Browsing by Subject "pelagic fishing"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Open Access
    Preliminary model of the impact of pelagic fishing on the South African west coast in the vicinity of seal and penguin colonies
    (2005) Plagányi, Éva E
    Preliminary work is summarised here concerning the development of a model of the impact of pelagic fishing on the South African west coast in the vicinity of seal and penguin colonies, for report to the CCAMLR Scientific Committee to parallel and inform their similar initiative concerning krill fishing in the vicinity of krill-dependent predator colonies in the Antarctic Peninsula region through which there is a flux of krill. The decision to model the impact of the South African fishery on penguin and fur seal breeding colonies is because it is a topic of local interest and because of the readier availability of data from both predator studies and pelagic fish surveys, which can be used to provide flux estimates. A spatial modelling framework is used to assess what level and localisation of the fishing effort might negatively impact the predators. The models developed build to some extent on an earlier approach (Plagányi et al. 2000) to explore the effect of different geometric distributions and degrees of synchrony in the abundance of anchovy and its zooplankton prey off the South African west coast.
  • Thumbnail Image
    Item
    Open Access
    Proposed performance statistics for evaluating the effects of pelagic fishing on African Penguin populations
    (2008) Plagányi, Éva E; Robinson, William
    Given the move towards adopting an ecosystem approach to fisheries in the pelagic sector, the new pelagic OMP needs to be tested in the light of not only the risk parameters as considered previously, along with catch statistics for the anchovy and sardine populations, but also parameters denoting risk to the African penguin population(s) Spheniscus demersus. Penguins have been chosen as a key predator species to consider because of their conservation status, and because of their potential sensitivity to changes in pelagic fish abundance and distribution as a consequence of their land-based breeding sites. A model of penguin dynamics has been developed for use as a penguin Operating Model to be coupled to the pelagic fish OMP. This paper summarises the proposed implementation and suggests performance statistics for use in evaluating the impact on penguins of predicted future pelagic fish trajectories under alternative harvest strategies (OMPs).