Rapp. Comm. int. Mer Médit., 36,2001
269
Introduction
The pink shrimp (Aristeus antennatus) is a demersal species that is
found on the muddy bottoms in the Mediterranean Sea and Atlantic Ocean
south of the Iberian peninsula, at depths from 200 m to deeper than 2000
m. It is the target of a very specific trawl fishery, which is considered to be
monospecific. Despite the fact that it has been studied in neighbouring
areas (1), we describe the biological parameters of the species for the first
time in an area defined between Cape Palos and Cape San Antonio.
Materials and Methods
Monthly random stratified samplings were carried out on pink shrimp
commercial catches from the Alicante Gulf landed in the port of Santa Pola,
from January 1995 to December 1998. Individuals from a total of 15,683
specimens were sexed and measured by their cephalothoracic length (CL).
In addition, monthly biological sampling from 5,062 additional indiv
i
d
u
a
l
s
was carried out during 1997. The parameters of the size-weight relationship
were determined by regression. The estimates of the Von Bertalanffy grow
t
h
parameters were obtained by the FISAT statistical package (2) from month-
ly length frequency distributions by sex for the 1995-1998 period. Maturity
was determined by macroscopic observation. For females, a scale of five
maturity stages modified from (3) was adopted, whereas for males maturi-
ty was a function of the shortening of the rostrum and the presence or not
of petasma fusion (4). Moulting of the individuals was determined by the
hardness of the carapace considering two stages: postmoulting (soft cara-
pace) and premoulting (hard carapace). Sexual ratios were calculated by
size class, expressed as the ratio of females to the total number of indiv
i
d
u-
als. Finally, the percentages of maturity by size for each sex were calculat-
ed, in order to determine the size at 50% first maturity.
Results
The sizes of the females in the catches varied from a minimum of 10.0
mm to a maximum of 66.2 mm CL, with a mean size in the sampling peri-
od of 29.3 mm CL. The males varied from a minimum of 14.6 mm to a max-
imum of 35.6 mm CL, with an average of 22.8 mm CL. Males represented
30% of the landings in number, whereas the remaining 70% corresponded
to females. The contribution by size class of the individuals by sex to the
yearly total landings showed a size dimorphism for the species (Fig.1). T
h
e
results obtained for the different size-weight relationships by sexes (Ta
b
l
e
I) showed a nega
t
ive allometry between the considered parameters.
Absolute growth parameters (Table II) gave high growth rate values (K, f’
)
,
which were higher in females. The mean contribution of postmoulted indi-
viduals was very low for the period studied (7.7% for males and 3.0% for
females) and appeared as a clear bimonthly pattern.
The sexual ratio (sr) by size class showed that, after an initial stage (18-
22 mm) when males predominated signific
a
n
t
l
y, females started to domi-
nate significantly throughout the whole range of sizes above 26 mm. T
h
e
mean sexual ratio for the whole period of the study was dominated by the
females (Ps = 0.70). The percentages of mature males showed a high ratio
throughout the year, with the immature ratios increasing from November to
March. In females, the ratios of mated females started to increase in spring,
reached the maximum during the summer (June-September) and then
decreased in the autumn. The spawning period occurred during the same
period, and it was especially intense in July and August. The percentages of
maturity by size class showed a 50% size at first maturity of 16.7 mm for
males and 23.5 mm for females according to the logistic model (Fig. 2).
H
ow
eve
r, the maturation stage, both for males and females, would have to
t
a
ke place within the first year of life, but with a life ex
p
e
c
t
a
n
cy of four and
five years respective
l
y.
Table I. Parameters of relative growth (size (mm)-weight (g) relationship:
Weight = a * Sizeb) calculated for males and females of Aristeus anten-
n
a
t
u
s.Levelofsignificance***=p<0.001,**=p<0.01,*=p<0.05and
NS=p<0.1 in the Student t-test.
Table II. Results of the growth parameters (size-age relationship) for the
VBGF model obtained using the FISAT (ELEFAN) programme, for males
and females of Aristeus antennatus, with t0 being adjusted for a CL
D
(first modal class obtained by Battacharya) of 21.46 mm in males and
25.65 mm in females.
Figure 1. Size contribution by sex to the annual landings of Aristeus
antennatusin Santa Pola port.
Figure 2. Logistic curves of sexual maturity in Aristeus antennatus.
References
(1) García-Rodriguez, M. and A. Esteban 1999. A comparison between the
biology and the exploitation level of two pink shrimp (Aristeus antennatus
Risso, 1816) stocks from two different areas in the Spanish Mediterranean. In:
von Paupel Klein, J.C. & Schram, F.R.(eds), The Biodiversity crisis and
Crustacea. Balkema Pub, Rotterdam, 721-732.
(2) Gayanilo jr, F.C., Sparre, P. and Pa
u
l
y, D. 1994. The FAO-ICLARM Stock
Assessment Tools (FISAT) User’s Guide. FAO Computerized Information
Series (Fisheries) nº 6. Rome, FAO, 186 pp.
(3) Relini Orsi, L. and Relini, G. 1979. Pesca e riproduzione del gambero rosso
Aristeus antennatusnel Mar Ligure. Quad. Civ. Staz. Idrobiol., Milano. 7.
(4) Sardá, F. and Demestre, M. 1989. Shortening of the rostrum and rostral
LENGTH COMPOSITION, GROWTH AND REPRODUCTION OF A MEDITERRANEAN RED SHRIMP
(ARISTEUS ANTENNATUS(RISSO, 1816), DECAPODA, DENDROBRANCHIATA) POPULATION IN
THE ALICANTE GULF (S.E. SPAIN)
M. García-Rodriguez* and A. Esteban
*Instituto Español de Oceanografía, Servicios Centrales, Madrid, Spain - mariano.garcía@md.ieo.es
Instituto Español de Oceanografía, Centro Oceanográfico De Murcia, San Pedro Del Pinatar, Murcia, Spain
Abstract
The pink shrimp (Aristeus antennatus) is a demersal species that is the target of a very specific trawl fishery in the Alicante Gulf (SE
Spain). This paper describes, for first time in this area, certain biometric relationships, as well as growth parameters and reproductive
patterns of the species. The results showed a sexual size dimorphism, with a negative allometry of growth that was higher in females. In
addition, females dominated in the catch composition. The spawning period occurred between the months of June to September and the
maturation stage, both for males and females, took place within the first year of life.
Keywords: Decapoda, Biology,Western Mediterranean
Groupa
berr.bsignif.r2n
males0.002060582.532250.02016***0.921332
females0.001878692.562690.00654***0.983730
YearsGroupL
8
(mm)K (year
-1
)t
0
Rn
f
’
95-98males51.00.360-0.5200.3822.97
females77.00.380-0.0650.1283.35
