Monitoring fish fauna at Funil Hydroeletric Power Plant fishway, Grande River, MG,
during the 2005/2006 upstream spawning migration
Débora Matioli Souza1, 2, Zoraia Silva2, Márcia Oliveira Barbosa Silva2, Glycia Ferreira de
Rezende2, Luly de Assis Nogueira2,3
1
Centro de Aqüicultura da Universidade Estadual Paulista
Bios Consultoria e Serviços Ambientais Ltda (peixebios@globo.com)
3
Centro Universitário de Lavras
2
Introduction
In Brazil the construction of big water reservoirs for hydroelectricity and public supply
was most developed in the 1960's and 1970's when several of Brazilian rivers were used for
the construction of dams.
The Paraná basin, which encompasses Grande river, outstands others basins not only
for its length but also for being the home of importants HPP (Hydroelectric Power Plant)
which generate eletric power, and yet for enabling the implementation of others.
Due to the great number of HPP installed in Minas Gerais State, its hydrography status
has changed from fluvial to lacustre. As a result the natural flow of its principal rivers has
been changed due to the sequence of artificial lakes, which causes changes in the chemical,
physical, and biological components in that environment.
The main effects of the dams construction is the fish fauna reestructuration by the
substitution of the big migratory fish species for the smaller and sedentary ones (Agostinho,
1994) and also the depletion in these populations. Such negative pressure upon migratory fish
populations is higher in chain reservoirs systems, similarly to what happens in upper Paraná
basin due to both higher environment fragmentation and lack of lotic stretch between dams.
Funil HPP, officially named Usina Engenheiro José Mendes Júnior, is located in the
upper flow of Grande river, between Lavras and Perdões cities in the Southern Minas Gerais.
It is the third of a serie of hydroelectrics impoundments carried out in Grande river basin,
between Furnas reservoir and Itutinga dam (Cachapuz, 2006).
A fish lift that transports fishes from downstream to upstream started to run at the
Funil HPP in November 2003. The installation of fishways in HPPs is intended to attenuate
the impact caused on the fishes migratory flow. However, as such mechanisms are new,
studies that determine their effectiveness and limitation are required. Thus, this work had the
objective to monitoring both quantitatively and qualitatively the structure of the fish
community which utilized the Funil HPP fishway during the 2005/2006 upstream spawning
migration (piracema).
Material and Methods
Fish fauna at the Funil HPP fish lift was monitored from November 2005 to April
2006, when around 18 hoppers were dayly lifted between 7AM and 8 PM. Four of them were
sampled 5 days a week between 7 AM and 5 PM. A big gill net was installed at the sluice
leading to a chanell which drains towards the forebay, so that as the fishes were released from
the hopper they would be caught in the gillnet which had remained in the water inside the
chanell. Fishes were taken out using a smaller gill net, put in a 120 polystyrene box
containing aired water, and then identified, counted, and finally weighed and measured
individually. The average weight per specie was used to estimate the number of individuals
when great volume of small fishes was lifted. Some individuals were sacrified and their
gonads were taken out for reproductive activity evaluation. The fishes were identified until
the lowest possible taxonomic level, using specific literature. The gonads maturation stage
proposed by Bazzoli (2004) were considered in order to evaluate the reproductive activity.
The following were the parameters analysed: composition, numerical abundance, biomass,
and reproduction activity of the fish fauna which used the Funil HPP Fishway during the
2005/2006 upstream spawning migration.
Results and Discussion
A total of 994,118 individuals belonging to 4 Orders, 11 Families, and 25 species were
recorded in the monitored hoppers. These species number stands for 52% of the fish fauna
described by Bios (2006) for the Funil HPP area of influence. This value is higher than that
presented by the Yacyretá dam lift in the mid Paraná basin in 1995, which transported 44% of
the species registered in that area (Agostinho et al., 2003), specially knowing that whitin 48
species described in the Funil area of influence many are small fishes, not performing
significative migratory activities and found only in floodplain lakes, far from the fish lift
entrance (Bios, 2006). The most numerous species in the Funil HPP fish lift were
Bryconamericus stramineus (61,2%); Pimelodus maculates (28,6%); Astyanax fasciatus
(3,7%); Leporinus friderici (1,8%); Leporinus elongatus (1,4%) that standing for 96,7% of the
number of transported fishes (Figure 1).
Others
Leporinus elongatus
Leporinus friderici
Astyanax fasciatus
Pimelodus maculatus
Bryconamericus stramineus
0
200000 400000 600000 800000
N
Figure 1. Number of individuals belonging to the most
numerous species in the Funil HPP fish lift from
November 2005 to April 2006.
Regarding to the transposed biomass, 28,749 kg of fishes were registered in the
monitored hoppers. The most numerous species transposed in the fish lift were Pimelodus
maculatus (67,7%); Leporinus friderici (9,7%); Leporinus elongatus (9,2%); Leporinus
obtusidens (3,8%); and Astyanax fasciatus (3,1%), standing for 93,5% of the transposed
biomass (Figure 2).
Others
Astyanax fasciatus
Leporinus obtusidens
Leporinus elongatus
Leporinus friderici
Pimelodus maculatus
0
5000
10000
15000
20000
Biomass (Kg)
Figure 2. Most representative species in biomass in the
Funil HPP fish lift from November 2005 to April 2006.
As for seasonal variation in these species movement by the fish lift, Bryconamericus
stramineus was numerically higher in the months of March and April 2006, whereas for the
Pimelodus maculatus it was in December 2005, decreasing gradually until April 2006.
Astyanax fasciatus was most numerous in January and February 2006 and so were Leporinus
friderici and Leporinus elongatus (Table 1). For reophilic and migratory species (P.
maculatus, L. friderici, and L. elongatus) such a change is probably related to the reproductive
peak, when they swim upstream towards the spawning suitable areas. The movement of other
not migratory species, in spite of their reophilic behavior, is probably not strictily related to
reproduction and it can be a little trophic migration.
Table 1. Number of individuals belonging to the five most frequent species in the Funil HPP
Fish lift from November 2005 to April 2006.
Period
Species
Nov / 05
Dec / 05
Jan / 06
Feb / 06 Mar / 06 Apr / 06
B. stramineus
14.698
5.230
57.174
5.825
351.220
174.337
P. maculatus
19.071
104.929
73.719
53.157
32.521
1.223
A. fasciatus
307
4.329
20.893
10.648
923
136
L. friderici
351
1.305
7.825
7.124
1.081
72
L. elongatus
468
1.429
6.128
5.680
532
50
Fishes of different sizes (standard length) and weights were caught from 1g and 3 cm
for B. stramineus to 2500 g and 46,5 cm for Salminus brasilliensis. The low numbers found
for Prochilodus lineatus and S. brasiliensis in the Funil HPP fish lift can be related to the
monitoring routine used. Vono et al. (2004) findings for research conducted at Igarapava HPP
fishway – Grande river showed that some species, including P. lineatus, a nocturnal specie,
used the fishway at different schedules.
Conclusions
Funil HPP Fish lift was found to be effective in the analysed period, since it
transposed fishes from different Orders (Characiformes, Siluriformes, Gymnotiformes and
Perciformes), of different sizes, which perform either long reproductive or short trophic
migrations. For this reason the system enabled both young and adult fishes from different
lineage species and reproductive patterns to transpose the dam trying to reach the headwaters.
Standing out the transposition of fishes which perform long reproductive migrations such as
Salminus brasiliensis; Prochilodus lineatus; Leporinus friderici, Leporinus elongatus and
Leporinus obtusidens.
These results suggest that this monitoring should continue under a different schedule
and during different months, so that a more effective operation routine could be set, in special
for the migratory species.
Acknowlegements
We thank the Consórcio Funil: Companhia Vale do Rio Doce and Companhia Energética de
Minas Gerais for the support to the project.
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