Life-history characteristics of Brachyplatystoma rousseauxii

[Silurus]

A García Vásquez, J-C Alonso, F Carvajal, J Moreau, J Nuñez, J-F Renno, S Tello, V Montreuil & F Duponchelle, 2010. Life-history characteristics of the large Amazonian migratory catfish Brachyplatystoma rousseauxii in the Iquitos region, Peru. Journal of Fish Biology 75: 2527–2551.

Abstract

The main life-history traits of the dorado Brachyplatystoma rousseauxii, a large Amazonian catfish undertaking the largest migration known for a freshwater fish species (from the nursery area in the estuary of the Amazon to the breeding zones in the head waters of the western Amazon basin close to the Andes), were determined from a 5 year sampling of >15 000 specimens in the Peruvian Amazon. The breeding season occurred during the falling and low-water periods, which is hypothesized to be an adaptation to maximize the chances of young stages to reach the estuary. The size at first sexual maturity was slightly larger for females than males, c. 91 and 83 cm standard length (LS), respectively. Both males and females reproduce for the first time at >3 years old. The fecundity per spawning event ranged from 481 734 to 1 045 284 oocytes for females weighing 25 and 34 kg, respectively. Seasonal variations of body condition were similar among sexes, but differed between immature specimens that had a higher condition during the low-water period and lower condition during rising waters, and mature individuals that showed the opposite pattern. The growth characteristics were estimated by LS frequency analysis. For females, the best fitting models gave a mean birth date in August, during the height of the breeding cycle, with the following von Bertalanffy growth function parameters: LS∞ = 153·3, K = 0·29 and t0 =– 0·37 years. For males, the best fitting model gave a mean birth date in July, also during the height of the breeding period, with LS∞ = 142, K = 0·30 and t0 =– 0·36 years. At a given age, females were systematically larger than males and the size difference increased with age. The largest females sampled (148 cm LS) was 11 years old and the largest male (134 cm LS) was 9 years old. The mortality estimates were higher for males total (Z) = 1·34, natural (M) = 0·52 and fishing (F) = 0·82 than for females (Z = 0·98, M = 0·50, F = 0·48). The life-history patterns of B. rousseauxii are discussed in light of the available knowledge about this species and the understanding of its complex life cycle.

[MatsP]

Interesting. Does this paper go into the life-history of any other Pimelodid species? Or offer references for?

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Mats

[bekateen]

An older paper, which might have been a lead-up to this 2010 publication, is now accessible HERE:

Garcia Vasquez, A., Nunez, J., Renno, J.-F., & F. Duponchelle. (2006). Aspectos reproductivos de dorado Brachyplatystoma rousseauxii. In : Renno, J.-F. (ed.), Garcia, D.C. (ed.), Duponchelle, F. (ed.), Nunez, J. (ed.), del Castillo, T.D. (préf.), Soler, P. (préf.). Comunicaciones del coloquio international : biologia de las poblaciones de peces de la Amazonia y piscicultura. Lima (PER) ; Paris : IIAP ; IRD, p. 30-35. Coloquio Internacional de la Red de Investigacion Sobre la Ictiofauna Amazonica : Biologia de las Poblaciones de Peces de la Amazonia y Piscicultura, 1., Iquitos (PER), 2005/06/27 - 2005/07/01 ISBN 9972-667-31-6.
https://horizon.documentation.ird.fr/ex ... 050733.pdf

Resumen
Se presenta los resultados del estudio sobre la biologia reproductiva deI dorado

Brachyplatystoma rousseauxii

realizado por un periodo de 5 anos (1995-1999) en lquitos, Amazonía Peruana, La longitud media de madurez sexual varió de 105.6 a 114.6 em en hembras y 94.6 a 100.9 em cn machos respectivamente, siendo las hembras las que mayores longitudes alcanzaron. El período de reproducción oeurre entre los meses de Mayo a Noviembre, eon mayor intensidad en Agosto y Septiembre eoincidiendo con cl descenso del nivel de las aguas.

Palabras Claves: Brachyplatystoma rousseauxii, talla de primera madurez, período reproductivo

[Viktor Jarikov]

The results of the study on the reproductive biology of the dorado are presented.
Brachyplatystoma rousseauxii carried out for a period of 5 years (1995-1999)
in lquitos, Peruvian Amazon, The mean length at sexual maturity varied from
105.6 to 114.6 em in females and 94.6 to 100.9 em in males respectively,
the females being the ones that reached the greatest lengths. The reproduction period occurs between the months of May to November, with greater intensity in
August and September occur with the drop in water levels.