Assessing Chilean EAs

img_5168Throughout the world, environmental assessments (EAs) are used to determine likely impacts of large scale projects and activities on the environment. The Chilean environmental assessment system (SEIA) has been in place for roughly 20 years, and during that time, Chile has constructed many water projects (including dams and canals), and aquaculture (especially salmon aquaculture) has boomed. With a dearth of information about native freshwater fishes, one question that came to mind was to see how large-scale projects (that are known to have significant deleterious impacts on freshwater fishes throughout the world) could assess their potential impacts to a freshwater fish fauna that was so poorly defined.

In Chile, EAs are split into two basic categories: Declaraciones de Impacto Ambiental (DIAs) and Estodios de Impacto Ambiental (EIAs). DIAs represented the vast majority of all water projects and aquaculture activities (i.e., >90%), and – of the subsample assessed – none contained any characterization or assessment of freshwater fishes. EIAs for aquaculture activities also contained no characterization freshwater fishes or assessments of impacts to freshwater fishes. In contrast, of 33 EIAs for water projects, 21 contained some sort of characterization of freshwater fishes, but there was no standardization of methodologies, there was evidence of misidentification of fishes, and no (apparent) assessment of potential issues associated with the sampling gear used. Furthermore, only 2 contained any quantitative assessment of potential impacts to characterized fishes. In all, less than 1% of all EAs in aquaculture and water projects included any characterization of freshwater fishes that could be affected by the project, less than 0.1% quantitatively assessed the impacts of the project in question to local fishes, and none assessed impacts to the larger watershed.

The general assessment of the Chilean EA process is that is is not currently set up to characterize resident freshwater fishes or assess impacts to those fishes due to the projects in question. It also is not currently set up to assess the larger impacts of projects within a watershed context (let alone a multi-watershed context, as in the case of salmon aquaculture). However, recent and current programs at the ministerial level toward increased sustainable development – in addition to movement on a biodiversity conservation law – imply potential for change to include freshwater fish conservation at various stages of territorial and site planning.

The manuscript for this evaluation is currently under review.

OdVs in the Maule, Biobío, and Toltén

Nematogenys inermis

Recently, I helped the team at the Centro de Cambio Global complete the aquatic ecology portion of the “Cuencas 2” project, funded by the Chilean Ministry of Energy. Our team was in charge of assessing a number of “Objetos de Valoración” (OdV) within the Maule, Biobío, and Toltén watersheds of Central and Southern Chile to assist with future sustainable hydropower development in Chile. In this framework, OdVs are – very broadly speaking – features or conditions in the watershed (either terrestrial or aquatic) that are determined to be of concern (environmentally, ecologically, socio-culturally, or economically) when considering the question of sustainable development.


Two major contributions I provided to the process were in the assessment of probable distributions of native and exotic fish species throughout these three watersheds as well as the creation of an additional OdV, “Watershed Accessibility,” which is an index that describes the proportion of the watershed accessible from any one river reach.

Probable Fish Distributions

The probable distributions of freshwater fishes were based on fundamental principles of ecohydrology at meso-spatial scales, and utilized many of the data derived for characterizing the physical characteristics of the watersheds that were done as another part of the Cuencas 2 project. The fish presence data were from the Chilean Ministry of Environment (MMA, native fishes) and the Chilean National Fisheries Service (Sernapesca, exotic fishes).

Three fish-species OdVs were generated for the watersheds: potential presence of endangered or vulnerable species, potential presence of native species, and general “intactness” of local fish communities. In general, rainbow and brown trout (exotic to Chile) were determined to be mostly in the mountainous uplands, while native fishes tended to be more predominant in the downstream, valley, portions of the watersheds. These general patterns comported with the general descriptions in the literature.

Watershed Accessibility

One major concern when thinking about hydropower development and fish ecology is the impact of dams on migration of fishes. One of the iconic examples of this is the impact of dams on salmon migration throughout coastal North America and Northern Europe. This type of migration (scientifically defined as anadromy) is not a feature of Chilean fishes, though. Two groups of Chilean fishes that do migrate to and from the ocean are freshwater eels (which are catadromous) and galaxids (which are amphidromous). However most of the rest do not migrate to the sea, but do utilize various portions of a watershed for different parts of their life histories. In other words, they are potadromous.

When considering the question of fish movement among Chilean fishes, therefore, the classical image of salmon returning to a natal stream is literally exotic to the Chilean condition. Instead, the most common image is that of a native species accessing various parts of a watershed during the year and throughout its life cycle, and never venturing out to the ocean. In such a case, therefore, the longitudinal accessibility – from the mountains to the river mouth and back again – is not as great a concern as topological accessibility – from one tributary system to another.

The “Watershed Accessibility” OdV is an attempt to create an index that determines the available amount of watershed that can be accessed from any one river segment, which is a potentially far more important measure of what is often termed “ecological connectivity” (which is an analogue of the terrestrial ecology concept of “fragmentation”) than is described by various measurements of longitudinal connectivity. Its inclusion as one of the official OdVs to be considered by the Ministry of Environment is, I believe, a crucial step in defining an ecosystem metric which has the somewhat unique condition of Chilean fishes in mind.

Next Steps

The work done at the Centro de Cambio Global was on three of eleven watersheds that span the geographic area of Central Chile through to Patagonia. The other eight watersheds – and their OdVs – were characterized by teams from the University of Chile (watersheds in the Los Rios and Los Lagos Regions) and the University of Concepción (watersheds in Chilean Patagonia). We are currently working on a set of papers that will explain the modeling process and results of our combined work.

If you are interested in learning more about the project or its results, please feel free to contact me.