2 
Fishery Bulletin 116(1) 
species. Some studies have, for example, reported poor 
retention of PIT tags in 2 tropical sea cucumbers, Ho- 
lothuria whitmaei and Actinopyga miliaris (Purcell et 
al., 2008). In fact, only 8 d after release in suitable reef 
habitats, just one-quarter of H. whitmaei individuals 
tagged by Purcell et al. (2008) retained PIT tags and 
no A. miliaris individuals retained them. Similar re¬ 
sults were found for the gray sea cucumber (Holothuria 
grisea ), where the retention of the PIT tag was low, 
with 100% being lost by week 9 (Rodrlguez-Barreras 
et al., 2016), but in the case of Cucumaria frondosa, 
results on tag retention were much improved (Gianasi 
et al., 2015). Implanting the tag in an oral tentacle of 
C. frondosa to reach the hydrovascular system of the 
aquapharyngeal bulb resulted in the best retention 
rates in full-size individuals: from a maximum of 92% 
after 30 d to 68% at the end of the experimental period 
(300 d). Efficacy was lower in smaller individuals (84% 
after 30 d and 42% after 300 d). 
In a pioneer work, Ebert (1978) studied growth of 
the sea cucumber known as the lolly fish ( Holothuria 
atra) by tagging the plates of their calcareous rings 
with tetracycline. The growth of the plates was used to 
estimate growth parameters for the Brody-Bertalanffy 
growth equation. Subsequently, other methods based on 
weight and size data have been undertaken to study 
growth in both wild and cultured sea cucumber popula¬ 
tions. For example, Battaglene et al. ( 1999 ) calculated 
sea cucumber length from wet weight measurements, 
using a polynomial regression. Measurements of spe¬ 
cific growth rates and relative weight increase have 
also been obtained for sea cucumbers (Yang et al., 2005; 
Dong et al., 2008), while other studies have adapted 
different growth models like Francis’s model and the 
von Bertalanffy model to calculate weight and length 
data (Conand, 1988; Herrero-Perezrul et al., 1999; de 
la Fuente-Betancourt et al., 2001; Uthicke et al., 2004; 
Sulardiono and Prayitno, 2012). Interestingly, some 
consistent differences in growth rates have been ob¬ 
served between tropical species of sea cucumber, such as 
Stichopus vastus, the Florida sea cucumber (Holothuria 
floridana), the lolly fish, and the mammy fish (Actinopy¬ 
ga nobilis), exhibite slow growth rates (Ebert, 1978; de 
la Fuente-Betancourt et al., 2001; Uthicke et al., 2004; 
Sulardiono and Prayitno, 2012) and some temperate 
species, such as Australostichopus mollis and C. fron¬ 
dosa, that grow faster than the previously mentioned 
tropical species but also show some seasonal variation 
(Hamel and Mercier, 1996; Slater and Jeffs, 2010). 
Holothuria (Rowethuria) arguinensis has a restrict¬ 
ed distribution in the northeast Atlantic Ocean, from 
Portugal to the Canary Islands and Mauritania in 
northwestern Africa, although recently, it was record¬ 
ed in the Southwestern Mediterranean Sea (Alicante, 
Spain) and in Algerian waters, implying that it is colo¬ 
nizing the Mediterranean Sea (Gonzalez-Wangiiemert 
and Borrero-Perez, 2012; Mezali and Thandar, 2014). 
Holothuria arguinensis is one of the new target spe¬ 
cies of NE Atlantic and Southwestern Mediterranean 
fisheries, where catches driven by its high commercial 
value, are increasing (Gonzalez-Wangiiemert and Go- 
dino, 2016; Gonzalez-Wangiiemert et al., 2016; Roggatz 
et al., 2016). Illegal harvest of this species in Portugal 
and Spain, is a threat to the sustainability of the fish¬ 
ery, especially in the Ria Formosa lagoon, at Portimao 
and Albufeira (South Portugal), and at the coast of Ca¬ 
diz (South Spain) (Gonzalez-Wangiiemert and Godino, 
2016). Also, this species is targeted for aquaculture de¬ 
velopment for both commercial production and restock¬ 
ing (Dominguez-Godino et al., 2015). 
The species has been linked to the presence of sea¬ 
weed and seagrass meadows of Cymodocea nodosa and 
Zostera noltii, with reported densities up to 563 indi¬ 
viduals/ha (Faro, South Portugal) (Gonzalez-Wangiie¬ 
mert et al., 2013; Siegenthaler et al., 2015). The home 
range of H. arguinensis individuals has been estimated 
to average 35 m 2 , and individual movements are close 
to 10 m/d (Siegenthaler et al., 2015). 
An average size of 255 mm was reported for this 
species in Gran Canaria (Canary Islands, Spain) and 
a maximum size of 370 mm (Navarro et al., 2013). In 
Ria Formosa (South Portugal), Gonzalez-Wangiiemert 
et al. (2013) found individuals ranging between 70 to 
360 mm, and having an average size of 221 mm and 
a multimodal size-frequency distribution. Three years 
later, Gonzalez-Wangiiemert et al. (2016), considering 
H. arguinensis populations throughout the geographi¬ 
cal range of this species, estimated a positive allome- 
tric growth. In that study, individuals ranged from 90 
to 360 mm in length and had significant differences in 
mean size between sampled areas, such that individu¬ 
als from Sagres (SW Portugal) were significantly longer 
than those from Ria Formosa. 
Our aim was to obtain growth parameters from 
length-frequency data of the species H. arguinensis in¬ 
habiting the Ria Formosa (South Portugal), by fitting 
different growth models: the nonseasonal von Berta¬ 
lanffy and the Hoenig seasonal von Bertalanffy models. 
Material and methods 
Study area 
Ria Formosa is a coastal lagoon located in the Algarve 
region (South Portugal) (Fig. 1). Its area is approxi¬ 
mately 105 km 2 , half of which is intertidal and cov¬ 
ered by sand, mud and marshes (Duarte et al., 2007). 
It is composed of a system of barrier islands with small 
ponds, inlet deltas, and barrier platforms (Pacheco et 
al., 2010). The water temperature varies between 12°C 
and 13°C in winter and 27°C and 28°C in summer. 
Variations in salinity are small due to the low fresh¬ 
water input into the lagoon, ranging between 35.5 and 
36.9 throughout the year (Ribeiro et al., 2008), with 
the exception of surface waters for brief periods after 
heavy winter rainfall (Ribeiro et al., 2008; Rodrigues 
et al., 2015). 
Ria Formosa, was declared a Natural Park in 1987 
(Decreto-Lei No. 373/87, available from website) and it 
