A dead porpoise washed up at Rossall, the Fleetwood Coastguard team said.
Its measurements were taken for the Natural History Museum before the carcass was reported to Wyre Council.
A dead porpoise also washed up at Blackpool this week.
Earlier this year, experts told The Gazette the increasing number of porpoises washing up proves efforts to clean up the Irish Sea are working.
“The Irish Sea is hugely important,” senior campaigns officer for the Wildlife Trust in Lancashire, Alan Wright, said.
“Its muddy image is brilliant for wildlife because it actually means it supports lots of different creatures, from small micro-organisms that feed smaller wildlife like prawns, crabs, and other shellfish.
“They, in turn, feed larger fish like mammals and sea birds. Jellyfish are abundant. We see many washed ashore, and they are food for turtles.”