https://www.mass.gov/files/documents/2019/03/08/Whale%20Speed%20Limit_030819.pdf

The Division of Marine Fisheries has enacted two emergency regulations to protect vulnerable aggregations of endangered northern right whales in Cape Cod Bay. These regulations, effective immediately, are designed to reduce the risk of collisions with vessels and entanglements.

Vessel Speed Limit

Through May 15, 2018 a 10 knot vessel speed limit will be in effect for those waters of Cape Cod Bay south of 42° 08’ north latitude and those waters north of Cape Cod east of 70° 10’ (map). Exempt from this rule are emergency and enforcement vessels, as well as those vessels operating within Plymouth Bay shoreward of Gurnet Point and Barnstable and Wellfleet Harbors. This new state rule applies only to vessels less than 65’ overall length; vessels greater than 65’ length operating in state and adjacent federal waters are already subject to a longstanding seasonal federal 10 knot vessel speed limit. The duration when this speed restriction is in effect may be shortened based on the results of continuing aerial surveys by PCCS.

Right whales are critically endangered species. They seasonally migrate into Massachusetts waters and aggregate in Cape Cod Bay to feed on zooplankton. In recent years more than 50% of the known right whale population is observed in our waters during late winter/early spring. The most recent aerial survey on April 22, 2018 observed more than 100 right whales within Western Cape Cod Bay, about 25% of the known population. The right whale population has been decreasing since 2010 due to continued mortality and low birth rates. The most persistent sources of human-caused mortality are ship strikes and entanglements with fishing gear.