Feeding and Spawning of Sphyraena jello in the North-West of Persian Gulf
This study, being conducted in 2006-2007, attempts to
investigate its biological habit and characteristics in Iran`s water of
the Persian Gulf. For the sampling purpose, three major landings namely
Bushehr, Deylam and Genaveh were selected to obtain samples from commercial
catches. The sampling is composed of 655 males and 515 females during
a twelve month period. By studying the feeding through the counting method,
it is revealed that, Liza subviridis characterized by 42.8% and
Sepia pharaonis by 8.4% made the highest and lowest stomach content,
respectively. The findings showed that male fish in smaller size will
mature sooner than females specimen but this sex ratio or proportion was
not significantly different except during October and September. Such
a difference between male and female in different months could be originated
from longer residing of female group in spawning ground compared to male
group. The earlier spawning lasted during September-October and there
was a peak of spawning in feeding in August. The lowest fat proportion
for both male and female genders was reported 0.10 and 0.11, respectively
in October; but the highest level of condition factor was reported to
be 0.59 and 0.63 during November and June.
Pick handle Barracuda (Sphyraena jello)belongs to family of Sphyraenidae
(Walters, 1966) which is also known as sea wolf signifying its savage
and aggressive behavior while preying. Out of this fish family, 20 barracuda
species inhabit in the world (Salini et al., 1994) four of which
can be found in the Persian Gulf waters, which include: Big eye Barracuda
(Sphyraena forsteri), Yellow mouth Barracuda (Sphyraena obtusata),
Swelling Barracuda (Sphyraena putnamiae) and Pick handle barracuda
(Sphyraena jello) which seems to be the most important and abundant
fish species being deprived of any fundamental and systematic biological
research in Iran. The available data on its distribution are only available
from the resources found in Yemen, Gulf of Aden, India, The Philippines,
Kenya, Malaysia and some South-east Asian, West Atlantic Ocean countries
and some areas of Caribbean and Pacific Ocean. Thus, conducting a study
on its feeding regime, spawning time and any other characteristics in
the Persian Gulf water specially in the Iranian Bushehr coastal water
as the main inhabitant and fishing ground of the fish may seem necessary
since any pertinent data would be used in the areas of aquaculture, stock-assessment,
sustainable exploitation, management and setting closed season in spawning
season as well as comparing the results with the available data from other
The fish is physically characterized by a wide and long anatomy with
lateral strips and it is often found in the tropical and semi tropical
water bodies. Having sharp teeth on its jaws, the fish attacks its prey
in an ambush and by its jaws, so that the fish can easily wound and grind
its prey (Porter and Motta, 2004). Some studies attribute origin of this
fish to those fish species inhabiting in Coral reefs as their safe shelter
(Aburto-Oropeza and Balart, 2001). On the other hand some reports state
that even certain fishermen have been.
Commercially, the fish is highly valuable and contributes greatly to
the fisheries economy of the countries enjoying such resources. According
to recent investigations by the Iranian Fisheries Research Organization
2004, entitled Feeding Mass of Barracuda fish in the Persian Gulf and
Sea of Oman, the fish yielding three tons of catch every year is ranked
five out of ten key species. Therefore, given its economic role, this
study investigates its biological characteristics in the Iranian Bushehr
water and was carried out during 2006-2007.
MATERIALS AND METHODS
Bushehr Province is characterized by primary landing ground out of which,
three are of prime significance which was used for the sampling purpose
for this study. The selected landings are: Bushehr, Genaveh and Deylam.
Sampling was carried out in various inhabitants and from the delivered
catch. To do so 300 specimens was studied biologically in each month and
90 pieces were dissected (From March 2006- February 2007), their total
length was measured with 0.5 cm and 50 g weight precision. Having done
the dissection, fish stomach was removed and following by a cut on its
wall, it was washed up totally. Content of the stomach was investigated
and frequency of each species was calculated through numerical method.
To estimate the intensity of fish feeding, GSI was measured (Au, 1979).
Given the time lapse between the catch and examination due to particular
circumstances, in some cases, certain parts of the stomach content had
been destroyed. To identify the depleted fish Eolith were considered in
organs of one fish (Porter and Motta, 2004). Having carried out the measurement
process of both length and weight of all the sample pieces in a 12- month
period, biological data on the dissected fish were analyzed through Statgraph
software (Blaber, 2000). Through condition factor formula the Condition
factor Kf = W/ L3. 100 (Froese and Pauly, 2005)
was estimated and any changes along GSI and proportion of gonad weight
and body weight GSR (or gonosomatic ratio) were investigated. After removing
the gonads from the fish stomach, they were investigated in seven maturity
stage procedure (Wainwright and Richard, 1995).
A significant relationship (95%) was found between fish length and weight
in Pick handle Barracuda and this species has isometric growth with slope
(b) of 3.35 for the female and 3.20 for male specimen, respectively (Table
1, 2). The lowest condition factor of both male
and female during October proved to be 0.37 and 0.35, while during June
and November was estimated 0.45 and 0.47, respectively as the highest
level (Table 2).
The status of gonads of 655 male and 515 (Table 1)
female ones were examined proportion of gender for various months showed
to be different but the Chi-square test indicated a significant difference
between the sex ratio in various months except July and September (Table
3). It was found out that the spawning peak for Striped Barracuda
in Bushehr coastal waters is during July and September. Out of 180 S.
jello fish explored that 52 of their stomach had feeding and classified
as full or semi-full stomachs, but the remaining 128 of stomachs were
roughly empty (Table 4).
|| The t-test for b-value with regard to male and female
Pick handle Barracuda in NW Persian Gulf waters
||Comparison of K, GSR and GSI of Pick handle Barracuda
in the NW Persian Gulf waters
|| Sex ratio (M: F) for S. jello (χ2
Test) in the NW Persian Gulf water
r = 12(95%) df = r-1 = 11, χ2 = 8.425,
ni: Observed frequency, nith: Expected frequency
R: Number of sampling months
||A comparison of stomach contents for S. jello
in different months
GSR index of female fish amounts to its peak in July (GSR = 5.33), while
the lowest rate was reported in November (0.78) (Fig. 1).
However, male fish proved to enjoy the highest GSR index in April (Table
Feeding index for female fishes decreased from 4.11 in October to 1.93
in April , which got to be increased then till June and amounted to 3.36,
GSI changes proved to be slow which decreased to the lowest rate i.e.,
1.68 in February (Fig. 2).
Examination of the gastro content among the male fish showed that Liza
subviridis enjoyed the highest rate i.e., 42.8% but Sepia pharaonis
showed the lowest rate i.e., 5.9%. The highest and lowest gastro content
rates belonged to male Tenualosa ilisha species as 39.8% and Anodontostoma
chacunda as 6.4% (Fig. 3).
||Changes in GSR for S. jello (2006-2007) in the
NW Persian Gulf water
|| The changes of GSI for S. jello in the NW Persian
|| The stomach contents of S. jello in the NW Persian
Gulf water (2006-2007)
Lack of significant difference in B-value concerning the relationship
between length and weight with b = 3 on the basis of B-value supports
an isometric growth of fish. Comparison of K, GSI and GSR indices indicated
that K value decreases parallel to the approach of spawning peak. GSR
index of female fish amounts to its peak in July (GSR = 5.33), while the
lowest rate was reported in November. However, male fish proved to enjoy
the highest GSR index in June and July; on the other hand changes in feeding
index had negative correlation with that of GSR, indicating that feeding
ratio possibly takes declining trend at the peak of spawning. Seasonal
sexual maturity of Pick handle Barracuda showed that its sexual organs
mainly rest during the winter and autumn or they are at the early stages
of development (Barletta-Bergan et al., 2002). Furthermore, signs
of sexual maturity and spawning were recorded from August till late September.
This study also indicated that there was a peak of spawning during June
and July and the youngest ones, i.e., 10-20 cm specimen have been caught
as a by-catch of shrimp trawl in Bushehr coastal water in this period.
According to the investigation carried out in this water under question,
the proportion of male and female is 57 and 43%, respectively. However,
the proportion fluctuates in favor of male fish in the spawning season
(Nahhas et al., 2006) holds that sex ratio of Barracuda in the
Caribbean region at p<0.05, which may be attributed to longer stay
of female group in the spawning grounds than the male group (Hood et
The studies indicated that Barracuda is a carnivorous species and attacks
its prey through either camouflage or in an ambush and tears it into pieces
by its sharp jaws (Ramachandran et al., 2006). Skolow (1998) study
indicates that the fish feeds on planktons on the water in its post-larvae
and juvenile stages of life cycle and then starts to be carnivorous from
maturity at which it feeds on shellfish, cephalopods, crustacean and other
fishes. RLG mean estimator at 64% indicates the claims made so far and
the claims that it attacks fish schools such as Liza subviridis,
Tenualosa ilisha and Sepia pharaonis (February-April) and
other pelagic and semi-pelagic species. According to the study conducted
by Blaber (2000) in the West Indian Ocean, lobster, cephalopods and other
invertebrate compose the main content of its stomach as an indication
of differences compared with similar research findings in other areas.
Fish species and other aquatics in coral reefs include some parts of its
prey (Dorenbosch et al., 2004). CV = 0.13 as and index of empty
gastro signifies gluttonous nature of the fish. The increase of GSI in
September and October sustains the fact that the fish takes the best advantage
of environmental nutrition condition, which in turn results in an increase
of energy in its body. It occurs when its gonads are evacuated which by
themselves, due to the decrease in their capacity, lead to further space
for magnifying the capacity of its stomachs and consequently appropriate
feeding (Halpern, 2004). The study carried out by reveals that the highest
feeding takes place in October and November in the Bushehr water, which
sustains the findings of the present study.
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