A Preliminary Fishery Quality Index for Portuguese Streams

Abstract

Abstract.-There is a need to quantify the multivariate quality of a recreational fishery at the site scale to better communicate the relative quality among sites to the public and anglers. Borrowing on the general approach of multimetric indices of biotic integrity (IBIs), we developed fishery quality indices (FQIs) from species quality indices (SQIs) based on measures of fish abundance and size structure for northern and central Portuguese streams. Our FQIs showed regional patterns indicating a range in fishery quality. Higher coldwater FQI scores were mostly found in the northwestern (Minho and Lima), northeastern Douro, and northern Tagus basins. Higher warmwater FQI scores occurred in the eastern Tagus basin. The species that contributed the most to warmwater FQI scores were largemouth bass Micropterus salmoides, pumpkinseed Lepomis gibbosus, the cyprinid Luciobarbus bocagei, chubs Squalius carolitertii and S. pyrenaicus, and nases Pseudochondrostoma duriense and P. polylepis. The chubs, nases, and brown trout Salmo trutta contributed the most to coldwater FQI scores. As expected, our indices were correlated with river size and with disturbance at the catchment, segment, and site scales. Regression models for separate coldwater and warmwater FQIs were stronger than those for the individual SQIs and for an all-site FQI. The correlation was positive between the coldwater FQI and a coldwater IBI but negative between the warmwater FQI and warmwater IBIs. The proposed FQIs offer a quantitative approach for assessing relative fishery quality among sites and for making regional assessments given an appropriate study design. The component SQIs and SQI metrics of the FQIs can be disassociated to determine the population and species characteristics most affected by various environmental variables.

Modelling Stream-Fish Functional Traits in Reference Conditions: Regional and Local Environmental Correlates

“…This result is concordant with the findings of Oliveira et al [44] in the least disturbed and forested areas of northern and central Portugal, who found more and larger individuals in midelevation streams with gentler slopes. Possibly, lower gradient sites, with intermediate flow levels, tend to show higher diversity of available habitats for fish.…”

“…We found that the density-based metrics strongly influenced by the regional gradient R1 displayed unimodal relationships, indicating lower fish densities in the northern reaches that had higher catchment relief and slope, and strong runoff events, and higher densities at some intermediate levels. This result is concordant with the findings of Oliveira et al [44] in the least disturbed and forested areas of northern and central Portugal, who found more and larger individuals in midelevation streams with gentler slopes. Possibly, lower gradient sites, with intermediate flow levels, tend to show higher diversity of available habitats for fish.…”

“…The majority of sites were sampled by wading, but a few rivers with mean depths exceeding 0.8 m were electrofished by boat moving downstream, again sampling all habitat types, but focusing on the margins. Although capture efficiency estimates, assumed to be constant across sites, were not available for the study area, previous works indicated that this sampling effort was sufficient to ensure accurate characterization of fish species composition and abundance in the studied streams [27] , [43] – [44] . Fish were identified and measured in the field and returned alive to the water.…”

A Fish-Based Index of Biotic Integrity for Neotropical Rainforest Sandy Soil Streams—Southern Brazil

“…Although there is no standardization in the collection methodologies for studies of fish-based IBIs in Brazil, there are some papers developing this tool in many states, especially in the South-Central region [10,35,39,[85][86][87]. However, we suggest the adoption of an electrofishing protocol as an initial step for a single regional tool that would facilitate the use of fish data collected by colleagues throughout all localities, similar to the one used by Oliveira et al [88] in Portugal.…”

Feeding ecology of non-native centrarchids (Actinopterygii: Perciformes: Centrarchidae) in two Iberian reservoirs with contrasting food resources

“…Scientists have long recognised the importance of feeding strategies in the ecological success of animal species, but, despite the importance of invasive bass and pumpkinseed as negative drivers of native fish assemblages (Clavero et al 2013) and, in the case of bass, as a favoured angling species (Oliveira et al 2009), available information about their feeding ecology in Iberia is still limited. Investigations conducted so far have addressed a single system (García-Berthou 2002), only one species (Zapata and Granado-Lorencio 1993) or a sole sampling period (Godinho et al 1997), thus precluding a more comprehensive understanding of these species ecology in variable Iberian freshwater ecosystems.…”