Lemos et al.: Stock identification of tainha (Mugil liza) by analyzing stable isotopes in otoliths 
203 
Table 1 
Sites in southern Brazil where juvenile tainha (Mugil liza) were sampled in 2011, the number of fish sampled at each 
site («), and the mean values of the stable isotopes ratios (S^^C, 8^^0), salinity (Sal.), total length (TL), and total weight 
(TW) of the fish sampled at each site. Standard deviations are given in parentheses. 
Sites 
n 
513C (%o) 
§180 (%o) 
Sal. 
TL (mm) 
TW(g) 
1 
Chui 
15 
=6.716 (0.71) 
0.509 (0.16) 
28.5 
28.2 (0.88) 
0.232 (0.03) 
2 
Patos Lagoon Estuary 
16 
=6.793 (0.30) 
0.306 (0.20) 
7.5 
29.5 (0.89) 
0.284 (0.02) 
3 
Cassino Beach 
18 
-6.709 (0.30) 
0.451 (0.23) 
27.9 
28.6 (1.09) 
0.200 (0.01) 
4 
Mostardas 
11 
=7.057 (0.26) 
0.383 (0.16) 
29.1 
28.0(1.01) 
0.209 (0.02) 
5 
Tramandai 
6 
-6.774 (0.43) 
0.385 (0.13) 
30.2 
28.3 (1.21) 
0.213 (0.03) 
6 
Passo de Torres 
15 
-7.169 (0.47) 
0.361 (0.18) 
11.0 
28.0(1.19) 
0.248 (0.03) 
7 
Laguna 
13 
-7.323 (0.16) 
0.261 (0.11) 
31.1 
28.0 (0.86) 
0.221 (0.09) 
8 
Pontal do Parana 
3 
-7.209 (0.62) 
0.320 (0.22) 
30.0 
28.3 (0.57) 
0.270 (0.05) 
9 
Rio de Janeiro 
7 
-3.754(0.51) 
-1.141 (0.20) 
30.0 
28.1 (0.69) 
0.217 (0.02) 
2008) has led to an approach to identifying stocks and 
population units that is interdisciplinary. These inte¬ 
grated approaches can provide strong evidences for the 
identification and delineation of fish stocks (Cadrin et 
aL, 2014). Chemical analysis, for example, provides a 
greater refinement than genetic analysis alone for iden¬ 
tifying a stock (Campana and Thorrold, 2001; Cadrin et 
al., 2014), and the combination of both approaches is 
encouraged (Campana et al., 1994; Cadrin et al., 2014). 
Our aim was to use isotopic analysis of and 
8^^C carbonate from otoliths of juvenile fish to test the 
hypothesis that there is a single stock of tainha within 
the area where 95% of the commercial catch of this 
species occurs in southern Brazil. 
Materials and methods 
Specimens were collected between June and October 
2011 at 9 sites along the southern Brazilian coast (Fig. 
1) after the reproductive period. One sampling was 
performed at each of these sites. A beach seine net (9 
m long; 1.5 m high) with 13-mm stretch mesh in the 
wings and 5-mm stretch mesh in the center 3-m sec¬ 
tion was pulled perpendicular to the beach. Salinity 
was measured at each sampling site. All fish caught 
were transported on ice to the laboratory. Individual 
fish were identified and weighed (in grams), and their 
total length (TL, in millimeters) was measured. 
Differences in the lengths and weights of individu¬ 
als between the 9 sampling sites were tested by using 
an analysis of variance (ANOVA). All fish were young- 
of-the-year ranging in size between 27 and 31 mm TL. 
Pairs of sagittal otoliths (right and left) were removed 
from each specimen and sent to the Institute de Geo- 
ciencias da Universidade de Brasilia for analysis. Both 
whole otoliths were ground to a fine powder, and iso¬ 
topic ratio mass spectrometry was used for isotopic 
analysis of carbonates with Vienna Pee Dee Belemnite 
limestone as the standard. 
Differences in the isotopic values among sampled 
sites were tested by using ANOVA. Isotope values are 
described by using the standard “§ per thousand (%o)” 
notation defined as 
~ (T^sample | standard -DxlOOO, 
where H = iSQ/iso or i3c/i2c. 
Results and discussion 
The values of 5^®0 and (from -2 to -!-4%o and from 
-9 to -i-l%o, respectively) found in the otoliths of tainha 
(n=104) (Table 1) were within the expected ranges for 
marine species (Kalish, 1991). The isotopic values of 
the carbon and oxygen revealed 2 groups and there¬ 
fore the existence of at least 2 stocks (rather than the 
single stock that we had hypothesized) that have 2 en¬ 
vironmentally distinct spawning areas within the over¬ 
all study area. One group, representing samples taken 
between the states of Parana and Rio Grande do Sul, 
constitutes the southern stock: 0.381%o (standard er¬ 
ror [SE] 0.10) and -6.936%o (SE 0.46), respectively for 
5^®0 and 5^^C. The second group comprised individuals 
hatched in the north near Rio de Janeiro: -1.141%o (SE 
0.20) and -3.754%o (SE 0.51), respectively for and 
§i3C. 
The values of and from Rio de Janeiro 
and the southern states differed significantly (ANOVA: 
23.92 [P<0.0001 and 20.45 (P<0.00001), respectively) 
(Fig. 2). Homogeneity among values of 5^®0 and in 
the samples from the southern states indicates that all 
individuals from this area were hatched in waters with 
the same, or very similar, temperatures. Results from 
analysis indicated an inverse relationship between the 
environmental temperature and values of otolith 5^®0 
(Kalish, 1991; Thorrold et al., 1997), revealing that 
southern individuals were hatched in cooler waters 
than those waters inhabited by individuals from Rio 
de Janeiro. On the basis of the relationship proposed 
