Patterns of reproduction and growth of the catfishIheringichthys labrosus(Lütken, 1874) after a reservoir formation

Abstract

Summary This work contributes to the knowledge of the reproduction, growth parameters and mortality rates of Iheringichthys labrosus in a newly‐formed reservoir. A total of 554 males and 1227 females were collected over 12 consecutive months, 1998–1999, from sites in the Corumbá Reservoir, Brazil, using gillnets (meshes: 2.4–16 cm). Information on each individual, i.e. standard length (cm), weight (g), sex, and gonadal development phase was recorded. The pectoral spines were removed to estimate age. The number of juveniles and adults, males and females, reproductive sites and seasons were estimated. First maturation length was estimated using a likelihood function fitted by binomial distribution. Growth parameters were estimated using the von Bertalanffy equation. Total instantaneous mortality was obtained through a linearized catch curve method. Standard length varied from 6.0 to 20.5 cm. Growth showed negative allometry for both sexes. The reproduction period was August to December in all environments sampled and first maturation length was 11.5 cm. All individuals were adults with 17.0 cm standard length. Ages varied from zero to 7 years. Asymptotic length, growth coefficient and t0 for the entire population were 27.79 cm, 0.12 and −2.64, respectively. Instantaneous and annual mortality rates were 0.90 and 0.59, respectively.

Long‐term study of the reproductive timing of the Neotropical catfish Iheringichthys labrosus (Lütken, 1874): Influence of temperature and river discharge

“…The proportion of sex was skewed towards females, as they were larger than males, which accords with the findings of previous work on I. labrosus (Bazzoli et al, ; Holzbach et al, ; Soares de Santana et al, ; Suzuki et al, ) . This is probably attributable to sexual size dimorphism in this species.…”

“…Santana et al, 2016). In contrast, at higher latitude reproduction begins later (from September to December) such as at Furnas reservoir (20°40′S 46°19′W)(Bazzoli et al, 1997; Table 7,Figure 6).Consistently, Suzuki et al (2013) reported a later beginning of the reproduction (November to December), at southern location (22°39′S, 52°21′W).…”

“…We found a latitudinal pattern of the reproductive period of I. labrosus (Table , Figure ). Reproduction at lower latitude (17°59′S 48°31′W) occurred earlier and lasted for a longer period (from August to December) (Soares de Santana et al, ). In contrast, at higher latitude reproduction begins later (from September to December) such as at Furnas reservoir (20°40′S 46°19′W) (Bazzoli et al, ; Table , Figure ).…”

“…Iheringichthys labrosus was proposed as a model species for bio-monitoring programmes due to their dominance in the Lower Uruguay River, throughout the year (Saizar et al, 2010;Tana, 2007). The information about the reproductive cycle of I. labrosus is relatively abundant, particularly in the south of Brazil (Bazzoli, Cangussu, Rizzo, & Santos, 1997;Holzbach et al, 2009;Reynalte-Tataje & Zaniboni-Filho, 2008;Soares de Santana, Cantarute Rodrigues, & Dei Tos, 2016;Suzuki, Garcia, & Orsi, 2013). However, environmental factors driving the timing of reproduction are still unclear.…”

“…A subsample of 30 individuals in a representative size spectra (>12 cm) were used to calculate the indices in each campaign. In order to reduce potential bias of immature individuals and males, we used only females larger than 12 cm (above the size at first maturation defined by Soares de Santana et al (2016); 11.5 cm). The individuals were measured for standard length (Lst, ±0.1 cm) and total weight (±0.01 g), then liver and gonad were carefully dissected and weighed (±0.001 g) and the eviscerated weigh was also recorded (±0.01 g).…”