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Distribution and exploitation of Nile perch Lates niloticus in relation to stratification in Lake Victoria, East Africa

Journal of Great Lakes Research

By:
, , , , and
DOI: 10.1016/j.jglr.2013.06.009

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Abstract

Stratification restricts habitable areas forcing fish to balance between favourable temperature and minimum dissolved oxygen requirements. Acoustic surveys conducted during the stratified and isothermal periods on tropical Lake Victoria indicated that stratification of temperature and dissolved oxygen (DO) affected vertical distribution of Nile perch. There was higher mean temperature (25.6 ± 0.5 °C) and lower DO (6.4 ± 1.8 mg/l) during stratified period compared to the isothermal period (mean temperature 24.9 ± 0.3 °C; mean DO 7.3 ± 0.6 mg/l). Higher mean densities of Nile perch were recorded in the coastal (0.44 ± 0.03) and deep (0.27 ± 0.02 g/m3) strata during the stratified compared to the isothermal season (coastal: 0.24 ± 0.01; deep: 0.12 ± 0.02 g/m3). In addition, Nile perch density in the upper 0–40 m depth layers in the coastal and deep strata increased by over 50% from the isothermal to the stratified season. Daily landings from 65 motorised fishing boats between October 2008 and September 2010 show higher mean catch (26.29 ± 0.17 kg/boat/day) during stratified compared to the isothermal (23.59 ± 0.15) season. Thermal stratification apparently compresses the habitat available to Nile perch and can potentially result in higher exploitation. Managers should evaluate the potential benefits of instituting closed seasons during the stratified period, and stock assessment models should take into account the seasonal niche compression.

Geospatial Extents

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Distribution and exploitation of Nile perch Lates niloticus in relation to stratification in Lake Victoria, East Africa
Series title:
Journal of Great Lakes Research
DOI:
10.1016/j.jglr.2013.06.009
Volume
39
Issue:
3
Year Published:
2013
Language:
English
Publisher:
Elsevier
Contributing office(s):
Texas Cooperative Fish and Wildlife Research Unit
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Great Lakes Research
First page:
466
Last page:
475
Other Geospatial:
Lake Victoria