BIOMETRIC PARAMETERS OF WILD WRECKFISH (Polyprion
americanus)
B. Álvarez-Blázquez*, F. Linares, R.M. Cal, J.L. Rodríguez, J.M. Martínez, M.
Sánchez, N. Lluch, E. Pérez, P. Domingues and JB. Peleteiro
*IEO
- Instituto Español de Oceanografía, C. Oceanográfico de Vigo, Subida a Radio Faro 50,
36390 Vigo, Spain. blanca.alvarez@vi.ieo.es
Introduction
The wreckfish (Polyprion americanus) is a much appreciated species from the
gastronomic point of view. The renowned quality this fish is well known, both nationally
as in the international market. This makes wreckfish a good candidate for marine
aquaculture diversification.
Preliminary results on the biology (Wakefield et al., 2013) and culture (Peleteiro et al.,
2014) of this species suggest that this is a fast grower. Wreckfish also acclimates easily
to captivity and handling, and despite their large sizes, no mortality related to handling
has been observed. This species readily accepts prepared diets in captivity, and is
characterized by its low metabolism and inhabiting great water depths.
The present research was designed to obtain information on biochemical composition,
biometric parameters, sexual differentiation and maturity of wild caught wreckfish,
which are important for a success culture of this species.
Materials and methods
A total of 86 wild caught wreckfish, from the Azores (North Atlantic, Portugal) fisheries
were sampled between February 19th, 2014 and March 25th, 2015. Total length (cm),
perimeter (cm) and total and eviscerated weight (Kg) were recorded for each fish.
Additionally, perivisceral fat was collected and its % was determined. Gonads, liver,
stomach and intestine were also collected from each fish and weighed, to determine the
respective indexes. Samples from each gonad were also preserved to be studied through
histology to determine maturation stage.
Results
Table I: Biometric parameters of wild caught wreckfish (n= 68, *n=28))
PARÁMETERS (n= 86)
TOTAL LENGHT (cm)
ST LENGHT
PERÍMETER
WEIGHT (Kg)
EVIS. WEIGHT (Kg)
FAT PERIVIS. WEIGHT (g)
STOMACH WEIGHT (g)
INTESTINE LENGHT (cm)
INTESTINE WEIGHT (g)
GSI FEMALES*
GSI MALES*
SHI
VSI
MÍN-MÁX
54-98
48-99
40-81
2,6-18,0
2,4 - 16,0
0-339,3
54,2-457,2
61-144
34,2-274,0
0,05-0.65
0,01-0,54
0,02-3,11
2,40-16,02
MEAN
75,36
65,99
55,13
7,25
6,73
70,42
147,98
96,48
94,48
0,29
0,11
1,27
7,26
STD
7,39
7,66
6,14
2,22
2,00
71,93
72,12
13,96
61,57
0,17
0,11
0,53
2,11
A total of 28 males, 28 females were identified. 30 undetermined animals were recorded.
The weight/length ratio was determined both for males and females (Fig, 1).
A statistical analysis (ANOVA) was performed for all variables studied, for each sex.
Females were larger (78.30±7.613 cm), has higher perimeter (57.82±7.781 cm), total
weight (8.21±2.901), eviscerated weight (7.55±2.554) and GSI (0.287±0.170) compared
to males length (73.96±5.416), perimeter (54.45±4.015), total weight (6.74±1.453),
eviscerated weight (6.27±1.275) and GSI (0.11±0.111). For the remaining parameters,
there were no significant differences (p>0.05).
Weight (Kg)
20.00
15.00
MALES
y = 0.248x - 11.595
R² = 0.7711
10.00
FEMALES
y = 0.3526x - 19.4
R² = 0.8522
5.00
0.00
55
65
MALES
FEMALES
75
Lenght (cm)
85
95
Fig 1. Length/weight ratio for wild males (n=28) and females (n=28) from the Azores
fisheries between February 2014 and March 2015.
Histological analysis of the gonads for females <10 Kg showed developed oogonia in
small cyst-or nest-like structures, primary oocytes (perinuclear stage) and
previtellogenetic oocytes. For females >10 Kg, early previtellogenic oocytes were
observed, and in a 18 Kg female, the ovary contained many large vitellogenetic stage
oocytes. For males around 50 cm in length and 2-4 Kg in total weight, the gonads
contained clusters of spermatogonia and spermatocyte which were irregular in shape and
densely stained. From individuals measuring 70 cm in total length and 6 Kg, the gonads
contained all other stages of spermatogenesis: spermatocyte, spematids and spermatozoa.
Only a 10 Kg male captured in September 2014 was fluyent.
Conclusions:
Important differences in perivisceral fat were observed in these wild caught fish, which
were not related to time, season of capture or sex. This information is important for
nutrition studies and future elaboration of artificial feeds for this species.
Sexual dimorphism with total length, perimeter, total weight was demonstrated, as well
as significant differences in gonads, and GSI from males and females.
The macroscopic appearance and microscopic structure of female gonads is described
here for specimens of this species between 3 and 18 Kg, and 55 to 85 cm of total length,
and the gonocoric character and late maturation of the species is confirmed (Wakefield,
2014).
References:
Wakefield C.B., Newman S.J. and B.W. Molony. 2013. Exceptional longevity, slow growth and
late maturation infer high inherent vulnerability to exploitation for bass groper Polyprion
americanus (Teleostei: Polyprionidae). Aquatic Biology 18: 161-174.
Peleteiro J.B., Saavedra C., Pérez-Rial E., Soares E.C., Álvarez-Blázquez B. y Vilar A. 2011.
Diversificación de especies en acuicultura marina. Desarrollo de técnicas de cultivo de la cherna
(Polyprion americanus). En Congreso Nacional de Acuicultura 2011. Castelldefels (Girona)
España. 21-24/11/2011.
Adknowledgements:
Co-funded by the Seventh
Framework Programme
of the European Union
This project has received funding from the European Union’s Seventh Framework Programme for
research, technological development and demonstration (KBBE-2013-07 single stage, GA 603121,
DIVERSIFY).