INCOFISH : WP7INCOFISH : WP7Simple indicators for sustainable Simple indicators for sustainable

fisheries fisheries Lima, 4-7 december 2006Lima, 4-7 december 2006

Reports ActivitiesReports Activities

ByBy

Birane SAMB and Fambaye N’GOMBirane SAMB and Fambaye N’GOM

Centre de Recherches Océanographiques de Centre de Recherches Océanographiques de Dakar ThiaroyeDakar Thiaroye

Dakar SénégalDakar Sénégal

Senegal is located in North Senegal is located in North West AfricaWest Africa

Atlantic Ocean MAP of AFRICA

Map of Senegal

Importance of fisheries sector Importance of fisheries sector in Senegalin Senegal

• 11 500 000 habitants with more than 11 500 000 habitants with more than 50% of population in coastal zone 50% of population in coastal zone

• 700 km coastline, with continental shelf 700 km coastline, with continental shelf area of 24 000 kmarea of 24 000 km22

• First sector of exportFirst sector of export

Importance of fisheries sector Importance of fisheries sector in Senegal (suite)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

FisheriesFisheries

– 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.

Marine ResourcesMarine Resources

• Marine resources are characterized by their Marine resources are characterized by their diversitydiversity

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

DifferentsDifferents step of work step of work

• DatabaseDatabase

• List of species with biological List of species with biological parameter and referenceparameter and reference

• Fish rulerFish ruler

• Calcul of simple indicators for some Calcul of simple indicators for some speciesspecies

DATA BASEDATA BASE

Espèce1

Length frequency

Other biological parameter

Length frequency from catches

Length frequency from survey

Lm growth parameter

L max

List of species with biological List of species with biological parameter (example of output)parameter (example of output)

Nom commun Taxon scientifique Taille de 1° maturité sexuelle : L50 ♀ (cm)

Taille de 1° maturité sexuelle : L50 ♂ cm)

Taille de 1° maturité sexuelle des indéterminés :L50 (cm)

Zone d'étude Référence Taille de 1ère maturité

POISSONS

Sardinelles Sardinelle ronde Sardinella aurita 18.0 LF Sénégal Camarena Lurhrs T., 1986 20.0 LF Sénégal Conand, C., 1977 Sardinelle plate Sardinella maderensis 16.0 LF Sénégal Camarena Lurhrs , T., 1986 17.6 LT 16.8 LT Sénégal Diouf, P.S., 1996 Sardines Sardine commune Sardina pilchardus 18.5 LF 15.5 LF Afr.centre est FAO, 1979 Ethmaloses Ethmalose d’Afrique Ethmalosa fimbriata 18.0 LT 17.5 LT Sénégal Diouf, P.S.,1996 18 -19 LF Sénégal Scheffers, W.J., 1976

Alose rasoir Ilisha africana 13.6 LT Sénégal Diouf, P.S.,1996

Mérous Mérou gris Epinephelus aenus 40.0 LF Sénégal Levenez, J. J., 1993 33 à 34 LS Sénégal Sembène, B., 1995 Mérou badèche Epinephelus alexandrinus 27.0 LS Sénégal Sembène, B., 1995 Badèche Mycteroperca rubra 32 à 36 LS Sénégal Sembène, B., 1995 Pageots Pageot à taches rouges Pagellus bellottii 14.5 LF Sénégal Levenez, J. J., 1993 14.1-15.3 LF Sénégal Franqueville, C., 1979 16.5 LT Sénégal Franqueville, C., 1983 15.50 Sénégal Franqueville, C., 1983 Machoirons Machoiron banderille Arius heudelotii 34. 0 LF Guinée Domain, F. et al., 1999 Machoiron de Gambie Arius latisculatus 30. 0 LF Guinée Domain, F. et al., 1999 27.0-28.0 LF Guinée Sidibe, A., 2003 Arius parkii 31.0 LF Guinée Domain, F. et al., 1999 Pagres Pagre à points bleus Sparus caeruleostictus 23.0 LF Sénégal Levenez, J. J. ,1993 Geret, M., 1974 Sparaillon africain Diplodus bellottii 12.0 LS Ndiaye, A.M., 1994 Dentés Denté à gros yeux Dentex macrophtalmus 18.0 LT Cap vert Magnússon, J. and J.V.V. Magnússon, 1987 17.0 LT AF. ouest Domaneski, L.N. et Stepkina, M.V., 1971 Dentex angolensis 15.4 LT Côte d'Ivoire Konan, J., 1979 Dentex gibbosus 34.7 LT 38.6 LT Iles Canaries Pajuelo, J.G. and J.M. Lorenzo, 1995 Merlus Merlu du Sénégal Merluccius senegalensis 38.0 LT 32.0 LT Sénégal FAO, 1980 35.0 LT Sénégal FAO, 1986 Merlu d'Afrique tropicale Merluccius polli 35.2 LT Sénégal FAO, 1986

Fish rulerFish ruler

• SEE FILESEE FILE

Calcul of simple indicators for Calcul of simple indicators for some important species in some important species in

SenegalSenegal

MaterialMaterial

•Length frequency data from catches of artisanal fisheries

•Biological parameter from database

• Indicators_spreadsheet_tool.xls

MethodMethod

• LmLm is Length at first maturity and refers to the length at is Length at first maturity and refers to the length at which 50% of the individuals in a population have reached which 50% of the individuals in a population have reached reproductive maturity.reproductive maturity.

• L90-100L90-100 is the length where 90-100% of individuals in a is the length where 90-100% of individuals in a population have reached reproductive maturity and is population have reached reproductive maturity and is calculated as Lm x 1.14calculated as Lm x 1.14

• Lopt Lopt is the length at which the fewest individuals of a is the length at which the fewest individuals of a population have to be harvested in order to reach the population have to be harvested in order to reach the maximum biomass. The maximum biomass. The optimum harvest rangeoptimum harvest range is that is that from 10% lower than Lopt to 10% higher than Lopt (Lopt ± from 10% lower than Lopt to 10% higher than Lopt (Lopt ± 10%)10%)

• Lopt = Linf * (3 / (3 + M/K))Lopt = Linf * (3 / (3 + M/K))• Mega-spawnerMega-spawner is an individual who has reached a size at is an individual who has reached a size at

least 10% larger than Lopt for a population.least 10% larger than Lopt for a population.

ANALYSE ON THE STATE OF SOME DEMERSAL ANALYSE ON THE STATE OF SOME DEMERSAL SPECIES CAUGHT BY SENEGALESE FISHERIES SPECIES CAUGHT BY SENEGALESE FISHERIES

USING SUSTAINABLE INDICATORSUSING SUSTAINABLE INDICATORS

• Pagellus bellotiiPagellus bellotii

• Sparus caeruleostictusSparus caeruleostictus

• Galeoides decadactylusGaleoides decadactylus

• Pseudupeneus prayensisPseudupeneus prayensis

Figure 1. Length frequency of Pagellus bellotii landed from 1990 to 2003 in Senegal where Lm is the length of first maturity, Lopt is length with maximum yield per recruit can be obtained and Lmax is the maximum size reached during this period

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Taille (cm)

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Super-reproducteurs

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1990 1992 1994 1996 1998 2000 2002

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Most fish are captured after their first size of Most fish are captured after their first size of maturity.maturity. But these fish were captured before the economic But these fish were captured before the economic optimal size. optimal size. The large specimens withThe large specimens with size 10 % larger thansize 10 % larger than the the optimal size miss almost in the captures.optimal size miss almost in the captures.

•The annual percentage of mature fish in the The annual percentage of mature fish in the captures is close to or approaching the target of captures is close to or approaching the target of 100%.100%.

•The annual percentage of fish with the optimal The annual percentage of fish with the optimal size in the captures is relatively low compared with size in the captures is relatively low compared with the target of 100 %.the target of 100 %.

•The annual percentage of mega-spawners is below The annual percentage of mega-spawners is below 30 - 40% representative a healthy structure of age.30 - 40% representative a healthy structure of age.

It would be more interesting to capture fish with a It would be more interesting to capture fish with a higher size to approach the optimal weighthigher size to approach the optimal weight

Read PandoraRead Pandora Pagellus Pagellus bellotiibellotii

Figure 2. Annual percentages of fish mature, fish at size optimal and megaspawners of Pagellus bellotii in the catches

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Super-reproducteursMaturesJuvéniles

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1990 1992 1994 1996 1998 2000 2002

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Taille optimaleSuper-reproducteurs

Most of fish are caught before their first length Most of fish are caught before their first length of maturity. of maturity. Fish are caught before the optimal size. Fish are caught before the optimal size. Mega-spawners miss almost in the captures.Mega-spawners miss almost in the captures.

•The annual percentage of mature fishes is very low The annual percentage of mature fishes is very low compared with the target of 100%.compared with the target of 100%.

•The annual percentages of fishes with the optimal The annual percentages of fishes with the optimal size and mega-spawners in catches is very low. size and mega-spawners in catches is very low.

This very weak value is an indication of depletion of This very weak value is an indication of depletion of stock.stock.

These indicators suggest that the stock is in a state These indicators suggest that the stock is in a state of overexploitationof overexploitation

Figure 4. Annual percentages of fish mature, fish at size optimal and megaspawners of Sparus caeruleostictus in the catches

Figure 3. Length frequency of Sparus caeruleostictus landed from 1990 to 2003 in Senegal where Lm is the length of first maturity, Lopt is length with maximum yield per recruit can be obtained and Lmax is the maximum size reached during this period

Bluespotted seabreamBluespotted seabream

Sparus caeruleostictusSparus caeruleostictus

0.00

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1990 1992 1994 1996 1998 2000 2002

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Taille optimale

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1 9 13 17 21 25 29 33 37 41 45 49Taille (cm)

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Super-reproducteurs

Matures

Taille optimale

Most of fishes are above the size for first Most of fishes are above the size for first maturity and in the range of the optimal size maturity and in the range of the optimal size where the maximal yield can be obtained. where the maximal yield can be obtained. Mega-spawners are little represented in the Mega-spawners are little represented in the total catches.total catches.

•The annual percentage of mature fishes is The annual percentage of mature fishes is below the target of 100 %. below the target of 100 %.

• The annual percentage of fishes with the The annual percentage of fishes with the optimal size declined since 1993optimal size declined since 1993 to reach 18 % to reach 18 % in 2003.in 2003.

•The annual percentage of mega-spawners is The annual percentage of mega-spawners is below 30 – 40 % representative a healthy below 30 – 40 % representative a healthy structure of age.structure of age.

In spite of the increase of mature fishes in In spite of the increase of mature fishes in catches, indicators suggest that the stock of catches, indicators suggest that the stock of the small captain is also threatened by an the small captain is also threatened by an overexploitation.overexploitation.

Figure 5. Length frequency of Galeoides decadactylus landed from 1990 to 2003 in Senegal where Lm is the length of first maturity, Lopt is length with maximum yield per recruit can be obtained and Lmax is the maximum size reached during this period

Figure 6. Annual percentages of fish mature, fish at size optimal and megaspawners of Galeoides decadactylus in the catches

Small captainSmall captain

Galeoides Galeoides decadactylusdecadactylus

0.0010.0020.0030.0040.0050.0060.0070.0080.0090.00

100.00

1990 1992 1994 1996 1998 2000 2002Années

Po

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Super reproducteurs

Taille optimale

Matures

Figure 8. Annual percentages of fish mature, fish at size optimal and megaspawners of Pseudupeneus prayensis in the catches

LmaxLopt

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10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 48Taille (cm)

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Lopt

Figure 7. Length frequency of Pseudupeneus prayensis landed from 1990 to 2003 in Senegal where Lm is the length of first maturity, Lopt is length with maximum yield per recruit can be obtained and Lmax is the maximum size reached during this period

The catches are constituted by individuals whose The catches are constituted by individuals whose size is in size is in the range length where the maximum the range length where the maximum yield can be obtained.yield can be obtained.The mega-spawners are also little represented in The mega-spawners are also little represented in catches. catches.

•The percentage of mature fishes is very low The percentage of mature fishes is very low compared with the target of 100 %.compared with the target of 100 %.

•However the percentage of fish with the optimal However the percentage of fish with the optimal size increased since 1990 to reach 80 % in 2003.size increased since 1990 to reach 80 % in 2003. •But he percentage of mega-spawners is below 30 – But he percentage of mega-spawners is below 30 – 40 % representative a healthy structure of age. 40 % representative a healthy structure of age.

These results suggest that the stock is not in These results suggest that the stock is not in situation of overexploitation situation of overexploitation ..

West african goatfishWest african goatfish

Pseudupeneus prayensisPseudupeneus prayensis

Thanks for your attentionThanks for your attention