Event Title

Session E4: Are Fish Passes the Best Strategy for Fish Conservation in South America?

Location

Groningen, The Netherlands

Event Website

http://fishpassage.umass.edu/

Start Date

23-6-2015 11:35 AM

End Date

23-6-2015 11:50 AM

Description

Abstract:

Most of the large rivers of South America are impounded specially for power production. Fisheries management has been based on stocking, fisheries’ harvest limits and the construction of fish passes. However, the low fishery yield and the precarious conservation status of native migratory populations in the dammed rivers indicate that these strategies have not been satisfactory. The objectives of such management strategies should be related to the existence of critical habitats, such as reproduction sites and nursery areas. Because most rivers in South America are serially impounded, there is substantial risk of confining populations within short reaches lacking critical fish habitats. In addition, large reservoirs impose a different kind of barrier to migrating fish, creating a diffuse gradient of hydraulic/limnologicalconditions that affects fish behaviour and functions as an extensive environmental filter that discourages downstream movements. Based on current and proposed river regulation scenarios, we conclude that conservation of Neotropical migratory fish will be much more complicated than previously believed, and in most situation fish passes will not be a solution. We propose that only by keeping free flowing rivers in the different river basins, we could maintain self-sustainable populations over the long term. In Minas Gerais state, Brazil, our data indicate that it would be possible to implement this strategy, transforming long stretches of river channels in conservation units, and losing less than 10% of the hydropower capacity. However, this initiative should be undertaken immediately, since 300 new dams are planned to be built in the near future, precluding the existence of long enough rivers to keep migratory fish populations.

Comments

Presenting Author Bio: Fish biologist, PhD on Water Resources, Associate Professor at the Federal University of Lavras. The main subjects of research are fish ecology, impact of dams, and land use effects on the fish fauna.

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Jun 23rd, 11:35 AM Jun 23rd, 11:50 AM

Session E4: Are Fish Passes the Best Strategy for Fish Conservation in South America?

Groningen, The Netherlands

Abstract:

Most of the large rivers of South America are impounded specially for power production. Fisheries management has been based on stocking, fisheries’ harvest limits and the construction of fish passes. However, the low fishery yield and the precarious conservation status of native migratory populations in the dammed rivers indicate that these strategies have not been satisfactory. The objectives of such management strategies should be related to the existence of critical habitats, such as reproduction sites and nursery areas. Because most rivers in South America are serially impounded, there is substantial risk of confining populations within short reaches lacking critical fish habitats. In addition, large reservoirs impose a different kind of barrier to migrating fish, creating a diffuse gradient of hydraulic/limnologicalconditions that affects fish behaviour and functions as an extensive environmental filter that discourages downstream movements. Based on current and proposed river regulation scenarios, we conclude that conservation of Neotropical migratory fish will be much more complicated than previously believed, and in most situation fish passes will not be a solution. We propose that only by keeping free flowing rivers in the different river basins, we could maintain self-sustainable populations over the long term. In Minas Gerais state, Brazil, our data indicate that it would be possible to implement this strategy, transforming long stretches of river channels in conservation units, and losing less than 10% of the hydropower capacity. However, this initiative should be undertaken immediately, since 300 new dams are planned to be built in the near future, precluding the existence of long enough rivers to keep migratory fish populations.

https://scholarworks.umass.edu/fishpassage_conference/2015/June23/76