INFORMATION DOCUMENTS : (continued)

PRELIMINARY CATALOGUE OF CULTIVATED AND CULTIVABLE FISH SPECIES IN THE SAHELIAN ZONE

CATALOGUE PRELIMINAIRE DE POISSONS D'ELEVAGE DANS LE SAHEL, DE FAIT ET EN POTENTIEL (continued)

Mugil cephalus
(Mugilidae)

Mugil falcipinnis
(Mugilidae)

Mugil grandisquamis
(Mugilidae)

Polypterus senegalus
(Polypteridae)

Salmo gairdneri
(Salmonidae)

Salmo trutta
(Salmonidae)

Sarotherodon galileus
(Cichlidae)

Sarotherodon heudeloti
(Cichlidae)

Sarotherodon macrochir*
(Cichlidae)

Sarotherodon mossambica
(Cichlidae)

Sarotherodon multifasciata
(Cichlidae)

Sarotherodon niloticus
(Cichlidae)

Sarotherodon tholloni
(Cichlidae)

Tetraodon fahaka
(Tetraodontidae)

Tilapia rendalli
(Cichlidae)

Tilapia zilli
(Cichlidae)

MONOGRAPH ON OPERATION FISHERIES, MOPTI

by

P. Raimondo
responsable de la formation
Opération Pêche, Mopti
Service des Eaux et Forêts
Mali

1. PHYSICAL DATA

Activities under Operation Fisheries cover three Regions (4th, 5th and 6th Regions) comprising 14 Districts and 59 Sub-Districts (see Annex 1).

1.1 Location

The area of operations involves the whole Central Delta and the lake area, extending to the loop of the Niger. The area is about 400 km from north to south and some 600 km from east to west. It is bounded by Douna in the south (Latitude 13°8' North), Bamba in the north (Latitude 17°6' North), Labbezanga in the east (Longitude 0°41' East) and Markala in the west (Longitude 6°6' West).

1.2 Relief

The slight difference in level explains the vast extent of the Niger River Delta situated between the altitudes of 272 and 262 m, with a very slight drop of 0.05‰.

1.3 Climate

The Niger and Bani basins and the remaining hydrographic network within the area of operations have three types of climate:

• North Sudan type in the Markala-Mopti section;
• South Sudan type in the Niafunke-Dire-Gao section;

• North Sahel type in the Tombouctou-Gourma-Rharous section.

The main climatological features are due to the circulation of two masses of air:

• tropical continental air from the Sahara, which is dry and hot in summer; it generally comes from the northeast; this air mass is commonly called Harmattan;

• maritime equatorial air, humid and unstable, relatively fresh; it comes from the St. Helena anticyclone, from a southwesterly direction; this air mass is commonly called Monsoon.

1.31 Winds

The wind pattern is dominated by the Harmattan from the east and northeast during the dry season and by the Monsoon from the southwest or south during the rainy season.

In general, wind velocity is quite low, usually 2–4 m per sec.

1.32 Temperatures

Differences in daily temperatures and annual averages are more pronounced in the north than in the south.

1.33 Rainfall

The area of operations lies between the isohyets of 700 mm in the south and of 100 mm in the north. Normal annual rainfall decreases gradually from south to north (by about 1 mm per km).

The rainy season generally lasts four and a half months; it usually begins in May and ends in September. There is a very prominent maximum in August.

But in the past three years an increasing rain deficit compared with normal rainfall has been recorded in Mali and the neighbouring countries. It has greatly reduced the level of water courses, cutting down flooded and lake areas.

Table I

Average Temperatures (1941–70: Source - National Meteorological Service)

Table II

Rain Deficit 1971–72–73 (Source: Hydraulics Division)

1.34 Relative Humidity

Considering the latitude of the area, relative humidity is very high.

Table III

Relative Humidity in % (1951–70: Source - National Meteorological Service)

Lows are recorded in March at Markala and Mopti and in February at Gao; highs in August at all three stations.

1.35 Evaporation

Potential evapotranspiration grows markedly from south to north.

Table IV

Evaporation: Observatory 1973 (Source: OICMA Kara)

1.4 Hydrography

The hydrographic network of the area consists of many water courses, numerous lakes, innumerable permanently water-filled depressions and a vast zone flooded at high water.

1.41 Water Courses

The most important water courses where fisheries are particularly developed are listed in the following table:

Table V

Names of Water Courses (Source: Hydraulics Service)

Other water courses include:

1. in the Dioro area:

   • the Nakry branch
   • the Dioro branch

   • the Sama branch, which is very important for fisheries;

2. in the Diafarabe-Mopti area:

   • the Mayo Pio (at Nouhoun Bozo)
   • the Mayo Sagona (opposite Koa)
   • the Mayo Mora (between Makame and Ouro Modi)
   • the Mayo Makadie or Sono

   • the Mayo Donguel (opposite Sahouna).

All these affluents flow north-northeastward, parallel to the Diaka.

On the right bank of the Niger:

• the Soye branch (or Tokayaoro), an important affluent of the Bani between Sofara and Teke.

1.42 Lakes

Table VI

Lakes on the right bank of the Niger (Source: Hydraulics Division)

This represents a water area ranging from 1 115 to 1 267 square kilometres.

Table VII

Lakes on the left bank of the Niger (Source: Hydraulics Division)

This represents a water area ranging from 1 398 to 2 230 square kilometres.

The most important water-filled depressions are:

• Kabara, up to about 60 square kilometres
• Tanda, up to about 110 square kilometres
• Takadji, between 3 and 90 square kilometres, depending on the Niger floods

• Gossy.

Table VIII

Data on Niger River Water (Barigondaga)

Note: Additional data are unavailable at present. The table will be completedand forwarded at the beginning of 1975.

Table IX

Data on Bani River Water (Djibitaga)

1.5 Biological Factors: Flora and Fauna

1.51 Aquatic Vegetation

Vegetation covers the whole zone subject to submersion and varies with the nature of the bodies of water.

1. Areas with muddy bottom:

   • Benthon
   • Phytoplankton
   • Zooplankton
   • Echinochlea stagnina (bourgou)
   • Rotalas

   • Limnophilias

2. Areas with rocky bottom:

   • Rotula aquatica
   • Arthrosolem foliosus

   • Phragmites vulgaris

Plant associations form the most important biotopes for fish, especially those feeding on plants and for fry development.

1.52 Invertebrates

The rocky bottoms of the basins in the minor beds of rivers are covered with a freshwater mollusc - Etheria elliptica - which restricts the use of active fishing gear, especially seines.

The following other invertebrates are generally found:

• Caelatura aegyptica
• Corbicula flumina his
• Mutela dubia
• Mutela rostrata
• Viviparus nuicolor

• Cleopatra sp.

1.53 Fish

The waters of Mali are very rich in fish species (see index of scientific names and families, as well as vernacular names in Bambara, Sonrai and Boxo in Annex 1).

All species are edible and nearly all of them are actually consumed. Quality and nutritive value are good. These species, which feed on benthon, plankton and fish, make good use of trophic possibilities in the rivers. The area subject to flooding is of extreme importance to fry growth and fish fattening.

1.54 Predominant Species

On the basis of the fishermen's experience and catches (not quantified), the training team's survey resulted in the following order of predominant species, by sector:

Table X

Predominant Species

1.55 Predators

There are large numbers of fish-eating birds, especially:

• Ardea cinerea
• Ceryle nudis

• Haliaetus vocifer claneans

The following birds abound at low water:

• Phalacrocorax africanus
• Pelecanus rufescens
• Halcyon senegalensis

• Podiceps cristatus