Movement and longitudinal distribution of a migratory fish ( Salminus brasiliensis) in a small reservoir in southern Brazil

Lucas De Fries,Luís Fernando Da Câmara,Lisiane Hahn,Fernando Gertum Becker,Bruna Arbo Meneses,Sandra Maria Hartz

doi:10.1590/1982-0224-20180119

Lucas De Fries, Luís Fernando Da Câmara + Show 4 more

Open Access

https://doi.org/10.1590/1982-0224-20180119

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Abstract

ABSTRACT We investigated whether the movement and distribution of the migratory fish, Salminus brasiliensis, were affected by a small reservoir. We also examined how movement and distribution were related to water temperature, flow, and rainfall. In December 2011 and January 2012, 24 individuals were captured downstream from the dam, tagged with radio transmitters and released in the reservoir (5.46 km² total area). After being released in the reservoir, 18 of the 24 tagged fish travelled upstream, taking an average of 16.6 days to leave the reservoir, with daily movements varying from < 5 km/day to > 24 km/day. However, only seven tagged specimens (29.16%) returned to the lower reservoir section, while the rest remained in the intermediate and upper reservoir sections. Longitudinal distributions and movements were positively related to both upstream flow into the reservoir and water temperature. We found evidence that S. brasiliensis can recognize the longitudinal gradient and is able to continue its upstream migration. On the other hand, the reservoir negatively affected downstream movements, possibly because disorientation prevented movement to the lower reservoir section. Based on these results, we suggest that the impact of small reservoirs on migratory fish species should be objectively addressed in environmental impact assessments and management programs.

Highlights

The construction of dams and their associated reservoirs has been a major concern for biodiversity conservation because they alter river communities and environments (Nilsson et al, 2005; Agostinho et al., 2008)
We investigated the movement of Salminus brasiliensis (Cuvier, 1816), one of the main migratory species of the Paraná-Paraguay River basin, in a small reservoir located in southern Brazil
We investigated the movement and distribution of S. brasiliensis in the Monjolinho reservoir, which is located in the Passo Fundo River 4 km upstream of its confluence with the Uruguay River in southern Brazil (Fig. 1)

Summary

Introduction

The construction of dams and their associated reservoirs has been a major concern for biodiversity conservation because they alter river communities and environments (Nilsson et al, 2005; Agostinho et al., 2008). Migratory neotropical fish have been affected by the construction of dams (Agostinho et al, 2008; Gubiani et al, 2010) since they need to perform extensive migratory movements (>1,000 km, Godoy, 1975; Agostinho et al, 2003; Barthem et al, 2017) between critical habitats. For the conservation of demographic and genetic dynamics, fish movement through fishways and reservoirs must be efficient in both downstream and upstream directions (Pelicice et al, 2015). Downstream fish movement is considered a more critical problem than upstream movement (Antonio et al, 2007; Makrakis et al, 2007a, 2007b; Makrakis et al, 2012)

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