Modélisation spatiale de l’écosystème Sénégalogambien By Birane SAMB Fishery Biologist CRODT, Dakar, Sénégal

Présentation au sujet: "Modélisation spatiale de l’écosystème Sénégalogambien By Birane SAMB Fishery Biologist CRODT, Dakar, Sénégal"— Transcription de la présentation:

1 Modélisation spatiale de l’écosystème Sénégalogambien By Birane SAMB Fishery Biologist CRODT, Dakar, Sénégal bsambe@yahoo.fr

2 Senegal is located in North West Africa Atlantic Ocean MAP of AFRICA Map of Senegal

3 Importance of fisheries sector in Senegal 11 500 000 habitants with more than 50% of population in coastal zone 700 km coastline, with continental shelf area of 24 000 km 2 First sector of export

4 Importance of fisheries sector in Senegal (suite) Takes an important place in the supply of animal proteins 600 000 indirect employments 15% of the working population Annual consumption 26kg/year/ha where in Africa the mean consumption is 8.2 /year/ha

5 Fisheries –The artisanal fishery consists of motorised canoes using a variety of gear. Essential catches are done by artisanal fisheries –The industrial fishery is undertaken by trawlers or purse seiners, some of which are foreign vessels operating under commercial agreements.

6 Marine Resources Marine resources are characterized by their diversity (i) Pelagic resources consisting of clupeids engraulids, carangids, scombrids, tuna and sharks. These species constitute up to 75% of the stocks. (ii) Demersal resources which have a higher economic value include crustaceans (shrimps, lobsters, and crabs), molluscs, cephalopods as well as bony fish (serranids, lutjanids, sciaenids, mullets, etc.), rays, and sharks. (iii) Coastal and estuarine resources, comprising bivalves and fish (cichlids, mullets, etc).

7 Objectives Use Ecosim and Ecospace to Study the impacts of fisheries on the ecosystem

8 Definition groupes Oiseaux marins Mammifères marins Pélagiques du large: Sharks Rays Céphalopodes: poulpes, seiches, calmars et autres Merous Pagre Otolithe Others demersals Sardinelle ronde Sardinelle plate Others pélagiques Zooplancton Meiobenthos Macrobenthos Producteurs benthiques Phytoplancton Rejets Détritus

9 Habitat and assign habitat

10 Location of MPA 2 at the north 2 at the south

11 Scenario modelling Les scénarios suivants sur 10 ans ont été testés : -hausse d’effort de la pêche artisanale et maintien du niveau actuel de la pêche industrielle (scénario 1) -baisse d’effort de la pêche artisanale et maintien du niveau actuel de la pêche industrielle (scénario 2) -hausse d’effort de la pêche industrielle et maintien du niveau actuel de la pêche artisanale (scénario 3) -baisse d’effort de la pêche industrielle et maintien du niveau actuel de la pêche artisanale (scénario 4)

12 Result of scenario 1 PA increase

13 Result of scenario 2 PA decrease

14 Preliminary conclusion Two groups constitute the main targets for fisheries. Pelagics fish stocks and demersal species. Actual level of stocks are overexploitation of demersal stock like mérou, pagre et otolithe. Small pelagic fish like Sardinella are less exploited. Model indicate clearly that increase of artisanal fishing effort continue to the overexploitation. In contrario all measures leading to decrease the pressure of artisanal gear will help to restore the abundance of species.

15 Next step Make scénario about variation of size of MPA location of MPA