Act No. 11709, “Installation and maintenance of fish passes in rivers falling under national jurisdiction” was passed by the National Congress on 19 September 1933 (Castello, 1982). Its main provisions are:
Following the promulgation of this Act, the Executive will ensure that fish passes are installed and maintained in existing and new dams built in rivers falling under national jurisdiction, where the presence of such dams obstructs the passage of fish.
In dams where fish passes have already been installed, the Executive shall, through the National Irrigation Department, order the owners, concession holders or users to undertake the necessary repairs to bring the structures into conformity with the provisions of article 1, giving them 70 days in which to comply with the order. The owners, concession holders or users shall be obliged to inspect and maintain the fish passes and prevent poaching along a distance of 100 m up and downstream of the dam.
Failure to comply with the provisions of this Act shall result in the withdrawal of the concession or the demolition of the dams, if these do not provide a public service.
Several cases may be cited where fish passes were not installed in dams built in rivers, belonging to the Plata Basin, which contain significant quantities of migratory species.
Sao Paolo State's Act No. 2250 of 28 December 1927 stated (Godoy, 1985):
“16. Any person, who for any reason whatever, obstructs the waters of rivers or streams shall be obliged to construct passes to allow the free passage of fish.”
At national level, decree No. 24643 of 10 July 1934, “Water Code” stated:
“143. In all hydroelectric developments, measures shall be taken to protect the public interest.
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(f) by providing protection and an unobstructed passage for fish;”
There was a change of attitude by the Brazilian federal authorities in 1983 based on objections put forward by fishery biologists working in Brazil and experts engaged to look into the advisability of constructing fish pass installations (Castello, 1982).
The law was amended by Decree Law No. 794 of 19 October 1938, “First Fishery Code” (Castello, 1982; Godoy, 1985). Article 68 of that Decree Law states that rivers and streams shall be provided with facilities designed to preserve river fauna. These may be structures to assist the passage of fish or a fish hatchery.
It also stated that studies would be undertaken by the Hunting and Fishing Service which would then recommend appropriate measures. Recommendations regarding measures for the protection of the aquatic fauna in the case of dam construction are now made by the Fishery Development Department (SUDEPE).
Article 2 of the SUDEPE resolution No. 46/71 states that SUDEPE is the sole body responsible for: choosing the fauna protection system or method; deciding on the size and location of the required installations; and granting approval for service projects and works. Article 3 states that every watercourse in which there is a dam shall, in principle, be provided with at least one hatchery or hatchery sub-unit. The number may be increased where SUDEPE deems this to be necessary.
The first paragraph of this article states that where there are several dams in a watercourse, SUDEPE shall decide which shall be provided with a hatchery and what proportion of construction, operating and maintenance costs shall be shared by all permit or concession holders (Alzuguir, 1976).
Article 8 of this Fisheries Act states that dams and dikes shall, in general, be constructed so as to enable fishways inclined at an angle of not more than forty-five degrees to be installed to facilitate the passage (of fish) (Lilyestrom and Taphorn, 1978).
