Assessment and ecological characterization of the blue
crab (jaiba, Callinectes arcuatus) in the Gulf of Nicoya,
Costa Rica
Farid A. Tabash
Background
The Gulf of Nicoya is an estuary on the Pacific side of Costa Rica. It is an
important fishing area. Because of declining returns in the demersal fish and
shrimp fishery, fishers are looking for alternative fish resources. Recently interest
in the exploitation of the blue crab (Callinectes arcuatus) as an alternative resource
has increased (see photos). In 1997 40 fishing permits were granted for blue crab in
the Gulf of Nicoya. Because until now the crab population was unexploited, this is
a good time to investigate the crab population and look at the effects of the
emerging fishery.
Distribution and ecology
Work by DeVries et al. (1983) showed that the crabs are distributed in the inner
Gulf of Nicoya and along the eastern side of the outer Gulf (see map). During the
dry season (December to April), females migrate to the waters of higher salinity in
the outer gulf to spawn. Larvae are probably carried back into the inner gulf by
advective streams (Epifanio and Dittel 1982). Stomach content analysis shows that
crabs are primarily carnivores with a preference for slow preys like molluscs and
shrimps (Table 1).
Table 1. Occurrence of food categories (% of stomachs encountered) in
Callinectes arcuatus of three size classes (mm). Data from Saucedo
(1997).
Category
<60
60-90
91-140
fish
8.6
19.0
12.1
crustacea
65.5
47.6
21.8
molluscs
41.4
33.3
16.3
plant material
8.6
14.3
4.7
unidentified
43.1
47.6
32.7
Characteristics of crab traps
Some experiments were done to determine the catch characteristics of the crab
traps used by the fishers. Traps are made of chicken wire, measure 60x43x28 cm
and are baited with fish (jack, ray). Both the time needed for a trap to be saturated
and the maximum number of crabs caught per trap are variable, ranging from 2 to
7 hours and from 4 to 28 crabs per trap, respectively (see Figure 1 with data from
Cascante).
Figure 1. Saturation of crab traps in the Gulf of Nicoya, Costa Rica.
Reproduction and population dynamics
50% of C. arcuatus males and females are mature at a length (carapace width) of
82 mm and 67 mm, respectively. Some population dynamics parameters
determined from samples collected between May 1996 and February 1997 are
given in Table 2.
Table 2. Some population dynamics parameters of
Callinectes arcuatus in the Gulf of Nicoya.
L
194
mm
y-1
K
1.0
C
0.4
WP
0.97
y
Z
4.99
y-1
M
3.74
y-1
F
1.25
y-1
Further research
Crabs may play an important role in the ecosystem of the Gulf of Nicoya. If young
crabs and shrimps are important in the diet of demersal fish (esp. sciaenids and
snooks), then an increased exploitation of the crab population and the continuous
exploitation of the shrimp may affect the productivity of the commercially
important demersal fish (biological interaction). One point of interest is the sex
ratio in the catches. In traps, the majority of crabs caught are males while in trawl
hauls more females appeared (Dittel et al. 1985). Apparently males and females
occupy different spaces in the gulf or display different migration patterns.
References





Cascante, S. (in prep.) Determination of the optimal fishing effort in the fishery on the crab
Callinectes arcuatus in the internal part of the Gulf of Nicoya. Tésis de Licenciatura,
Universidad Nacional, Heredia.
DeVries, M.C., C.E. Epifanio and A.I. Dittel (1983) Reproductive periodicity of the tropica crab
Callinectes arcuatus Ordway in Central America. Estuarine, Coastal and Shelf Science 17, 709716.
Dittel, A.I., C.E. Epifanio and J.B. Chavarría (1985) Population biology of the portunid crab
Callinectes arcuatus Ordway in the Gulf of Nicoya, Costa Rica, Central America. Estuarine,
Coastal and Shelf Science 20, 593-602.
Epifanio, C.E. and A.I. Dittel (1982) Comparison of dispersal of crab larvae in Delaware Bay,
USA and the Gulf of Nicoya, Central America. p. 477-487 in: Estuarine Comparisons (ed. by
V.S. Kennedy). Academic Press, New York.
Saucedo, R.A. (1997) Hábitos alimentarios, morfometría y patrones de maduración de
Callinectes arcuatus (Crustacea: decapoda) en el Golfo de Nicoya, Costa Rica. Tésis de
Licenciatura, Universidad Nacional, Heredia. 68 p.
UNA-LUW Home EBM
Golfo de Nicoya