The Tropical Pacific Coast of Mexico
311
20.4 Human Impacts and Management Needs
20.4.1 Fisheries
The region is characterized by diverse (more than 28) indigenous cultures,
each exploiting natural resources in a sustainable way. Numerous shell
middens (Tivela and Crassostrea) in Chantuto-Panzacola and TeacapanMarismas Nacionales date back to 1,500 B.P. and pigment extraction from
the purple sea snail (Purpura panza) since prehispanic times suggests
important fishing activities by indigenous populations prior to the discovery of the Americas (Flores-Verdugo et al. 1997).
In rocky coastal areas lobsters (Panulirus inflatus and Panulirus gracilis) and octopus are important fisheries resources for fishermen and
fishing intensity appears to be related to the local tourist industry (Briones-Fourzan 1995). At sandy beaches and coastal lagoons, catches of the
shrimps Penaeus vannamei and P. californiensis in Sinaloa/Nayarit and P.
vanamei and P. occidentalis in Chiapas may represent up to 90 o/o of total
fisheries. Shrimp fishing (Litopenaeus and Farfantepenaeus) in the Gulf of
Tehuantepec is largely restricted to upwelling areas, which are affected by
strong winds and El Nifio events.
Beaches are important nesting grounds for olive Ridley (Lepidochelis
olivacea), black (Chelonia agassizi), hawksbill (Eretmochelis imbricata),
and leatherback (Dermochelis coriacea) turtles (Marquez-Millan 2000).
After catches of marine turtles increased from 2 tons in 1963 to about
14.5 tons in 1968, fishing was finally banned in 1972/1973. However, poaching of eggs and adult turtles continued and on some beaches turtle nests
decreased from 200,000 before 1960 to less than 2,000 in 1996, though olive
Ridley turtle populations appear to be making a recovery.
20.4.2 Environmental Problems
Most coastal lagoon and mangrove ecosystems of the tropical Pacific coast
of Mexico have suffered the impact of increased sedimentation (i.e.,
1 em year- 1 in the Huizache-Caimanero lagoon; de la Lanza and GardaCalderon 1991) as a result of agriculture and deforestation activities in the
drainage basin of rivers. Furthermore, urban, industrial, and agricultural
freshwater demands have reduced river flow, and groundwater extraction
(up to four wells per km 2 in the coastal plain ofTeacapan) has lowered the
water table in wetlands. Reduced river flow has led to seasonal closure of
inlets (i.e., El Verde Camacho lagoon), impeding migration of aquatic
311
20.4 Human Impacts and Management Needs
20.4.1 Fisheries
The region is characterized by diverse (more than 28) indigenous cultures,
each exploiting natural resources in a sustainable way. Numerous shell
middens (Tivela and Crassostrea) in Chantuto-Panzacola and TeacapanMarismas Nacionales date back to 1,500 B.P. and pigment extraction from
the purple sea snail (Purpura panza) since prehispanic times suggests
important fishing activities by indigenous populations prior to the discovery of the Americas (Flores-Verdugo et al. 1997).
In rocky coastal areas lobsters (Panulirus inflatus and Panulirus gracilis) and octopus are important fisheries resources for fishermen and
fishing intensity appears to be related to the local tourist industry (Briones-Fourzan 1995). At sandy beaches and coastal lagoons, catches of the
shrimps Penaeus vannamei and P. californiensis in Sinaloa/Nayarit and P.
vanamei and P. occidentalis in Chiapas may represent up to 90 o/o of total
fisheries. Shrimp fishing (Litopenaeus and Farfantepenaeus) in the Gulf of
Tehuantepec is largely restricted to upwelling areas, which are affected by
strong winds and El Nifio events.
Beaches are important nesting grounds for olive Ridley (Lepidochelis
olivacea), black (Chelonia agassizi), hawksbill (Eretmochelis imbricata),
and leatherback (Dermochelis coriacea) turtles (Marquez-Millan 2000).
After catches of marine turtles increased from 2 tons in 1963 to about
14.5 tons in 1968, fishing was finally banned in 1972/1973. However, poaching of eggs and adult turtles continued and on some beaches turtle nests
decreased from 200,000 before 1960 to less than 2,000 in 1996, though olive
Ridley turtle populations appear to be making a recovery.
20.4.2 Environmental Problems
Most coastal lagoon and mangrove ecosystems of the tropical Pacific coast
of Mexico have suffered the impact of increased sedimentation (i.e.,
1 em year- 1 in the Huizache-Caimanero lagoon; de la Lanza and GardaCalderon 1991) as a result of agriculture and deforestation activities in the
drainage basin of rivers. Furthermore, urban, industrial, and agricultural
freshwater demands have reduced river flow, and groundwater extraction
(up to four wells per km 2 in the coastal plain ofTeacapan) has lowered the
water table in wetlands. Reduced river flow has led to seasonal closure of
inlets (i.e., El Verde Camacho lagoon), impeding migration of aquatic