Using pesticides against Green Crabs? Maine tried it in the 1950s.

 In the mid-20th century (late 1940s to 1950s), responding to a massive green crab population boom that was devastating the state's soft-shell clam industry, the Maine Department of Sea and Shore Fisheries (a precursor to the modern Department of Marine Resources) did test chemical pesticides on mud flats to control the crabs. [1, 2, 3, 4]

The 1950s Pesticide Trials

During this period, the state—in coordination with the U.S. Fish and Wildlife Service—conducted experimental treatments on coastal mud flats. [1]

• Targeted Species: The European green crab (Carcinus maenas), an invasive predator that decimates soft-shell clam and blue mussel populations. [1, 2]
• Chemicals Used: Early experiments utilized chlorinated hydrocarbons like DDT, as well as rotenone. The goal was to poison the intertidal zone to kill off the crabs before they could eat juvenile clams. [1, 2, 3]
• Results and Aftermath: These indiscriminate chemical treatments proved ineffective, caused significant collateral damage to other non-targeted marine life, and were ultimately abandoned. The crab onslaught of the 1950s was naturally—and abruptly—stalled by a series of unusually cold winters in the early 1960s, which froze the flats and  reduced the green crab population. [1, 2]