Paper authors: Kate Watermeyer, Astrid Jarre, Lynne J Shannon, Patrick Mulumba, Jakobus Botha.

Journal: Ecological Modelling

Blog author: Kate Watermeyer

Citation: Watermeyer, K. E., Jarre, A., Shannon, L. J., Mulumba, P., & Botha, J. (2018). A frame-based modelling approach to understanding changes in the distribution and abundance of sardine and anchovy in the southern Benguela. Ecological Modelling, 371, 1-17.

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Marine ecosystems are complex, and it can be difficult to disentangle the drivers of change.  Kate Watermeyer, along with colleagues in the Marine Research Institute (MA-RE) at the University of Cape Town, used a frame-based modelling approach to get a better idea of what caused changes in sardine and anchovy in the southern Benguela upwelling system, and what it might mean for management of the fishery.

Figure 1: The southern Benguela supports a high fish biomass because of cold, nutrient-rich water, upwelled during windy summers on the west coast of South Africa.

The southern Benguela is a very productive and economically important eastern boundary current system off the west and south coasts of South Africa. During the mid- to late 1990s, a range of species shifted their distribution eastwards, most notably sardine and anchovy. These small pelagic fish play a vital biological role in the system and also support the second most valuable fishery in the region. The frame-based model was designed to assume fishing and environment as drivers of changing distribution, based on what is currently understood about the processes involved.

Sardines provide food for many predators in the southern Benguela and also support a valuable fishery. Photo credit Basheer Tome via Flickr

Through testing and sensitivity analyses, we showed that a frame-based modelling approach is a useful addition to the toolkit for understanding system-level changes in small pelagic fish, and how different patterns of fishing pressure may affect fish distribution. The paper lends support to the continued careful consideration of spatialized management approaches for the South African sardine fishery.

For more information on this research, contact Kate at kate.watermeyer@deakin.edu.au.