Panama canal expansion results in non-native fish invasion

Non-native fish are invading Lake Gatun following the Panama canal expansion according to a new report in Nature Ecology and Evolution by Smithsonian Scientists.

The recent expansions of the Panama and Suez canals leading to non-native fish species invading new habitats has scientists concerned. Why? Because the no body knows the repercussions.

"We’re seeing a shift from predominantly freshwater fish to marine fish in the Panama Canal (Lake Gatun) in a short period of time," said Mark Torchin, STRI marine ecologist. "The concern is that if fish invasions continue there is a good chance of some of those fish moving into the other ocean, with unknown environmental consequences."

Only four years after the Panama Canal expansion, 11 new marine fish species have been recorded in Lake Gatun,  taking the total number of marine fish species known in the lake from 18 to 29. In some areas of the lake, marine fish such as jacks, snooks, mojarras and ladyfish have entirely replaced freshwater fish.

Salinity in the lake increased, with the cause of this undetermined, some theories include increased ship traffic and lock usage and the new locks’ design, which incorporates recirculation of water. 

"These marine fish invasions are an early warning sign of what could happen if no corrective measures are taken," Castellanos-Galindo said. "Along both coasts of Panama there are hundreds of fish species that could tolerate the conditions of an even slightly brackish canal. We don’t know what the ecological and socioeconomic consequences of these fish crossing the canal to either the Pacific or the Atlantic would be."

"We can document the Panama Canal invasions because we have good, standardized and quantitative pre-expansion data," said D. Ross Robertson, STRI ichthyologist. "We need to get back out there to collect more data to find out exactly what is going on and to provide the science that will help policy makers mitigate the potential impact. This is a really good example of how the pandemic has interrupted field work with important implications for environmental decision making."

Read the full report A new wave of marine fish invasions through the Panama and Suez canals