DOI: 10.5061/dryad.9p8cz8whj
title: Functional responses of fisheries to hydropower dams in the Amazonian Floodplain of the Madeira River

description: 1. Tropical river fisheries support food security for millions of people
 but are increasingly threatened by hydropower development. How dams affect
 these fisheries remains poorly known in most regions. Here, we used a
 functional traits approach to evaluate the extent to which the composition
 of fishery yields in the Madeira River Basin the largest sub-basin in the
 Amazon, respond to dam construction. We also explored how dams affected
 the monetary value of yields and fishing-based income of the communities.
 2. We collected fishing data in 17 locations distributed more than 300 km
 across upstream, reservoir, and downstream zones during pre-and post-dam
 construction periods. We interviewed 711 fishers from 13 communities to
 assess fishing income during pre- and post-dam periods. 3. Catch-per-unit
 effort (CPUE) declined significantly, i.e., by 37%, after dam
 construction. Multivariate analysis yielded six species clusters according
 to trait syndromes related to life history, migration,
 swimming-performance/microhabitat-use and economic value that were
 associated with the environmental data characteristic of pre- and post-dam
 periods. Comparison of CPUE of each cluster indicated that large species
 with periodic life-history strategy and regional or long-distance
 migratory behavior were most affected by dam construction, with CPUE
 declining by, on average, 31%. Declines in yields and shifts in functional
 composition of the fishery yields resulted in average decline of 21% in
 the monetary of functional clusters and 30% in fishing income. 4.
 Synthesis and applications. Our study indicates that the implementation of
 the dams and associated changes in environmental conditions affected the
 functional composition of yields and reduced catches, negatively affecting
 the fishing-based income of the studied communities in the Madeira
 River.Whereas catches of all functional clusters declined after the dams,
 species possessing large body sizes, traits related to a periodic life
 history strategy, either with long-distance or regional migratory
 behaviors, and the greatest economic importance appeared to be
 particularly vulnerable. These results imply that hydropower expansion
 will cause detrimental effects for fisheries and the livelihoods they
 sustain. Our results underscore the urgent need for considering
 alternative sources of renewable energy (e.g., solar power and in-stream
 turbines) to avoid irreversible socio-environmental damages of large dam
 projects. In river reaches where dams are already in operation or under
 construction, minimizing impacts will require improving operational
 protocols to reduce hydrological alterations and developing research and
 technology to improve the functionality of fish passages. In these
 locations, addressing losses in fishery value and fishing-based income
 will also require the implementation of fair compensation measures.
 Maintaining fish production requires conserving flow pulses and
 free-flowing rivers and tributaries critical for completing life cycles of
 fish species with vulnerable traits.
description: Fishery data: The fishery data were collected by a monitoring
 program coordinated by the Ichthyology and Fisheries Laboratory of the
 Federal University of Rondônia that included 17 locations from November
 2003 to February 2005, and again from April 2008 to November 2013 (Fig. 1,
 Table S2). This dataset consists of standardized interviews conducted with
 fishers on a daily basis after their return from fishing trips. Data from
 before closure of the dam, Nov- 2003 to Nov- 2011, represented pre-dam
 period and data from after closure of the dams, Dec- 2011 to 2013,
 represented post-dam construction, following Cella-Ribeiro et al. (2017).
 The data recorded included yield (total kg/fishing trip), taxon (common
 names of species, or of species group, Table 1), and effort (fishers/day)
 of fishing trips. We calculated catch-per-unit effort (CPUE) for every
 month (CPUE = monthly yields of fish divided by monthly fishing effort
 (Petrere et al., 2010) for each taxa group and period (pre- and
 post-dam).  Environmental data: Water level data
 (stage) were obtained from gauges of the Brazilian water agency (Agência
 Nacional de Águas ANA, www.hidroweb.ana.gov.br). Gauges were selected
 according to their proximity to the fishery monitoring locations. Obtained
 data was aggregated at a monthly scale to get a ‘seasonal hydrology’
 indicator for the study area. We used land cover data from the European
 Space Agency Climate Change Initiative’s Land Cover project (ESA-CCI;
 http://maps.elie.ucl.ac.be/ CCI/) as described in Chaudhari et al. (2019). The data comprised an annual time series of land cover mapped at a 300 m spatial resolution based on combinations of map from several remote sensing instruments. The classification follows the LULC classes defined by the UN Land Cover Classification System (LCCS). Based on these classes, we calculated annual areas of forest cover, urbanization, and flooding (flooded area) at two scales: the floodplain (locally called ‘várzea’) and a 20 km buffer to each side of the river. This buffer size was shown to encompass the expansion of the reservoir (Cochrane et al., 2017). We used Pearson correlation tests to evaluate collinearity among land cover variables. Flooded area was negatively correlated (−0.97) with forest cover and positively correlated with urban areas (0.94). These correlations were expected because during and after the construction of the dams, forests were submerged (see Introduction and Cochrane et al., 2017), and the population as well as urbanization have increased substantially. To avoid data multicollinearity and assure visualization of results in biplots, we used flooded area  (water_all_buffer, water_all_flood) and excluded forest and urban areas from the analyses.
description: This dataset contains the environmental data (seasonal hydrology
 and flooded area at buffer or floodplain scales, and the pre- or post-dam
 periods) (R table), and the CPUE of each taxon (L table).