Combating Desertification through Enhancement of Woody Floral Diversity in the Drylands of Kenya: Analysis, Milestones, and Strategies

Desertification remains one of the most challenging phenomena in the drylands of Kenya, where it affects about 80% of the country. This is because of persistent degradation of these areas by climatic variations, human activities, and overgrazing by livestock and wildlife. In these areas, inhabitants suffer from widespread acute poverty and other adverse effects of drought. In order to effectively and efficiently combat desertification and reduce the impacts of further degradation, the Government of Kenya and partners are committed to developing and implementing methods, approaches, strategies, and mechanisms that would slow down or reverse this phenomenon. This chapter covers an in-depth review of advances made so far in the area of woody resources restoration and sustainable management in the drylands of Kenya through biodiversity assessments, conservation, rehabilitation, afforestation, and reafforestation initiatives and research. Achievements, challenges, and opportunities encountered are highlighted for sustainable development and wise utilization of dryland woody and allied resources

Experimental evaluation of influence of FADs on community structure and fisheries in coastal Kenya

Fish aggregating devices (FADs) have been widely used by commercial fisheries to increase the catchability of pelagic stocks in the open sea. FADs have the potential to enhance nearshore small-scale fisheries where stocks are often overfished. This study examined changes in catch composition, abundance, catch and effort, and aspects of diversity in Kenya's nearshore coastal fisheries after deployment of anchored fish aggregating devices (AFADs). The study combined both fishery independent and dependent methods in assessing changes in fish assemblages post-deployment. Results showed orders of magnitude increase in length, weight, commercial value, and catch per unit effort (CPUE) of landed catch after deployment of FADs suggesting that FADs had a positive effect on the local fishery. Species richness at FAD sites increased post-deployment (n = 281) compared to pre-deployment values (n = 223). Simultaneous use of several complementary structural indices may be required in order to accurately describe and monitor fish assemblages around the FADs. The findings suggest that AFADs are capable of creating both short and long-term impacts on livelihoods, with the potential to deflect pressure on the overfished nearshore fish stocks. However, more research will be needed on redistribution of fish around FADs, design and placement configuration, and site selection amongst others

Managing emerging fisheries of the North Kenya Banks in the context of environmental change

The North Kenya Banks have long been considered an important emerging fishery with the potential to spur economic growth for local fishing communities. As a regionally important extension to the otherwise narrow East African continental shelf, the North Kenya Banks remain under studied with implications for efforts to develop a sustainable fisheries management strategy. The local marine ecosystem is known to be strongly influenced by wind driven upwelling processes with seasonal variability driven by the changing monsoon seasons being of particular importance. Nevertheless, the Western Indian Ocean is warming due to anthropogenic climate change with evidence indicating reduced ocean productivity in future. How the ecosystem of the North Kenya Banks will respond is currently uncertain but is of great importance due to the significance of coastal fishery resources to coastal communities, and growing Blue Economy initiatives to exploit the North Kenya Banks fisheries more widely. There is, however, limited knowledge of the processes influencing productivity over the North Kenya Banks regions and currently there is no management plan in place to sustainably manage the fishery resources. Here, information about the North Kenya Banks fisheries are examined in relation to environmental processes and threats from climate change impacts with suggestions for future research and management directions

Seasonal variation in the length-weight relationship and condition factor of thirty fish species from the Shimoni artisanal fishery, Kenya

Seasonal variation in the length-weight relationship (LWR) and condition factor were assessed for 3 704 fish specimens constituting 30 fish species belonging to 11 families. The fish were sampled from artisanal fisher catches on the south coast of Kenya between March 2014 and March 2015. The regression results for the LWR were 0.57 for Siganus luridus and 0.97 for Lutjanus argentimaculatus during the northeast monsoon (NEM), and 0.76 for Scolopsis ghanam and 0.98 for Parupeneus macronema during the southeast monsoon (SEM). The ‘b’ values ranged from 1.8 for Siganus luridus to 4.3 for Plectorhinchus gaterinus during the NEM, and 1.4 for Plectorhinchus chubbi to 3.2 for Parupeneus heptacanthus during the SEM. The mean ‘b’ values for the SEM and NEM seasons were 2.73 and 2.63 respectively and significantly differed from 3 (t–test, P < 0.5). Mean condition factors of 0.37 (S.E = 0.01) during the NEM, 0.34 (S.E = 0.01) during the SEM for Hemiramphus far and 0.56 (S.E = 0.03) during the NEM, and 0.59 (S.E = 0.03) during SEM for Cheilio inermis were recorded indicating that these species were feeding poorly, the environment was not conducive, or that high competition for food from other species existed, while the other species had mean condition factors above 1 during the two seasons. The condition factor significantly differed for eleven species during the two seasons (P < 0.05).

Propulsion-gear-based characterisation of artisanal fisheries in the Malindi-Ungwana Bay, Kenya and its use for fisheries management

In Kenya, like other tropical countries, coastal artisanal fishery is multispecies, multigear and multifleet in nature with many management challenges. The Malindi-Ungwana Bay in particular, supports both the artisanal fishery and the semi-industrial bottom trawl shrimp fishery presenting a management challenge. Recent stock assessment surveys have identified catch composition of the semi-industrial bottom trawl fishery in the bay but artisanal catches remain barely described. This study describes, the artisanal fish catch composition (total number of species caught, sizes and trophic levels), and catch per-unit-effort (CPUE) for each of the most popular propulsion-gear categories used in the bay. We make a case that the use of specific propulsion-gear categories can be dynamically managed to encourage the recovery of selected fish groups and thus support fisheries management. A total of 4 269 finfish belonging to 177 species and 66 families were sampled by the 5 most popular propulsion-gear categories between 2009 and 2011. The total number of species caught was highest for canoe-gillnet, mashua-gillnet and foot-seine net, and lowest for foot-handline and mashua-handline. Significant differences in catch composition existed between the different propulsion-gear categories. The CPUE was not significantly different between propulsion-gear, although this was on the average highest for canoe-gillnet and mashua-gillnet, and lowest for the foot-handline. The highest trophic level of 4.0 was recorded for mashua-gillnet and the lowest 3.4 and 3.2 for canoe-gillnet and foot-seine net respectively. The use of specific combinations of propulsion-gear categories, give an alternative approach in management recommendation of the coastal artisanal fisheries in the tropics, from the traditional gear-based management initiative. This study, singled out the mashua-gillnet, canoe-gillnet and foot-seine net as suitable units for monitoring the artisanal fisheries in Malindi Ungwana Bay since mashua-gillnet lands the highest mean trophic level and largest sized individuals, and canoe-gillnet and foot-seine net land the highest number of species caught and smallest sized individuals

Reproductive biology and body condition of exploited populations of Emperor Angelfish, Pomacanthus imperator (Bloch, 1787) along the Kenyan Coast

A substantial proportion (in terms of value and quantity) of the Pomacanthus imperator catch on the Kenyan coast are traded, and the species is also harvested as food in the artisanal fishery. However information on their reproductive biology is scanty. The overall sex ratio differed significantly from 1:1 according to chi-square test (p<0.05). Sizes at maturity (L50) were estimated to be 25cm and 28cm TL for females and males respectively. Fecundity was estimated to be in the range of 17,790-266,472 with a Mean ±SE of 79,353±11,747, and was linearly related to total length and ovary weight. March-April was the main period of reproductive activity based on gonad somatic indices and monthly proportion of mature individuals. The LWR indicated isometric growth both in males and females of P. imperator, as the allometric coefficient b values were not significantly different from the expected isometric value of 3 (Student’s t-test; p=0.12). Relative condition factor did not vary significantly between the months sampled. The reproductive parameters obtained from this study provide some baseline information for management of this species which has proven to be highly vulnerable to depletion due to overfishing.

Hook size selectivity in the artisanal handline fishery of Shimoni fishing area, south coast, Kenya

Selectivity of five handline fishing hook sizes was determined following Holt’s 1963 model using data that was collected during January to June, 2016. A total of 966 fish specimens comprising of 65 species belonging to 23 families were sampled. Fish abundance was low for large sized hooks while catch rate was higher. Species diversity was higher during the northeast monsoon season and at the study sites of Mpunguti and Nyuli. However, species diversity decreased with increase in hook size. All hook sizes had a higher selection for mature Lethrinus borbonicus while hook size No. 8 selected immature Lethrinus lentjan. Hook sizes No. 9 and 10 selected mature L. lentjan and Lethrinus rubrioperculatus, hook size No. 15 selected immature L. lentjan, L. rubrioperculatus and Aprion virescens, while hook size No. 16 selected immature A. virescens and L. rubrioperculatus. Species similarity was higher for fish caught by hook sizes No. 16 and 15, and No. 8 and 9, while those captured by hook size No. 10 differed from those caught by other hook sizes. The larger hook size No. 8 is recommended for the sustainable exploitation species in the artisanal handline fishery in Shimoni fishing area. Future work needs to consider the effects of bait type and size and the stock status of the fish under exploitation

Microplastic pollution in the surface waters of creeks along the Kenyan coast, Western Indian Ocean (WIO)

Microplastic pollution has been recognized as a global threat in marine environments and a danger to prey, predators and humans. Yet there have been limited studies in the Western Indian Ocean (WIO) and along the Kenyan coast making it difficult to estimate the extent of such pollution. This is the first study on microplastics (MPs) in the surface waters within creeks (Tudor, Port-Reitz and Mida creeks) in Kenya. Sampling was done in January/ February and September 2018 to collect microplastics from surface water. Neuston nets of 500 μm (large) and 250 μm (medium) size were towed for ten minutes and 50 litres of seawater sieved through a 20 μm net (small) in three replicates. The samples were digested in 10 % Potassium Hydroxide, sieved, and then filtered with cellulose nitrate membrane microfilters. Concentrations of total microplastics, different shapes and colours were established under a microscope. High concentrations of small size (20-250 μm) MPs were encountered and Tudor and Port Reitz had higher concentrations compared to Mida Creek. The study provides data on microplastic concentrations within the creeks and recommends focussing on small size microplastics for monitoring purposes, which due to their high concentrations can be hazardous to organisms