Biology of the African lungfish Protopterus aethiopicus Heckel 1851, and some aspects of its fishery in Lake Baringo, Kenya

Mlewa, Chrisestom Mwatete (2003) Biology of the African lungfish Protopterus aethiopicus Heckel 1851, and some aspects of its fishery in Lake Baringo, Kenya. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

The introduction of the marbled lungfish (Protopterus aethiopicus) into Lake Baringo created a new fishery. This study describes the life history characteristics and movements of this population, and provides baseline biological information for more rational exploitation and management of its fishery. Biological data were obtained from fishery landings, while movement and space use were studied using ultrasonic telemetry. -- Biological data indicate Lake Baringo lungfish grow allometrically, individual growth in length was about 14.5 cm year ⁻¹. Males mature later than females, but are less abundant in open waters, likely because they spend more time in inshore spawning areas. Spawning occurs year-round, probably related to the lack of a predictable rainy season in Lake Baringo. Internal differentiation of the digestive tract was apparent contrary to previous reports. Their diet in Lake Baringo is primarily piscivorous. -- Ultrasonic telemetry showed lungfish are not sluggish, but rather make nonrandom daily movements (likely in search of prey) in the open waters and were active at night as well as in the day. Their movements consisted of: 1) shorter daily movements over several weeks or months, followed by 2) a series of successive longer daily movements over a few days, and there was evidence of navigational ability. Sonically tagged lungfish ranged widely but tended to avoid shallow inshore waters where crocodiles are abundant. However, some had home ranges of varying size (5.8 - 19.8 km²) and which were occupied for 2 - 4.5 months. Ultrasonic-tagged fish were always relocated in the lake, however, one radio-tagged lungfish was caught in a swamp upstream on the Molo River about 4.5 months after release, indicating lungfish can and do migrate out of the lake. -- Radio telemetry results suggested that P. aethiopicus are not obligate air breathers. Aerial respiration is necessary, however, during stress situations and this probably explains the death of most lungfish caught on long-lines. Attaching hooks to long leaders will allow hooked fish to access the surface and increase live lungfish landings, which earn more income. Maintenance of a viable lungfish fishery in Lake Baringo depends on protection and conservation of shallow inshore riparian areas and control of illegal fishing practices.

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