Inland fisheries of tropical Africa

Marshall, B. E.

doi:10.1002/9781118394380.ch28

Cited by 5 publications

(5 citation statements)

References 52 publications

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“…The sustainability of these fisheries will be crucial for the food security of the rapidly growing human population of sub-Saharan Africa, which is projected to double by 2050 [6]. Multiple threats, however, are imperiling freshwater fish stocks in Africa, including overexploitation, habitat degradation, introduction of exotic species, and aquaculture [7][8][9][10]. Africa's most populous country, Nigeria (population ~225 million) in West Africa, ranked 9th globally for inland fisheries yield in 2020, accounting for 3% of the global total and ~11% of Africa's total (Table 1).…”

Section: Introductionmentioning

confidence: 99%

Critically Small Contemporaneous Effective Population Sizes Estimated for Stocks of the African Bonytongue in Western Africa

Hurtado,

Mateos,

Caballero

et al. 2024

Fishes

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Inland capture fisheries play a critical role in supporting food security and livelihoods in Africa. Therefore, it is important to evaluate the genetic health of exploited fish populations. The African bonytongue, Heterotis niloticus, supports important commercial and subsistence fisheries in western Africa. However, sharp declines in stocks have been reported. Herein, we estimate contemporary effective population sizes (Ne) of four Heterotis populations in Nigeria, three in Benin, and five in Cameroon using Linkage Disequilibrium methods. Ne estimates were used to assess genetic short-term (i.e., inbreeding depression) and long-term (i.e., loss of evolutionary potential) risks. Ne point estimates obtained with the best estimator (out of 16), as determined by computer simulations, were <50 (range = 5.1–36.2) for nine of the twelve populations examined, which is below the minimum recommended for avoiding the potential deleterious effects of inbreeding depression (original criterion Ne ≥ 50, revised to Ne ≥ 100); and well below the minimum recommended for populations to retain evolutionary potential (original criterion Ne ≥ 500; revised to Ne ≥ 1000). The lower bound of the confidence interval for two of the remaining populations was below the minimum recommended to retain evolutionary potential (with the point estimate of one of them also below this threshold), and for some methods, values were lower than the minimum recommended to avoid inbreeding depression. Accordingly, our results suggest that urgent conservation and management plans are needed to guarantee the persistence and sustainability of the H. niloticus populations examined.

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Section: Introductionmentioning

confidence: 99%

Critically Small Contemporaneous Effective Population Sizes Estimated for Stocks of the African Bonytongue in Western Africa

Hurtado,

Mateos,

Caballero

et al. 2024

Fishes

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show abstract

“…Sustainability of these fisheries will be crucial for the food security of the rapidly growing human population of sub-Saharan Africa, which is projected to double by 2050 (United Nations-Department of Economic and Social Affairs-Population Division, 2019). Multiple threats, however, are imperiling native freshwater fish stocks in Africa, including overexploitation, habitat degradation, introduction of exotic species, and aquaculture (Abban, 1999;Lind et al, 2012;Marshall, 2016;Olaosebikan and Bankole, 2005). Therefore, it is important to conduct research that informs the sustainable use of these resources.…”

Section: Introductionmentioning

confidence: 99%

Critically Small Contemporaneous Effective Population Sizes for Stocks of the African Bonytongue in West Africa

Hurtado,

Mateos,

Caballero

et al. 2023

Preprint

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Inland capture fisheries play a critical role in supporting food security and livelihoods in West Africa. Therefore, it is important to evaluate genetic health of exploited fish populations. The African bonytongue, Heterotis niloticus, supports important commercial and subsistence fisheries in West Africa. Sharp declines of stocks have been reported, however. Herein, we estimate contemporary effective population sizes (Ne) of four Heterotis populations in Nigeria, three in Benin, and five in Cameroon using the Linkage Disequilibrium method with correction for age structure. Ne estimates were used to assess genetic short-term (i.e., inbreeding depression) and long-term (i.e., loss of evolutionary potential) risks. Analyses failed to obtain Ne point estimates for two populations. For the remaining ten populations, corrected Ne point estimates fell well below 500, the minimum recommended for populations to retain evolutionary potential; with eight populations below 100 (range 2.8–83.5), the minimum recommended to avoid inbreeding depression, one borderline (100–125), and one above this threshold (312–392). The lower 95% confidence interval bound of Ne for eleven populations was very small (0.7–14.6), and for the remaining population it was 44.2. Accordingly, all populations examined can be considered potentially at risk of inbreeding depression.

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“…Capture inland sheries in Africa produced an estimated 3,004,437 metric tons in 2018, an amount only surpassed by that from Asia at 7,953,840 metric tons [5]. Inland sheries in Africa, however, are facing growing threats that include overexploitation, habitat degradation, and introduction of exotic species that can impact native sh stocks [6,7]. Given that human populations and economies are growing rapidly in Africa, impacts from these threats are expected to increase [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…Inland sheries in Africa, however, are facing growing threats that include overexploitation, habitat degradation, and introduction of exotic species that can impact native sh stocks [6,7]. Given that human populations and economies are growing rapidly in Africa, impacts from these threats are expected to increase [7,8]. The human population in sub-Saharan Africa is projected to double by 2050 [9], and it is estimated that one in every four people will be undernourished in this region [10].…”

Section: Introductionmentioning

confidence: 99%

Genetic Identification and Diversity of Stocks of The African Bonytongue, Heterotis Niloticus (Osteoglossiformes: Arapaiminae), in Nigeria, West Africa

Oladimeji

Caballero

Mateos

et al. 2021

Preprint

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Inland fisheries are an important source of protein and income for people in Africa, and sustainable fisheries management requires knowledge of regional stocks. Presently, information regarding genetic diversity of African freshwater fishes is very limited. Here we present findings from a spatial analysis of genetic patterns in the African bonytongue, Heterotis niloticus, an important component of inland fisheries in West Africa. The species is common throughout Western and Central Africa and the Nile Basin; and has been introduced for aquaculture in locations across Africa. Nigeria has the largest fishery for African bonytongues, representing ~86% of the global total. Recent declines in yields at some Nigerian locations, however, suggest current levels of exploitation may be unsustainable. Habitat degradation also may be impacting some stocks. Despite its commercial and nutritional importance, the African bonytongue has been the subject of scant research to support management. We examined patterns of genetic diversity in natural populations of H. niloticus at four locations in Nigeria, including Kainji Lake, a reservoir on the Niger River in north-central Nigeria, and three southtern localities (Ethiope River, Igbokoda River, and Epe Lagoon), as well fish from the Ouémé River delta near Porto Novo, Benin. Eighty-five specimens were genotyped for nine microsatellite-loci. Genetic diversity estimates were highest at Kainji Lake, and substantially lower at southern localities. High levels of genetic differentiation were detected between samples from Kainji Lake and those from the southern localities. Low, yet significant FST values were observed among samples from southern Nigerian localities that were more differentiated from the sample from nearby coastal Benin. We thus recommend that African bonytongues from the five locations be considered distinct genetic stocks and managed accordingly.

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Inland fisheries of tropical Africa

Cited by 5 publications

References 52 publications

Critically Small Contemporaneous Effective Population Sizes Estimated for Stocks of the African Bonytongue in Western Africa

Critically Small Contemporaneous Effective Population Sizes Estimated for Stocks of the African Bonytongue in Western Africa

Critically Small Contemporaneous Effective Population Sizes for Stocks of the African Bonytongue in West Africa

Genetic Identification and Diversity of Stocks of The African Bonytongue, Heterotis Niloticus (Osteoglossiformes: Arapaiminae), in Nigeria, West Africa

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