Food and feeding habit of Sarotherodon melanotheron, Rüppell, 1852 (Pisces: Cichlidae) in Sakumo Lagoon, Ghana

No Abstract

Review of the Distribution of Waterbirds in Two Tropical coastal Ramsar Lagoons in Ghana, West Africa

Areview of waterbirds was undertaken in two coastal Ramsar lagoons, namely the Keta and Muni Ramsar sites in Ghana, West Africa, from August 2010 to March 2012 to determine the status of diversity and abundance of key waterbired species that utilize the lagoons. A total of 20,217 of waterbirds belonging to 25 different species, 19 genera and 10 families were counted in the two lagoons. Maximum count of 19,757 contributing to 97.7% of the total counts was recorded in Keta Lagoon area while 460 contributing to 2.3% of the total count was recorded in the Muni Lagoon area. By comparison with the Save the Seashore Birds  Project-Ghana (SSBP-G), which started in 1983 and ended in 1985, a total of 53,500 of waterbirds were counted in the Keta Lagoon, an indication of a 63.1% decline in waterbirds abundance. Atotal of 24 species was recorded in the Keta Lagoon and its surrounding floodplains (H.= 0.94, J.= 0.68 and d.= 2.32), whilst the Muni Lagoon recorded a lower number of species of 12 (H. = 0.82, J. = 0.76 and d. = 1.79). The Keta Lagoon recorded higher numbers of waterbirds because the Keta Lagoon is less turbid and shallow, and, therefore, waterbirds were able to stalk and easily locate their prey as compared to the Muni Lagoon, which recorded the lowest numbers possibly due to siltation and, hence, waterbirds could not locate fish fingerlings. Generally, the diversity of waterbirds utilizing both lagoons has declined over the past 27 years as compared to the results from the SSBP-G. Public awareness programmes to highlight the importance of lagoons and waterbirds as environmental indicators is recommended. This could be achieved through education and enforcement of existing wildlife laws and international conventions. In addition, conservation initiatives governing the conservation of waterbirds by the Ghana Wildlife Division of the Forestry Commission is urgently recommended

The Cetaceans of Ghana, a Validated Faunal Checklist

The cetaceans of Ghana and the Gulf of Guinea have, until recently, remained unstudied. Periodical monitoring of artisanal fisheries for bycatches in seven Ghanaian artisanal fishing ports and landing sites over 1996-2004 has provided photographic and specimen evidence to validate occurrence of 18 species (17 odontocetes, 1 mysticete) in a tropical, predominantly pelagic cetacean fauna. At least nine species and subspecies had not previously been documented for Ghana (with asterisk), and four species are authenticated for the first time in the Gulf of Guinea (double asterisk), i.e. Tursiops truncatus, Stenella clymene, S. longirostris longirostris*, S. attenuata, S. frontalis, Delphinus capensis capensis*, Lagenodelphis hosei, Steno bredanensis, Grampus griseus, Peponocephala electra*, Feresa attenuata**, Globicephala macrorhynchus, Orcinus orca*, Pseudorca crassidens*, Kogia sima**, Physetermacrocephalus*, Ziphius cavirostris** and Megaptera novaeangliae . Also, the limited published information on distribution, natural history and conservation status is critically reviewed for each taxon. Indications are that most species encountered off Ghana may be widely distributed in the Gulf of Guinea, most notably the long-beaked common dolphin. The vulnerable Atlantic humpback dolphin, Sousa teuszii, remains unrecorded in Ghana and neighbouring nations despite apparently suitable coastal habitat. It is suggested that localized extinction may be blamed, possibly the result of accumulative bycatches and disturbance. A number of other cetacean species not yet encountered could occasionally occur in Ghana’s waters, e.g. Balaenoptera brydei, Mesoplodon densirostris, Kogia breviceps, Stenella coeruleoalba and Delphinus delphi

Trophic relationships and spawning habits of post-impoundment fish stocks of Lake Volta in Ghana

No Abstract Available Ghana J. Sci, Vol.42 2002: 61-7

Studies on the current state of the limno-chemistry and potential fish yield of Lake Volta (Yeji sector) after three decades of impoundment

This study aimed at providing information on the current state of one of the relatively high fish production areas of Lake Volta the Yeji sector. As in its early life, the water of Lake Volta was found to be oligotrophic, with low concentrations of nitrates, nitrites and phosphates which ranged between 0.51 and 0.82, 0.02 and 0.05, and 0.34 and 0.41 mg l-1, respectively. Sodium was the dominant ion, with a mean concentration of 12.1 mg l-1. Generally, the ionic dominance pattern recorded was Ca>Na>K>Cl>Mg. Considerable increase in turbidity is regarded as a major limiting factor affecting primary production and resultant potential fish yield. As a result of turbidity, oxygen saturation levels were high (>100 %) at the surface, possibly leading to the restriction of primary production at the air-water interface. The difference in temperature between the surface and bottom was narrow (1.7°C), with practically no thermal stratification in the Yeji sector of the lake. This suggests mixing of waters between the surface and deeper layers, thereby enhancing oxygen availability in sufficient concentrations for fish life clear to the bottom. Based on the morpho-edaphic model, the potential fish yield estimate of the lake has declined from 32.8 kg ha1 in 1974 to 29.0 kg ha1 in 1995/96. The decline is attributed to limnological changes in the lake, notably increased turbidity. Ghana Journal of Agricultural Science Vol. 38, 2005: 65-7

Exploitation Rates and Management Implications for the Fisheries of Bontanga Reservoir in the Northern Region of Ghana

The exploitation rates of eight major component fishery species, Auchenoglanis occidentalis, Brycinus nurse, Clarias gariepinus, Hemichromis fasciatus, Marcusenius senegalensis, Oreochromis niloticus, Sarotherodon galilaeus and Tilapia zillii, of gill net fishery of Bontanga reservoir, were studied from March 2004 to March 2006 based on length-based models. The exploitation rates (E) of A. occidentalis and H. fasciatus were 0.7 and 0.6, which exceeded the optimization (Eopt) criterion of 0.5 for sustainable exploitation of fisheries, indicating that these species were over exploited. For B. nurse and S. galilaeus, E . 0.5, indicating that these species were at their maximum rates of exploitation. For C. gariepinus, M. senegalensis, O. niloticus and T. zillii, E < 0.5, indicating that these species were not over exploited. Based on the selection factor of the legal minimum gill net mesh size of 5 cm of Ghana Fisheries Act 625, the estimated mesh size for catching the eight species ranged from 9.9.19.3 cm, calling for an upward review of the legal minimum mesh size of gill nets from 5 to 10 cm for sustainable exploitation of reservoir fisheries. The adoption of minimum mesh size of gill nets of 10 cm, restriction of further entry into the fishery, control rights and community based co-management system are some management options suggested to enhance sustainable exploitation and management of the fisheries

The status of fish diversity and fisheries of the Keta lagoon, Ghana, West Africa

The fish and fisheries of three fish landing sites around the Keta lagoon in Ghana have been studied. A total of 18 fish species belonging to 13 families were encountered in the study. Four of the species were found to be commercially important notably, the cichlids (Tilapia guineensis and Sarotherodon melanotheron), the Bonga shad, (Ethmalosa fimbriata) and the blue-swimming crab, (Callinectes amnicola). The most important shell fish was the blue swimming crab (Callinectes amnicola). All the fishes showed isometric growth values from 2.6 to 3.0. Mean monthly condition factor (K) was between 0.3 ± 0.5 and 13.9 ± 1.8. Occurrence of fish species caught in commercial fishing was 32.3 per cent for Callinectes amnicola, 18.5 per cent for Tilapia guineensis and 13.9 per cent for Sarotherodon melanothron. Total weight of fish caught in experimental fishing was 2.7 tonnes. From experimental fishing with cast nets, Ethmalosa fimbriata accounted for 41.8 per cent (percentage of occurrence) of the total catch, whilst T. guineensis accounted for 29.2 per cent, Sarotherodon melanotheron accounted for 23.3 per cent and Callinectes amnicola accounted for 5.7 per cent. Shannon-Wiener species diversity of fish species was highest in Woe (0.76), followed by Anloga (0.46) and least in Anyanui (0.14). The Keta lagoon was found to be an important nursery ground for some juvenile marine species including Clupeidae, Mugilidae, Lutjanidae, Peneidae, Carangidae, Sciaenidae and Pomadasyidae. The most occurred fishing gears were the brush parks (Acadja) (29.1 %) and basket traps (23.2 %), whilst the least occurred gear was the encircling net (1.8 %). There is the deployment of multiplicity of fishing gears which was highly pronounced at Anloga where fishing appeared to be a daily source of income. Fisheries in the Keta lagoon are threatened from irresponsible fishing and environmental degradation. Management strategies that could be applied to enhance fishery productivity include re-establishment of estuarine conditions, preservation of vital habitats such as vegetation cover around the lagoon, and the development of aquaculture

Pen Culture of the Black-Chinned Tilapia, Sarotherodon Melanotheron in the Aglor Lagoon in Ghana

Pen-fish-culture as a culture-based fisheries approach was investigated in the Aglor Lagoon from December 2003 to June, 2004. The fish used in the study was the Black-chinned tilapia Sarotherodon melanotheron. The growth performance of S. melanotheron cultured for six months in the Aglor Lagoon under three different treatments were monitored. In the first treatment, the cultured fish was fed with a feed of 29.80 % protein at 3 % body weight once a day. In the second treatment, bamboo was stacked at a density of 6 per metre square in pens to serve as substrate for periphyton growth and development. In the third treatment, there was no feeding (control). There was significant difference in growth between the fed and the unfed S. melanotheron in the pens, with no significant difference in growth between the fish that subsisted on periphyton de-veloped on bamboo and the other treatments. S. melanotheron cultured in the bamboo equipped pens had the best condition factor of 3.57 ± 0.23. The experimental values of b obtained from the length-weight relationship (W = aLb) for the three treatments were 2.07, 2.13 and 2.80 for feeding, unfed and bamboo respectively. From the results, the least yield was obtained from the unfed control pen (0.045 kg/m2), whilst the highest was from the bamboo equipped pens (0.183 kg/m2)

Records of Fraser\'s dolphin Lagenodelphis hosei Fraser 1956 from the Gulf of Guinea and Angola

Although Fraser's dolphins Lagenodelphis hosei are considered to inhabit deep tropical waters worldwide, their occurrence in the tropical eastern Atlantic Ocean from the Gulf of Guinea southwards to Angola is only represented by two specimen records from Ghana. During cetacean surveys carried out concurrently with geophysical seismic surveys off Nigeria in 2004 and off Angola in 2007 and 2008, a pod of 150 probable Fraser's dolphins was videoed 130 km south of Nigeria and schools of 120 and 60 animals were photographed 170 km and 140 km respectively off the coast of Angola. All records occurred in deep water (>1 000 m). Cetacean bycatch was monitored at six artisanal Ghanaian fishing ports between 1998 and 2000. Four Fraser's dolphin specimens comprising one adult, one juvenile and two calves were photographed at two ports. Drift gillnets were identified as the probable cause of mortality for at least two specimens. Two sightings of Fraser's dolphins off Angola provide the first at-sea records for the Gulf of Guinea region and, together with bycaught specimens, confirm new southern and eastern distribution limits for the species within the Atlantic Ocean. Further information is required on the status of Fraser's dolphins and the potential impact of fisheries bycatch on this species within the Gulf of Guinea. Keywords: Angola; Fraser's dolphin; Ghana; Lagenodelphis hosei; NigeriaAfrican Journal of Marine Science 2008, 30(2): 241–24