The 100-yard buffer turned not good to protect seals in the glacial fjords of Alaska from cruise ships' and tour boats' disturbances. Federal regulators issued new guidelines that advise ships to stay 500 yards away.
Issued by the National Marine Fisheries Service of National Oceanic & Atmospheric Administration (NOAA), the new guidelines are voluntary but "strongly recommended". They are aimed at the flourishing ship traffic around tidewater glaciers which draw both tourists and harbor seals.
The 100-yard-buffer was determined in the 1990s. Most operators comply with it. However, recent studies revealed that harbor seals are easily disturbed by cruise vessels well beyond 100 m (about 110 yards). Such disturbances make nursing pups particularly vulnerable, according NOAA officials.
A study of NOAA, published in July in the Plos One journal, found that up to 14% of the seals in a fjord had flushed into water when a cruise ship had been present. A previous study found that harbor seals had been 25 times more likely to enter water when ships were 100 m away than they had been if the vessels were 500 m (547 yards) away.
According to NOAA scientists, cruise-ship traffic in Southeast and Southcentral Alaska's glacial fjords has increased 10-fold since 1980s. Still, the activity is unregulated at 4 of the 5 most-visited sites - Disenchantment Bay, Tracy Arm and Endicott Arm in Southeast and College Fjord, Prince William Sound. Glacier Bay National Park, which is the final destination, does have mandatory restrictions in order to protect harbor seals during the pupping season as the concern is about disturbances that could separate mothers and nursing pups. In a study published in 2014, NOAA scientists said that even in Glacier Bay, seals had been disturbed by cruise ships at a distance just under 500 m.
By adhering to the 500 m buffer, cruise operators will avoid violating Marine Mammal Protection Act. A “take” under federal law is anything that causes “any change of behavior on the part of the marine mammal”. As ship traffic causes harbor seals to leave ice haulouts, it could be considered "unauthorized takes".