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]

Searsport Harbor Maintenance Dredging update Report from ACOE's April 13, 2026 meeting

FROM Maine Dredge Team Meeting Notes April 13, 2026 (Full mtg notes) (pdf)

ACOE followup meeting  June 24th, 2026, 6:00pm to 7:30pm.
Location: Searsport Community Building, 42 Prospect Street, Searsport, Maine 04974.

Purpose Provide an overview of the Preliminary Assessment for the proposed

maintenance dredging of the Searsport Harbor Federal Navigation Project.

Searsport Harbor Maintenance Dredging (Searsport, ME) 

o Description: Mechanical maintenance dredging of approximately 40,000 cy of mixed sand and silt that is not suitable for open water disposal due to elevated mercury levels. The channel is 3,500 ft long and 500 ft wide with a 1,500-ft-wide turning basin in front of the piers at Mack Point. It is authorized to a depth of -35 ft MLLW with 2 ft of overdepth. 

o Disposal: Proposal includes the construction of two confined aquatic disposal (CAD) cells – one starter cell and one primary cell – just west of the FNP. The top 3 ft of sediment in the starter cell location (~ 5,200 cy) would be held in scows during construction. Sediment below the surficial layer (~17,000 cy), which is suitable for open water disposal, would be taken to the Rockland Disposal Site (RDS), approximately 25 nm south of Searsport Harbor. Then the top 3 ft of sediment from the starter cell and primary cell location (~10,200 cy) would be placed into the starter cell. Next, the remaining suitable material in the primary cell footprint (~44,500 cy) would be taken to RDS. Finally, the unsuitable materials from the FNP would be placed in the primary CAD cell.

 Approximately 3 ft will be left at the top of the cell for natural cap.

o History: First constructed in 1962; no maintenance dredging has been conducted 

o Status: Environmental review underway; USACE to hold public information meeting; targeting 2027-28 dredging window 

o Meeting question: What is the water depth at the CAD cell location? Answer: Most recent survey shows a range between 25 – 31 ft deep at MLLW.

o Meeting comment: Full design is not yet completed – whether a starter cell is needed is not finalized; multiple scows or a large scow would be needed if a starter cell isn’t used; keeping this option flexible allows more contractors to bid and can make the project less expensive. 

o Meeting question: How are the sediments in the channel and CAD cell different in terms of suitability?  Answer: the top 3 ft of the CAD cell is also not suitable – it would be held at the site while the deeper, suitable sediment is taken to RDS. 

o Meeting question: How could the presence of CAD cells affect potential wind port development in the area? Answer: Designs have been shared with Sprague and they do not have any issues. 

o Meeting comment: The need for maintenance dredging after over 10 years of planning is a higher priority so ships don’t have to wait on tides. 

o Meeting comment: Pat will provide information on composition of clean material 

 After the meeting, all the documentation for the Searsport project was posted here: https://www.nae.usace.army.mil/Missions/Civil-Works/Navigation/Maine/SearsportHarbor/ Information on the composition of the material can be found in the Draft Preliminary Assessment, Suitability Determinations, CAD Cell Investigation Report, and Engineering Designs 

o Meeting question: Were beneficial uses of the material considered vs. disposal at RDS? 

Answer: Yes, capping contaminated areas in Penobscot Bay was considered but there is uncertainty on whether this would be successful and several years of testing and studies would be required, which would delay the maintenance dredging too long considering vessel draft requirements

END