Villanueva Gomila et al.: Early life history of Acanthistius patachomcus 
457 
What we know is that A. patachonicus is a long- 
lived (maximum age recorded for fish ~47 cm in total 
length was 40-41 years, see Rubinich, 2001), slow- 
growing fish that reaches 65 cm in total length and 
4 kg in weight (Irigoyen et al., 2008). It is a dioe- 
cious partial spawner and fertilization is external. 
The spawning season of this species extends between 
September and December off the coast of Buenos Ai- 
res province and in Northern Patagonia (Ciechomski 
and Cassia, 1976; Dell’Arciprete et ah, 1987), where 
at least a fraction of its populations congregate in 
massive spawning aggregations (Irigoyen 2 ). No data 
about its early life stages are available in the scien- 
tific literature. 
In this study, the development of A. patachoni- 
cus from the egg stage to the posttransition juvenile 
stage (sensu Vigliola and Harmelin-Vivien, 2001) is 
described, and the distinctive features of its early 
life stages are compared with those of other species 
of Acanthistius. In addition, abundance and distribu- 
tion patterns of larvae in the San Matias Gulf (SMG) 
and San Jose Gulf (SJG), in Northern Patagonia, and 
in adjacent waters are presented. Beyond a purely sci- 
entific interest, identification of the early stages of A. 
patachonicus will help to identify spatial and temporal 
patterns in reproduction and, in turn, will shed light 
on the location of spawning and nursery grounds for 
this species. 
Materials and methods 
Collection of samples 
Eggs and yolk-sac larvae came from in vitro fertiliza- 
tion. Ripe adults were caught by trawling near the 
mouth of SMG (41°45'S 63°28'W) on 11 November 
1978, on board the RV Walther Herwig. Hydrated oo- 
cytes and sperm were mixed in a bucket with saltwa- 
ter. Later, the fertilized eggs were washed and trans- 
ferred to 2-L buckets containing seawater at 18°C. At 
approximately every 2 h over the course of a week, a 
variable number of eggs (between 16 and 39 eggs) and 
yolk-sac larvae (between 1 and 47 larvae) in different 
developmental stages were taken from the buckets and 
fixed in 5% formalin. 
Aboard the RV Puerto Deseado on the Argentine 
shelf in November 2009, 41 ichthyoplankton samples 
were collected during the research cruise CONCACEN 
2009, which was conducted by the Consejo Nacional de 
Investigaciones Cientificas y Tecnicas (CONICET) and 
the Servicio de Hidrografia Naval and also involved the 
Centro Austral de Investigaciones Cientificas (CADIC) 
and Centro Nacional Patagonico (CENPAT) (Table 1; 
Fig. 1). Another 212 ichthyoplankton samples were 
2 Irigoyen, A. J. 2014. Personal commun. Centro Nacional 
Patagonico (CENPAT), Consejo Nacional de Investigaciones 
Cientificas y Tecnicas (CONICET), Puerto Madryn, Chubut, 
U9120ACD Argentina. 
collected monthly during a 2-year survey that we con- 
ducted) aboard outboard motorboats in the SJG, cover- 
ing a regular grid of 25 stations, from October 2011 
through March 2012 and from September 2012 through 
April 2013 (Table 1; Fig. 1). No samples were available 
for January and November 2012 within the SJG. In 
addition, 105 ichthyoplankton samples were collected 
during 2 surveys, CC-01/08 and EH-05/11, conducted 
by the Institute Nacional de Investigacion y Desar- 
rollo Pesquero (INIDEP, based in Mar del Plata, Ar- 
gentina) in December 2008 and November 2011 aboard 
the RV Capitan Canepa and RV Eduardo Holmberg, 
respectively. 
Ichthyoplankton tows were made with Hensen nets 
with mouth diameters of 70 cm (CONCACEN, SJG), 
multinets (CC-01/08) with square mouths (50x50 cm), 
and bongo nets (EH-05/11) with mouth diameters of 
60 cm, all fitted with 300-pm mesh. General Oceanics 3 
(Miami), Hydro-Bios (Altenholz, Germany), and T.S.K. 
(Tsurumi-Seiki Co., Ltd., Yokohama, Kanagawa, Ja- 
pan) flowmeters were mounted in the mouths of the 
nets to estimate the volume of filtered water. Towing 
speed ranged between 77 and 154 cm/s. During the 
research cruise CONCACEN 2009, 2 plankton tows (1 
oblique tow (depths sampled: 5-172 m) and 1 horizon- 
tal tow (depths sampled: 1-20 m), were made at each 
station. During the 2 surveys in the SJG, tows were 
oblique tows (depths sampled: 7-52 m) or horizontal 
tows (depths sampled: 3-28 m), depending on bottom 
depth, to increase the volume of water sampled. Hor- 
izontal tows were made a few meters below the sur- 
face when conducted aboard the RV Puerto Deseado 
and close to the bottom of the seafloor when conducted 
aboard motorboats within the SJG. Tows were horizon- 
tal during the survey CC-01/08 (depths sampled: 0-57 
m) and oblique during the survey EH-05/11 (depths 
sampled: 9-60 m). Maximum depth for each ichthyo- 
plankton tow was recorded by depth sensors attached 
to the nets (Table 1). Water temperature was recorded 
with sensors coupled to the nets or with conductivity, 
temperature, and depth (CTD) sensors (during sur- 
veys CC-01/08 and EH-05/11, water temperature was 
recorded with a SBE 25 Sealogger CTD and SBE 19 
SeaCAT Profiler CTD [Sea-Bird Electronics, Bellevue, 
WA], respectively). 
Samples were fixed immediately after collection and 
preserved in 5% formalin. Larval abundance was ex- 
pressed as the number of larvae/1000 m 3 . 
Only one posttransition juvenile was available, and 
it was used for the description of that stage. This speci- 
men was caught near Mar del Plata, Argentina, in De- 
cember 1963 in a bottom shrimp net at a depth of less 
than 30 m. No further details were found on the label 
to identify the collection lot (ichthyoplankton collec- 
tion, INIDEP, uncataloged). 
3 Mention of trade names or commercial companies is for iden- 
tification purposes only and does not imply endorsement by 
the National Marine Fisheries Service, NOAA. 
