Socio-economic interest of Taxa
|Keywords||Fauna, socio-economic interest|
‘Taxa’, of socio-economic interest
There are essentially two categories of species with socio-economic interest:
- Pisces and Crayfish are exploited forms;
- Leech, Mollusks (Bulin and Planorbe), Mosquitoe and other biting Dipters, as vectors of diseases and sources of harm.
The interest of these species in terms of the biodiversity source is relatively small, except concerning the human activities that they engender (exploitation or conflict) and which constitute often the sources of impacts on the biodiversity. Certain autochtonic species of fish constitute an economic wealth that one would try to manage conveniently so as to ensure its conservation and its lasting exploitation.
° Fish and fishing
The fario Trout, which has disappeared from certain water places in Morocco, enjoys a relatively greater protection than other species, favorized by its great value for sport fishing and, especially, by its geographic (and ecological) repartition which distances it from large urban and agricultural centers.
Shad is even more endangered. The rare shad which escape marine fishing finds less and less rivers to enter in freshwater; when they do penetrate, they have to escape pollution (Sabatier, 1993) to arrive at the dams (very numerous and without scale of fish). The Great Shad in particular has become extremely rare, while it was sold in great quantities just ten years ago. The hope for the rehabilitation of this species in certain water courses is at the origin of its recent prohibition for fishing by the Ministry of Agriculture.
The eel continues to mark its presence in water courses, lagoons, coastal merjas, drainage canals, which still escape an excess of pollution. Eel culture practiced in certain coastal waters is probably an adequate form of management for its conservation, though one must imagine its eventual exhaustion, in the long term, of the stock of reproducers which descend to the sea.
Considering their small value in fishing, the measures of conservation are rarely evoked for the Barbels. While they are reputed as having demographic strategies favorable to their auto-conservation, this “simplistic” argument should not lead one to neglect studying their biology, especially since no evidence has been found for a long time on the survival of certain endemic species.
° Vectors of diseases and other harmful animals
Mosquitoes are all destructive, but the most harmful are the Anopheles which transmits malaria. In Morocco, the concerned are Anopheles maculipennis (ssp. labranchiae), A. sergenti and A. multicolor, to cite the most prevalent. The Aedes are equally very harmful and we cite, for report, the species A. equinus, guilty of transmitting the equine plague.
Two vector Mollusks of ‘bilharziose’, (Bulinus truncatus and Planorbarius metidjensis) are largely widespread in Morocco, particularly in the hot, calm or slow waters of pouring of plains (merjas, irrigation canals, death arms of rivers, etc.). The disease is still noticed in our days in Saharan Morocco, all the low Atlantic plains (Haouz, Abda-Haha, Doukkala, Tadla, Gharb...) and in the North-East (Low Moulouiya, Plain of Bou Areg...). The irrigation canals in all these plains consist an ecological region favorable to the disease (abundance of the host and great frequency of its contacts with man).
The Sanguses (Hirudo medicinalis H. troctina, Haemopis sanguisuga, Limnatis nilotica) have been causing mortalities sometimes among livestock and man. Nonetheless, we do not of a program, nor of means to fight employed officially in Morocco, against sanguses.
° Regions of major interest for biodiversity
The greatest concentration of endemic species can be found in three mountainous regions: the High Central Atlas, The Middle Central Atlas, and the Centro-Occidental Rif, followed by the Maamora-Zemmour, then the Atlantic Meseta.
These results are little surprising in the measure that our mountains are the seat of particular climatic phenomenan compared to the rest of the country; living beings having undergone an ecological isolation during all the quaternary and it is normal to find a high total of endemism, with the development, even, of an exlusive fauna of each mountainous region, the highest mountain masses most rich in water also most rich in endemics. To this original fauna, automatically considered vulnerable, is added an entirety of cold water ‘taxa’, (psychrostenotherm) common with Europe and which have confined themselves to the fresh waters of the mountains; among these, certain species with a west-Mediterranean repartition have become relatively rare and merit measures of conservation.
The abundance of sources and cold water courses, habitats most favorable to endemism in the Mediterranean region (Giudicelli and Dakki, 1981); Dakki, 1986a, 1987), explains the originality of the fauna in mountains. Temporary waters are far from negligible since they harbor a fauna that is strictly proper to the region. Hot running water, in particular at the level of mid-Atlantic and high-Atlas piedmonts where the speed of pouring water is still appreciable, have also their endemics, among which one finds several species with tropical affinities.
It is legitimate to ask oneself if the elevated number of endemics in certain regions is not linked to a great effort of prospecting of these, knowing that the systematiciens orient themselves in preference towards mountain zones or the chances of discovering new species for science are great. This hypothesis is not to be overlooked, though it does not apply to certain regions, such as the mountains of the Rif, where we estimate that the research is late and the number of endemics is under-estimated. Our knowledge of Moroccan terrain and our numerous harvests in diverse regions confirm in a great part the actual results.
Outside the mountains, the Atlantic ‘meseta’ shows an interest especially for certain river pisces‘fluviaux’ endangered fish and for the sub-terranean fauna or, temporary waters.
Let us remember the vulnerability of several species is due not only to their rarity, but also to the dangers they undergo in the more or less short term. The numerous impacts which deteriorate the biological quality of the waters of the meseta’ would be thus in great part at the origin of the classification of certain zones of this region as priority. This permits at least to anticipate the limitations of the impacts.