Overview

Following on the heels of two productive Orinoco expeditions in 2003 and 2004, I teamed up again with labmate David Werneke, fellow ichthyologist Mark Sabaj Pérez (from the Academy of Natural Sciences) and Venezuelan colleague Oscar Leon Mata (from the University of the Llanos Ezequiel Zamora) to revisit southern Venezuela in 2005. Inspired by my 2004 discovery of a highly distinctive fish fauna above Salto Tencua – the first major waterfall on the Ventuari River – a goal for this expedition was to explore above another major waterfall. This time we targettted the mighty Salto de Oso, or Bear Falls, which is the first major waterfall on the Siapa River. Also joining us on this expedition were my labmate Ricardo Betancur, Colombian ichthyologists Mariangeles Arce, ecology assistants Mayme Grant and Erin Richmond, and my friends Tim Wesley, David Brooks, and Juan Valadez.

        The Siapa River is a large blackwater tributary of the Casiquiare Canal, placing it within the Amazon Basin. It flows north out of the remote Parima Mountain range, a long series of peaks and escarpments that delineates the border between Brazil and Venezuela. To reach the Siapa from the Museo de Ciencias Naturales in Guanare, our home base in Venezuela, we had to drive 16 hours to Puerto Ayacucho, then board a boat at Puerto Samariapo and travel up the Orinoco River past San Fernando de Apure to the outpost town of Esmeraldas. From Esmeraldas, we boated down the Casiquiare Canal and into the Amazon Basin.

        Upon arriving at the Siapa, our excitement was dampened by swarms of biting blackflies that besieged us from dawn to dusk. Even more discouraging, the rains had arrived earlier than expected and very few habitats remained shallow enough to be sampled. We reached the waters above Salto de Oso after weeks of travel, but despite our best efforts, the raging river was almost impossible to sample effectively. To salvage the trip, we returned to the habitats that had been most fruitful for us in the past – the confluence of the Orinoco and Ventuari.

        Despite the disappointment that forced us out of the Siapa, our 2005 collections in main-channel and tributary habitats of the upper Orinoco continued to yield many intriguing discoveries, including the new genera and species Micracanthicus vandragti (Lujan and Armbruster, 2011), Soromonichthys stearleyi (Lujan and Armbruster, 2011), and 'Pseudancistrus' pectegenitor (Lujan et al., 2007). Specimens collected during this trip are now cataloged at AUM, ANSP and MCNG (field number prefix VEN05), where they continue to benefit ichthyological research. Published papers that have already benefited from collections and observations made during this trip include the following:

The Lupe Melys, our principal research vessel for the 2005 expedition.

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1. View from the bow of the Lupe Melys, in the main channel of the Orinoco, onto Cerro Yapacana. 2. Ornamental fish holding pins in the confluence of the Orinoco and Ventuari Rivers. 3. Consolidating and packing collections on the landing of Esmeraldas. 4. The large treble hook of a peacock bass fishing lure that got accidentally embedded in one of Mark Sabaj Pérez's fingers. 5. Blackfly bites coating the hands and feet of Tim Wesley after our time in the Siapa River. 6. Camping on a sandbar in between Cerro Duida and Esmeraldas. 7. Tissueing specimens on a rock island in the Casiquiare Canal. 8. A variety of fish being smoked. 9. Life onboard the Lupe Melys. 10. Mariangeles, Mayme, and Erin consolidating collections. 11. Tim and Mariangeles consolidate collections. 12. Trying out the draw on a Yanomami bow and arrow. 13. Sleeping conditions aboard the Lupe Melys. 14. The first crew at the Tama-Tama bifurcation. 15. The second crew at Macaruco landing. 16. A Yanomami village on the Casiquiare.  Photos 1, 2, 7, 12, 14 by M. Sabaj Pérez.

Fishes

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1. Brachyplatystoma filamentosum (Pimelodidae), 2. Ageneiosus inermis (Auchenipteridae), 3. an aggregation of Rhaphiodon vulpinus (Cynodontidae), Serrasalmus rhombeus (Serrasalmidae), and Cichla orinocensus (Cichlidae) caught via fly fishing, 4. the holotype of Pseudancistrus pectegenitor (Loricariidae), 5. the holotype of Soromonichthys stearleyi (Loricariidae), 6. Rineloricaria fallax (Loricariidae), 7 & 8. an undescribed species of Exastilithoxus (Loricariidae).  Photos 1 and 2 by M. Sabaj Pérez.

Sponsors

This fieldwork was sponsored by NSF grant DEB-0315963, the All Catfish Species Inventory

2005 Expedition to the Casiquiare Canal, Venezuela

Work