Resilience of Key Biological Parameters of the Senegalese Flat Sardinella to Overfishing and Climate Change

Bâ, Kamarel; Thiaw, Modou; Lazar, Najih; Sarr, Alassane; Brochier, Timothée; Ndiaye, Ismaïla Abderhamane; Faye, A.; Sadio, Oumar; Panfili, Jacques; Thiaw, Omar Thiom; Brehmer, Patrice

doi:10.1371/journal.pone.0156143

Cited by 29 publications

(45 citation statements)

References 22 publications

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“…The effect of SST and CUI does not hide the influence of Chl‐a and WTI which had significant effect on both sardinella recruitment success in this study. These observed differences might be due to their physiological characteristics which are relatively distinct: S. aurita is more sensitive to temperature and salinity fluctuation than S. maderensis , which tolerate higher change in salinity and temperature (Ba et al., ; Cury & Fontana, ). This is also explained by the fact that, even if both species occupy the same area in Senegal (Cury & Fontana, ), their relative abundance strongly differs between Northern Senegal (in connection with Mauritania) and Southern Senegal (Capet et al., ; Ndoye et al., ), warmer and less sensitive to the detrimental effects of a strong upwelling season.…”

Section: Discussionmentioning

confidence: 99%

“…The migration of S. maderensis is less marked around its nursery area (Boëly, ; Cury & Fontana, ), suggesting that this species is able to adapt more readily to environmental variations. Sardinella maderensis is less sensitive to climatic/environmental fluctuations than S. aurita and has a less flexible adaptive strategy resulting in a smaller plasticity of their biological parameters (Ba et al., ). Moreover, S. maderensis showed smaller variability of biological and demographic parameters than S. aurita (Cury & Fontana, ).…”

Section: Introductionmentioning

confidence: 99%

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Contrasted optimal environmental windows for both sardinella species in Senegalese waters

Diankha

Bâ

Brehmer

et al. 2018

Fisheries Oceanography

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We investigate Sardinella aurita and Sardinella maderensis recruitment success relative to the variability of oceanographic conditions in Senegalese waters using generalized additive models (GAM). Results show that recruitment of both species is marked by a strong intra‐annual (seasonal) variation with minimum and maximum in winter and summer, respectively. Their interannual variations are synchronous until 2006 (recruitment decreasing), while from 2007 there is no synchrony. The model developed shows that sardinella recruitment variability is closely related to the tested environmental variables in the study area. However, the key environmental variables influencing the recruitment success are different for both species: the Coastal Upwelling Index and the sea surface temperature for S. aurita and S. maderensis, respectively. We report that recruitment success of S. aurita and S. maderensis are associated with distinct ranges of sea surface temperature, upwelling intensity, wind‐induced turbulence, concentration of chlorophyll‐a and north Atlantic oscillation index. Considering food security and socio‐economic importance of both stocks, we recommend that consideration is given to the environmental variability in the small pelagic fish national management plans, particularly in the context of climate change.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Contrasted optimal environmental windows for both sardinella species in Senegalese waters

Diankha

Bâ

Brehmer

et al. 2018

Fisheries Oceanography

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“…According to our results, the abundance of both S. aurita and S. maderensis in Senegal could then decrease in the future through a weakening of upwelling‐favorable winds. Furthermore, a northward shift of the Azores anticyclone may increase the northward migrations of S. aurita during summer, while S. maderensis may stay in Senegalese waters owing to its less migratory behavior and higher tolerance to environmental fluctuations (Ba et al., ).…”

Section: Discussionmentioning

confidence: 99%

“…Because of the spatial variability and strong seasonality of the coastal upwelling, S. aurita spawning is not uniform along the coast but occurs preferentially over the Arguin Bank (Mauritania), the south of Cap‐Vert (Senegal) (Boëly, Chabanne, & Fréon, ; Boëly, Chabanne, Fréon, & Stéquert, ; Conand, ) and, to a lesser extent, in between the two regions (Fréon, ). For S. maderensis , two spawning periods of S. maderensis were determined (Ba et al., ). The first spawning period was from April to October, with two spawning peaks, one in June–August and the other in October.…”

Section: Introductionmentioning

confidence: 99%

Effect of environmental conditions on the seasonal and inter‐annual variability of small pelagic fish abundance off North‐West Africa: The case of both Senegalese sardinella

Thiaw

Auger

Ngom

et al. 2017

Fisheries Oceanography

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The objective of this study was to assess the effect of environmental variations on the abundance of Sardinella aurita and Sardinella maderensis in Senegalese waters in the upwelling system. Monthly data indicating the abundance of sardinella were first estimated from commercial statistics, using Generalized Linear Model from 1966 to 2011. Abundance indices (AIs) were then compared with environmental indices, at the local scale, a Coastal Upwelling Index (CUI) and a coastal Sea Surface Temperature (SST) index, and on a large scale, the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the Multivariate El Niño Southern Oscillation Index (MEI), using correlations and times series analyses. The results showed that the abundance of sardinella is determined by a strong seasonal pattern and inter‐annual fluctuations. The abundance of S. aurita peaked in spring and in autumn, whereas that of S. maderensis peaked in the warm season (July–September). The trend of the sardinella abundance was significantly correlated with the CUI, especially in autumn and spring. Interannual fluctuations of S. maderensis and S. aurita abundance are, respectively, driven by the precocity and the duration of the upwelling season that is attributed to distinct migration patterns. Both sardinella species also respond with a delay of around 4 years to the winter NAO index and the autumn CUI, and the AMO index, respectively, both related to migration patterns. The wide variations in sardinella biomass are caused by variations in environmental conditions, which should be considered in the implementation of an ecosystem‐based approach in sardinella stocks management.

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“…Along the Senegalese littoral, there is an increase in the average sea surface temperature, due to the global climate change [55]. In fact, our climate results severe and prolonged drought since 1997 [56].…”

Section: Discussionmentioning

confidence: 99%

Assessment of Climate Trends and Land Cover/Use Dynamics within the Somone River Basin, Senegal

Barry¹,

Traoré²,

Ndiaye³

et al. 2017

AJCC

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This study was undertaken mainly to 1) investigate temporal trends in annual rainfall and temperature; 2) identify discontinuities in the time series; and 3) assess the Land Use/Land Cover Change (LULC) in the Somone coastal lagoon, within the river basin. The study examined temporal trends in rainfall (1931-2016) and temperature (1961-2016) datasets of Somone river basin, and breaks in time series using Mann-Kendall non-parametric test and other suitable statistical tools. Temporal evolution in LULC was assessed for the years 1954, 1978, 2003 and 2016. Analysis indicates a significant decreasing trend in precipitation over the basin. These trends are much more pronounced for minimum and average rainfall than for maximum and annual amplitudes. Contrary to precipitation, surface air temperature shows a significant increasing trend for its minimum and averages, and a decreasing trend for its maximum and amplitudes. A significant break in precipitation was observed in 1958, while surface air temperature presents much longer breaks within the years 1975 and 1977, and 1991 and 1993. A more direct implication of climate change on LULC patterns is increased in unproductive salt pans (Sabkhas). Increase in Sabkhas gave rise to conversion of forest lands to agricultural lands of local farmers in search for fertile soils to cater for the food needs of a growing population. Otherwise, the development of the settlements, favored by the tourism activity and agriculture crisis, is another cause of croplands decreasing. The findings of the present research clearly indicate that the impacts of climate change are exacerbated by rapid urbanization in the basin.

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Resilience of Key Biological Parameters of the Senegalese Flat Sardinella to Overfishing and Climate Change

Cited by 29 publications

References 22 publications

Contrasted optimal environmental windows for both sardinella species in Senegalese waters

Contrasted optimal environmental windows for both sardinella species in Senegalese waters

Effect of environmental conditions on the seasonal and inter‐annual variability of small pelagic fish abundance off North‐West Africa: The case of both Senegalese sardinella

Assessment of Climate Trends and Land Cover/Use Dynamics within the Somone River Basin, Senegal

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