Active and Closed Unusual Mortality Events

Since 1991, 72 marine mammal unusual mortality events have been declared.

Active Unusual Mortality Events

No.	Year Declared	Name	Species	Body of Water/Location	Cause
65	2018	Atlantic Minke Whale	Minke whale	Atlantic Ocean	Suspect Human Interaction (Entanglement)/Infectious Disease
64	2017	North Atlantic Right Whale	North Atlantic right whale	Atlantic Ocean, Canada, and U.S.	Human Interaction (Vessel Strike/Rope Entanglement)
63	2017	Atlantic Humpback Whale	Humpback whale	Atlantic Ocean	Suspect Human Interaction (Vessel Strike)

Nonactive Unusual Mortality Events—Closure Pending

No.	Year Declared	Name	Species	Body of Water/Location	Cause
67	2018	Northeast Pinniped	Harbor and gray seal	Atlantic Ocean	Infectious Disease

Closed Unusual Mortality Events

No.	Year Declared	Name	Species	Body of Water/ Location	Number of Animals	Date Range	Cause
71	2021	Atlantic Florida Manatee	Manatee	Atlantic Ocean, Florida	1,392	December 1, 2020 through April 30, 2022	Malnutrition secondary to ecological factors (e.g. change in forage)
70	2019	Alaska Ice Seal	Bearded, ringed, and spotted seal	Bering and Chukchi Seas	284	June 1, 2018 through December 31, 2019	Ecological Factors
72	2022	Maine Pinniped	Harbor and gray seal	Atlantic Ocean	181	June 20 to July 20, 2022	Infectious Disease
69	2019	Northern Gulf of Mexico Bottlenose Dolphin	Bottlenose dolphin	Northern Gulf of Mexico, Florida Panhandle, Alabama, Mississippi, Louisiana	337	February 1, 2019 to November 30, 2019	Ecological Factors
68	2019	West Coast Gray Whale	Gray Whale	Pacific Ocean	690	December 17, 2018 to November 9, 2023	Ecological Factors
66	2018	Southwest Florida Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico	183	July 1, 2018 to June 30, 2019	Biotoxin
62	2015	Guadalupe Fur Seal and Northern Fur Seal	Guadalupe fur seal and northern fur seal	Pacific Ocean, California, Oregon, and Washington	715 Guadalupe fur seals; 170 northern fur seals	January 1, 2015 to September 2, 2021	Ecological factors
61	2015	Alaska and British Columbia Large Whale	Fin and humpback whale	Pacific Ocean, Gulf of Alaska, United States; British Columbia, Canada	52	April 23, 2015, to April 16, 2016	Undetermined; secondary ecological factors
60	2013	Mid-Atlantic Bottlenose Dolphin	Bottlenose dolphin	Atlantic Ocean, New York to Florida	~1,650	July 1, 2013, to March 1, 2015	Infectious disease
59	2013	Florida Indian River Lagoon Bottlenose Dolphin	Bottlenose dolphin	Atlantic Ocean, Indian River Lagoon, Florida	79	January 9, 2013, to December 31, 2013	Ecological factors
58	2013	Florida East Coast Manatee	Manatee	Indian River Lagoon, Florida-East Coast	111	January 1 to December 26, 2013	Infectious disease secondary to ecological factors (e.g. change in forage)
57	2013	California Sea Lion	California sea lion	Pacific Ocean, California	8,122	January 1, 2013, to September 30, 2016	Ecological Factors
56	2012	Texas Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico, Texas	126	November 1, 2011, to March 31, 2012	Biotoxin
55	2011	Alaska Pinniped	Bearded, ribbon, ringed, spotted seal, and walrus	Bering and Chukchi Seas, Alaska	~657	May 1, 2011, to December 31, 2016	Undetermined
54	2011	Northeast Pinniped	Gray and harbor seal	Atlantic Ocean, Maine, New Hampshire, Massachusetts	784	June 1, 2011, to November 15, 2012	Infectious Disease
53	2011	South Carolina Bottlenose Dolphin	Bottlenose dolphin	Atlantic Ocean, South Carolina	37	February 27, 2011, to May 30, 2011	Undetermined
52	2011	Florida Manatee	Manatee	Atlantic Ocean, Gulf of Mexico, Florida	143	December 16, 2010, to February 13, 2011	Ecological Factors
51	2010	Florida St. Johns River Bottlenose Dolphin	Bottlenose dolphin	St. Johns River, Florida	23	May 24, 2010, to November 7, 2010	Undetermined
50	2010	Northern Gulf of Mexico Cetacean	Bottlenose dolphin, Atlantic spotted dolphin, spinner dolphin, melon-headed whale, sperm whale, pygmy sperm whale , dwarf sperm whale, pantropical spotted dolphin, Gulf of Mexico Bryde’s whale, minke whale, short-finned pilot whale, Risso’s dolphin, Blainville’s beaked whale, Clymene dolphin, rough-toothed dolphin	Northern Gulf of Mexico, Florida Panhandle, Alabama, Mississippi, Louisiana	1,141	March 2010 to July 2014	Human Interaction
49	2010	Florida Manatee	Manatee	Atlantic Ocean, Gulf of Mexico, Florida	~529	January 11, 2010, to April 9, 2010	Ecological Factors
48	2009	Virginia Bottlenose Dolphin	Bottlenose dolphin	Atlantic Ocean, Virginia	40	April 21, 2009, to June 30, 2009	Undetermined
47	2008	California Harbor Porpoise	Harbor porpoise	Pacific Ocean, California	170	May 1, 2008, to December 31, 2009	Ecological Factors
46	2008	Indian River Lagoon Bottlenose Dolphin	Bottlenose dolphin	Atlantic Ocean, Indian River Lagoon, Florida	48	May 2, 2008, to September 4, 2008	Undetermined
45	2008	Mid-Atlantic Small Cetacean	Short-beaked common dolphin, Atlantic white-sided dolphin	Atlantic Ocean, New Jersey to North Carolina	35	January 1, 2008, to April 26, 2008	Undetermined
44	2008	Texas Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico, Texas	113	February 1, 2008, to March 31, 2008	Undetermined
43	2007	Northwest Guadalupe Fur Seal	Guadalupe fur seal	Pacific Ocean, Oregon, Washington	29	June 20, 2007, to March 31, 2008	Undetermined
42	2007	California Blue Whale	Blue whale	Pacific Ocean, California	6	September 8, 2007, to November 29, 2007	Human Interaction
41	2007	Southwest Florida Manatee	Manatee	Gulf of Mexico, Southwest Florida	54	March 7, 2007, to April 28, 2007	Biotoxin
40	2007	California Cetacean	Short-beaked common dolphin, harbor porpoise, minke whale, sperm whale	Pacific Ocean, California	91	February 10, 2007, to September 30, 2007	Undetermined
39	2007	Texas to Louisiana Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico, Texas, and Louisiana	65	February 27. 2007 to July 26, 2007	Undetermined
38	2006	Everglade Manatee	Manatee	Gulf of Mexico, Everglades, Florida	24	November 9, 2006, to December 31, 2006	Biotoxin
37	2006	Northwest Harbor Porpoise	Harbor porpoise	Pacific Ocean, Pacific Northwest	114	January 11, 2006, to December 20, 2007	Undetermined
36	2006	Northeast Pinniped	Gray, harbor, harp, and hooded seal	Atlantic Ocean, Maine to Virginia	~800	April 20, 2006, to October 31, 2007	Infectious Disease
35	2005-2006	Northeast Large Whale	Humpback whale	Atlantic Ocean, Maine to Virginia	48	January 1, 2006, to December 31, 2007	Undetermined
34	2006	Alaska Sea Otter	Sea otter	Pacific Ocean, Alaska	~491	January 1, 2004, to October 1, 2012	Undetermined
33	2005-2006	Florida Panhandle Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico Panhandle, Florida	~93	September 19, 2005, to April 30, 2006	Biotoxin
32	2005	Northeast Large Whale	Minke, humpback, and fin, and sperm whale	Atlantic Ocean, Canada to Maryland	34	July 1, 2005, to November 7, 2005	Undetermined
31	2005	North Carolina Harbor Porpoise	Harbor porpoise	Atlantic Ocean, North Carolina	43	February 12, 2005, to May 8, 2005	Undetermined
30	2005	West Florida Multi-Species	Bottlenose dolphin, manatee	Gulf of Mexico, Florida	~190 dolphins; ~92 manatees; ~38 manatees	July 1, 2005, and Nov 30, 2006; March 4, 2005, to December 31, 2005; July 17, 2006, to December 31, 2006	Biotoxin
29	2004	Virginia Small Cetacean	Bottlenose dolphin, harbor porpoise, Atlantic white-sided dolphin, short-beaked common dolphin, Risso’s dolphin, short- and long-finned pilot whale, minke whale	Atlantic Ocean, Virginia	~52	May 1, 2004, to July 12, 2004	Undetermined
28	2004	Mid-Atlantic Small Cetacean	Bottlenose dolphin, short-beaked common dolphin, Risso's dolphin, pygmy sperm whale, short-finned pilot whale, dwarf sperm whale, minke whale, Atlantic white-sided dolphin, Atlantic spotted dolphin, pantropical spotted dolphin, Clymene dolphin, Sowerby’s beaked whale, Gervais’ beaked whale, fin whale	Atlantic Ocean, New Jersey, Maryland, North Carolina, South Carolina, Georgia	~37	July 1, 2004, to December 31, 2004	Undetermined
27	2004	Florida Panhandle Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico, Panhandle, Florida	107	March 10, 2004, to April 13, 2004	Biotoxin
26	2003-2004	Northeast Minke Whale and Harbor Seal	Minke whale, harbor seal	Atlantic Ocean, Maine	~22 minke whales; ~42 harbor seals	May 1, 2003, to November 30, 2003	Undetermined
25	2003	Florida Manatee	Manatee	Gulf of Mexico, Florida	~96	March 2 to September 3, 2003	Biotoxin
24	2003	Gulf of Maine Large Whale	Humpback whale, fin whale, minke whale, long-finned pilot whale	Atlantic Ocean, Gulf of Maine, Canada to Massachusetts	21	June 17, 2003, to September 1, 2003	Undetermined
23	2003	California Sea Otter	Sea otter	Pacific Ocean, California	~69	January 1, 2003, to October 1, 2003	Ecological Factors
22	2002	Florida Manatee	Manatee	Gulf of Mexico, Florida	34	March 10, 2002, to April 8, 2002	Biotoxin
21	2002	California Multi-Species	California sea lion, short-beaked common dolphin, sea otter	Pacific Ocean, California	~500	January 1, 2002, to December 31, 2002	Biotoxin
20	2001	Hawaiian Monk Seal	Hawaiian monk seal	Pacific Ocean, Northwest Hawaiian Islands	~11	March 24, 2001, to February 5, 2002	Ecological Factors
19	2001	Florida Indian River Lagoon Bottlenose Dolphin	Bottlenose dolphin	Atlantic Ocean, Indian River Lagoon, Florida	~30	May 1, 2001, to October 31, 2001	Undetermined
18	2000	Harbor Seal	Harbor seal	Pacific Ocean, California	~26	Not Available	Infectious Disease
17	2000	California Sea Lion	California sea lion	Pacific Ocean, California	184	June 23, 2000, to December 1, 2000	Biotoxin
16	1999-2001	Pacific Gray Whale	Gray whale	Pacific Ocean, California, Oregon, Washington	~651	January 1, 1999, to December 31, 2000	Undetermined
15	1999-2000	Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico, Panhandle, Florida	115	August 5, 1999, to May 20, 2000	Biotoxin
14	1998	California Sea Lion	California sea lion	Pacific Ocean, California	70	May 15, 1998, to June 19, 1998	Biotoxin
13	1997	Harbor Seal	Harbor seal	Pacific Ocean, California	~90	Not Available	Infectious Disease
12	1996	Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico, Mississippi	~30	Not Available	Undetermined
11	1996	Florida Manatee	Manatee	Gulf of Mexico, Florida	149	March 5, 1996, to April 27, 1996	Biotoxin
10	1996	Right Whale	North Atlantic right whale	Atlantic Ocean, Georgia, Florida	~6	Not Available	Human Interaction
9	1994	Texas Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico, Texas	~72 (57)	December 1, 1993, to April 30, 1994	Infectious Disease
8	1994	California Common Dolphin	Short-beaked common dolphin	Pacific Ocean, California	~53	Not Available	Undetermined
7	1993	Pinniped	California and Steller sea lion, harbor seal	Pacific Ocean, Washington	~53	Not Available	Human Interaction
6	1992-1993	California Sea Lion	California sea lion	Pacific Ocean, California	~1000	January 1, 1992, to December 31, 1992	Ecological Factors
5	1992	Texas Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico, Texas	220	January 1, 1992, to May 31, 1992	Undetermined
4	1992	Northeast Pinniped	Gray and harbor seal	Atlantic Ocean, Maine to Massachusetts	~24	September 1, 1991, to April 30, 1992	Undetermined (suspect Infectious Disease)
3	1991	Bottlenose Dolphin	Bottlenose dolphin	Gulf of Mexico, Sarasota, Florida	30	Not Available	Undetermined
2	1991	California Sea Lion	California sea lion	Pacific Ocean, California	~160	September 1, 1991, to December 31, 1991	Infectious Disease
1	1991	Northeast Pinniped	Harbor seal	Atlantic Ocean, New Jersey	~34	Not Available	Undetermined

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Last updated by Office of Protected Resources on 03/27/2025

Unusual Mortality Event Marine Mammal Health and Stranding Response Program

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