Rôle possible d'une intensification des alizés sur le changement de répartition des sardines et sardinelles le long de la côte Ouest africaine

Abstract

The probable changes in the pattern of sardine and sardinelle distribution along the west African Coast,caused by an intensijication of the trade winds.

Spawning season and temperature relationships for sardine (Sardina pilchardus) in the eastern North Atlantic

“…However, a con£icting relationship is observed for the most southerly area of Mauritania and Senegal, which is generally beyond the southern limit of sardine spawning. This region has become increasingly favoured for spawning due to intensi¢cation of the trade winds and consequent upwelling of cool water through the 1970s and intermittently to 2003 (John et al, 1980;Binet, 1988;FAO, 2003), although a converse declining trend is seen in the present study in the number of days of spawning temperatures in the overall range. The lack of any consistent relationship is reinforced by observations of declining trends in spawning in Biscay and o¡ Portugal through the 1990s (Stratoudakis et al, 2003), but with no equivalent trends in the present analysis of the annual extent of optimum or overall spawning temperatures.…”

“…Sola¤ et al, 1990); ¢nally, for the north-west African regions, the predicted spawning seasons imply a rather more coherent pattern than occurs in reality, due to spatial and temporal variability in upwelling and topographic in£uences of coastal capes and bays on the current system (Binet, 1988;Ettahiri et al, 2003).…”

“…O¡ Morocco and the northern half of western Sahara, the main spawning season is in the winter (NovemberM arch; Furnestin, 1955;Sedletskaya, 1973;Roy et al, 1989) thus avoiding the most intense (April^October) upwelling period (Binet, 1988). Furnestin & Furnestin (1959) summarized seven years' data o¡ Morocco showing this variability, with the main spawning season being in the winter and, to a lesser extent, in the spring.…”

Long-term changes in landings of small pelagic fish in the eastern Adriatic-possible influence of climate oscillations over the Northern Hemisphere

“…Different biological phenomena such as production fluctuations (Pucher-Petković 1970), changes in phytoplankton species composition (Pucher-Petković et al 1971), higher biomass and a changed zooplankton community composition (Vu<etić 1970) were all observed and related to the stronger inflow from the Mediterranean into the Adriatic. Also, different aspects of interactions between thermohaline properties and phytoplankton and fisheries were recognised in many papers (5upanović 1968, 2krivanić & Zavodnik 1973, Regner & Ga<ić 1974, Pucher-Petković et al 1987, Regner et al 1987, 1988, Marasović et al 1988, Vu<etić & Alegria-Hernández 1988. Studies of longterm changes should take into account eutrophication; however, irrespective of the significantly advanced eutrophication in the Northern Adriatic and in Adriatic coastal waters, recent research has pointed to the fact that climatic fluctuations are still crucial for the Adriatic ecosystem dynamics (Marasović et al 1995).…”

Reproductive Biology of Round Sardinella (Sardinella Aurita) (Valenciennes, 1847) in Senegalese Coastal Waters

“…The system of trade-winds (the upwelling phenomenon) and the Canary Current make this area is one of the most productive in the world (Binet, 1988;Roy, 1992;Chavance et al, 2004). During the period 1990-2010, total catches of small pelagic fish have fluctuated with an average of about 1.8 million tons in the six countries of the Sub-Regional Fisheries Commission (SRFC) and Morocco (CSRP, 2012).…”