First Annual Long Island Natural History Conference


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Thirty Years of Marine Mammals and Sea Turtles around Long Island
Rob DiGiovanni
(Session 2, 10-10:45)

Robert A. DiGiovanni Jr., Allison Chaillet DePerte, Kimberly F. Durham and Julika N. Wocial. Riverhead Foundation for Marine Research and Preservation

The occurrences of marine mammals and sea turtles have been reported opportunistically through the New York State Marine Mammal and Sea Turtle Rescue Program (NYSMMSTRP) for over three decades. Since 1980 the NYSMMSTRP has recovered 4,324 marine mammal and sea turtles. Of these animals 49% (n=2,130) were pinnipeds, 35% (1,523) were sea turtles and 16% (n=671) were cetaceans. These recoveries encompass 27 species of cetaceans, five species of pinnipeds and four species of sea turtles. Five of the whale species and three of the sea turtle species are listed as endangered the remainder of the animals have threatened or protected status.  Since 1996 the Riverhead Foundation for Marine Research and Preservation has been monitoring the marine mammal and sea turtle population in southern New England and the New York Bight. Aerial surveys conducted for whales and dolphins during the fall, winter and spring of 2004-2005 revealed 12 species represented by 2,134 animals encountered in the New York Bight. Recent opportunistic sighting events have reported a group of 150 bottlenose dolphins (Tursiops truncatus) in Long Island Sound during the summer of 2009. Since this initial sighting dolphins have been sighted in Long Island Sound each summer.

Seal survey flights have observed a dramatic increase in harbor seals (Phoca vitulina) since the surveys conducted during the 1980’s. In 2001 sightings of gray seals (Halichoerus grypus) rose from less than 25 animals along the eastern Islands of Long Island to over 195 during a flight conducted in 2008. Recent data suggests these animals may be arriving earlier in the season and remain in the area into late spring early summer.

Sea turtles once thought to be a rare occurrence in New York waters back in the 1980’s are becoming more prevalent in Long Island Sound, the south shore of Long Island and in the bays and estuaries. Previous studies have been limited to the Peconic and Gardiners Bay. Satellite tagged animals have been observed using LIS on a regular basis as well as the western Long Island. An opportunistically recovery of an Atlantic green sea turtle in the Carman’s river located in the north east portion of the Great South Bay is further evidence that more survey work need to be done in these waters.  Although the number of encounters has increased they only represent a fraction of the animals in these waters. More effort is needed to determine the seasonal abundance and distribution of these animals.   

Robert A. DiGiovanni Jr  started his career with marine mammals and sea turtles back in 1992 working with the Okeanos Ocean Research Foundation as a Stranding Technician. While working with the New York State Marine Mammal and Sea Turtle Rescue program he earned his Bachelors degree from Long Island University in 1995. He is one of the principal members of the Riverhead Foundation for Marine Research and Preservation which formed in 1996 picking up where Okeanos left off.  He earned his Master’s degree in Applied Ecology from Stony Brook University in 2001.

He has conducted aerial, land and shipboard surveys for marine mammals and sea turtles since 1995. He has worked extensively with NOAA Fisheries on marine mammal and sea turtle abundance surveys. In 2001, 2011 and 2012 he worked with NOAA Fisheries, Northeast Fisheries Science Center on a harbor seal capture project. He has satellite or radio tracked three species of cetaceans, including the first satellite track of a risso’s dolphin (Grampus griesus).  Through his involvement with the Riverhead Foundation for Marine Research and Preservation he has satellite over 125 animals including four species of pinnipeds and three species of sea turtles in the United States and in Mexico.


© 2012 Long Island Nature Organization, Harbor Electronic Publishing