The Gulf of Nicoya, Costa Rica
Area description
The Gulf of Nicoya is an estuary on the Pacific coast of Costa Rica (See map). The gulf is fringed with mangrove forests and surrounded
by agricultural lands. With a surface area of 1,630 km2, the gulf can be
divided an inner gulf of about 630 km2 and generally less then 20 m deep; and
an outer gulf of about 1,000 km2 that has a depth ranging from 20 m in the
north to more than 200 m where it faces the Pacific ocean. Because of river runoff,
salinity in the gulf fluctuates between dry and rainy seasons.
The fishery
The gulf produces 20% of Costa Rica's total catch. Five major fishery types can be
distinguished in the Gulf of Nicoya:
- The artesanal gillnet fishery (inner gulf, 2700 boats) for white shrimp (Penaeus
stylirostrus and P. occidentalis);
- The shrimp trawling fleet (outer gulf, 74 trawlers);
- The longline fishery (430 boats), mostly in the outer part of the gulf, directed
at a variety of demersal and pelagic fish;
- The sardine fishery (3 seine boats);
- The exploitation of "piangua" (Anadara tuberculosa) in the
mangroves.
The fishery of Costa Rica
The fishery in Costa Rica's Pacific waters consists of an offshore longline fishery
and a demersal trawl and gillnet fishery. The offshore fishery catches species for which a
good international market exists, like dolphinfish (Coryphaena hippurus), marlin
(Makaira mazara), sailfish (Istiophorus platypterus), tuna and sharks,
making this fishery one of the most profitable in Costa Rica. Although the offshore
resources have not been studied fully, there are indications that this fishery can be
further developed.
The situation in the demersal fishery is completely different. This fishery includes a
trawler fleet of 87 boats, 2700 small and medium-sized artesanal boats employing gillnets
and 3 medium sized purse seiners. Easy access, government support and lack of other
sources of subsistance have led to overexploitation in this fishery, as demonstrated by
levelling off of the total catch since the 1980's and an increasing effort. Most of the
production of the demersal fishery comes from the Gulf of Nicoya, an estuary in the
northwest of Costa Rica.
Gulf of Nicoya: environment
The environment of the Gulf is highly variable, both in time and in location. Salinity
fluctuates according to season. During the rainy season, river runoff causes a surface
flow of freshwater in the inner gulf in a southern direction. Salt water flows back into
the inner gulf in deeper layers. This leads to vertical stratification. In the dry season,
with less river runoff the tides break the stratification. The outer gulf is more or less
premanently stratified and has a more oceanic character.
Inner and outer gulf also differ in depth (5-20 m and 20-200 m, respectively) and bottom
type (muddy and sandy/rocky, respectively).
Species and gears of the Gulf of Nicoya fishery
The most important species of the Gulf of Nicoya fishery are :
- Shrimps (Penaeus occidentalis and P. stylirostris, as well as
other species) caught by the trawlers and by the gillnets
- Sciaenids ("corvina", mainly Cynoscion spp.) caught by gillnets
and as bycatch in the shrimp trawls
- Snappers ("pargo", mainly Lutjanus guttatus) caught by the
artesanal longlines and as bycatch in the shrimp trawls
- Small pelagics ("sardina", mainly the anchoveta Cetengraulis
mysticetus and three species of sardine Opisthonema spp.) caught with the purse
seins (both industrial and artesanal)