Reproductive strategy of Psectrogaster rhomboides Eigenmann & Eigenmann, 1889, a freshwater fish from Northeastern Brazil

Abstract

Summary Several environmental parameters related to the spawning season of the freshwater fish, Psectrogaster rhomboides were identified. The hypothesis predicts synchrony of the spawning season with the rainy period, presenting a seasonal reproductive strategy. This study investigated the total body length and body mass, sex ratio, body size at first sexual maturity, gonadosomatic index, condition factor, fecundity and reproductive period of P. rhomboides in the natural environment. Twelve monthly samplings (mean n = 20) were carried out from March 2009 to February 2010. Fish were captured using 4 cm diameter cast nets and environmental parameters such as rainfall, temperature, dissolved oxygen concentration, pH and electrical conductivity of the water were registered. The sampled population of P. rhomboides (n = 444) showed a sex ratio of 1 : 1. Females attained first sexual maturity at 15 cm total length and males at 15.3 cm total length. Spawning occurred from March to May, with high gonadosomatic index values during the rainy season. This species is a total spawner, with a mean fecundity of 6188 (±367) mature oocytes. P. rhomboides presents a seasonal reproductive strategy, providing a population increase and exploitation of the environmental resources during the rainy period. Rainfall (196.5 ± 4.9 mm) and the concentration of dissolved oxygen (7.82 ± 0.7018 mg L−1) were influential factors during the spawning season. Gonadosomatic index and the condition factor were negatively correlated during the gonadal development cycle of this species. The monthly gonadosomatic index values show that spawning begins when the rainy season is at its maximum and ends synchronously (females r = 0.9171; males r = 0.889) with the end of the rainy season.

Periodic life history strategy ofPsectrogaster rutiloides, Kner 1858, in the Iquitos region, Peruvian Amazon

“…As for most other species of Characiforms (Goulding, ; Tello et al., ; Vazzoler and Menezes, ; Ruffino and Isaac, ), the reproductive cycle of P. rutiloides coincides with the first part of the flooding period before the water levels reach a maximum. As also reported for Psectrogaster rhomboides , Eigenmann and Eigenmann 1889, in Brazil (Soares de Araújo et al., ), a close connection was observed between the breeding cycle and the rainfall cycle: the first ripe females were observed in October, a few weeks after the September begin of the rainy season; the last were observed in February, when the rains strongly abated. Although the rains again increased in March and lasted until June, no more ripe females were observed, suggesting that rainfall is not the only clue acting on the timing of the breeding period for P. rutiloides .…”

“…More surprising are the very low fecundities reported for other species of Psectrogaster:~21 258 oocytes for a 130 g female in P. ciliata in the Caura River, Venezuela (Rodr ıguez-Olarte et al, 2001), approximately four and five times that of a female P. rutiloides in the Ucayali and Loreto regions, respectively. In northeastern Brazil, Soares de Ara ujo et al (2013) reported fecundity ranging between 1096 and 10 137 oocytes for The present study provides the first information on age, growth and mortality of P. rutiloides. Otolith readings of P. essequibensis, G€ unther, 1864, in the Itenez basin, Bolivia (Siangas et al, 2012), provided the only other published information on Psectrogaster spp.…”

“…In northeastern Brazil, Soares de Araújo et al. () reported fecundity ranging between 1096 and 10 137 oocytes for P. rhomboides . Although these authors did not give the corresponding length or mass of the females used, their highest values were ~10× lower than those observed in P. rutiloides by Zaldívar et al.…”

“…To our knowledge, age at first maturity had thus far never been estimated for any Psectrogaster species, nor was there an estimation of size at maturity for P. rutiloides . However, size at maturity had been determined for a few other Psectrogaster species: 104 mm (S L ) for P. amazonica in central Amazonia, Brazil (Amadio and Bittencourt, ) and ~150 mm (T L or ~120 mm S L ) for P. rhomboides in northeastern Brazil (Soares de Araújo et al., ). Size at maturity of P. rhombeoides , which represented ~88% of the maximum length (~170 mm) observed during the Soares de Araujo et al (2013) study was likely overestimated owing to the method used (cumulative percentages).…”

On the relation amongst limnological factors and fish abundance in reservoirs at semiarid region

“…In addition, Cichla and Cichlasoma, both of which are common in coastal regions (Oliveira et al, 2005;Beltrão et al, 2009), also become less abundant in the dry season. In contrast, non-predator species generally displayed no seasonal patterns, although migrating species such as Leporinus spp., P. brevis and Curimatidae tend to become more abundant in the rainy season during the annual spawning season (Gurgel et al, 2012;Peressin et al, 2012;Silva Filho et al, 2012;Araújo et al, 2013). The low abundance of these species in PS and EQ may be associated with isolation from adjacent water courses due to the absence fish ladders in the dams (Antonio et al, 2007).…”