Completeness of national freshwater fish species inventories around the world

Abstract

The aim was to discriminate the countries with relatively comprehensive inventories of freshwater fishes from those with insufficiently prospected inventories. We used a data set of 16,734 freshwater fish species with a total of 1,373,449 occurrence records. Accumulation curves relating the increase in the number of species to the number of records, and completeness values obtained after extrapolating these curves to estimate the total number of predicted species were calculated for each country using the RWizard application KnowBR. Using the final slope values of the accumulation curves, the obtained completeness values, and the ratio between the number of records and the observed species, maps and plots representing the location of good, fair and poor quality inventories at country level were obtained. Inventory completeness ranged from 5.3% (Guinea-Bissau) to 108.4% (United Kingdom), with a pooled mean of 65.9%. We observed that a completeness higher than 90%, a slope lower than 0.02 and a ratio of records/species observed greater than 15 were good thresholds for identifying countries with good quality inventories; only 26 countries met these requirements, mainly located in Europe and North America. However, more than 71% of countries worldwide have inventories that can be categorised as of poor quality. Furthermore, even those countries with relatively accurate national inventories possess a high variability in the completeness of their provincial or regional inventories.