Fish sampling in the marine-dominated Kariega Estuary, South Africa, using a demersal otter trawl: day/night effects

  • SE Bailey
  • NC James

Abstract

Very few demersal fish assemblage studies using otter trawls in estuaries have been done in South Africa and none of these have tested for the effects of diel period. This study aimed to test whether diel period affects otter trawl catches in the clear, permanently open Kariega Estuary in terms of both species composition and abundance. Fish were sampled by day and night from 30 October to 1 November 2007 at 15 sites using an otter trawl. More species were collected at night, when there were higher catch rates for all key species, with the exception of Rhabdosargus holubi, which was more abundant during the day. Overall assemblages collected by day and by night were similar, with six species accounting for over 90% of the catch in both day and night samples. Both day and night samples reflected differences related to region, with the highest mean CPUE during day and night sampling being recorded in the head region.

Keywords: abundance, demersal fish assemblages, diel period, estuaries, species composition

African Journal of Aquatic Science 2013, 38(1): 115–120

Author Biographies

SE Bailey
South African Environmental Observation Network, Elwandle Node, Private Bag 1015, Grahamstown 6140, South Africa
NC James
South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa
Published
2013-03-07
Section
Articles

Journal Identifiers


eISSN: 1727-9364
print ISSN: 1608-5914