Microcohorts of white shrimp, Litopenaeus vannamei, were sampled with a cast net at fortnightly intervals in the Mar Muerto Lagoon, Southern Mexico. Shrimp recruited to the lagoon throughout the sampling period (January to August 1993). Mean growth rates of microcohorts ranged from 0.21 to 1.21 mm total length (TL) per day. Juvenile shrimp mainly between the sizes of 70 to 80 mm TL emigrated from the lagoon. Growth and the onset of emigration appeared to be related to water salinity

Medina-Reyna, C.E.

English

Aquatic Commons

Naga, The ICLARM Quarterly (Vol. 24, Nos. 3 & 4) July-December 200130
Growth and Emigration of White Shrimp,
Litopenaeus vannamei, in the
Mar Muerto Lagoon, Southern Mexico
C.E. Medina-Reyna
Introduction
In 1998, commercial landings of
penaeid shrimp in Mexico were about
48 600 t valued  at US$270 million
(Secretaría del Medio Ambiente,
Recursos Naturales y Pesca, 1999).
The Pacific shrimp fishery generates
61% of Mexican shrimp and the Gulf
of Tehuantepec region contributes
16.7% to this production. In the Gulf
of Tehuantepec, Pacific coast of
Southern Mexico, Litopenaeus
vannamei is numerically the most
important species in estuarine
landings and represents 40% of the
oceanic harvest.
The distribution of L. vannamei
extends from Mexico to Peru. Like
many penaeids, it utilises coastal
lagoons during the juvenile phase of
its life cycle and migrates offshore for
subsequent maturation and
reproduction (Garcia and Le Reste
1981). The  magnitude of the Mar
Muerto Lagoon shrimp production and
its importance as the largest nursery
ground in the Gulf of Tehuantepec
suggests the desirability of
investigating the growth of L. vannamei
and factors responsible for the onset of
offshore emigration. It is noted that Mar
Abstract
Microcohorts of white shrimp, Litopenaeus vannamei, were sampled with a cast net at fortnightly intervals in
the Mar Muerto Lagoon, Southern Mexico. Shrimp recruited to the lagoon throughout the sampling period (January
to August 1993). Mean growth rates of microcohorts ranged from 0.21 to 1.21 mm total length (TL) per day. Juvenile
shrimp mainly between the sizes of 70 to 80 mm TL emigrated from the lagoon.  Growth and the onset of emigration
appeared to be related to water salinity.
Muerto Lagoon has no resource
management plan due mainly to scarce
biological information on this shrimp.
The Mar Muerto Lagoon system
(Figure 1) is one of the largest
estuaries in Mexico and provides
nursery habitat for white shrimp and
several fish species. L. vannamei
typically constitutes 95% of catches
with daily peaks in production
reaching 10 tons. An oceanic fishery
also depends on L. vannamei, largely
in the southern Gulf of Tehuantepec.
Most penaeid shrimp exhibit rapid
growth which is correlated with
environmental factors. No information
is available on the growth of the Mar
Muerto Lagoon penaeids. While the
timing of shrimp emigration from
estuaries varies with species and
geographic area, a number of factors
have been suggested as causal stimuli
Fig. 1. Map of Mar Muerto Lagoon, México showing the sampling stations.
16
°
30
'
16
°
30
'
16
°
15
'
16
°
00
'
Gulf of Tehuantepec
Mar Muerto
Boca de Tonalá
93°50'94°00'94°10'94°20'94°30'
La
tit
ud
e 
(°N
)
Longitude (°W)
Gulf of México
Gulf of Tehuantepec
Pacific Ocean
21 dec(12.40pm) 21/12/01, 5:25 PM30
Naga, The ICLARM Quarterly (Vol. 24, Nos. 3 & 4) July-December 2001 31
(see Garcia and Le Reste 1981 and
Garcia 1984 for a review).
This paper presents the first
estimates of seasonal differences in
growth rates and emigration for L.
vannamei in Southern Mexico.
Materials
and Methods
Sampling was carried out in the
Mar Muerto Lagoon; 23 sampling
stations were selected (Figure 1).
Samples were collected between
January-August 1993 at 2-week
intervals. A cast net with 10 mm
nylon mesh and a circular area of 28
m2 was used. Cast net efficiency and
avoidance due to depth was set at
70% and 30% respectively. At each
station, five throws were taken
around a previously fixed stick.
Catches were immediately sorted and
counted and then total length (mm)
and weight (g) were determined.
Water temperature (°C) and salinity
(ppt) were recorded at each station.
The castnet length-frequency
data was used to construct length-
frequency histograms. A computer
program, MIX (MacDonald 1986),
was used to fit normal curves to the
component cohorts in each
distribution. Growth rates were
estimated by following the mean
size of the youngest cohort over
consecutive sampling periods. Older
cohorts were excluded from the
analysis because of the effect of
emigration on the cohort mean.
Modal progression graphs (Laurec
and Le Guen 1981) were constructed
from seven microhabitats identified
in the lagoon.
A tiny shrimp fishery operates
throughout the main channel and
employs 200 m long and 1.5 m wide
gillnets. Fortnightly catch samples
were treated in the same manner as
above, as well as recording site and
duration of operation.  Tiny shrimp
fishery samples provided the
approximate size of shrimp at the
onset of emigration (L
e
). Declines in
the frequency of shrimp within the
emigrating size classes over
consecutive sampling intervals were
used to identify possible periods of
emigration.
The length-weight relationships
were estimated using the computer
program FISHPARM (Prager et al.
1989) that implements Marquardt’s
algorithm for nonlinear least-
squares parameter estimation.
Results
and Discussion
Shrimps were captured
throughout the periphery of the
lagoon and in limited numbers along
the main channel. Catches were
highest in the protected areas of the
lagoon (locally called “tablón”)
where depth was less than 1 m and
bottom substrate was muddy.
Shrimps concentrated in the middle
of the lagoon for most of the sampling
period and in the connection channel
with Oriental Lagoon.
Juvenile shrimp were present
throughout the sampling period
declining over the month of
February and increasing during
March to May (Figure 2). This
abundance pattern is a product of the
dry season postlarval recruitment
reported in this area (Medina-Reyna
et al. 1998). During June, juvenile
shrimp were heavily fished and
abundance was at a minimum.
Growth rates were estimated over
the size range 40-110 mm TL (Table
1). Microcohorts were identified
succesfully in all the different habitats
along the lagoon. Growth rate
estimates ranged from 0.20 to 1.21 mm
TL per day. Microcohorts exhibited
a seasonal fluctuation in their growth
pattern due to climatic conditions
(Table 2). The mean growth rate
during the dry season was 0.44 mm
TL per day, and 0.61 mm TL per day
during the rainy season. This suggests
that salinity affects mean growth rate.
80
70
60
50
30
40
10
0
J F M A M
Month
Ca
tc
h 
(t)
Ab
u
n
da
nc
e 
(sh
rim
ps
 m
2 )
Dry season Rainy season
Catch
Abundance
J J A
20
1.6
1.4
1.2
1
0.6
0.8
0.2
0
0.4
Fig. 2. Abundance pattern of L. vannamei in the locality of Santana-Chileta tablon. Bars
indicate the monthly catch recorded for the cooperative-holder of the tablon.
f
i
s
h
b
y
t
e
21 dec(12.40pm) 21/12/01, 5:25 PM31
Naga, The ICLARM Quarterly (Vol. 24, Nos. 3 & 4) July-December 200132
The highest mean growth increments
calculated for the habitats showed
some areas were more favorable for
juvenile shrimp. These estimates are
at the lower end of those made for
other lagoons from the Pacific side
of Mexico (Table 3). Intraspecific
space allocation for juvenile shrimps
impacts food partitioning and growth
could be limited due to overcrowding
(Universidad de Sinaloa 1987).
Length-weight relationships
estimated in two localities in the
lagoon during the two seasons (Table
4) showed that juvenile shrimp may
be under adverse conditions (b=2.5-
2.6) during the dry season, while
conditions were more favorable
(b=2.9)  during the rainy season.
Microcohorts entered the lagoon
system throughout the sampling period.
Cohorts emigrated at about 2.5-4.0
months (72 to 121 days) after estuarine
recruitment (Table 5). L. vannamei
began to leave the lagoon upon
attaining about 60 mm TL with most
emigration occurring between 70 and
80 mm TL. Size at emigration
increased with progression of the rainy
season (Table 5). Mortality during the
dry  season appears to limit the
abundance of microcohorts grown
under stressful conditions and high
fishing effort prevailing during this
period (Medina-Reyna1999), and
affects subsequent oceanic recruitment.
The rainy seasons’s microcohorts spent
relatively more time in the lagoon
growing at higher rates compared to dry
season microcohorts.Emigration did
not appear to be related to temperature
as thermal oscillation is not strong in
this region of Mexico. Emigration was
related to salinity fluctuations. In fact,
the relationship was inverse (Le=
90.355-1.4184 (Salinity, r= -0.784,
p<0.05) due to the antiestuarine
condition prevailing during dry season
(Figure 3). Emigration occurs all-year
round in Mar Muerto Lagoon and
appears to be influenced by salinity
conditions.  It is noted that increased
Table 1. Growth rate of white shrimp microcohorts estimated by habitat in the Mar
Muerto Lagoon, Mexico.
Habitat Microcohort k (mm/d) TL Range(mm) Season
Reforma Agraria 1 0.45   60-75 Dry
2 0.61   40-60 Dry
3 0.31   40-60 Dry
4 0.48    45-70 Dry
5 0.51   50-90 Rainy
6 0.81   65-80 Rainy
Estero Tular 1 0.47   60-75 Dry
2 0.24   55-65 Dry
4 1.21 50-110 Rainy
5 1.01   55-90 Rainy
6 0.65   49-90 Rainy
La Angostura 1 0.42   40-60 Dry
2 0.51   65-90 Rainy
3 0.31   60-65 Rainy
San Andres 1 0.37   70-80 Dry
2 0.35   60-70 Dry
3 0.35   50-90 Rainy
4 0.41   50-70 Rainy
5 0.38   50-70 Rainy
Los Tules 1 0.55   75-85 Dry
2 0.61   55-85 Dry
3 0.20   75-85 Dry
4 0.66   60-95 Dry
5 0.56 45-100 Dry
6 0.40   75-95 Rainy
7 0.70   50-95 Rainy
8 0.59   50-70 Rainy
9 0.77   50-65 Rainy
Santa-Chileta 1 0.44   65-90 Dry
2 0.67   60-85 Dry
3 0.63   45-95 Dry
4 0.73   65-80 Rainy
5 0.50 60-100 Rainy
6 0.38   65-95 Rainy
7 0.59   45-90 Rainy
8 1.01   55-75 Rainy
Punta Paloma 1 0.41   65-90 Dry
2 0.40 75-100 Dry
3 0.47 65-105 Dry
4 0.64 65-100 Rainy
5 0.69   50-95 Rainy
Table 2. Seasonal mean growth rates (mm/d) of white shrimp (L. vannamei) estimated
in the Mar Muerto Lagoon, Mexico. Standard deviations in parentheses.
Habitat Dry season Rainy season
Reforma Agraria 0.46 (0.105) 0.66 (0.152)
Estero Tular 0.27 (0.151) 0.97 (0.243)
La Angostura 0.42 (0.054) 0.41 (0.102)
San Andres 0.36 (0.011) 0.37 (0.037)
Santa-Chileta 0.62 (0.107) 0.62 (0.236)
Los Tules 0.52 (0.163) 0.61 (0.137)
Punta Paloma 0.43 (0.030) 0.66 (0.027)
Mean growth rate 0.44 (0.103) 0.61 (0.181)
21 dec(12.40pm) 21/12/01, 5:25 PM32
Naga, The ICLARM Quarterly (Vol. 24, Nos. 3 & 4) July-December 2001 33
productivity of coastal waters
(associated with increased rainfall and
reduced salinities) may be the direct
causative factor affecting growth (see
Garcia and Le Reste 1981, Garcia
1984).
References
Edwards, R. R. C. 1977. Field experiments on
growth and mortality of Penaeus vannamei
in a Mexico coastal lagoon complex.
Estuarine Coastal Mar. Sci. 5:107-126.
Garcia, S. 1984. A note on environmental
aspects of penaeid shrimp biology and
dynamics, p. 268-271. In J. A. Gulland
and B. J. Rothschild (eds.) Penaeid
shrimps: their biology and management.
Fishing News Books Ltd. UK.
Garcia, S. and  L. Le Reste. 1981. Life cycles,
dynamics, exploitation and management
of coastal penaeid shrimp stocks. FAO
Fish. Tech. Pap. 203, 215 p.
Laurec, A. and J. C Le-Guen. 1981. Dynamique
des populations marines exploitées. Tome
I: Conceptes et modèles. Rapp. Scient. Tech.
No. 45, 118 p. CNEXO.
MacDonald, P. D. M. 1986. The length-
frequency procedure for analysis of age
composition, p. 1-21. In Summerfelt, R. C.
and B. W. Menzel (eds.) Age and Growth
of fish.  Iowa State Univ. Press. Ames, Iowa.
Medina-Reyna, C. E. 1999. La retención de
las artes de pesca de camarón como
indicador de la estrategia pesquera en la
Laguna Mar Muerto de Oaxaca. Ciencia
y Mar (México) 7:13-22.
Medina-Reyna, C. E., Morales-Pacheco, O.
and H. T. Salinas-Orta 1998. El
reclutamiento de las postlarvas de
camarón blanco (Penaeus vannamei) en
el Golfo de Tehuantepec : Una revisión.
Ciencia y Mar (Mexico) 5:33-44.
Prager, M. H.,  Recksiek, C. W. and S. B.
Saila. 1987. Nonlinear parameter
estimation for fisheries Oceanography.
Technical Report 87-10. Old Dominion
University. Dept. of Oceanography
Norfolk, VA. USA.
Secretaría del Medio Ambiente, Recursos
Naturales y Pesca. 1999. Anuario
estadístico de Pesca 1998. Dirección Gral.
de Estadística y Registro Pesquero, México.
Su
rfa
ce
 te
m
pe
ra
tu
re
 (°
C)
Su
rfa
ce
 s
a
lin
ity
 (p
pt)
To
ta
l l
en
gt
h 
(m
m)
40
35
30
25
20
100
90
80
70
60
50
40
30
J1 J2 F1 F2 M1 M2 M1 M2
Rainy seasonDry season
J1 J2 J1 J2A1 A2 A1 A2
100
90
80
70
60
50
40
30
20
10
0
Fig. 3. Mean total length of L. vannamei in the Mar Muerto Lagoon over
time; vertical bars indicate mean (+), maxima (   )and minima (  ).
f
i
s
h
b
y
t
e
Table 3. Comparison of mean growth rates (mm/d) of white shrimp (L. vannamei) in
habitats sampled in Mar Muerto Lagoon and other coastal lagoons in Mexico.
Habitat/Area Highest Lowest
Reforma Agraria 0.81 0.31
Estero Tular 1.21 0.24
La Angostura 0.51 0.31
San Andres 0.41 0.35
Santana-Chileta 0.77 0.20
Los Tules 1.01 0.38
Punta Paloma 0.69 0.40
Huizache (1969)* 2.85 0.88
Huizache (1973)* 1.96 0.88
Huizache (1973-74)* 1.64 0.51
Huizache (1974)* 1.54 0.53
Huizache (Edwards 1977) 1.78 1.29
Palmillas * 1.23 0.24
Mar Muerto Lagoon 1.21 0.20
(This study)
* cited in Universidad de Sinaloa, 1987
21 dec(12.40pm) 21/12/01, 5:25 PM33
Naga, The ICLARM Quarterly (Vol. 24, Nos. 3 & 4) July-December 200134
Table 4. Length-weight relationship of white shrimp (L. vannamei) sampled in the Mar
Muerto Lagoon, Mexico.
Locality Season a b r2 n
Rancho Salinas Dry 0.016 2.6 0.85 163
Rincón Juárez Dry 0.018 2.5 0.86 207
Rancho Salinas Rainy 0.011 2.9 0.97 76
Rincón Juárez Rainy 0.010 2.9 0.98 186
Table 5. Monthly variation of length (L
e
), weight (W
e
) and age (A
e
 in days) at emigration
of white shrimp (L. vannamei) estimated in the Mar Muerto Lagoon. Weights were
calculated using parameters in Table 4.
Month Season L
e
 (mm) W
e
 (g) A
e
 (days)
January Dry 75.7 3.6 100
February Dry 76.1 3.7 101
March Dry 59.4 1.8 72
April Dry 60.2 1.8 73
May Dry -* -* *-
June Rainy 66.3 2.5 84
July Rainy 79.5 4.2 106
August Rainy 88.1 5.6 121
Mean 72.2 4.4 94
* no sampling due to adverse weather condition
Universidad de Sinaloa. 1987. Estudio para
la determinación de la migración y
abundancia de postlarvas y juveniles de
camarón en el área de Palmillas, Mpio.
de Escuinapa, Sin. Final Report to
Secretaría de Pesca, México, 315 p.
___________________
C.E. Medina-Reyna is from the Instituto de
Industrias of the Universidad del Mar
(UMAR), Apdo. Postal 47, Puerto Angel,
Oaxaca, 70902 México.
e-mail : peneion@angel.umar.mx
21 dec(12.40pm) 21/12/01, 5:26 PM34


Growth and emigration of white shimp, Litopenaeus vannamei, in the Mar Muerto Lagoon, Southern Mexico

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Growth and emigration of white shimp, Litopenaeus vannamei, in the Mar Muerto Lagoon, Southern Mexico

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