Environmental history of one of the largest freshwater neotropical fish ( Zungaro jahu ) from otolith isotopic analysis

AVIGLIANO, ESTEBAN; POUILLY, MARC; VARGAS, FACUNDO; PENHA, JERRY; SILVA, NATALIA; BOUCHEZ, JULIEN; SÁNCHEZ, SEBASTIAN; VOLPEDO, ALEJANDRA V.

RIVER RESEARCH AND APPLICATIONS

JOHN WILEY & SONS LTD

Año: 2023 p. 1 - 11

1535-1459

The Manguruyú Zungaro jahu, endemic to the La Plata Basin, is one of the largestneotropical fish species whose life history is virtually unknown. The objectives of thisstudy were to determine if Z. jahu is a large-scale migratory species and to describehabitat use throughout ontogeny using the otolith Sr isotope (87Sr/86Sr) ratio. Surfacewater samples were collected in 2020 at four sites representing the main watercourses of the Great Pantanal in Brazil (upper Paraguay, Cuiabá, S˜ao Lourenço andVermelho rivers). Eighteen fish individuals were collected from the Paraná River(Argentina). New water 87Sr/86Sr data were incorporated into previously establishedstatistical models to infer the fish habitat use through the otolith 87Sr/86Sr ratios.The water 87Sr/86Sr ratio of the upper Paraguay tributaries varied (0.7209 and0.7229) and were the highest in the La Plata Basin. The dispersal area of Z. jahu wasrestricted to the surroundings of the confluence of the Paraná and Paraguay rivers.Fish showed chemical signatures compatible with those of the middle Paraná (88%),Paraguay-Pilcomayo-Bermejo (50%) and the lower/upper Paraná (66%). The discriminantanalysis based on otolith core indicated natal origins from the middle Paraná(37%), upper Paraná (32%), and Paraguay sub-basin (32%). The dispersal area ofZ. jahu migrations could be restricted to the surroundings of the confluence of Paranáand Paraguay, which highlights the need to review regional fishing regulations, especiallybetween latitudes 30–34 S.