The Fishes of Lake Olbolossat

Gilbert Kosgey; Joseph Gathua

doi:10.15468/tm5mx2

The Fishes of Lake Olbolossat

Citation

Kosgey G, Gathua J (2024). The Fishes of Lake Olbolossat. Wangari Maathai Institute for Peace and Environmental Studies, University of Nairobi. Occurrence dataset https://doi.org/10.15468/tm5mx2 accessed via GBIF.org on 2024-12-11.

Description

Lake Olbolossat is a high altitude alkaline lake in central Kenya. The lake is an important wetland in Central Kenya supporting livelihood of over 2 million people and is a home to variety of species including endangered species. It is also an important source of water for the landscapes’ in Laikipia and Isiolo counties. However, despite its importance, the ecosystem is currently threatened by anthropogenic activities complicated by adverse effect of climate change. In order to restore and conserve the Lake Ecosystem and its associated biodiversity, there is urgent need to unlock its biodiversity. Field survey that was conducted in November 2023 was aimed to documenting various taxa and socio-economic dynamics associated with the lake towards enlisting it as 7th Ramsar site in Kenya. Despite the importance of fish in ecosystem functioning, they are threatened by many anthropogenic impacts such as climate change, loss and transformation of their natural habitats, introduction of invasive species, pollution and excessive nutrient loading rates among others. The deterioration of these processes is often rapid and difficult to reverse in lakes. Therefore, the assessment of aquatic fish distribution in Lake Olbolossat is paramount for informed conservation and management measures towards the listing of Lake Olbolossat as a potential Ramsar Site. This dataset contains results of desktop review and field survey undertaken to: (1) establish the species composition, abundance and distribution of fishes of Lake Olbolossat (II) assess the fish conservation threats and offer recommendations for informed conservation and management measures The dataset contains 28 records of fishes of Lake Olbolossat. The data were formatted according to the Darwin Core Standards by Ichthyology Section, National Museums of Kenya before publishing through the IPT at the National Museums of Kenya, Nairobi.

Purpose

Information regarding the herpetofauna of Lake Olbolossat has been scanty and scattered making it difficult to clearly understand their status. This study was conducted to assess the current status of the species in the aftermath of the recent drying of the lake.it also helps the managemnt authorities to make decisions on the steps to take in the lakes management plan.

Sampling Description

Study Extent

Fish sampling was carried out in the main lake and closely related wetlands including streams draining into the lake. The study area was subdivided into six sections that coincided with political boundaries for county wards. Diverse methodologies were applied depending on habitat type and knowledge on fish species habitat preference. Hand seining was used in the shallow open waters. A seine net, 3m length with 2 wooden buttons was employed. This is used by drawing the net in shallow waters by two persons from each end for a distance. In rivers and canals, electrofishing was employed. This method uses a combination of back pack electrofishing machine and a seine net where two people block one side and as one shock the water immobilising the fish that are collected with the seine net. Monofilament gill net of mesh sizes of 10 mm measuring 30m long by 1.5m wide was used in open deeper waters. The nets were tied end to end and left at each site for a period of two hours. The net were observed at intervals of 30 minutes to avoid overfishing in case the net catches more fish than expected. The fish samples were removed from the net and kept temporarily in a bucket of water mixed with a killing agent waiting processing. The catch was observed, identified to species level, counted and recorded in the field note book. Where fish of the same species were caught, some were returned into the water. The fish samples photographs were taken immediately they were caught before they lose the natural color in accordance with ichthyological standards. Fish were then immersed into a well labelled container with 10% formalin for fixation and taken to Ichthyology Section of National Museums of Kenya for species verification using available taxonomic keys and reference collections, then preserved in 70% ethanol as voucher reference collections.

Sampling

Different methods were used in during fishing; hand seining, electrofishing, gill netting and dip netting.

Quality Control

Species identification was done on site by a team of ichthyologists from the Ichthyoloy Section, National Museums of Kenya. 

Method steps

1. Field data transformed to conform to the Darwin Core standards. 2. Dataset cleaning and validation by taxa experts. 3. Dataset validation on https://www.gbif.org/tools/data-validator 4. Dataset and metadata publishing on GBIF using NMK's IPT.

Taxonomic Coverages

Geographic Coverages

The survey was done in Lake Olbolossat and associated rivers and streams.

Bibliographic Citations

Crafter, S.A., Njuguna S.G. and Howard G.W. (1992) Wetlands of Kenya. Proceedings of the KWWG seminar on wetlands of Kenya, NMK, Nairobi, Kenya, 3-5 July 1991. Gland: IUCN -
Krhoda, G.O. (1992). The Hydrology and Function of Wetlands. Pp. 13-22 in Crafter, S.A., Njuguna S.G. and Howard G.W. (eds) Wetlands of Kenya. Proceedings of the KWWG seminar on wetlands of Kenya, NMK, Nairobi, Kenya, 3-5 July 1991. Gland: IUCN -
Mathenge M. W. (2014). Effects of natural resource based conflicts on community livelihoods in Lake Ol’Bolossat catchment area, Nyandarua County, Kenya. Msc. Thesis Kenyatta University, School of Environmental Studies. 139pp -
NEMA (National Environment Management Authority) (2007). Lake Ol-Bolossat Management Plan 2008-20√3. Kenya Wetlands Forum. Nairobi, Kenya -
Okumu J. (2017). Lake Ol’Bolossat, synthesis report. East Africa Wild Life Society technical report. -
Schierner, F., Zalewski, M. and Thorpe, J. E. (1995). Land/Inland water ecotones: intermediate habitats critical for conservation and management. Hydrobiologia 303: 259–264. -
Terer T., Odeny D., Kirika P., Mbale M., Yego R., Malonza P.K., Muchai V., Kochey J., Gathua J., Kosgei G., Muchane M.N., Waithaka K.M., Wamiti W. & Njoroge P. (2019). Rapid Biodiversity Assessment of Lake Ol’ Bolossat: Habitat characterization, water quality, fungi, plants, birds, mammals, invertebrates, fish, amphibians and reptiles. NMK and/Birdlife International, Nairobi, Kenya. -

Contacts

Gilbert Kosgey
originator
position: Research Scientist
National Museums of Kenya
Museum Hill
Nairobi
40658 - 00100
Nairobi
KE
Telephone: +254728724748
email: 2kipscham@gmail.com

Joseph Gathua
originator
position: Senior Laboratory Technologist
National Museums of Kenya
Museum Hill
Nairobi
40658 - 00100
Nairobi
KE
Telephone: +254722635622
email: josephgathua@yahoo.com

Gilbert Kosgey
metadata author
position: Research Scientist
National Museums of Kenya
Museum Hill
Nairobi
40658 - 00100
Nairobi
KE
Telephone: +254728724748
email: 2kipscham@gmail.com

Joseph Gathua
metadata author
position: Senior Laboratory Technologist
National Museums of Kenya
Museum Hill
Nairobi
40658 - 00100
Nairobi
KE
Telephone: +254722635622
email: josephgathua@yahoo.com

Gilbert Kosgey
administrative point of contact
position: Research Scientist
National Museums of Kenya
Museum Hill
Nairobi
40658 - 00100
Nairobi
KE
Telephone: +254728724748
email: 2kipscham@gmail.com

Joseph Gathua
administrative point of contact
position: Senior Laboratory Technologist
National Museums of Kenya
Museum Hill
Nairobi
40658 - 00100
Nairobi
KE
Telephone: +254722635622
email: josephgathua@yahoo.com