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  • 1
    Online Resource
    Online Resource
    Cage farming in the environmental mix of Lake Victoria: An analysis of its status, potential environmental and ecological effects, and a call for sustainability
    Michigan State University Press ; 2022
    In:  Aquatic Ecosystem Health & Management Vol. 25, No. 4 ( 2022-10-01), p. 37-52
    Details
    In: Aquatic Ecosystem Health & Management, Michigan State University Press, Vol. 25, No. 4 ( 2022-10-01), p. 37-52
    Abstract: Lake Victoria is the second largest freshwater lake in the world that was once a biodiversity hotspot hosting over 500 endemic haplochromine cichlids that were later decimated by exotic introductions and anthropogenically driven environmental and ecological changes. The environmental and ecological changes in the lake over the years have been attributed to overfishing, eutrophication, introduction of exotic species, pollution and possibly climate change. The lake's capture fishery, which is the main economic activity directly and indirectly supporting over 40 million people, has continued to decline after experiencing a boom between the 1970s and 1990s following the introduction of Nile Perch (Lates niloticus) and Nile Tilapia (Oreochromis niloticus). In order to augment capture fisheries from the lake, cage culture was introduced in 2005, but its sustainability and influence on the ecology of the lake are not well understood. In this review, we examine the genesis of degradation of Lake Victoria and assess the role of cage culture as both a solution to the current situation and a cause for concern for the ecology of the lake. To compile this review, we utilized data in the grey and published literature. Studies show that the degradation of the lake can be traced back to the 1930s when the trophic status and ecology of the lake started showing signs of anthropogenic influence. The Nile Perch was introduced in early 1960s to replenish the fishery but its ecological impacts were felt in 1970s and 1980s when the native haplochromine species started to disappear from catches. Progressively, the ecological changes and management concerns in the lake have become a complex mix of exotic species introductions, eutrophication, and overfishing. In this mix of persistent ecological changes, the once thriving capture fisheries revolving around the two exotic species (L. niloticus and O. niloticus) have significantly declined threatening the livelihoods of millions of people directly and indirectly involved in the fisheries. These declines necessitated the introduction of cage culture in 2005 to fill the increasing demand for fish from the lake. Ever since, cage numbers have increased tremendously ( & gt;6 000 by 2020) and is now operated by over 60 different firms which are owned either individually or by groups. Over 70% of the cages have been installed in shallow areas within the Winam Gulf which goes against the guidelines on cage installation and operation; regulations on cage farming were introduced after the activity had gained momentum in the lake. Limnological data in areas of the lake that have been stocked with cages has shown evidence of negative effects on water quality. This decline in water quality can be attributed to remnant feeds used in cages, of which 50% are the sinking types, and wastes from fish excretion and egestion. Although data are limited, the potential influence of cage farming on the already altered ecology and environment of Lake Victoria needs to be recognized and investigated. This study recommends studies targeting operations of cages in the lake, including a comprehensive environmental audit to inform their sustainability and relevant policy.
    Type of Medium: Online Resource
    ISSN: 1463-4988 , 1539-4077
    URL: Article
    DOI: 10.14321/aehm.025.04.37
    Language: English
    Publisher: Michigan State University Press
    Publication Date: 2022
    detail.hit.zdb_id: 2014970-0
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Future demand and supply of aquafeed ingredients: Outlines to commercialize non-conventional protein ingredients to enhance aquaculture production for food security in sub-Saharan Africa
    Michigan State University Press ; 2022
    In:  Aquatic Ecosystem Health & Management Vol. 25, No. 4 ( 2022-10-01), p. 75-84
    Details
    In: Aquatic Ecosystem Health & Management, Michigan State University Press, Vol. 25, No. 4 ( 2022-10-01), p. 75-84
    Abstract: Aquaculture, being the fastest growing food sector, is expected to provide the highly needed animal protein for about 9.7 billion people globally by 2050. The world population is likely to consume 178 million tons of food fish/aquatic animals by 2028, whereby 58% of fish will likely be from aquaculture. Growth of food fish production is expected to increase overall production of aquafeeds to over 87 million tons by 2025. Aquafeed production relies largely on fishmeal which is getting expensive due to its multiple use and scarcity. A remedy to this situation is the use of non-conventional protein sources, which may be of plant (leaves, cereals, pulses etc.) or animal (insects, worms, etc.) origin. This paper demonstrates the potential of non-conventional ingredients for aquaculture. It was found that crude protein levels of selected non-conventional plant ingredients ranged from 25-71% while those of animal origin were from 66-72%. Inclusion levels of 5-40% and 25-66% were recommended in aquafeeds, respectively, from ingredients of plant and animal origin. Performances of fish fed aquafeeds containing selected non-conventional ingredients have been reviewed. Presence of anti-nutrients, chitin and high lipid in feed ingredients, and shortcomings in processing and mass production technologies, have been identified as the main challenges limiting the commercialization of the selected feed ingredients. To remove the unwanted factors and to enhance inclusion of non-conventional ingredients in aquafeeds, authors suggested varied strategies. The strategies such as defatting, heat treatment, extrusion cooking, solvent extraction, dehulling, fermentation, ensiling, genetic modification and inclusion of enzyme are identified as some of the most efficient methods. Effective and affordable technologies to improve nutritional value should be validated through research for adequate and consistent supply of aquafeed in Sub-Saharan Africa. Consequently, provision of sufficient, quality and affordable aquafeeds will promote sustainable aquaculture production and reduce fishing pressure and pollution in natural aquatic ecosystems.
    Type of Medium: Online Resource
    ISSN: 1463-4988 , 1539-4077
    URL: Article
    DOI: 10.14321/aehm.025.04.75
    Language: English
    Publisher: Michigan State University Press
    Publication Date: 2022
    detail.hit.zdb_id: 2014970-0
    SSG: 12
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
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