Genetic homogeneity among breeding grounds and nursery areas of an exploited Lake Malawi cichlid fish

Martin J. Genner*, Paul Nichols, Paul W. Shaw, Gary R. Carvalho, Rosanna L. Robinson, George F. Turner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Citations (SciVal)

Abstract

1. Nursery areas are commonly recognized as important habitats for the management and conservation of fish stocks. Here we report the use of nursery areas by an exploited offshore cichlid in Lake Malawi, Rhamphochromis longiceps.

2. Like all haplochromine cichlids that have been studied, the species is a maternal mouthbrooder that broods eggs for several weeks following spawning. We found evidence that during this brooding period females migrate from open water to release juveniles in three shallow peripheral waterbodies (Chia Lagoon, Unaka Lagoon, Lake Malombe). However, it was unclear whether there is geographical population structuring within the species, which could indicate stock differences in their use of these nursery habitats, or if the lake contains a genetically panmictic population that employs nursery habitats opportunistically.

3. To investigate spatial and temporal population structuring within the lake we genotyped populations at seven microsatellite DNA loci. Overall, we found no significant spatial structuring among juveniles from the peripheral lagoons or among breeding males within the main lake body. Moreover, we found no evidence of temporal structuring among males on the breeding grounds within Lake Malawi or females entering Chia lagoon. Together, these results suggest that Lake Malawi contains a genetically homogeneous population of R. longiceps.

4. At present we know little of the distribution of juvenile R. longiceps elsewhere in the Lake Malawi basin, but their absence from surveyed rocky and sandy littoral habitats makes it possible that the species is dependent upon a small number of nearshore nursery areas, including these lagoons. As such, conservation of lagoon habitats and monitoring of exploited fish stocks within them may be important for effective preservation of biodiversity within the catchment.

Original languageEnglish
Pages (from-to)1823-1831
Number of pages9
JournalFreshwater Biology
Volume53
Issue number9
Early online date15 May 2008
DOIs
Publication statusPublished - 01 Sept 2008

Keywords

  • migration
  • PSEUDOTROPHEUS-ZEBRA
  • SYMPATRIC SPECIATION
  • MICROSATELLITE LOCI
  • population genetics
  • SPECIES RICHNESS
  • POPULATION-STRUCTURE
  • speciation
  • haplochromine cichlids
  • IDENTIFICATION
  • AFRICA
  • fishing
  • microsatellite DNA
  • CONSERVATION
  • EVOLUTION

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