Tagiiafico et al.: Exploitation and reproduction of Aetobatus narmari in the Los Frailes Archipelago, Venezuela 
311 
with lengths of 10.1-11.5 cm DW still had their yolk 
sac; in larger specimens, the yolk sac had disappeared 
completely and nourishment had been provided by 
uterine milk or histotrophe through the numerous 
trophonemata present in the adult uterine walls. 
Size at sexual maturity 
The smallest recorded sizes at which females were 
nongravid, gravid, and postgravid were 106 cm, 
150 cm, and 167 cm DW, respectively. The smallest 
mature male measured 97 cm DW. 
The average length (L 50 ) at maturity was estimated 
at 129.2 cm DW for males (Fig. 4A). Joint confidence 
intervals (95%) for parameter estimates ranged from 
125 to 134.9 cm DW for L 50 and from 0.105 and 0.195 
for the slope of the regression. For females, L 50 was 
estimated at 134.9 cm DW (Fig. 4B), and joint con- 
fidence intervals ranged from 128.8 to 139.8 cm DW 
for L 50 and from 0.09 to 0.216 for the slope. 
Discussion 
Effort, catch, and catch per unit of effort 
Aetobatus narinari is usually captured as incidental 
catch in artisanal and industrial fisheries through- 
out its range. Directed fisheries for this species are 
uncommon and, to our knowledge, this study and that 
of Cuevas-Zimbron et al. (2011) are the first accounts 
of fisheries for which A. narinari is the target species. 
The total catch landed during the 29-month study 
period from August 2005 to December 2007 was 
55.9 metric tons, 64% of which was taken during 
the first 6 months of 2006 and 2007. In this fishery, 
a close relationship was observed between catch in 
weight and numbers and fishing effort in number 
of trips (coefficient of determination [r 2 ] = 0.85), but 
peak catches did not correspond with high CPUE 
values. Maximum observed catches in the first 
months of 2006 and 2007 were preceded by high 
CPUE values in the months of December 2005 and 
January and December 2006, during which 100% 
of the fishing trips were positive for catch of A. nari- 
nari. CPUE, especially in weight per trip, tended to 
decrease as the fishing season progressed, which may 
be explained by local depletion or migration (or by 
both) of A. narinari out of the fishing area studied. It 
is likely that the high CPUE values and percentage 
of positive trips in December and January acted as a 
trigger for initiating the fishing season in the first 
months of the year. The overall estimated mean CPUE 
of 3 individuals caught per trip in the Los Frailes 
Archipelago, Venezuela, during this study was similar 
to values reported for Seybaplaya, Mexico, by Cuevas- 
Zimbron et al. (2011) but less than the 6 individuals 
per trip reported for Campeche, also in the southeast- 
ern Gulf of Mexico. However, trips in Seybaplaya and 
in the Los Frailes Archipelago were for 1 day, whereas 
Disc width (cm) 
Figure 3 
(A) Length-frequency histogram (cm DW ) of male (n = 321) 
and female (« = 846) Aetobatus narinari caught in the Los 
Frailes Archipelago during the period from August 2005 
to December 2007. (B) C ombined length-weight relation- 
ship for male (rc = 105) and female (/j= 185) individuals of 
A. narinari sampled during the period from August 2005 
to December 2007. 
trips in Campeche were for 1-3 days. High numbers 
of fish caught per trip were observed in our study 
during December-February, coincident with periods 
of high availability of A. narinari reported for the 
southeastern Gulf of Mexico (Cuevas-Zimbron et al., 
2011). High CPUE values in our study also occurred 
in July-Oetober, but they did not result in an impor- 
tant increase in fishing effort and catch. This lack of 
increase in fishing effort and catch is probably related 
to the existence of more lucrative alternate fisheries 
( Scomberomorus spp. and Octopus spp.) that are active 
particularly during this season of the year. A similar 
switch in target species (from A. narinari to Octopus 
maya) occurs during the second half of the year in 
the southeastern Gulf of Mexico (Cuevas-Zimbron et 
al., 2011). 
