Was Lates late? A null model for the Nile perch boom in Lake Victoria

PLoS One. 2013 Oct 18;8(10):e76847. doi: 10.1371/journal.pone.0076847. eCollection 2013.

Abstract

Nile perch (Lates niloticus) suddenly invaded Lake Victoria between 1979 and 1987, 25 years after its introduction in the Ugandan side of the lake. Nile perch then replaced the native fish diversity and irreversibly altered the ecosystem and its role to lakeshore societies: it is now a prised export product that supports millions of livelihoods. The delay in the Nile perch boom led to a hunt for triggers of the sudden boom and generated several hypotheses regarding its growth at low abundances--all hypotheses having important implications for the management of Nile perch stocks. We use logistic growth as a parsimonious null model to predict when the Nile perch invasion should have been expected, given its growth rate, initial stock size and introduction year. We find the first exponential growth phase can explain the timing of the perch boom at the scale of Lake Victoria, suggesting that complex mechanisms are not necessary to explain the Nile perch invasion or its timing. However, the boom started in Kenya before Uganda, indicating perhaps that Allee effects act at smaller scales than that of the whole Lake. The Nile perch invasion of other lakes indicates that habitat differences may also have an effect on invasion success. Our results suggest there is probably no single management strategy applicable to the whole lake that would lead to both efficient and sustainable exploitation of its resources.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms*
  • Animal Migration
  • Animals
  • Ecosystem
  • Introduced Species
  • Lakes*
  • Models, Biological*
  • Perches / growth & development*
  • Population Density
  • Time Factors
  • Uganda

Grants and funding

This work is part of the integrated project ‘Exploitation or eutrophication as threats for fisheries? Disentangling social and ecological drivers of ecosystem changes in Lake Victoria (SEDEC)’, supported by the Netherlands Organization for Scientific Research (NWO/WOTRO) grant number W01.65.304.00. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.