Project

Mussel Bed Mapping

Mussel beds are retreating deeper into the ocean. You can help keep track of them.

Mussel beds are inching towards more subtidal zones, and are becoming harder to spot. During extreme low tides, you might be able to catch a glimpse. Send us your photos of mussel beds during low tides, and we will develop an acoustic mapping plan so we can keep track of where they are.

Project Goals:

  • Collect geolocated photos of mussel beds during very low tides.
  • Use the data to inform ongoing acoustic scanning research.
  • Update regional maps of mussel beds — they haven't been mapped in more than 20 years.

We need your help!

On days with negative or very low tides, within an hour of low tide, you can support ongoing research efforts by going out to the coast and taking photos. Submit your photos and whether or not you saw mussels on the Ecosystem Investigation Network.

Ecosystem Investigation Network

The best time to collect data is during very low tides (negative tides). Upcoming dates and times* for negative tides in 2026 include:

  • June 14, 4:38 am
  • June 15, 5:33 am and 5:39 pm
  • June 16, 6:29 am and 6:36 pm
  • June 17, 7:23 am and 7:32 pm
  • June 18, 8:18 am
  • June 19, 9:13 am
  • June 20, 10:09 am
  • June 21, 11:04 am
  • July 13, 2 4:23 am
  • July 14, 5:20 am and 5:26 pm
  • July 15, 6:15 am and 6:23 pm
  • July 16, 7:08 am and 7:18 pm
  • July 17, 7:58 am and 8:13 pm
  • July 18, 8:48 am
  • July 19, 9:38 am
  • July 31, 7:02 am
  • August 1, 7:36 am
  • August 2, 8:10 am
  • August 3, 8:48 am
  • August 11, 4:12 am
  • August 12, 5:07 am and 5:16 pm
  • August 13, 5:59 am and 6:10 pm
  • August 14, 6:47 am and 7:02 pm
  • August 15, 7:33 am and 7:52 pm
  • August 16, 8:18 am and 8:42 pm
  • August 28, 5:53 am
  • August 29, 6:27 am
  • August 30, 7:01 am and 7:20 pm
  • August 31, 7:38 am and 8:02 pm
  • September 1, 8:18 am and 8:48 pm
  • September 10, 4:51 am and 5:06 pm
  • September 11, 5:38 am and 5:56 pm
  • September 12, 6:22 am and 6:44 pm
  • September 13, 7:04 am and 7:29 pm
  • September 26, 5:12 am and 5:31 pm
  • September 27, 5:48 am and 6:12 pm
  • September 28, 6:27 am and 6:55 pm
  • September 29, 7:08 am and 7:40 pm
  • September 30, 7:51 am and 8:28 pm
  • October 7, 3:09 pm
  • October 8, 4:04 pm
  • October 9, 4:30 am and 4:54 pm
  • October 10, 5:14 am and 5:41 pm
  • October 11, 5:55 am and 6:24 pm
  • October 26, 5:13 am and 5:46 pm
  • October 27, 5:56 am and 6:32 pm
  • October 28, 6:42 am and 7:21 pm
  • October 29, 7:31 am and 8:13 pm
  • November 24, 4:24 pm
  • November 25, 4:31 am and 5:14 pm
  • November 26, 5:22 am and 6:06 pm
  • November 27, 6:15 am and 7:00 pm
  • November 28, 7:10 am and 7:56 pm
  • December 23, 3:19 am and 4:07 pm
  • December 24, 4:12 am and 5:00 pm
  • December 25, 5:07 am and 5:53 pm
  • December 26, 6:02 am and 6:46 pm
  • December 27, 6:57 am and 7:39 pm
  • December 28, 7:55 am and 8:34 pm

*The best times are one hour before to one hour after the above times, which represent peak low tide.

Why do we want to find mussel beds?

For years now, mussel beds have been moving further offshore from the intertidal zone to the subtidal zone. The intertidal zone is the area where the ocean meets the land between high and low tides. The subtidal zone is below mean low tide and is rarely exposed. Maine mussel farmers have been able to collect baby mussels still swimming around to grow and harvest mussels on ropes. The mussels use their byssal threads to stay attached to the ropes which hang down from floating rafts.

Because mussel farms can still catch wild baby mussels and wild mussel harvesters have been able to find mussels in the subtidal zone, we know they are still around. The issue is that we can only see some of the edges of these mussel beds during extremely low tides. Another challenge is that the last time mussel beds were mapped was in the early 2000s by Maine Department Marine Resources (DMR).

Our scientists can use active acoustics to quantify different bottom types by sending sound waves to the ocean floor and measuring the echoes. This is very similar to echo location used by marine mammals. This technique can be used to differentiate active blue mussel beds (Mytilus edulis) from other bottom types. In order to maximize time and effort we need your help to tell us where to go.

Very low or negative tides generally happen when the low-water level is lower than the zero point, tide height is measured with a negative number and is called a minus tide. Tide tables are based on average tidal data obtained at a given location for many years.  On any of these very low tide days, within an hour of low tide, we need folks like you to Show Us Your Mussels!

Contributing to this project is easy. Just head out to the coast, and take a picture of mussel beds (whether or not you see mussels), and enter the data using the Ecosystem Investigation Network.

Our scientists will aggregate your data and create a plan for where to take acoustic measurements to map out the mussel beds. Our lead scientist, Aaron Whitman will have ten days this spring to map mussel beds in Casco Bay. To do this effectively, he needs your help to know where to go.

Project Team

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