Fish populations, gill net catches and gill net selectivity in the Kwando River, Namibia Tor F. Næsje, Clinton J. Hay, Nande Nickanor, Johan H. Koekemoer, Rita Strand and Eva B. Thorstad NINA Project Report no. 27 Directorate Resources Management Norwegian Institute for Nature Research Ministry of Fisheries and Marine Resources Tungasletta 2 Private Bag 13 355 Windhoek NO-7485 Trondheim Namibia Norway Fish populations, gill net catches and gill net selectivity in the Kwando River, Namibia Tor F. Næsje*, Clinton J. Hay**, Nande Nickanor**, Johan H. Koekemoer**, Rita Strand* and Eva B. Thorstad* * Norwegian Institute for Nature Research Tungasletta 2, NO-7485 Trondheim, Norway ** Directorate Resources Management Ministry of Fisheries and Marine Resources Private Bag 13 355 Windhoek, Namibia nina Project Report 27 Næsje, T.F., Hay, C.J., Nickanor, N., Koekemoer, J.H., Strand, Norwegian Institute for Nature Research R., and Thorstad, E.B. 2004. Fish populations, gill net catches (NINA) issue the following publications: and gill net selectivity in the Kwando River, Namibia. - NINA Project Report 27. 64pp. NINA Project Report This series presents the results of the institutes’ projects Trondheim, september 2004 when the results are to be made available in English. The series may include reports on original research, literature reviews, analysis of particular problems or subjects, etc. ISSN 1502-6779 The number of copies printed will depend on demand. ISBN 82-426-1480-6 In addition to this report series published in English, Management areas: NINA publish the following series in Norwegian: Fish, sustainable utilisation NINA Fagrapport (scientifi c reports) Copyright ©: This series present the results of NINAs own research Norwegian Institute for Nature Research (NINA) work, overviews of problems, existing knowledge within a topic, literature reviews and material gathered from The report can be quoted with references to the source outside sources. The reports are issued as an alternative or a supplement to international publication when timing, the nature of the material or the sector targeted, call for it. NINA Oppdragsmelding (assignment report) Editor: This is the minimum report supplied by NINA when ex- Tor F. Næsje ternal research or investigative assignments have been NINA completed. The numbers of copies are limited. Design and layout: NINA Temahefte (topic) Kari Sivertsen These series present special topics. They are targeted at NINA the general public or specifi c groups in the community, e.g. the agricultural sector, environmental departments, Cover photo: tourism and outdoor recreation, organizations etc. It is Clinton J. Hay therefore more popular in its presentation form, with (MFMR) more illustrations than the previously mentioned series. Prints: Norservice A/S Most of the publications mentioned above are in Norwe- gian, but will also have an English abstract and legends of Stock: 400 fi gures and tables in English. Address to contact: NINA Fakta-ark (fact sheet) Tor Næsje These double-pages sheets give (in Norwegian) a popu- NINA lar summary of other publications to make the results of Tungasletta 2 NINAs work available to the general public (the media, NO-7485 Trondheim societies and organizations, various levels of nature ma- NORWAY nagement, politicians and interested individuals). Tel: +47 73 80 14 00 Fax +47 73 80 14 01 NINAs staffs also publish their research results in inter- [email protected] national scientifi c journals, popular scientifi c periodicals, http://www.nina.no and newspapers. Accessibility: Open Contracting sponsor: Norwegian Agency for Development Cooperation Project no.: 13530 (NORAD) Ministry of Fisheries and Marine Resources (MFMR) Signature of responsible person: Norwegian Institute for Nature Research (NINA) 2 nina Project Report 27 Preface mal system of fisheries management, the informal (or traditional) component in Namibia has remained. Næsje, T.F., Hay, C.J., Nickanor, N., Koekemoer, J.H., However, the studies document the calls from all lev- Strand, R., and Thorstad, E.B. 2004. Fish populations, els for an improved and effective system for fisheries gill net catches and gill net selectivity in the Kwando management in the region. Reasons cited for the need River, Namibia. - NINA Project Report 27. 64pp. include: increasing number and magnitude of conflicts over fisheries – both within countries and with neigh- The White Paper “Responsible Management of the bouring countries; a perceived decline on the condi- Inland Fisheries of Namibia” was finalised in December tion of fish stocks in the rivers; an increasing number 1995, and forms the basis for a new law and regula- of fishermen exploiting the resource; price increases tions concerning fish resources management in the of fish; and the potential for increased stress on the different freshwater systems in Namibia. Since all fishery as other components of the farming system perennial rivers in Namibia forms the border to neigh- are in decline because of the current drought. bouring countries, management of the fish resources also depends on a regional co-operation. The effects In the present report, the fish populations in the Kwando on the fish resources caused by subsistence, com- River are described on the basis of five surveys per- mercial and recreational fisheries in the neighbouring formed in the period 1997-1999. The fish populations states must also be taken into consideration. When in the Zambezi and Chobe Rivers were studied in the implementing fisheries regulations for such complex same period (1997-2000) (Hay et al. 2002). systems, information on the fish resources and their exploitation are needed. The project is a collaboration between the Freshwater Fish Institute of the Ministry of Fisheries and Marine Based on a series of studies of the fish resources in Resources, Namibia, and the Norwegian Institute for the perennial rivers, recommendations will be given Nature Research (NINA). The work has received for management and regulations of fisheries in the financial support from the Norwegian Agency for Caprivi Region. The management regulations are aim- Development Cooperation (NORAD), the Ministry ing to involve local, national and international authori- of Fisheries and Marine Resources in Namibia and the ties and stakeholders. It is a priority to secure a sus- Norwegian Institute for Nature Research. tainable utilisation of the fish resources for the ben- efit of local communities and future generations, and We would like to express our gratitude towards the important aspects of fisheries management have been Director, Resource Management, Dr. B. Oelofsen and studied to form the basis for new management strate- the Deputy Director, Resource Management, Dr. H. gies. Studies involve descriptions of the fish resources Hamukuaya for their support and encouragement (Hay et al. 2002, this report), the exploitation of fish during the project. We are also thankful to Prof. P. resources and stakeholders, including the socioeco- Skelton and Mr. R. Bills from South African Institute nomic infrastructure of local societies (Næsje et al. for Aquatic Biodiversity (SAIAB, formerly J.L.B Smith 2002, Purvis 2001a, b, Hay et al. in prep), fishing com- Institute of Ichthyology) who verified the identifica- petitions (Næsje et al. 2001), and migrations and habi- tion of some of the fish species, and to Dr. Trygve tat utilisation of important fish species (Økland et al. Hesthagen who read through and commented a pre- 2000, 2002, Thorstad et al. 2001, 2002, 2003a, b). vious version of the report. The studies of fish migrations conclude that certain fish The following staff members from the Freshwater species may migrate between countries, both along and Fish Institute are all gratefully acknowledged for their across the river system, which emphasise the impor- involvement in the field surveys or data punching: T.P. tance of a joint local and regional co-management of Windstaan, J.H. Engelbrecht, A. Iyambula, S. Stein, S. the fish resources both on national and international Beukes, A. Kahuika, J. May, E. Hayango, S. Jonas, N. scale. Other species, however, are more stationary Lukas, B. May, A. Mulundu, A.N. Mulundu, the late S. and are more vulnerable to local exploitation. The Pootinu and E. Shikambe. biological and sociological aspects of the subsistence, semi-commercial and recreational fisheries in Caprivi Windhoek/Trondheim, September 2004 have documented that in the absence of a strong for- C.J. Hay T.F. Næsje 3 nina Project Report 27 Contents Preface ............................................................................... 3 5.1.3 Catches in other gears than gill nets ....24 Summary .......................................................................... 5 5.1.4 Catches in gill nets during autumn and spring ....................................................25 1 Introduction ................................................................. 7 5.2 Body length distributions and gill net selectivity ................................................................ 26 2 Study area .................................................................... 8 5.2.1 Body length distribution in gill nets 2.1 The Caprivi Region ................................................8 and other gears ..........................................26 2.2 The Kwando River .................................................9 5.2.2 Body length at maturity ...........................26 5.2.3 Life history and gill net selectivity for 3 Materials and methods .........................................11