RESUMO
In Costa Rica, the Gulf of Nicoya shrimp fishery originated in 1952 and represented one of the most important economic activities in the region. Nevertheless, overfishery reduced the captured volumes to levels that prevent this commercial activity. I analyzed official fishery statistics between 1991 and 1999. These species involved are: two species of white shrimp, (Litopenaeus occidentalis and L. stylirostris), the "titi" shrimp (Xiphopenaeus riveti), the brown shrimp (Farfantepenaeus californiensis), the "pinki" shrimp (F. brevirostris) and the "fidel" shrimp (Solenocera agassizi). All the species reached the Maximum Sustainable Yield in the decades of 1970 and 1980 and are now found at over-exploitation levels. I recommend that this shrimp trawl fishery be completely closed down.
Assuntos
Animais , Penaeidae/classificação , Pesqueiros , Costa Rica , Densidade Demográfica , Dinâmica PopulacionalRESUMO
In agreement with the Broecker and Penn two-boxes model, I generated a biogeochemical balance model for the Gulf of Nicoya (Guanacaste, Costa Rica) using two nutrient reservoirs: surface water and deep water. The mixing zone was located at a depth of 20 m. There is a balance between surface waters descending to the bottom and upwelling waters that carry nutrients and other chemical elements to the surface. The main source of nitrogen (nitrate), was the outlet of the Tempisque and Tárcoles rivers. The Gulf of Nicoya is a net source of Dissolved Inorganic Nitrogen (DIN) with an availability rate of 87 x 10(3) mol day(-1) in the dry season and 3044 x 10(3) mol day(-1)in the rainy season. Dissolved Inorganic Phosphate (DIP) was estimated in 27 mol day(-1) in the dry season and 207 mol day(-1) in the rainy season. The dynamics of these biolimited nutrients, in relation to runoff seasonal variations, fits the biological processes reported for the gulf, for example, for variations in primary productivity levels, and maturity and reproduction seasons for species with short and long life cycles.