited, but a decreasing trend in catch per unit effort in two of the datasets examined allowed some preliminary withinseason assessment of population size (using a depletion model) at selected landing sites. The use of a migration bias correction formula suggested a net emigration from the lagoon, which might be indicative of adult movement into deeper waters. Depletion models seem to be useful as a management tool and should be tested further against more substantial monthly catch-and-effort data. In the interim, a precautionary approach of instituting a national seasonal closure for octopus fishing following periods of peak recruitment may have both economic and conservation benefits. © NISC (Pty) Ltd.
Guest J.R.,National University of Singapore |
Guest J.R.,University of New South Wales |
Baird A.H.,James Cook University |
Maynard J.A.,French National Center for Scientific Research |
And 6 more authors.
PLoS ONE | Year: 2012
Background: Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. Methodology/Principal Findings: Surveys to estimate the bleaching and mortality indices of coral genera were carried out at three locations with contrasting thermal and bleaching histories. Despite the magnitude of thermal stress being similar among locations in 2010, there was a remarkable contrast in the patterns of bleaching susceptibility. Comparisons of bleaching susceptibility within coral taxa and among locations revealed no significant differences between locations with similar thermal histories, but significant differences between locations with contrasting thermal histories (Friedman = 34.97; p<0.001). Bleaching was much less severe at locations that bleached during 1998, that had greater historical temperature variability and lower rates of warming. Remarkably, Acropora and Pocillopora, taxa that are typically highly susceptible, although among the most susceptible in Pulau Weh (Sumatra, Indonesia) where respectively, 94% and 87% of colonies died, were among the least susceptible in Singapore, where only 5% and 12% of colonies died. Conclusions/Significance: The pattern of susceptibility among coral genera documented here is unprecedented. A parsimonious explanation for these results is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. These data also lend support to the hypothesis that corals in regions subject to more variable temperature regimes are more resistant to thermal stress than those in less variable environments. © 2012 Guest et al.
Humber F.,Aberdeen Center |
Humber F.,University of Exeter |
Godley B.J.,University of Exeter |
Ramahery V.,Aberdeen Center |
And 2 more authors.
Animal Conservation | Year: 2011
Fisheries are considered a major driver of population declines for many marine vertebrate species, and yet for some, data on the levels of direct catch are lacking, often due to the logistical challenges in assessing artisanal fisheries in remote and developing regionsUsing community members to collect data can provide access to a greater wealth of information than that obtained by local or foreign researchers, often at a reduced financial costWe monitored the harvest of marine turtles at 12 major villages in Madagascar using community members as data collectors (sous collecteurs) from each village, at a total cost of
Le Manach F.,University of Plymouth |
Gough C.,Aberdeen Center |
Harris A.,Aberdeen Center |
Humber F.,Aberdeen Center |
And 2 more authors.
Marine Policy | Year: 2012
Madagascar, the world's fourth largest island, is one of the world's poorest developing countries, and its people depend heavily on marine resources for subsistence and income. Exports of these resources and foreign fishing access agreements are also important, at least from a large-scale economic perspective. In recent years, concerns have been voiced amongst local fishers and industry groups regarding the growth of the country's fishing effort. Despite these concerns, existing knowledge of the scale, composition and trends of Malagasy fisheries remains poor, and there is negligible information regarding unreported catches and illegal fishing in Madagascar's waters. Small-scale fisheries, which are often substantial in developing countries such as Madagascar, are often unreported or underestimated. Unfortunately, fisheries legislations, management plans and foreign fishing access agreements are often influenced by these incomplete data, leading to serious over-estimations of resource availability. This also appears to be the situation in Madagascar, where the reconstruction of total catches by all Malagasy fisheries sectors conducted here showed that total catches between 1950 and 2008 were twice the volume reported by national fisheries agencies. Most importantly, much of the subsistence sector is missing from official statistics, and signs of decline have already been observed in several stocks, suggesting that current levels of catches are likely to be exceeding sustainable yields. This has profound implications for the economic and ecological sustainability of fisheries, as well as food security in a country where people rely heavily on the ocean for their daily protein needs and livelihoods. © 2011 Elsevier Ltd.