WEST BOOTHBAY HARBOR — Marine scientists and lobster harvesters in Maine’s largest fishery say some fishermen may be abandoning a key conservation method practiced for nearly 100 years at a time of growing fears that a run of record hauls is coming to an end.

The mandatory practice, called v-notching, requires lobstermen to mark the tail flipper of any egg-bearing lobster they catch and then let it go. The notch alerts other lobstermen that lobster is off-limits and helps ensure the future of the species.

State officials say about 66 percent of egg-bearing females surveyed in 2013 were v-notched, down from nearly 80 percent in 2008.

The decline comes at a time when the state’s lobster catch has boomed from about 70 million pounds in 2008 to more than 125 million pounds in 2013.