Mexico has increased its population of 81,249,000 inhabitants in 1990 to
97,361,711 inhabitants in 2000, with a growth rate of 1.60% (INEGI, 2000).
The population growth has produced a rapid urban expansion, requiring major
quantities of water extracted from the rivers as sources of fresh water
for cities. The great rivers in Mexico are being or already are affected
due that the subterranean waters have been depleted or have to go through
a tight management for not finishing them. Together with the rapid population
growth comes the waste waters from cities and towns which are loaded with
organic mater, contaminants and trash.
|| Increase on the use
of water for irrigation of crops. Any medium sized river is being used for
irrigation. This water is returned to the environment loaded with agricultural
contaminants (insecticides and fertilizers).
||Large scale destruction due to
the use of ancient culture methods such as slash and burning of the jungles,
woods and riparian vegetation. This combined with the opening of new lands
for cattle growth. The irrigation of fields on step areas creates a major
problem of erosion of river basins and the deposition of the eroded material
destroys areas once used by river otters.
||Using the fields for
the extraction of oil, the land filling of wetlands with the same purpose
and the destruction of mangrove and marshes for shrimp aquaculture is also
destroying river otter's habitats.
with industrial, agricultural and municipal wastes, threaten the food chain
of which river otters depend. Mexican industrial development is vital for
Mexican Government because it creates more jobs for a growing population;
but it is also a threat to river otter habitats, due that industry needs
large quantities of fresh water (in example: cleaning of electronic components
for computers). Industrial development has a large impact on small urban
areas, the rivers becoming drainages loaded with pollution.
|| Land ownership is
a problem that creates civilian and ecological difficulties, when landless
people from other states or region invades areas in good state of conservation
to open them for agriculture using slash and burn techniques, they are devastating
everything to obtain the maximum yield in less time. Once that land is render
sterile it is abandoned, leaving eroded and unproductive lands.
|| Fishing methods such as the use
of venoms extracted from toxic plants, small quantities of TNT (which is
prohibited in México), quick lime and electrocution (with dynamos)
have caused unbalances on complete river ecosystems.
||The creation of new
fishing camps and the increase in the fishing power along the coast of Baja
California Peninsula will make very difficult that sea otters will reestablish
naturally in México. The large use of gillnets along the Pacific
coast of Baja California had produced the entanglement of sea otters (Gallo-Reynoso
and Rathbun, 1997). There is an urgent need of establishing regulations
on the use of this gillnets around specific areas where sea otters have
been observed regularly. There is only one Biosphere Reserve (Reserva de
la Biósfera del Vizcaíno) with enough coastal areas that would
be able to protect an small but viable population of sea otters. Even though
rules shall be well applied.
||There is also the urgent need of
establish campaigns for a "new water culture", on which water
uses should produce a minimum or none effect in the riparian environment.
||There is little knowledge on the
influence that pollution have on river otters. There is no studies on scats
or in the river courses that would indicate the pollution load in areas
where river otter populations are stable, and in those in which river otter
populations are decreasing.
|| River otters are still hunted
for their fur, mainly to supply family needs in the poorest areas. River
otter cubs are also used as pets in some coastal areas of Mexico. There
is no large scale capture and there is no black market for selling their
furs. Even though furs have been found in the artisanal industry and tourists
stores (wallets, jackets, purses made of river otter fur).