Prediction of Lake Victoria's response to varied fishing regimes using the Atlantis ecosystem model

Nyamweya, Chrisphine S.; Sturludóttir, Erla; Tómasson, Tumi; Taabu‐Munyaho, Anthony; Njiru, M.; Stefansson, Gunnar

doi:10.1016/j.fishres.2017.05.014

Cited by 17 publications

(17 citation statements)

References 18 publications

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“…The late 1990s and 2000s saw the dominance of Caridina nilotica and haplochromines in the diet, the reason being that Nile perch predation on R. argentea was reduced when their preferred prey (haplochromines) are plentiful (Nyamweya et al . ). Increased haplochromines in perch diet are attributed to a resurgence of the species after the decline of Nile perch, although the dominance of C. nilotica in their diet could be attributed to increased hypoxia in the lake.…”

Section: Ecological Impacts Of Nile Perchmentioning

confidence: 97%

“…Despite the increasing effort, Nile perch catches have remained stable after the Nile perch boom, indicating fishing pressure may not be the only driver of the species’ abundance in Lake Victoria (Nyamweya et al . ). The Food and Agricultural Organisation (FAO) of the United Nations calculated that the boom created 180,000 jobs in the fishing industry in the 1980s alone.…”

Section: Socio‐economic Impacts Of Nile Perchmentioning

confidence: 97%

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Impacts of Nile Perch, Lates niloticus, introduction on the ecology, economy and conservation of Lake Victoria, East Africa

Aloo¹,

Njiru

Balirwa

et al. 2017

Lakes & Reservoirs

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Nile perch were secretly introduced into Lake Victoria in the 1950s, and officially in the 1960s, amid unresolved controversy. Proponents were of the view that the introduction would improve fisheries production and sport fishing. Although the former objective was achieved, the side effects were dire, including extinction of many native species, especially the ecologically important haplochromines, because of predation. The introduction also changed the habitat, trophic dynamics and water clarity. The change in water clarity is thought to be responsible for hybridization of haplochromines, further contributing to the loss of species diversity among cichlids. The establishment and expansion of the Nile perch also altered the fishery and socio‐economic settings characterizing the lake. A local economy which, until the early 1980s, was based on native fish species has been replaced by an export‐oriented exotic fish processing industry that destroyed the once‐cherished traditional resource. Other socio‐economic issues associated with Nile perch include the high HIV/AIDS prevalence among fishers, and border conflicts attributable to the migratory and transboundary nature of the fishery resource. Conservation measures for the fishery should include establishment of co‐management units that have so far registered both successes and challenges. Other efforts include establishment of the Nile perch Fisheries Management Plans that focus on curbing overfishing and eradicating illegal fishing.

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Section: Ecological Impacts Of Nile Perchmentioning

confidence: 97%

Section: Socio‐economic Impacts Of Nile Perchmentioning

confidence: 97%

Impacts of Nile Perch, Lates niloticus, introduction on the ecology, economy and conservation of Lake Victoria, East Africa

Aloo¹,

Njiru

Balirwa

et al. 2017

Lakes & Reservoirs

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“…To meet these needs, recent investigations have constructed ecosystem‐level models for evaluating freshwater and marine communities around the globe (Nyamweya et al 2017; Sturludottir et al 2018; Fay et al 2019). For example, food web models leveraging the results of observational or experimental studies have often been used to enhance understanding of the structure of an ecosystem and identify leading indicators or nodes most sensitive to perturbation spanning multiple levels of biodiversity (e.g., genes, species, guild; Masi et al 2017; Sturludottir et al 2018; Fu et al 2019; Hansen et al 2019).…”

Section: What Tools Are Advancing the Understanding Of Emergent Properties Of Aquatic Systems?mentioning

confidence: 99%

“…End‐to‐end ecosystem modeling approaches, which seek to represent all components of socio‐ecological systems, have enabled comparisons of system‐level outcomes from different scenarios and cost–benefit analyses of management actions (Beaugrand 2014; Möllmann et al 2015). Such models have served as tools to explore the socioeconomic implications of changing ecosystem structure (Fay et al 2019), evaluate resource management strategies (Nyamweya et al 2017), and project the impacts of future climatic and harvest scenarios (Olsen et al 2018). For example, Fay et al (2019) modeled the northeastern United States and found that changes in fishing effort led to strong responses, with clear tradeoffs among species and fishery sectors, but that regional market sales scaled nonlinearly with total landings, and regional income was relatively similar across scenarios.…”

Section: What Tools Are Advancing the Understanding Of Emergent Properties Of Aquatic Systems?mentioning

confidence: 99%

How Does Climate Change Affect Emergent Properties of Aquatic Ecosystems?

et al. 2021

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Emergent properties of ecosystems are community attributes, such as structure and function, that arise from connections and interactions (e.g., predator-prey, competition) among populations, species, or assemblages that, when viewed together, provide a holistic representation that is more than the sum of its individual parts. Climate change is altering emergent properties of aquatic ecosystems through component responses, a combination of shifts in species range, phenology, distribution, and productivity, which lead to novel ecosystems that have no historical analog. The reshuffling, restructuring, and rewiring of aquatic ecosystems due to climate impacts are of high concern for natural resource management and conservation as these changes can lead to species extinctions and reductions in ecosystem services. Overall, we found that substantial progress has been made to advance our understanding of how climate change is affecting emergent properties of aquatic ecosystems. However, responses are incredibly complex, and high uncertainty remains for how systems will reorganize and function over the coming decades. This cross-system perspective summarizes the state of knowledge of climate-driven emergent properties in aquatic habitats with case studies that highlight mechanisms of change, observed or anticipated outcomes, as well as insights into confounding non-climate effects, research tools, and management approaches to advance the field.

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“…It has been used to test a number of management scenarios for different areas. It has, for example, been used to test management scenarios with different discarding regulations (Fulton et al 2007), scenarios of gear shift to reduce by-catch (Kaplan et al 2012) and different fishing pressure scenarios (Nyamweya et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Exploring the effects of discarding using the Atlantis ecosystem model for Icelandic waters

Sturludóttir

2018

Sci. Mar.

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Summary:Discarding fish has been a part of the fisheries for centuries but it has been very difficult to monitor how much is discarded, especially in areas where it is an illegal activity. In this study the ecological and economic effects of discarding were investigated using the Atlantis model for Icelandic waters. Five different scenarios were compared, using different discarding rates and selectivities. The results showed that a complete stop of discarding fish (cod and haddock) and landing everything instead had little ecological and economic impact. Improved selectivity, which would result in not catching the fish that would be discarded, had great beneficial economic effects. The increase in biomass led to higher landings, which consequently led to higher revenue. Also, the cost decreased with increasing biomass, which increased the profit of the fisheries. None of the five scenarios had great ecological effects but only discarding of cod and haddock, which have low discard rates, were considered in this study.Keywords: Icelandic waters; discards; selectivity; ecosystem model; Atlantis; cod; haddock. Exploración de los efectos de los descartes mediante el modelo ecosistémico Atlantis para aguas islandesasResumen: Los descartes han sido parte de la pesca durante siglos, pero es muy difícil evaluar las cantidades descartadas, especialmente en áreas donde constituye una actividad ilegal. En este estudio se investigan los efectos ecológicos y económicos del descarte mediante el uso del modelo Atlantis para aguas islandesas. Se comparan cinco escenarios con distintas tasas de descarte y selectividad. Los resultados muestran que el cese de los descartes de las especies de peces de mayor importancia comercial (bacalao y eglefino) y su descarga en tierra tiene impactos ecológicos y económicos menores. Una mejora de la selectividad que impidiera la captura de la fracción descartada tendría importantes beneficios económicos. El aumento de la biomasa conduciría a una mayor producción comercial y en consecuencia a unos mayores ingresos. Así mismo, los costes disminuirían con niveles de biomasa superiores, amplificando el beneficio económico producido por la pesca. En ninguno de los cinco escenarios se aprecian grandes efectos ecológicos, pero en este estudio solamente se consideran el bacalao y el eglefino, que tienen tasas de descarte relativamente bajas.Palabras clave: aguas islandesas; descartes; selectividad; modelo ecosistémico; Atlantis; bacalao; eglefino.Citation/Como citar este artículo: Sturludottir E. 2018. Exploring the effects of discarding using the Atlantis ecosystem model for Icelandic waters. Sci. Mar.

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Prediction of Lake Victoria's response to varied fishing regimes using the Atlantis ecosystem model

Cited by 17 publications

References 18 publications

Impacts of Nile Perch, Lates niloticus, introduction on the ecology, economy and conservation of Lake Victoria, East Africa

Impacts of Nile Perch, Lates niloticus, introduction on the ecology, economy and conservation of Lake Victoria, East Africa

How Does Climate Change Affect Emergent Properties of Aquatic Ecosystems?

Exploring the effects of discarding using the Atlantis ecosystem model for Icelandic waters

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