Centropomus Parallelus Poey Research Articles

Reproductive biology of the fat snook Centropomus parallelus Poey, 1860 (Teleostei, Centropomidae) and implications for its management in the southern Atlantic Ocean.

The reproductive biology of Centropomus parallelus was described from 589 individuals captured in estuarine and coastal waters in Southern Brazil. Length-frequency distribution showed the dominance of males in smaller length-classes (132-290 mm LT ), whereas females were dominant in larger length-classes (>290 mm LT ). Total length at maturity (L50 ) was 180 mm LT and corresponded to 29% of the maximum length recorded. Histological sections revealed one hermaphrodite (205 mm LT ) and few immature females. Life history traits provided herein can contribute to sustainable fisheries management practices.

Reproductive biology of the protandric hermaphrodite fat snook Centropomus parallelus Poey 1860 in a tropical estuary, northeastern Brazil

ABSTRACTThe aim of the present study was to analyze the reproductive aspects of the fat snook, Centropomus parallelus, in a tropical estuary. During the study period, 187 specimens were collected, including 73 females and 114 males. The length at first sexual maturity was estimated to be 224 mm for the females and 141 mm for the males. An extensive reproductive period, January to August, was observed for the females based on the gonadosomatic index. For the males, the highest values were from July to October. Sexual segregation was observed in length classes, with predominance of males and females in the smaller and larger sizes, respectively. This pattern, observed in protandric hermaphrodites, has been confirmed with the identification of an individual in sexual transition. The average relative fecundity was 14,260 oocytes. The average absolute fecundity was 491,036 oocytes/female, and the average size of the vitellogenic oocytes was 435 µm. Management actions are suggested for better conservation of the species.

Collaborative assessment of recreational fishing in a subtropical estuarine system: a case study with fishing guides from south‐eastern Brazil

AbstractKnowledge of recreational fisheries in Brazil is scarce and remains a critical issue to determine management actions. By adopting a collaborative approach that involved fishing guides, recreational fishing from the Iguape and Cananéia Lagoon Estuarine System (south‐eastern Brazil) was assessed. During the study period (from April 2009 to March 2010), 341 fishing operations (boat day−1) were monitored. A total of 10 051 fish specimens of 26 families and at least 51 species were examined. The fat snook, Centropomus parallelus Poey, was the most commonly caught species representing 51% of the fish caught. Annual fishing effort was estimated at 272 859 angler‐hours, and the mean catch‐per‐unit‐effort was 3.42 fish boat−1 h−1. Size structure of targeted species suggests that the populations are overexploited. The approach used in the study reinforces the importance of engaging different stakeholders in science and management and improving the communication among them.

Ammonia excretion in fat snook (Centropomus parallelusPoey, 1860) at different salinities

Ammonia excretion in fat snook (<i>Centropomus parallelus</i>Poey, 1860) at different salinities

Cultivation of juvenile fat snook (Centropomus parallelus Poey, 1860) fed probiotic in laboratory conditions

The objective of this study was to investigate the growth of juvenile fat snook (Centropomus parallelus) in laboratory conditions when fed a diet supplemented with the probiotic Lactobacillus plantarum. Changes in the intestinal flora, haematological parameters and growth performance were assessed using 180 fishes (54.2 ± 13.4 g each). The fishes were subjected to two treatments divided into six cages: 1) feed supplemented with probiotic, and 2) feed without probiotic (control). The temperature, dissolved oxygen and salinity were maintained at 25 ± 1 ° C, 4.0 mg.L-1 and 33 ‰, respectively. After 10 weeks of culture, the fishes fed probiotic had reduced viable culturable heterotrophic bacteria and Vibrio spp. and increased lactic acid bacteria in the intestinal tract, as well as a higher number of thrombocytes, leukocytes and lymphocytes in the blood. No significant difference was observed in the growth, survival or body composition, but the hepatosomatic index was significantly higher in the fishes fed with probiotic and control.

Compensatory growth responses in juvenile fat snook, Centropomus parallelus Poey, following food deprivation

The compensatory growth in juvenile fat snook (13.7 g) was evaluated in fish subjected to four treatments: continuously fed (control); subjected to 1 (D1), 2 (D2) and 3 (D3) weeks of food deprivation, followed by a 5-week re-feeding period. At the end of food deprivation, the body weights at the different treatments were significantly different and inversely related to the length of the food deprivation period (C=16.425 g; D1=14.024 g; D2=13.542 g; D3=12.228 g). During re-feeding, no differences were observed in the slopes of body weight growth curves among treatments, indicating failure in full growth compensation. In the first re-feeding week (week 4), although hyperphagia was observed for all re-fed groups, better food conversion ratios were detected only for D1 and D2, reflected in an enhancement in the specific growth rates. From week 5 onwards, no differences between treatments and control were detected for any variable. The total food intake was lower for D2 and D3 compared with the control. In the present study, fish showed partial compensatory growth when subjected to a maximum of 2 weeks of food deprivation. Therefore, the food deprivation can promote production losses, even considering a reduction in the total food intake.

Fish predation on brachyuran larvae and juveniles in the Pinheiros river, Guaratuba Bay, Paraná, Brazil

Fish predation is thought to exert an important influence on the demographical dynamics of larvae and juveniles of estuarine brachyuran crabs but few studies have investigated this phenomenon in nature. In this study, fishes were captured during full moons (in January and February 2005), when many brachyuran species are known to release their larvae. Samples were carried out in the Pinheiros river, Guaratuba Bay, Paraná, Brazil. The stomach contents of collected fishes were surveyed to determine the species that are most likely to prey on brachyuran immature forms in this location. Two techniques were used to capture fishes: manual samplings, using a 5-mm mesh size net (1.8m depth), and bottom trawling with a 20-mm mesh size net. The collected specimens were fixed using 10% formaldehyde and preserved in 70% ethanol. A total of 2941 fishes of 43 different species were collected and the stomach contents of 962 individuals were analyzed in laboratory. Food items were identified and quantified. The fish species captured using manual nets that showed the highest number of preyed zoeae per stomach was the clupeid Platanichthys platana (Regan, 1917). Sphoeroides testudineus (Linnaeus, 1758) and Centropomus parallelus Poey, 1860 showed the highest levels of predation on megalopae. Of the fish species captured using trawl nets, Genidens genidens (Cuvier, 1829) showed the highest average number of zoeae per analyzed stomach and Bairdiella ronchus (Cuvier, 1830) was the most important predator on brachyuran megalopae and on young juveniles. The obtained data indicate that brachyuran crab restocking efforts performed in the Guaratuba Bay should include strategies to avoid or, at least, reduce the access of fishes to the released early juvenile stages, given the potential substantial losses caused by fish predation. Considering that, in general, predation potential was 8.5 times lower in juveniles than in megalopae, releasing immature forms produced in laboratory in the juvenile phase or releasing megalopae into tethered areas and maintaining than under this condition until they reach the juvenile phase may be tested as a method to reduce losses given to fish predation.

Size-related shifts in dietary composition ofCentropomus parallelus(Perciformes: Centropomidae) in an estuarine ecosystem of the southeastern coast of Brazil

Size-related and seasonal evaluation of the dietary composition of fat snook (Centropomus parallelus Poey 1860) in the upper sector of an estuary of the southeastern coast of Brazil were carried out based on stomach analyses of specimens ranging from 40 to 170 mm standard length. Results reveal that C. parallelus is a carnivorous species feeding mainly on benthic crustaceans. Relatively high stomach replenishment suggests that this environment is an important feeding ground for fat snook juveniles. Multivariate analyses indicated that predator size effect is significantly more important than seasonal variation in determining dietary composition. Predator length was associated with increased consumption of palaemonid shrimps (Macrobrachium spp.) and grapsid crabs, and decreased foraging on tanaids (Kalliapseudes schubarti), thus showing a preference shift from smaller to larger prey. Predator length was also positively associated with an increase in the stomach repletion index. Additionally, allometric growth of both gape and head were consistently correlated with this ontogenetic dietary transition, suggesting that such changes might be related to an individual’s ability to capture and consume larger, more elusive prey. The digestive tube is short and grows isometrically, which is in accordance with the carnivorous habit of this estuarine fish and its maintenance through ontogeny.

Effects of stocking density and size distribution on growth, survival and cannibalism in juvenile fat snook (Centropomus parallelus Poey)

This study was carried out in order to determine the effect of stocking density and size distribution on growth, survival and cannibalism of fat snook (Centropomus parallelus Poey) juveniles. Three stocking densities (1.5, 3 and 6 fish L−1) were tested in two groups of fish: homogeneous [total length (TL)=22.1 mm; coefficient of variation of length (CV)=8%] and heterogeneous (TL=22.7 mm; CV=15%). The experimental design was factorial (3 × 2) using triplicates. Fish were reared for 30 days in 80-L circular tanks with an open flow-through system. There was no significant interaction between the two factors (density and size distribution). The highest cannibalism rate (14.2%) was observed in the heterogeneous group, which also had a significantly higher growth rate (TL=45.6 mm) than the homogeneous group (3.2% and TL=40.9 mm). Significant differences were found between the two lowest densities and the highest density (6.2%, 6.3% and 13.4% respectively). Growth was not affected by fish density. Cannibalism was the main cause of mortality. In 90% of the occurrences, whole prey ingestion was observed. According to the results obtained, cannibalism was positively correlated to density, although size grading of fat snook juveniles is recommended to control cannibalism in all the densities tested.

Early weaning of fat snook ( Centropomus parallelus Poey 1864) larvae

Feeding trials were conducted with fat snook larvae in an attempt to decrease the period of weaning without compromising larval growth and survival. Fat snook larvae of 30 days post-hatch (DPH; initial mean standard length = 9.6 ± 1.4 mm) were assigned to five feeding trials in which larvae received Artemia for 5, 10 and 15 days (co-fed with a locally prepared dry diet), Artemia for 10 days (co-fed with a commercial dry diet) and Artemia only (control treatment). Standard length, length-specific growth rate (SGR), condition index, and survival were monitored. Behavioral observations (swimming activity and feeding) were also conducted. Larval survival (over 91%) and condition were not significantly affected by treatment. Fat snook larvae were successfully weaned by 35 DPH, but larvae weaned by 40 DPH displayed higher growth rates (final mean SGR = 7.57% day − 1) and were significantly larger (final mean standard length = 16.4 mm) by the end of the experiment. There were no significant differences in any growth parameter between larvae weaned by 40 and 45 DPH. However, comparisons between treatments using different dry diets revealed a significant difference in the frequency of dry diet ingestion, although it did not influence the growth of larvae. Neither larval swimming time nor motionless duration was significantly different among treatments.

Validation of an ovarian biopsy method for monitoring oocyte development in the fat snook, Centropomus parallelus Poey, 1860 in captivity

The validation of an ovarian biopsy method for in vivo assessment of oocyte maturation in Centropomus parallelus was studied. Diameters of intra-ovarian oocytes siphoned with cannula were analyzed fresh and preserved with 1% formalin in 0.7% NaCl solution. Oocytes in different stages were present along the ovaries, up to the tertiary yolk globule stage, which had a unimodal diameter frequency distribution. The oocyte diameter means were not significantly different at four sites along the ovaries (P &gt; 0.05). Samples obtained with cannula were representative of the ovary central portion, in vivo and in vitro samples of the seven females examined were not significantly different (P &gt; 0.05). An estimate of the coefficient of variation corrected for bias (P &lt; 0.05) for 8 repeated in vivo samples was 1.9 ± 0.6. The results demonstrated that for the species, the biopsy method was satisfactory, providing representative samples of the ovaries.

The effects of lowering prey density on the growth, survival and foraging behaviour of larval fat snook ( Centropomus parallelus poey 1860)

Fat snook ( Centropomus parallelus) is a candidate species for aquaculture, but little work has been done towards commercialization of this species. A major constraint has been the inability to obtain consistent and predictable larval survival to metamorphosis, a consequence of high mortality during the first-feeding stage. Attempts have been made to increase survival by increasing prey density to levels (30–40 prey/ml) exceeding those used for rearing most marine species (5–20 prey/ml). Our objective was to investigate the effects of lowering prey densities during larval rearing on the foraging behaviour, growth and survival of fat snook. Larvae were raised from hatch to the commencement of metamorphosis (16 days) at four prey densities: 5, 10, 20 and 30 rotifers/ml. Survival was high in all treatments, but highest (38.8%) at 5 prey/ml. Fat snook larvae were found to be visually guided predators that forage with a saltatory search pattern. In the presence of prey, fat snook larvae spent the majority of their time in the pause or non-swimming state punctuated by occasional swimming bursts usually directed towards a prey item. The range of prey densities tested did not significantly affect growth rates or survival, and there were no differences in foraging behaviours between treatments. Therefore, we recommend production scale trials at these lower rotifer densities for larval fat snook as the results of this work imply that reducing prey densities to 5 rotifers/ml during the larval period would not affect juvenile production and would be more cost effective.