Reproduction, feeding and migration patterns of Prochilodus nigricans (Characiformes: Prochilodontidae) in northeastern Ecuador

Abstract

The black prochilodus, Prochilodus nigricans, is an important food fish distributed throughout aquatic habitats of the Ecuadorian Amazon. We sampled gonad weight, body condition, and feeding of this species to address the question of whether changes in these biological parameters are related to hydrological variation and migration patterns. High frequency of empty stomachs and poor body condition corresponded to migration periods. Gonad condition analysis revealed a single, discrete spawning period in April (end of rising water season). We synthesized our own and published observations on migration patterns of black prochilodus and presumptive factors that influence those movements. Mature individuals make lateral migrations from peripheral flooded habitats to large white water rivers to spawn. Eggs and larvae drift downstream to nurseries at least into Peru and perhaps into Brazil; there do not appear to be nursery habitats in Ecuador. After 6-18 months, they migrate upstream, recruiting to parental stocks. Long-distance migrations of black prochilodus and similar fishes in Neotropical rivers disobey political boundaries. Conservation and management of such migratory fishes, thus, requires international co-operation and integrated conservation efforts.Keywords: Black prochilodus, Condition factor, Gonadalsomatic index, Life-history, Stomach fullness.El bocachico, Prochilodus nigricans, es una fuente importante de proteínas, distribuido en hábitats acuáticos de las tierras bajas de la Amazonía ecuatoriana. Se muestreo el peso de las gónadas, la condición corporal, y alimentación de esta especie para determinar la relación de estos parámetros biológicos con la variación hidrológica y patrones migratorios. Una frecuencia alta de estómagos vacíos y la pobre condición corporal corresponde a períodos de migración. El análisis del estado de las gónadas reveló un corto periodo de desove en abril (fin de la temporada de aumento del río). Hemos sintetizado nuestras observaciones propias y publicadas sobre migraciones del bocachico, así como los factores que presumiblemente influyen en estos movimientos. Los peces adultos migran lateralmente desde hábitats periféricos inundados hasta ríos de aguas blancas para desovar. Los huevos y larvas flotan aguas abajo hasta llegar a sitios de crianza en Perú y posiblemente en Brasil; no parece haber hábitats de crianza en Ecuador. Después de 6-18 meses, los bocachicos migran aguas arriba, reclutando a las poblaciones parentales. Las migraciones a larga distancia del bocachico y peces similares en ríos Neotropicales desobedecen las fronteras políticas. Una gestión apropiada de este recurso requiere de cooperación internacional y esfuerzos integrados de conservación.Palabras Clave: Bocachico, Factor de condición, Historia natural, Índice gonadosomático, Llenura del estómago.

Population dynamics of Prochilodus nigricans (Characiformes: Prochilodontidae) in the Putumayo River

“…During the period from 2009 to 2017 and out of the > 10000 specimens measured, the maximum observed length for P. nigricans in the upper Putumayo was 34 cm SL for a total body mass of 1.02 kg. This is considerably smaller than the 40.5 cm SL and 1.24 kg reported in the Aguarico River (300 m.a.s.l) in the Ecuadorian Amazon (Silva, Stewart, 2017), the 43 cm SL and 2.6 kg observed in the Caquetá River (~ 120 m.a.s.l) in Colombia (Bonilla-Castillo et al, unpublished data) or the 45 cm and 2.65 kg observed in the middle Mamoré River (~160 m.a.s.l) in the Bolivian Amazon (Loubens, Panfili, 1995), but comparable to the 33 cm SL and 0.9 kg reported in Manacapuru Lake (~30 m.a.s.l, downstream of the Solimões River) in Brazil (Catarino et al, 2014) and 37 cm TL and 650 g in the Ucayali River (~ 150 m.a.s.l, Riofrío, 2002). A potential explanation for the smallest maximum sizes observed in the Putumayo could lie in the size selectivity of the fishing gears used in Puerto Leguízamo.…”

“…This study suggested a homogeneous population along the Amazon main stem (Santarém to Tabatinga), which would likely extend to the Peruvian Amazon. Although we cannot preclude the existence of distinct populations with different life history traits in the Putumayo River (present study) and the Aguarico (Silva, Stewart, 2017) or the Caquetá rivers, differences in environmental conditions or in exploitation regime may be more likely explanations to the observed size differences. Catarino et al (2014) reported that Manacapuru Lake was heavily exploited.…”

Ecosystem‐based management of Amazon fisheries and wetlands

“…The common nexus among interbasin long‐distance migratory Characiforms is that their movements for spawning and upstream dispersal centre on nutrient‐rich whitewater rivers (e.g., Araujo‐Lima & Goulding, ; Ribeiro & Petrere‐Jr, ; Silva & Stewart, ) (Figures and ). The floodplains of whitewater rivers are also their nurseries (Figure ) because of the relatively high primary production associated with nutrients brought downstream from the Andes or from headwaters associated with the Fitzcarrald Arch, a low hilly region in the upper Purus and Juruá basins (Melack & Forsberg, ; Regarda et al., ).…”

“…The concept of fish migration has an ancient history in the Amazon, which is explicit in the commonly used words piracema (fish exit or movement in Tupi) in Brazil (Veríssimo, 1895) and mijano in Spanish-speaking countries (Silva & Stewart, 2017). References to migratory fishes in the Amazon usually pertain to common food species of medium to large size (Barthem & Goulding, 2007;Ribeiro & Petrere-Jr, 1990).…”

“…-Lima & Goulding, 1997;Ribeiro & Petrere-Jr, 1990;Silva & Stewart, 2017) (Figures 7 and 8). The floodplains of whitewater rivers are also their nurseries (Figure 8) because of the relatively high primary production associated with nutrients brought downstream from the Andes or from headwaters associated with the Fitzcarrald Arch, a low hilly region in the upper Purus and Juruá basins…”