Perspective: Towards environmentally acceptable criteria for downstream fish passage through mini hydro and irrigation infrastructure in the Lower Mekong River Basin

Abstract

Tropical rivers have high annual discharges optimal for hydropower and irrigation development. The Mekong River is one of the largest tropical river systems, supporting a unique mega-diverse fish community. Fish are an important commodity in the Mekong, contributing a large proportion of calcium, protein, and essential nutrients to the diet of the local people and providing a critical source of income for rural households. Many of these fish migrate not only upstream and downstream within main-channel habitats but also laterally into highly productive floodplain habitat to both feed and spawn. Most work to date has focused on providing for upstream fish passage, but downstream movement is an equally important process to protect. Expansion of hydropower and irrigation weirs can disrupt downstream migrations and it is important to ensure that passage through regulators or mini hydro systems is not harmful or fatal. Many new infrastructure projects (<6 m head) are proposed for the thousands of tributary streams throughout the Lower Mekong Basin and it is important that designs incorporate the best available science to protect downstream migrants. Recent advances in technology have provided new techniques which could be applied to Mekong fish species to obtain design criteria that can facilitate safe downstream passage. Obtaining and applying this knowledge to new infrastructure projects is essential in order to produce outcomes that are more favorable to local ecosystems and fisheries.

A fresh look at inland fisheries and their role in food security and livelihoods

“…For example, fish passages can significantly reduce negative ecological impacts from the construction of instream barriers such as dams (Baumgartner, Boys, Barlow, & Roy, 2017;Baumgartner et al, 2014) and other measures can prevent damage or injury from flood sheer or pressure changes from small-scale hydropower dams (Thorncraft et al, 2013). Innovative design and operation of irrigation systems can provide improved habitat and connectivity for inland fisheries, thereby synergistically enhancing food production, livelihoods and sustainable development (Gregory, Funge-Smith, & Baumgartner, 2018).…”

Lower Mekong Fish Passage Conference: Applying innovation to secure fisheries productivity

“…Thus, effective mitigation strategies are needed to protect fisheries resources (Baumgartner et al . ).…”

Addressing fish-passage issues at hydropower and irrigation infrastructure projects in Indonesia

“…Further, the entrance location must be situated at the upstream migration limit and internal fishway hydraulics must suit the swimming ability of the target species (Bunt 2001). Developing robust solutions requires that fish ecologists, dam operators and engineers should work collaboratively to design effective solutions (Baumgartner et al 2014a).…”