Chinook Salmon (Oncorhynchus tshawytscha) in the Santa Cruz River, an Atlantic Basin of Patagonia

CIANCIO, J.; PASCUAL, M.A.; LANCELOTTI, J.; RIVA ROSSI, C.M.; BOTTO, F.

ENVIRONMENTAL BIOLOGY OF FISHES

Springer

Lugar: The Netherlands; Año: 2005 vol. 74 p. 219 - 227

0378-1909

We report the finding of an established population of exotic Chinook salmon spawning in headwaters of theSanta Cruz River system (Argentina), the first for this species in an Atlantic basin of South America.Spawning takes place in the Caterina River, a small tributary of Lake Argentino, located 488.5 km from theocean. Anadromy was verified by correspondence of N and C stable isotope ratios with those of fishcaptured by bottom-trawlers in the ocean and those of anadromous rainbow trout from the same riverbasin. The scale patterns of most fish examined were consistent with a stream-type life cycle (i.e., seawardmigration by juveniles after a full year in fresh water). Two potential origins were identified for thispopulation: in situ introductions of fish imported directly from the USA in the early 20th century or fishfrom two ranching experiments conducted in southern Chile during the 1980s. In the latter case, colonizationwould have proceeded through the Strait of Magellan, helped by prevailing eastward currents.