Though the biggest fears over the past several years have been farmed Atlantic salmon infesting wild salmon habitats, in Norway, it's wild salmon causing the problem.

A growing population of Pacific pink salmon -- typically found in huge volumes in Russia and Alaska -- are threatening Norway's wild salmon rivers, leaving researchers and regulators wringing their hands over how to handle the invasion.

In its most recent May trawl survey, Norway's Institute of Marine Research found record-high volumes of pink salmon, which it dubs "pukkellaks," using the fish's other common name, humpback salmon.