Night fell as the two scientists set to work unrolling the long nets from the end of the boat. The jungle gave life to the evening symphony: the sweet chirping of insects, the distant cries of monkeys, the occasional screeching of a kite. Crocodiles lay in the shallows, their eyes shining when the flashlights were lit.
Across the water, freighters made dark shapes as they glided through the seas.
The Panama Canal has connected distant nations and economies for more than a century, making it an important artery for global trade, and in recent weeks target of President-elect Donald J. Trump expansionist designs.
But lately, the channel has also connected something else: the vast ecosystems of the Atlantic and Pacific oceans.
The two oceans have been separated for about three million years, after the Isthmus of Panama came out of the water and separated them. The canal cut a path across the continent, but for decades only a few species of marine fish could pass through the waterway and the freshwater reservoir that feeds its locks, Lake Gatun.
Later in 2016 The Panama Canal was expanded allowing large ships and things began to change.
In less than a decade, scientists at the Smithsonian Tropical Research Institute in Panama found that fish from both oceans—snooks, jacks, snappers, and more—almost completely displaced the freshwater species formerly in the canal system. Fishermen who rely on these species around Gatun Lake, mainly peacock bass and tilapia, say their catches are dwindling.
Researchers are now concerned that more fish may begin to migrate from one ocean to another. And no potential invader is more of a concern than the venomous, candy-striped lionfish. They are known to inhabit the Caribbean coast of Panama, but not in the eastern Pacific Ocean. If they were to pass through the canal, they could destroy defenseless native fish, as they have done in the Gulf of Mexico and the Caribbean Sea.
Phillip Sanchez, a fisheries ecologist with the Smithsonian, said there are already more marine species than casual visitors to Lake Gatun. They are “becoming the dominant community,” he said. They “push everything else aside.”