Background & Summary

The Iberian Peninsula is considered one of the most biodiverse European regions and a fish biodiversity hotspot1. The Iberian freshwater fish fauna has the greatest European percentage of endemism (73% of the species) because of its long-term geographical isolation, which occurred during the last glaciation, the Mediterranean climate and the high number of different river basins2. This biodiversity is high at the species level but low at the family level, as most of the species belong to the family Cyprinidae2. Further, although local alpha diversity is low compared to that of tropical rivers, beta diversity, endemic species and threats make the Iberian rivers relevant ecosystems from the perspective of conservation3.

Iberian freshwater fish biodiversity is highly threatened: populations of 52% of the native species are under some degree of threat according to the International Union for the Conservation of Nature (IUCN)4. The main threat to Iberian freshwater fish is water extraction, which affects 60% of the native species, followed by introduced species (42% of the total Iberian freshwater fish richness), which affects 50% of the native species. Other important threats include climate change and pollution4.

The unique physical and biological characteristics and the long history of human activities make the Iberian Peninsula a very interesting place for the study of threats and conservation of freshwater fishes. However, Iberian freshwater fish species have received little attention5.

Gathering primary biodiversity data is necessary to improve our knowledge of the ecology, impacts and conservation status of freshwater fishes. Occurrence data are very useful for determining the distribution of species. However, distribution ranges are changing due to the diverse impacts caused by human activities. Accurately predicting the effects of human threats on communities and species requires more data. Time series of abundance data have proven essential for predicting population trends and assessing the risk of extinction of species6. If such data are accompanied by biological data, such as length and weight of individuals within a population, studies could be performed to analyse changes in population structure and dynamics caused by human impacts7. Models performed using these different data may prove more reliable for assessing human impacts and population trends, which would lead to better conservation and management plans for numerous species.

This Data Descriptor presents 12 different datasets of freshwater fish samplings in diverse locations of Spain performed by the Department of Environmental Biology of the University of Navarra in various rivers in Spain since 1992. Some of the studies have been completed, while others are open to further sampling campaigns in future years. In total, 146,342 occurrence records have been published to date, making this ichthyological collection one of the most important in Spain8, with the aim of offering the most complete information, both occurrence and measurement data, regarding the collected freshwater fish specimens.

Methods

Study area

Spain is the largest country of the Iberian Peninsula, located in southwestern Europe, delimited to the north by the Pyrenees and to the south by the Strait of Gibraltar. It is surrounded by the Mediterranean Sea to the East, the Cantabrian Sea to the north and the Atlantic Ocean to the West. The prevailing climate is Mediterranean, with hot, dry summers, rainy springs and autumns, and mild winters. Vegetation series in this climate are dominated by evergreen forests of holm oak (Quercus ilex L.) and shrubs (Quercus coccifera L., Thymus vulgaris L., Rosmarinus officinalis L. and others). In northern Spain, near the coast, the Oceanic climate predominates, with rain evenly distributed through the year, humid summers and mild winters. The vegetation there is dominated by deciduous forests of oak (Quercus robur L.) and beech (Fagus sylvatica L.). In the inland regions, these climates have continental and mountainous influences that create more extreme temperature variations.

These essential differences between climates shape and determine river ecosystems and species, creating four different freshwater ecoregions within the Iberian Peninsula9: the first includes the Cantabric Coast, with Oceanic climate. In this ecoregion, rivers are shorter and fast flowing through large mountains, with water all year. The second ecoregion is Eastern Iberia, which includes rivers that flow into the Mediterranean Sea (the Ebro, Ter and Júcar are the most important river basins). In this ecoregion, Mediterranean is the predominant climate, with continental characteristics in some areas. The third ecoregion is Western Iberia, which includes the Tagus and Duero river basins. These rivers flow to the Atlantic Sea through lands dominated by the Mediterranean climate. The last ecoregion is Southern Iberian; its most important basins are the Guadiana, Guadalquivir and Segura river basins. This ecoregion is dominated by the Mediterranean climate and includes the driest areas of the Iberian Peninsula. In the last three ecoregions, dominated by Mediterranean climate, rivers present high flow variability between seasons, with seasonal floods and droughts.

There are five main rivers in the Iberian Peninsula, the Ebro, Duero, Tajo, Guadiana and Guadalquivir, as well as numerous smaller basins. Due to this variability of climates, basins and habitats, the Iberian Peninsula has a high degree of freshwater fish biodiversity and endemism.

For this work, 233 localities of the Ebro, Duero, Tagus, Guadiana, Guadalquivir, Bidasoa, Ter, Muga and Turia river basins were sampled. They belong to eight Autonomous Communities and 15 provinces: Navarra, La Rioja, Catalonia (Lleida and Gerona), Aragon (Huesca, Zaragoza and Teruel), Castilla y León (Zamora, Burgos and Salamanca), Valencian Community (Valencia), Extremadura (Caceres and Badajoz) and Andalusia (Huelva and Córdoba). Most of the sampling locations (69%) and specimens (87%) were collected in Navarra, followed by Aragon, with 16% of the locations and 9% of the individuals. Eastern Iberia was the most sampled ecoregion, and the Ebro (Navarra, Aragon and La Rioja) was the most sampled river basin based on locations and specimens collected (Figure 1).

Figure 1
figure 1

Map of Spain with the locations of all the sampling sites (black dots), the rivers (grey lines) and the river basins (black lines).

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Samplings were conducted on dates during all seasons of the periods 1992–1998 and 2001-2015.

Field sampling

In total, 148,812 specimens were collected by electrofishing, using an external generator (Honda EC3600) connected to an electrofishing control box and backpack electrofishing units (300–600 V, 0.2–2A). Two electrofishing methods were used, varying among projects: three-run depletion between two stop-nets; and semi-quantitative surveys, giving fish densities by catch per unit of effort (CPUE, number of specimens captured per hour)10. The sampling time of the semi-quantitative samplings varied between 15 min and 2 h, with 30 min being the most common sampling duration. The captured individuals were anaesthetized with tricaine methanesulfonate (MS-222; Sigma Chemical Co., St. Louis, MO) or 2-phenoxyethanol, identified, counted and measured (total length in millimetres, and, in some cases, weight in grams). Species recording and identification were performed by R. Miranda, J. Oscoz, P.M. Leunda, I. Vedia, I. Tobes, C. García-Fresca and A. Vilches using suitable literature11,12.

Preservation

Once surveys were complete, fishes were returned to the river. For later studies, some captured specimens were euthanized with an overdose of anaesthesia, either preserved in jars with 70% ethyl alcohol or dried, and deposited in the Museum of Zoology of the University of Navarra. Each specimen was labelled with a unique collection number and introduced into the Museum database (Zootron v4.5 (ref. 13). In total, 2497 specimens from different datasets were preserved in jars or dried in the Museum (Table 1).

Table 1 Summary of the main characteristics of the datasets.
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Then, datasets were exported to DarwinCore v1.4 format, revised, and corrected if necessary. Finally, Integrated Publishing Toolkit (IPT) resources for each dataset were created, metadata were added, and the Darwin Core Archives were uploaded. The resources were published in the Spanish Global Biodiversity Information Facility (GBIF) IPT node (http://www.gbif.es/ipt).

The Museum of Zoology of the University of Navarra (MZNA, Pamplona, Spain) has curated the scientific research materials of the Department of Environmental Biology since 1980. The Museum has provided data for the GBIF14.

Data Records

Datasets include occurrence records and measurements (total length and weight) of captured fish. There are 146,342 occurrence records, representing 148,812 fish specimens. The collection comprises 13 families and 40 species of fishes (and one hybrid), belonging to the orders Anguilliformes, Cypriniformes, Siluriformes, Esociformes, Salmoniformes, Cyprinodontiformes, Scorpaeniformes and Perciformes. Cyprinidae is the most abundant family, with 25 species and 81% of the specimens. The other most abundant families are Salmonidae and Nemacheilidae, with 11 and 7% of the total specimens, respectively. Of the 40 species recorded, 20 are endemic to the Iberian Peninsula, and 14 are invasive. Moreover, 12 species are under some degree of threat according to the International Union for Conservation of Nature (IUCN)15: one is Critically Endangered, one Endangered, nine Vulnerable and one Near Threatened. Two species are not evaluated by the IUCN (Table 2).

Table 2 Species and specimens in the 12 datasets, along with family, IUCN category and zoogeographic origin data.
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Fish sampling data are split into 12 datasets with internal cohesion (Data Citations 1–12): six are part of PhD theses (Data Citations 1–6); five are multi-year funded projects (Data Citations 7–11) and another one (Data Citation 12) gathers several smaller samplings (Table 1). Datasets are accessible at the GBIF. All 12 datasets are in Darwin Core Archive format and have occurrence information for 35 Darwin Core terms: ocurrenceId, Modified, basisOfRecord, InstitutionCode, collectionCode, catalogNumber, Habitat, scientificName, kingdom, phylum, class, Order, Family, genus, specificepithet, taxonrank, scientificNameAuthorship, continent, country, stateProvince, locality, minimumElevationInMeters, maximumElevationInMeters, EVENTDATE, recordedBy, preparations, disposition, identifiedBy, verbatimEventdate, verbatimElevation, IndividualCount, decimalLongitude, decimalLatitude, geodeticDatum and verbatimCoordinates. They also include measurement information (total length and weight) of 9 Darwin Core elements: id, measurementID, measurementType, measurementValue, measurementAccuracy, measurementUnit, measurementDeterminedDate, measurementDeterminedBy and measurementRemarks.

Each GBIF resource contains a metadata section and the occurrence and measurements (length and weight) datasets in Darwin Core Archive format. Each resource has a different number of records and measurements, as well as a different type of records. Resources maintain an internal cohesion: project, river, studied species, etc. Three of the resources are ongoing projects and will be updated when necessary, whereas the other nine are finished projects (Table 1).

Technical Validation

The two electrofishing techniques used are standardised and have been validated16. Species identification was performed using suitable literature12, and scientific names were validated using W. N. Eschmeyer’s Catalog of Fishes17. Before publication in GBIF, DARWIN_TEST application (v3.3 (ref. 18)) was used to eliminate possible mistakes in the coordinates, characters, taxonomy and the date format.

Additional Information

How to cite this article: Rodeles, A. A. et al. Iberian fish records in the vertebrate collection of the Museum of Zoology of the University of Navarra. Sci. Data 3:160091 doi: 10.1038/sdata.2016.91 (2016).