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Tropical deep reefs (>30 m) are biologically and ecologically unique ecosystems with a higher geographic reach to shallow (

Small pelagic fish, including anchovies, sardines and sardinellas, mackerels, capelin, hilsa, sprats and herrings, are distributed widely, from the tropics to the far north Atlantic Ocean and to the southern oceans off Chile and South Africa. They are most abundant in the highly productive major eastern boundary upwelling systems and are characterised by significant natural variations in biomass. Overall, small pelagic fisheries represent about one third of global fish landings although a large proportion of the catch is processed into animal feeds. Nonetheless, in some developing countries in addition to their economic value, small pelagic fisheries also make an important contribution to human diets and the food security of many low-income households. Such is the case for many communities in the Zanzibar Archipelago and on mainland Tanzania in the Western Indian Ocean. Of great concern in this region, as elsewhere, is the potential impact of climate change on marine and coastal ecosystems in general, and on small pelagic fisheries in particular. This paper describes data and information available on Tanzania's small pelagic fisheries, including catch and effort, management protocols and socio-economic significance. Then, incorporating the rapidly improving understanding of the region's oceanography resulting from the application of remote sensing and oceanographic modelling, the paper undertakes the most complete assessment to date of the potential impacts of climate change on the small pelagic fishery of the Pemba Channel. Pathways of climate change impact are explored and crucial knowledge gaps, both in terms of the fishery itself and the wider ecosystem, are identified in order to guide future research activities. Although we analyse small pelagics in the specific context of the Pemba Channel, the key challenges identified in the analysis are likely to be relevant to many small pelagic fisheries in coastal nations heavily dependent on living marine resources. © 2020 The Authors

Under the impact of natural and anthropogenic climate variability, upwelling systems are known to change their properties leading to associated regime shifts in marine ecosystems. These often impact commercial fisheries and societies dependent on them. In a region where in situ hydrographic and biological marine data are scarce, this study uses a combination of remote sensing and ocean modelling to show how a stable seasonal upwelling off the Kenyan coast shifted into the territorial waters of neighboring Tanzania under the influence of the unique 1997/98 El Niño and positive Indian Ocean Dipole event. The formation of an anticyclonic gyre adjacent to the Kenyan/Tanzanian coast led to a reorganization of the surface currents and caused the southward migration of the Somali-Zanzibar confluence zone and is attributed to anomalous wind stress curl over the central Indian Ocean. This caused the lowest observed chlorophyll-a over the North Kenya banks (Kenya), while it reached its historical maximum off Dar Es Salaam (Tanzanian waters). We demonstrate that this situation is specific to the 1997/98 El Niño when compared with other the super El-Niño events of 1972,73, 1982-83 and 2015-16. Despite the lack of available fishery data in the region, the local ecosystem changes that the shift of this upwelling may have caused are discussed based on the literature. The likely negative impacts on local fish stocks in Kenya, affecting fishers' livelihoods and food security, and the temporary increase in pelagic fishery species' productivity in Tanzania are highlighted. Finally, we discuss how satellite observations may assist fisheries management bodies to anticipate low productivity periods, and mitigate their potentially negative economic impacts. © 2020 by the authors.

Global change is defined here for this review as changes caused by increasing greenhouse gas emissions resulting in a high CO2 world and the direct and indirect changes that ensue. Increasing green house gas emissions are causing three major impacts on the ocean: warming sea surface temperature (SST), ocean acidification and deoxygenation (Turley et al 2011). The latter two are poorly understood at present, particularly in Eastern Africa. Secondary impacts include sea level rise due to melting polar ice caps. Coral bleaching and death caused by SST rise has been extensively studied and measured (HoeghGuldberg 1999; Hughes et al. 2003), including in the WIO (Obura 2005, McClanahan 2009), with likely ecosystem phase shifts as coral reefs become dominated by macroalgae (brown algae such as Turbinaria, Sargassum spp.) (Bellwood et al. 2004; Hughes et al. 2005). Ocean acidification is likely to have enormous impacts on marine resources and hence fisheries (Turley et al. 2011), as ocean chemistry is changed and thus any marine organisms that rely on Ph sensitive chemical reactions will be affected. This field is still relatively new and early reports predict trophic level shifts as organisms with calcium carbonate skeletons, e.g molluscs, corals, are compromised. Deoxygenation is caused by ocean warming (oxygen becomes less soluble) which will result in less growth of most marine organisms and a shift to low oxygen tolerant organisms, often microorganisms. Coastal environments and people are also undergoing changes that are directly related to human pressures caused by development and other activities. These include increasing population, mechanisation (eg in fisheries), industrialisation (eg ports and coastal cities), pollution, and extraction of oil and gas. Published

In Kenya beach seines were prohibited through Fisheries Department legislation in 2001. Despite this ban, and the authorities’ attempts to enforce it, the beach seine fishery is still commonly used both at the Coast and in Lake Victoria; at the Coast the use of beach seines is increasing. Attempts to replace the beach seines with other gear have proved to be not as effective as hoped. In order to gain a better understanding of beach seining in the country, the root causes for its continued use and the difficulties in enforcing the ban, the newly established Ministry of Fisheries Development has requested FAO to include Kenya in the Global Study on Beach Seining currently being conducted by the Fisheries and Aquaculture Department of Rome Headquarters. From January to May 2008, the NGO Coastal Oceans Research and Development – Indian Ocean (CORDIO) East Africa has carried out the study with the financial support of the FAO Sub Regional Office for Eastern Africa based in Addis Ababa. In line with the term of reference of the study, a field survey has been undertaken in five landing sites (four in Coast Province and two in Nyanza Province) using participatory rural appraisal techniques and with the direct involvement of the local staff of the Fisheries Department. The follwing summarises the key findings and recommendations. Fishers from both Lake Victoria and the Coast were well aware of the negative impacts caused by beach seining operations. The most notable examples cited by both groups of fishers was the destruction of fish breeding ground habitats and the capture of juveniles. These were caused by the bottom dragging deployment method used to haul the nets, and the fine mesh, respectively. The most important positive impact of beach seining in both locations was income generation and employment leading also to food security from the consumption of part of the catches. In fact the catch sharing arrangements ensured that most of the fishing community benefit from the beach seine fishery. In addition, in both locations, the role of youth and women, the first especially during beach seining operations, the second more in marketing and processing of the catches was found to be very important. Within the scope of the present study it was not possible to measure the total number of households involved in beach seining, but for the Coast the total number of fishers was estimated to be anywhere between 11,000 and 18,000 out of a total 65,000 artisanal fishers. At Lake Victoria there are estimated to be 4,676 beach seine fishers in Suba District where the field study was done. This District accounts for around 51% of beach seine fishers in the Lake, therefore a total of around 9,400 beach seine fishers may be operating in Lake Victoria (Kenyan waters). Dependency on this gear extends further if the following figures are used: 186,336 people are enumerated to depend on fishing and fishery related activities for their livelihood in Suba District. Using the rough calculation of 30% are beach seine related, this gives an overall figure of 112,000 for the whole Lake. Thus in total, in Kenya, probably around 20,000 fishers are using beach seines, and at least a further 200,000 people may be dependent on this gear for their food and livelihoods. The use of the beach seine has persisted in both locations, despite the ban and despite the level of enforcement being higher in Lake Victoria than at the Coast. Beach seine use has increased over the last two years at the Coast. The major difference among the two case studies is that the majority of fishers at the Coast were driven to the beach seine fishery due to a lack of alternatives, while fishers in Lake Victoria are attracted to the beach seine gear due to the rich Nile perch fishery associated with the gear and the ready market that is readily available for the landed fish. The following management recommendations are proposed as temporary measures for the immediate term to address the difficulties in enforcement. They are put forward for discussion and consultation, particularly with the policy and management agency (FiD) and also the fishers themselves. We propose an iterative approach whereby options are put forward by different stakeholders and are then discussed and consensus reached on the most appropriate way forward. Published

Underwater censuses were used to measure species richness, abundance, and biomass of coral reef fish at nineteen reef slope study sites on the Kenyan coast, in 1987/1988. The survey was designed to examine the structure of the coral reef fish communities in relation to protection, fishing, sediment run-off from rivers, sea urchins, and collecting for the aquarium trade. A further twelve reefs were studied, but no censuses were carried out due to poor visibility or a lack of coral substrate. While species richness was highest in Marine National Parks where no fishing or collecting is allowed, the same was not true for fish abundance, or for biomass of commercially important fish. Some of the highest densities and weights of fish were recorded from the Marine National Reserves where traditional fishing methods are allowed. Standing stocks (biomass) of commercially important fish were negatively correlated with fishing intensity, and localized overfishing was evident near centres of high human populations. On the sparsely populated northern coastline, non-coralline reefs support exceptionally high standing stocks, due to minimal fishing pressure, and possibly a greater input of nutrients. Areas with higher fishing intensities had smaller standing stocks but not comparably smaller abundances. This suggests that more intense fishing is reducing average fish size. In genera] the results indicate that overfishing is not a major problem on Kenya's reef slopes. Two factors, siltation from rivers and dynamite "fishing" have a major impact on the fish communities. Reefs badly damaged from dynamiting in the Shimoni area, including Mako Kokwe in the Kisite Marine National Park, have negligible amounts of living hard coral and are characterised by a low species richness of fish, and exceptionally low densities of fish. For example the biomass of commercially important fish at Mwamba Midjira, which has been severely damaged by dynamiting, was only one tenth of the biomass recorded at Kisite, a neighbouring reef where no dynamiting occurs. Malindi Marine National Park has been subjected to a heavy influx of sediment from the Sabaki river since the early seventies. Coral die-off was evident, and densities and biomass of fish were of a similar magnitude to dynamited reefs, despite the prohibition of all fishing and collecting for the last 20 years. Similarly, coral die-off and sedimentation was apparent at survey sites close to the Tana river mouth, where fish censuses were not possible due to high silt content in the water. No correlation between sea urchin densities and predatory fish (15 species) densities was detected, suggesting that high fishing pressure is not responsible for high densities of sea urchins. High densities of sea urchins were observed on damaged (e.g. from dynamiting) reefs; possibly urchin survival is enhanced in the absence of corals. The total abundance of fish collected for the aquarium trade (48 species) did not differ significantly between a protected site and a site where collecting occurs, suggesting that collecting aquaria fish is not depleting stocks. However, several collectors use methods that are destructive to the reef substrate. In summary, it is clear that the effects of sediment offload from rivers and the use of dynamite far outweigh the effects of protective management and fishing on Kenya's coral reef fish communities. In the face of these impacts, marine park status is no guarantee that a high abundance and biomass of reef fish will be maintained, as exemplified by Malindi and Mako Kokwe Marine National Park sites. Standing stock estimates of commercially important reef fish are high in several reef areas where fishing pressure is low, except where sedimentation and dynamiting occurs. These two major problems have long been recognised (IUCN/UNEP 1985), but no policies have arrested their destructive effects. For the future of Kenya's coral reef fish, conservation action must address these issues. Published