Ecosystem-based assessment of the Malindi

Ecosystem-based assessment o f the Malindi-Ungwana Bay prawn
fishery using ecological indicators
Swaleh Khyria1 2, Boaz Kaunda-Arara 2, Renison Ruwa1and Philip Raburu2
1 Kenya Marine and Fisheries Research Institute, PO Box 81651 Mombasa, Kenya
E-mail: khvriask@ qm ail.com , reniruwa@ vahoo.com
2 D epartm ent o f Fisheries and A quatic Sciences, U niversity o f Eldoret, PO Box 11 25 Eldoret, Kenya
The study aimed to describe indicators th a t w ill co ntribu te to developm ent o f an ecosystem-based
approach to fisheries m anagem ent (EAFM) o f prawn resources in the M alindi-Ungwana Bay, Kenya. A
comprehensive EAFM is required to h oiistically assess and manage fisheries resources and th e ir
associated habitats. The project identified and assessed ecological indicators based on the
objectives o f su stain ab ility o f harvests, b io dive rsity conservation, and maintenance o f habitat
quality. A desktop analysis was perform ed on data sourced from ; the State D epartm ent o f Fisheries,
Research vessels, KMFRI, and on-project fie ld w ork. Trends in historical landings (1985-2010) o f the
prawns fro m the M alindi-Ungwana Bay were analysed using LOWESS. Num ber-size spectra analysis
was used to assess the ecological state o f the bay w hile, Biomass T ro p hic Level spectra (BTLS)
analysis was applied as a potential to o l fo r analysing m u lti-fa cto r effects on the bay. Indiseas based
ecosystem indicators were used to q u a n tify the im pact o f prawn fis h e ry on the bio dive rsity o f the
bay. Results indicate a long-term series w ith tw o peaks (in 1997 and 2000) in historical landings o f
penaeid shrim ps w ith a m onotonous decline in catches fro m 2002. Num ber -size spectra analysis
made from artisanal landings (2008-2012) indicated effects o f fish in g on the ecosystem. The
num ber-size spectra results showed increased fish in g m o rta lity w ith tim e (2008-2012) and a
general increase in fisheries p ro d u ctivity o f the bay. BTLS analysis using the fish by-catch data
indicated reduced levels o f biomass across tro p h ic levels and a decline in tro p h ic levels o f the fish
species caught, indicating a fishing - down o f the food web. Biodiversity and conservation based
indicators adopted fro m the Indiseas program showed the M alindi-Ungwana Bay ecosystem is
ecologically degraded in term s o ffis h sizes, tro p h ic characteristics and pro po rtio n o f predators. The
study recomm ended adoption o f the described ecological indicators and tools as means fo r
evaluating and m o n itoring the M alindi-Ungwana Bay resources and ecosystem status. However,
there is need to initiate more long-term m on itoring program s in order to strengthen the tem poral
scale o f analysis. A d d itio n a l socio-econom ic and biological data w ill be needed in order to develop a
holistic EAFM m odel fo r the m anagem ent o f the M alindi-Ungwana Bay resources.
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