Browsing by Author "Coetzee, Janet C"
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- ItemOpen AccessAccommodating dynamic oceanographic processes and pelagic biodiversity in marine conservation planning(Public Library of Science, 2011) Grantham, Hedley S; Game, Edward T; Lombard, Amanda T; Hobday, Alistair J; Richardson, Anthony J; Beckley, Lynnath E; Pressey, Robert L; Huggett, Jenny A; Coetzee, Janet C; Van der Lingen, Carl DPelagic ecosystems support a significant and vital component of the ocean's productivity and biodiversity. They are also heavily exploited and, as a result, are the focus of numerous spatial planning initiatives. Over the past decade, there has been increasing enthusiasm for protected areas as a tool for pelagic conservation, however, few have been implemented. Here we demonstrate an approach to plan protected areas that address the physical and biological dynamics typical of the pelagic realm. Specifically, we provide an example of an approach to planning protected areas that integrates pelagic and benthic conservation in the southern Benguela and Agulhas Bank ecosystems off South Africa. Our aim was to represent species of importance to fisheries and species of conservation concern within protected areas. In addition to representation, we ensured that protected areas were designed to consider pelagic dynamics, characterized from time-series data on key oceanographic processes, together with data on the abundance of small pelagic fishes. We found that, to have the highest likelihood of reaching conservation targets, protected area selection should be based on time-specific data rather than data averaged across time. More generally, we argue that innovative methods are needed to conserve ephemeral and dynamic pelagic biodiversity.
- ItemOpen AccessProgress report on recommendations from the International review panel report for the 2013 International Fisheries Stock assessment workshop:sardine(2014) de Moor, Carryn L; Butterworth, Doug S; Coetzee, Janet C; van der Lingen, Carl DThe international review panel report (MARAM/IWS/DEC13/General/4 Final Report) contained the following recommendations pertinent to sardine in response to key questions put to them at the annual stock assessment review meeting held at UCT from 2-6 December 2013. Comments on any progress in response to these recommendations are inserted in italics. As a general point of background information, the Small Pelagic Scientific Working Group agreed earlier in 2014 to finalise OMP-14 based on a single sardine stock operating model only, but coupled with some spatial management, the spirit of which is to be a “warm up period” with the expectation that the next OMP will quite likely require spatial management components. The development of new operating models and a new OMP is to be brought forward, commencing in early 2015 with the aim of being finalised before the end of 2016.
- ItemOpen AccessRecreational fish-finders - an inexpensive alternative to scientific echo-sounders for unravelling the links between marine top predators and their prey(Public Library of Science, 2015) McInnes, Alistair M; Khoosal, Arjun; Murrell, Ben; Merkle, Dagmar; Lacerda, Miguel; Nyengera, Reason; Coetzee, Janet C; Edwards, Loyd C; Ryan, Peter G; Rademan, JohanStudies investigating how mobile marine predators respond to their prey are limited due to the challenging nature of the environment. While marine top predators are increasingly easy to study thanks to developments in bio-logging technology, typically there is scant information on the distribution and abundance of their prey, largely due to the specialised nature of acquiring this information. We explore the potential of using single-beam recreational fish-finders (RFF) to quantify relative forage fish abundance and draw inferences of the prey distribution at a fine spatial scale. We compared fish school characteristics as inferred from the RFF with that of a calibrated scientific split-beam echo-sounder (SES) by simultaneously operating both systems from the same vessel in Algoa Bay, South Africa. Customized open-source software was developed to extract fish school information from the echo returns of the RFF. For schools insonified by both systems, there was close correspondence between estimates of mean school depth (R 2 = 0.98) and school area (R 2 = 0.70). Estimates of relative school density (mean volume backscattering strength; S v ) measured by the RFF were negatively biased through saturation of this system given its smaller dynamic range. A correction factor applied to the RFF-derived density estimates improved the comparability between the two systems. Relative abundance estimates using all schools from both systems were congruent at scales from 0.5 km to 18 km with a strong positive linear trend in model fit estimates with increasing scale. Although absolute estimates of fish abundance cannot be derived from these systems, they are effective at describing prey school characteristics and have good potential for mapping forage fish distribution and relative abundance. Using such relatively inexpensive systems could greatly enhance our understanding of predator-prey interactions.