Using the example of the alternation [to fish (det) river(s)]/[to fish prep (det) river(s)/], this paper adopts a corpus linguistics approach in order to show how it can contribute to studies in cognitive semantics, combining statistics with a more qualitative analysis. The main aim is to investigate whether these two constructions (with or without a preposition) correspond to a single meaning with alternations or to two distinct meanings. Two studies, both using the Web as corpus, were carried out to elucidate this issue. The first study compared occurrences of the two constructions on French and English websites and showed that, statistically speaking, the construction without a preposition occurs mainly in angling websites that have an emotional dimension, such as blogs. The second study, focusing solely on English websites, examined the lexical environment of the two constructions and identified certain distinct semantic classes for each construction, defining two semantic scenarios. These two semantic scenarios were found to correlate closely with the nature of the website. In light of the corpus evidence, the paper concludes in favor of two meanings, each concerned by one or the other construction (with or without a preposition). The role of the emotional dimension in the relationship between the angler and the river is crucial in determining the presence or absence of a preposition before river. Such a conclusion positions this study firmly in the perspective of cognitive sociolinguistics.