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Shifting baselines of Kenya’s exploited reef fishes

Updated: May 28



A FAR-LeaF research fellow is working hard to safeguard Kenya's' coral reef fish species for the future. Dr Levy Otwoma believes it is better to manage food security and sustainability through improved fisheries management, improved knowledge of conservation and monitoring, and increased understanding of the extinction risks by community and stakeholders.


The research project focuses on local extinction and shifting baselines of Kenya's' exploited reef fish that will lead to enhanced management and policy guidelines on fisheries management, protecting the 23 commercially important reef fish species at risk of local extinction in Kenya. Dr Otwoma says most current reef fish management strategies must deliver on their social, ecological and management goals. Though Kenya's marine and coastal environment is of high environmental and economic value with its natural bounties, an increase in population and unplanned development of towns coupled with the effects of climate change are accelerating the environmental degradation and biodiversity loss in this country.


This has severe consequences since coastal communities in Kenya depend on reef fish for daily livelihoods, food security, and protein intake. This calls for urgent capacity-building efforts to address the environmental, ecological, social, and economic challenges. The collapse of reef fish species could lead to the loss of substantial livelihood among Kenya's' fishermen. His work is unique. The pattern of extinction in tropical marine fish species is rarely investigated, particularly in poor coastal nations, and most research in these regions tends to focus on short-term aggregated monitoring records rather than species-level assessments.


The decline in exploited marine resources has been evident since 1950. A holistic understanding of reef fish species status is needed to counter the continuing loss of yields, income, and degradation of coral reefs. Through his research, Dr Otwoma hopes to increase coral reef fishes' resilience and support the continued provision of community benefits, including improved nutrition, livelihoods, and greater food security.



Dr Levy Otwoma (on the right) is interviewing a local fisherman along the Kenyan coastline.


To identify local extinctions, he conducted semi-structured interviews with 152 fishermen in six fishing villages along the Kenyan coastline – at least 20 fishermen per village – to determine changes in historically exploited coral reef fish populations over multiple temporal and spatial scales. He contacted specific resource users through fishery offices and beach management unit members at every landing site.


"We only interviewed active fishermen, some with over 30 years of fishing experience. The interviews were conducted one-on-one in a relaxed setting by five scientists who are native Swahili speakers. We showed them photographs of 23 species identified to be threatened with local extinction and asked them to identify and categorise the ones they recognised. Participants grouped the species into the following categories: ordinary – never seen – seen but never caught – declined over time. Following the categorisation of the species, participants were questioned on when they last saw/caught each species and where – we asked for specifics on depth, habitat and location.


"Specifically, we asked fishers to recall their typical catch rate for when they first began fishing and last fished. Finally, we asked fishers whether they considered any fish species to have undergone a decline in abundance. Questionnaire data gathered from this activity has already been analysed, and a manuscript on quantifying local extinction and shifting baselines based on local knowledge is being composed," he explained.


Dr Otwoma then had to corroborate and validate local extinctions within site ecological assessments. His team conducted the same semi-structured interviews with 30 long-term divers along the coastline of Kenya and undertook underwater surveys in four reef locations. He plans to estimate the degree of decline and extinction based on changes in species in relative abundance by comparing historical data sources with different contemporary data sources. He will assess the various trends of relative abundance of historically exploited species based on the proportional change in the total number of fish recorded between the archaeological records and contemporary underwater surveys, interviews, and catch records.


"To determine intergenerational shifts among fishers in their perception of changes in catch rates, the interview data collected will be disaggregated according to age to determine shifts in the fishers'' perceptions. Additional interviews are planned to supplement the data already gathered." The next step is to assess the status of the broad range of exploited coral reef fish species to determine those most vulnerable to extinction. He will then raise awareness through outreach and advocacy about the vulnerability of exploited reef fish among relevant stakeholders to safeguard Kenya's fish species in the future. The project has been well-received by communities and community leaders.


Heidi Sonnekus | FAR-LeaF Team


Image by Justin Hu

FUTURE AFRICA

RESEARCH LEADERSHIP FELLOWSHIP

The Future Africa Research Leadership Fellowship (FAR-LeaF) is an early career research fellowship program focused on developing transdisciplinary research and leadership skills.

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The programme seeks to build a network of emerging African scientists who have the skills to apply transdisciplinary approaches and to collaborate to address complex challenges in the human well-being and environment nexus in Africa.

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