Population dynamics and stock assessment of Ethmalosa fimbriata in Senegal call for fishing regulation measures

Baldé, Bocar Sabaly; Brehmer, Patrice; Sow, Fambaye Ngom; Ekau, Werner; Kantoussan, Justin; Fall, Moussa; Diouf, Malick

doi:10.1016/j.rsma.2018.08.003

Cited by 12 publications

(19 citation statements)

References 27 publications

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“…However, the work of Diankha et al (2018) have shown that the variability of Sardinella recruitment is related to fluctuations in surface temperature. These results are also consistent with those of Baldé et al (2018), which explain the variability of recruitment in Ethmalosa fimbriata, by the effect of local climate variability.…”

Section: Vulnerability Of the Sitessupporting

confidence: 91%

Identification and Characterization of Critical Sites for Small Pelagic Fish in the Coastal Marine Area of Senegal, West Africa

Ndour

Assiatou²,

Thiam³

et al. 2019

JBLS

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Better management of coastal marine resources generally requires good knowledge of habitats and resources. This need led to the performance of an identification and bioecological characterization study of critical sites for small pelagics in the Senegalese coastal marine zone. Biological and ecological data were collected using beach seines (12 to 28 mm mesh) and surface drifting gillnets (28 to 36 mm mesh) at sites identified by fishermen on the basis of surveys. The results of the study highlight the bioecological characteristics of these sites: (i) the Port-Baie Hann site - a nursery and spawning site with a high diversity for the target species; it is under marine pollution threat; (ii) the Mbodiène-Ngazobil site, with high diversity for target species and the Kafountine-Cap site are nursery and spawning sites under high fishing pressure, (iii) the Diakhanor-Sangomar site - a spawning site under the potential threat of exploration of offshore Sangomar oil in addition to the high fishing pressure. This work is a first flagship contribution to a process that should lead to the development and control of new tools for the effective and sustainable management of small pelagics at national and regional scales.

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Section: Vulnerability Of the Sitessupporting

confidence: 91%

Identification and Characterization of Critical Sites for Small Pelagic Fish in the Coastal Marine Area of Senegal, West Africa

Ndour

Assiatou²,

Thiam³

et al. 2019

JBLS

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“…In the waters of Senegal, which are located at the southern tip of the CCLME, small pelagic fishes are exploited intensively by artisanal fleets and dominate fishery landings by volume and value (Diankha et al, ). The bonga shad Ethmalosa fimbriata (Bowdich, 1825) is the third‐most commercially important clupeid species for the fisheries along the southern coast of Senegal (after round sardinella Sardinella aurita and madeiran sardinella S. maderensis also known as flat sardinella) (Baldé et al, ), with catches reaching 18,400 tons in 2015 (Thiao, Sow, Thiam, Fall, & Thiam, ). Ethmalosa fimbriata inhabits hypersaline, marine, brackish and freshwater habitats Charles‐Dominique, along the coasts of West Africa, from Mauritania to Angola (Charles‐Dominique & Albaret, ).…”

Section: Introductionmentioning

confidence: 99%

Bonga shad (Ethmalosa fimbriata) spawning tactics in an upwelling environment

Baldé

Döring

Ekau

et al. 2019

Fisheries Oceanography

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Successful recruitment in small pelagic fish populations inhabiting upwelling zones is subject to variation in fecundity and is driven by spatial and temporal fluctuations in environmental conditions, that is, mainly sea surface temperature, salinity and food availability. These fluctuations in abiotic factors have stimulated small pelagic fish populations to exhibit specifically adapted spawning tactics. To better understand to what extent a short‐lived exploited fish species such as bonga shad Ethmalosa fimbriata has adapted to an upwelling environment, we have investigated the interrelationship between upwelling intensity as a proxy for productivity and population fecundity by means of a virtual population analysis. We found that females of intermediate size contributed significantly more eggs to the population's fecundity than smaller or larger ones. Our model results further indicate that E. fimbriata exhibits a spawning preference at water temperatures of around 25°C and upwelling intensities of around 2.5 m3 s−1 m−1. Hence, we hypothesize that climate change‐driven increases in sea temperatures and modifications of upwelling‐favourable winds could significantly impact the species’ reproductive biology. To understand how climate change might impact fisheries, spawning tactics of small pelagic fishes are important to assess as well as their recruitment success. Such information is particularly relevant in countries where the fishery is critical at socio‐economic level, to better implement fisheries management addressing multiple stressors.

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“…The Petite Côte (14 ° 36 N at 13 ° 36 N, Figure 1) has a great geomorphological and biodiversity richness: cords and sand arrows, cliffs, bays, lagoons and mangrove estuaries (Saloum estuary, lagoon-estuarine system of Somone (Baldé et al, 2018). This area is home of a seasonal upwelling cell that affects ambient temperature fluctuations in the area.…”

Section: Study Areamentioning

confidence: 99%

“…For small-scale, data-poor fisheries where age data collection is often limited by lack of technical expertise and funds, length-frequency data is often the only form of information available for researchers and managers (Baldé et al, 2018). Length-frequency data, when available, can be used by researchers to inform management.…”

Section: Introductionmentioning

confidence: 99%

Fish-length based indicators for improved management of the sardinella fisheries in Senegal

Baldé

Fall

Kantoussan

et al. 2019

Regional Studies in Marine Science

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Fisheries management is difficult especially in developing countries where there are little or no data available for stock assessment. Here, a simple model based on the length-based Bayesian biomass (LBB) is applied to length frequencies collected on the two sardinella species (Sardinella maderensis and S. aurita) collected in Senegalese waters (2004 to 2014) to diagnose these stocks and to support the development of fishery management options that may improve the livelihoods of artisanal fishermen. Annual mean length of both species of sardinella showed a large variation during the decadal study period. It is assumed that such variations are due to environmental changes. According to our results, based on the current exploitation rate, both sardinella species are overexploited. To reverse these bad stock status, three management indicators were estimated for both sardinella: (i) length at first capture (Total Length (TL); 24 and 27 cm for S. maderensis and S. aurita, respectively); (ii) the length at maximum possible yield per recruit (TL; 26 and 29 cm for S. maderensis and S. aurita, respectively); and (iii) the optimal length for the first capture (TL; ; 25 and 28 cm for S. maderensis and S. aurita, respectively). According to Senegalese maritime fishing code, which sets the small pelagic fish size of the first capture 18 cm, we urge the Senegalese governments to press ahead with much needed reforms of the fishing code. We recommend capturing sardinella at the size to provide a natural safeguard against any recruitment failure related to environmental variability and allow individuals to grow and ensure the longterm survival of populations and thus sustainable fisheries. The results suggest that LBB model could be a tool to assess data-poor fisheries allowing the possibility to include in the analysis several years of length-frequency data with a minimum of prerequisites.

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Population dynamics and stock assessment of Ethmalosa fimbriata in Senegal call for fishing regulation measures

Cited by 12 publications

References 27 publications

Identification and Characterization of Critical Sites for Small Pelagic Fish in the Coastal Marine Area of Senegal, West Africa

Identification and Characterization of Critical Sites for Small Pelagic Fish in the Coastal Marine Area of Senegal, West Africa

Bonga shad (Ethmalosa fimbriata) spawning tactics in an upwelling environment

Fish-length based indicators for improved management of the sardinella fisheries in Senegal

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