366 
Fishery Bulletin 115(3) 
fishing fleets) found on the continental shelf in Argen- 
tina, Brazil, and Uruguay (Massa and Lasta 2 ). The ex- 
ploitation of this species throughout its range has led 
to declines in its population (Massa et al. 3 ), and it has 
a global classification of endangered (IUCN Red List of 
Threatened Species), with a designation of vulnerable 
in Argentina and Uruguay (Massa et al., 2006). Nar- 
rownose smooth-hound caught off the coast of Brazil 
are part of the southern stock that migrates north ev- 
ery year. Therefore, the exploitation in nursery areas, 
in particular, has led to recruitment overfishing and a 
decline of -85% in the total biomass from 1975 to 1995 
(Haimovici, 1997). In Brazil, this species is categorized 
as critically endangered in the IUCN Red List of Threat- 
ened Species (Massa et al., 2006). Given its migratory 
behavior, there is great concern for the conservation of 
this shark over its entire range of distribution (Massa 
et al., 2006; Molina and Lopez Cazorla, 2011). 
Sustainable fishing of small coastal sharks, which 
have a greater recovery potential (Stevens et al., 2000) 
than their larger counterparts, is theoretically possible 
to achieve if the key biological aspects are taken into 
consideration when designing management policy. The 
narrownose smooth-hound is one of the most studied 
sharks of Argentina: several scientific publications de- 
scribe its reproduction, food habits, and other aspects 
of its biology (Menni, 1985; Menni et al., 1986; Cous- 
seau et al. 4 ; Chiaramonte and Pettovello, 2000; Sidders 
et al., 2005; Cortes and Massa 5 ; Segura and Milessi, 
2009; Colautti et al., 2010; Molina and Lopez Cazor- 
la, 2011). However, little attention has been paid to 
age and growth of this species. To date, there are 2 
documents, a M.S, thesis from Brazil (Batista, 1988) 
and a technical report from Argentina (Hozbor et al. 6 ) 
2 Massa, A., and C. A. Lasta. 2000. Recursos a mantener: 
Gatuzo ( Mustelus schmitti). In Smtesis del estado de las 
pesquerias maritimas argentinas y de la Cuenca del Plata. 
Anos 1997-1998, con una actualizacion de 1999. Publicacio- 
nes Especiales INIDEP (S. I. Bezzi, R. Akselman, and E. E. 
Boschi, eds.), p. 129-137. [Available from Instituto Nacional 
de Investigacion y Desarrollo Pesquero, Paseo Victoria Ocam- 
po N°l, Escollera Norte, B7602HSA Mar del Plata, Provincia 
de Buenos Aires, Argentina.] 
3 Massa, A., C. A. Lasta, and C. R. Carozza. 2004. Estado 
actual y explotacion del gatuzo ( Mustelus schmitti). In Los 
peces marinos de interes pesquero. Caracterizacion biologica 
y evaluacion del estado de explotacion. Publicaciones Es- 
peciales INIDEP (R. P. Sanchez and S. I. Bezzi, eds.), p. 
67-83. [Available from Instituto Nacional de Investigacion 
y Desarrollo Pesquero, Paseo Victoria Ocampo N°l, Escollera 
Norte, B7602HSA Mar del Plata, Provincia de Buenos Aires, 
Argentina.] 
4 Cousseau, M. B., C. R. Carozza, and G. J. Macchi. 1998. 
Abundancia, reproduccion y distribucion de tallas del gatuzo 
( Mustelus schmitti) en la Zona Comun de Pesca Argentino- 
Uruguaya y en El Rincon. Noviembre, 1994. INIDEP Inf. 
Tec. 21:103-115. [Available from website.] 
5 Cortes, F., and A. Massa. 2006. Aspectos reproductivos del 
gatuzo ( Mustelus schmitti). Inf. Tec. INIDEP, 10 p. [Avail- 
able from website.] 
6 Hozbor, N. M., M. Saez, and A. M. Massa. 2010. Edad y 
crecimiento de Mustelus schmitti (gatuzo), en la region cos- 
tera bonaerense y uruguaya. INIDEP Inf. Invest. 49, 15 p. 
[Available from website.] 
that deal with this aspect. Science-based studies on 
age and growth are crucially important for research 
of population dynamics because, without accurate age 
and growth estimations, it is impossible to perform 
adequate fisheries stock assessments, make accurate 
forecasts, and provide effective management (Chugu- 
nova, 1963; Reeves, 2003; Methot and Wetzel, 2013). 
Therefore, the aim of this work was to provide accu- 
rate estimates of the age structure and growth param- 
eters for the population of narrownose smooth-hound : 
from Anegada Bay, an important shark breeding area \ 
in Argentina. 
Materials and methods 
Study area 
Anegada Bay, located in the south of Buenos Aires 
Province in Argentina, has a wide variety of habitats, 
including wide, muddy intertidal areas, sandy bottom 
substrates, and sand and gravel beaches. In Anegada '( 
Bay, a multi-use protected area, the Reserva Natural 
de Uso Multiple Bahfa San Bias, was designated in 
2001 (Provincial Law 12788; available from website), 
as a means of preserving not only fish species but also 
a wide variety of vertebrate species, such as several 
migratory birds, sea lions, and terrestrial mammals, 
that use the bay as nesting and feeding grounds. This 
bay is also considered a potential nursery area for 
narrownose smooth-hound (Molina and Lopez Cazorla, 
2011). Artisanal and recreational fisheries were the 
main human activities in Anegada Bay. Whereas the 
latter still continues, in recent years, artisanal fish- 
ing has been prohibited within the boundaries of the > 
reserve. 
This study was conducted in the southern part of J 
Anegada Bay, where 3 sampling stations were estab- 
lished: San Bias, Rfa, and Los Pocitos (Fig. 1). 
Sampling methods and data collection 
Specimens of narrownose smooth-hound were collected 
seasonally in 2008: in February (summer), May (au- 1 
tumn), August (winter), and November (spring). The 
fishing gear consisted of 2 batteries of 7 bottom gill 
nets. Each net was 25 m long, 2 m high, and had dif- 
ferent mesh sizes (64, 70, 80, 105, 135, 150, and 170 
mm stretched) so that a wide range of fish sizes could 
be captured. Nets were placed parallel to the coast of 
the sampling stations at dusk, and collected 12 hours 
later at dawn. 1 
All fish were first measured in situ to the nearest 
centimeter in TL and subsequently grouped into 1-cm 
size classes. A subsample composed of 10 randomly se- 
lected specimens of each size class was then used for > 
further analysis. These 10 individuals were measured to 
the nearest millimeter in TL, their sex was determined, 
and the portion of vertebral column from below the 
first dorsal fin was removed. Vertebrae portions were 
