Photo: Freshwaters Illustrated/Dave Herasimtschuk/USDA.

Trudeau knew that the hormone systems controlling mating were nearly identical in fish and mammals, and he reasoned that they should be similar in amphibians, too. Taking a page out of the fish reproduction playbook, he combined a hormone that stimulates cells in the pituitary gland with a chemical that blocks the neurotransmitter dopamine, which can interfere with breeding. This combination had been used extensively in fish, to encourage breeding stock for the aquaculture industry. But it hadn’t yet been tried in amphibians. Before Amphiplex, only individual hormones, sans dopamine blockers, had been used on captive amphibians, with mixed success.