2012 SOUTHEASTERN NATURALIST 11(1):23–34 First Records of the Melon-headed Whale (Peponocephala electra) and the Atlantic White-sided Dolphin (Lagenorhynchus acutus) in South Carolina James W.B. Powell1,*, David S. Rotstein2, and Wayne E. McFee1 Abstract - From January to May 2008, the first historical strandings of Peponocephala electra Gray (Melon-headed Whale) and Lagenorhynchus acutus Gray (Atlantic White-sided Dolphin) were recorded in South Carolina. A mass stranding of three Melon-headed Whales (2 males, 1 female) was recorded on 11 January 2008 along the Horry County coast in the cities of Myrtle Beach and North Myrtle Beach. Three additional Melon-headed Whales (1 male, 1 female, and 1 unknown sex) stranded as single individuals over the next two months at locations along the South Carolina coast. Lengths of the animals ranged from 161 to 250 cm, and the ages ranged from 1 to 24 years. On 4 May 2008, a single 263- cm, 17-year-old, male Atlantic White-sided Dolphin stranded in Horry County. The most striking commonalities observed during the Melon-headed Whale and Atlantic White-sided Dolphin necropsies were severe pulmonary distress and reactive lymphadenopathy. The strandings reported herein are the first records of Melon-headed Whales and Atlantic White-sided Dolphins in South Carolina. Introduction Prior to 1990, staff from The Charleston Museum responded to a limited number of marine mammal strandings in South Carolina and archived data and information dating back to 1852. From 1990 to 2005, marine mammal stranding response in South Carolina was directed by the South Carolina Department of Natural Resources (SCDNR) in collaboration with the National Ocean Service at the Center for Coastal Environmental Health and Biomolecular Research (CCEHBR) in Charleston under a permit issued from the National Marine Fisheries Service (NMFS). In 2005, the SCDNR relinquished control of the stranding network to CCEHBR until 2008, when Coastal Carolina University assumed the responsibility of managing the marine mammal stranding network. In 2011, all available information regarding historical marine mammal strandings in South Carolina was consolidated from historical archives at SCDNR and The Charleston Museum by the Coastal Marine Mammal Strandings and Assessments Program at CCEHBR, establishing a single source for all available data regarding South Carolina marine mammal strandings. The majority of records contain 1National Oceanic and Atmospheric Administration, National Ocean Service, Center for Coastal Environmental Health and Biomolecular Research, 219 Ft. Johnson Road, Charleston, SC 29412. 219117 Bloomfield Road, Olney, MD. *Corresponding author - james.powell@noaa.gov. 24 Southeastern Naturalist Vol. 11, No. 1 information on strandings of Tursiops truncatus Montagu (Bottlenose Dolphin), other odontocete species, and a few mysticete species, but no prior records of Peponocephala electra Gray (Melon-headed Whale) or Lagenorhynchus acutus Gray (Atlantic White-sided Dolphins) in South Carolina. The Melon-headed Whale is a tropical to subtropical pelagic delphinid distributed worldwide (Perrin 1976, Perryman et al. 1994), preferring deep, equatorial waters (Watkins et al. 1997). Previous records of Melon-headed Whales on the Atlantic coast of the United States are extremely limited, the first of which was a stranding that occurred on Assateague Island, MD, on 23 October 1984 (USNM 550399/WAM007) (Potter 1984). In the years following this first record, only 18 Melon-headed Whale strandings have been recorded along the US Atlantic coast (Table1). Strandings of this species along the US Atlantic coast have increased in recent years, as 16 of the 19 historical cases were recorded in 2006 and 2008. During vessel-based stock assessment surveys performed by the National Marine Fisheries Service (NMFS), Melon-headed Whales were sighted only twice along the Atlantic coast of the United States (1999 and 2002), both in waters greater than 2500 m deep off Cape Hatteras, NC (Waring et al. 2006). Sightings from aerial surveys in the oceanic northern Gulf of Mexico are more frequent and well-documented in all seasons (Mullin et al. 1994, Waring et al. 2006). While the population has not been estimated for the western North Atlantic, the northern Table 1. Field numbers and associated stranding information for historical records of Peponocephala electra on the US Atlantic coast, including first records for South Carolina reported herein. These are data from the NOAA Nationa Marine Mammal Helath and Stranding Response Database (NOAA 2011). Field # Stranding date Stranding location Length (cm) Sex USNM 550399 23 October 1984 Assateague Island, MD 246 F S-98-PE 27 March 1998 Matanzas, fl253 F MMSC 04-084 31 May 2004 Wildwood, NJ 246 M HBOI 0602 29 March 2006 Hutchinson Island, fl246 M HBOI 0603 29 March 2006 Hutchinson Island, fl244 M HBOI 0604 29 March 2006 Hutchinson Island, fl247 M HBOI 0605 29 March 2006 Vero Beach, fl265 M HBOI 0606 29 March 2006 Hutchinson Island, fl262 M CJH007 23 July 2006 Bald Head Island, NC 248 M MDB008 10 May 2008 Pea Island, NC 246 M VAQS20081066 11 June 2008 Chincoteague, VA 248 M VAQS20081069 16 June 2008 Pungoteague, VA 250 M HUBBS-0846-Pe 24 June 2008 Cape Canaveral, fl250 M SC0801 11 January 2008 Myrtle Beach, SC 239 F SC0802 11 January 2008 Myrtle Beach, SC 161 M SC0803 11 January 2008 North Myrtle Beach, SC 185 M SC0804 15 January 2008 Botany Bay Island, SC 250 F SC0805 2 February 2008 Kiawah Island, SC 237 U SC0807 10 March 2008 Raccoon Key, SC 230 M 2012 J.W.B. Powell, D.S. Rotstein, and W.E. McFee 25 Gulf of Mexico population is estimated at approximately 3400 individuals (Mullin and Fulling 2004), with estimated herd sizes ranging from 30 to 400 individuals in water depths from 669 m to over 3200 m. Although the western North Atlantic and the northern Gulf of Mexico stocks are considered separate for management purposes, there are currently no data available to resolve these units as distinct biological populations. The geographic range of the Atlantic White-sided Dolphin spans temperate and sub-polar waters from the Canadian North Atlantic southward to North Carolina (Reeves et al. 1999), stretching across the continental shelf and over submarine canyons, exceeding 2000 m in depth (Gowans and Whitehead 1995). Within their defined geographical range, strandings of Atlantic White-sided Dolphins are not uncommon (NOAA 2011). Although little information exists on the life history and feeding ecology of the species in the northwest Atlantic, sighting and stranding data indicate a shift from January to May away from the Gulf of Maine towards Virginia and North Carolina (Palka et al. 1997). Methods Between 11 January and 10 March 2008, six Melon-headed Whale strandings were recorded in South Carolina. A mass stranding of three whales was recorded on 11 January 2008 along the Horry County coast in the cities of Myrtle Beach (n = 2; SC0801 and SC0802) and North Myrtle Beach (n = 1; SC0803) (Fig. 1). All three whales stranded in a moderate state of decomposition and were located in the surf, suggesting the animals died at sea and were brought in by wind and currents. Over the next two months, three additional Melon-headed Whale strandings were recorded in different areas of Charleston County, SC. The first of these additional whales (SC0804–15 January 2008) was found approximately 200 km south of the mass stranding location on an isolated portion of Edisto Island in an advanced state of decomposition. An unidentifiable carcass reported 9 February 2008 on Kiawah Island (SC0805) was subsequently determined by genetics (Rosel and Block 1996) to be a fifth Melon-headed Whale specimen. On 10 March 2008, a sixth Melon-headed Whale was reported in an advanced state of decomposition on Raccoon Key in the Cape Romain National Wildlife Refuge (SC0807). In addition to the Melon- headed Whales, a single Atlantic White-sided Dolphin stranded in Horry County on 4 May 2008 (SC0814) (Fig. 1). Necropsies were performed on each animal according to established protocols (Geraci and Lounsbury 2005). Sections were collected for histology from various tissues and organs, preserved in 10% neutral buffered formalin, and processed for histology following standard techniques. Additional samples for histopathology were collected from lacerations, open wounds, healed external wounds, scar tissue, and skin lesions. Urine, feces, and stomach fluid were collected when present and analyzed for the harmful algal toxin domoic acid following protocols described in Fire et al. (2009). Thorough necropsies were 26 Southeastern Naturalist Vol. 11, No. 1 performed for each stranding case; however, only the three Melon-headed Whale carcasses involved in the initial mass stranding and the Atlantic Whitesided Dolphin were in adequate condition to provide substantial gross and histopathological findings. Stomachs were excised and complete analysis of gastric compartments was performed. Briefly, each chamber was systematically examined for gastric lesions and washed through a 1-mm sieve to collect any prey items and parasites. Squid beaks were counted and preserved in 70% ethanol. Parasites were preserved in an acetic acid-formaldehyde-alcohol (AFA) solution. Figure 1. Map of coastal South Carolina depicting locations of Melon-headed Whale (P. electra) and Atlantic White-sided Dolphin (L. acutus) strandings. 2012 J.W.B. Powell, D.S. Rotstein, and W.E. McFee 27 In order to estimate age at death, lower left teeth (numbers 13–16) from each animal were removed for age analysis. Teeth collected from SC0805 were no longer intact, so the largest diameter tooth available was selected for age estimation. Teeth were decalcified, sectioned, and stained with hematoxylin following previously established protocols (Hohn et al. 1989). Stained sections were wet mounted onto glass microscope slides and viewed under magnification to count growth layer groups (GLGs). Age estimates were determined based on assigning one year of life to each GLG following the prenatal dentine layer (Table 2). Testes and ovaries were examined to determine degree of sexual maturity. Testes or ovaries were excised, measured (cm), and weighed (g). Notes were made with regards to general size, presence of ovarian scarring, and presence or absence of seminal fluid. Each ovary was manually cross-sectioned anterior to posterior in slices approximately 2 mm in width. Slices were viewed under a dissecting microscope to observe any corpora or follicles. Complete crosssections of each testis were collected in formalin. Multiple sections of each testis cross-section were taken and analyzed through routine histology for degree of spermatogenesis. Skulls from all six Melon-headed Whales, complete skeletons from the three mass-stranded whales, and the complete Atlantic White-sided Dolphin skeleton were retained and processed through a dermestid beetle colony for thorough cleaning prior to analyses. Specimens were examined for skeletal and cranial lesions and anomalies. Twenty-five cranial measurements, adapted from those used by Perrin (1975), were taken to the nearest 0.5 mm from each skull using dial calipers (Table 3). Results Gross necropsy findings The most striking commonalities observed during the necropsies of the mass stranded Melon-headed Whales and the Atlantic White-sided Dolphin Table 2. Life-history characteristics of Peponocephala electra (P. e.) and Lagenorhynchus acutus (L. a.) specimens from South Carolina. Life-history characteristic SC0801 SC0802 SC0803 SC0804 SC0805 SC0807 SC0814 Species P. e. P. e. P. e. P. e. P. e. P. e. L. a. Total length of animal (cm) 239 161 185 250 237 230 263 Sex F M M F U M M Age estimate (years) 7 1 1.5 17 24 22 14 Left testis/ovary length (cm) - 9.5 9.3 - - - 13.5 Left testis/ovary weight (g) - 5.2 9.4 - - - 62.3 Right testis/ovary length (cm) - 10.2 8.6 - - - 15.5 Right testis/ovary weight (g) - 5.8 8.5 - - - 54.6 Presence of seminal fluid N/A No No - - - No Presence of ovarian corpora No N/A N/A - - - N/A Stomach contents Empty Squid Squid - - - Empty 28 Southeastern Naturalist Vol. 11, No. 1 were severe pulmonary distress and reactive lymphadenopathy. Both the left and right lungs were hemorrhagic and congested in each of the carcasses. Pulmonary lymphadenopathy was noted in each Melon-headed Whale carcass. Additionally, the right prescapular lymph node in SC0803 was fibrinous and reactive, and the bronchial cartilage was hemorrhagic. Lymphadenopathy was observed in the pulmonary, retropharyngeal, and lung associated lymph nodes of SC0814. In addition to the hemorrhaging observed in the lungs of all three Melonheaded Whales, hemorrhagic tissues were also noted in other major organs. The kidneys of SC0801 and SC0803 were hemorrhagic, and blood was noted to be pooling internally in the kidneys of SC0801. The brain of SC0802 was severely hemorrhagic; a copious amount of blood was noted in the braincase. SC0803 had the most extensive degree of hemorrhaging of the three whales, with nearly every major organ described as hemorrhagic. Table 3. Cranial measurements of P. electra and L. acutus specimens from South Carolina. All meristics are presented in millimeters (mm). Meristic SC0801 SC0802 SC0803 SC0804 SC0805 SC0807 SC0814 Condylobasal length 481.0 349.0 411.0 469.5 470.0 461.0 427.0 Length of rostrum 259.5 179.0 219.0 249.0 255.5 253.0 218.0 Width of rostrum at base 141.0 89.5 113.0 144.0 141.0 147.0 115.0 Rostrum width 60mm from base 120.0 68.5 82.0 110.0 110.5 115.0 84.0 Rostrum width ½ length 94.5 59.5 72.5 91.0 93.0 99.0 71.5 Rostrum width ¾ length 68.5 42.5 53.5 67.0 70.0 74.0 55.5 Premaxillary width at base 76.0 62.0 65.0 78.5 77.0 81.5 65.5 Premaxillary width at ½ length 65.0 34.5 42.5 56.5 60.5 61.0 42.0 Max width of premaxillaries 97.0 78.4 82.0 98.5 96.0 96.0 88.0 Tip of rostrum to external nares 326.0 219.0 266.0 323.0 324.0 320.0 283.0 Width of external nares 62.0 52.5 51.5 56.0 57.0 61.0 60.0 Maximum preorbital width 245.0 171.5 192.0 238.0 240.5 241.5 218.5 Maximum postorbital width 270.0 185.5 206.0 261.0 265.0 264.0 235.0 Maximum parietal width 198.5 161.5 168 201.0 190.5 199.0 202.0 Length of orbit 73.0 61.5 69.5 73.0 72.5 72.0 59.0 Length of antorbital process 47.0 34.5 39.5 53.0 50.0 55.0 59.0 Length of temporal fossa 101.0 70.0 75.5 88.0 99.0 88.5 82.0 Height of temporal fossa 67.0 46.0 55.0 63.5 68.0 57.0 42.0 Tip of rostrum to internal nares 309.0 200.0 250.0 295.5 290.0 282.0 253.0 Width of internal nares 71.0 54.0 64.5 76.0 76.0 75.0 73.0 Zygomatic width 264.0 181.0 227.0 258.0 262.5 261.5 230.0 Length of ramus 383.5 275.0 323.5 376.0 371.0 371.0 354.5 Height of ramus 92.0 64.0 74.5 87.0 94.5 87.5 68.5 Length of upper left toothrow 188.5 129.0 155.5 179.0 185.5 170.5 192.5 Length of lower left toothrow 172.5 134.5 147.7 168.0 172.5 155.0 189.0 Number of upper left teeth 22 - 24/24 23 21 - 36 Number of upper right teeth 22 - 24/24 23 22 20 36 Number of lower left teeth 22 24 24 24 21 20 37 Number of lower right teeth 22 24 24 22 20 20 36 2012 J.W.B. Powell, D.S. Rotstein, and W.E. McFee 29 Gastrointestinal abnormalities were noted in Melon-headed Whale cases SC0801 and SC0802, as well as Atlantic White-sided Dolphin case SC0814. Brown, watery fluid was collected from the intestines and stomach of SC0801 and SC0802. The intestinal walls of SC0801 and the gastric lining of SC0802 were hemorrhagic and thickened in comparison to the other Melon-headed Whale specimens observed. A green, viscous fluid was collected from the intestines of SC0814, and the mesenteric lymph nodes were reactive. Numerous parasitic cestode cysts were observed in the peritoneal cavities of SC0801, SC0807, and SC0814. Nematode parasites were found in each of the stomachs of the Melon-headed Whales and the Atlantic White-sided Dolphin. Parasitic cysts were observed in the lining of the fundic and pyloric chambers in SC0801 and in the lining of the fundic chamber of SC0803. Cardiac examination revealed thickened and rigid left ventricles in all three Melon-headed Whales and the Atlantic White-sided Dolphin (2.3, 2.0, 2.0, and 4.6 cm) when compared to the right ventricles (0.7, 0.8, 0.3, and 1.4 cm). The Atlantic White-sided Dolphin specimen presented with numerous lacerations and puncture wounds to the left side of the body, including a completely severed dorsal fin, two straight-line lacerations 37 cm in length, and 14 puncture wounds ranging from 1 to 4 cm in width. These wounds are similar in appearance to wounds on carcasses that have been involved with fishery interactions. All wounds appeared to have expanded with decomposition and the associated blubber and muscle did not appear hemorrhagic. Domoic acid (DA) was not detected in any sample (urine, feces, or stomach fluid) from any of the stranded individuals tested. The limit of quantification (LOQ) of this method was 1 ng DA per mL urine and stomach fluid and 4 ng DA per gram fecal sample, with a signal-to-noise ratio slightly above ten for standards. Histopathological findings Histopathology was only performed on samples from the three Melon-headed Whales involved in the 11 January 2008 stranding and on the Atlantic Whitesided Dolphin. Significant histological findings were not observed including disseminated infection, systemic inflammation, or major organ (kidney, liver, brain, lung, heart) specific changes that would lead to organ dysfunction. All cases had evidence of congestion in the lung and liver reflecting terminal stasis of blood. Findings in SC0801 included pulmonary interstitial fibrosis. Interstitial fibrosis is a non-specific reparative change that could indicate a site of prior infection with parasites, bacteria, or viruses. Histological findings from SC0802 were limited to lymphoplasmacytic interstitial pneumonia alveolar histiocytosis. Similar to SC0801, the changes were chronic, and a causal agent was not present. Histological findings from SC0803 included mild pulmonary interstitial fibrosis, mild myocarditis, granulomatous lymphadenitis of the pulmonary lymph node, and granulomatous gastritis (tunica muscularis). Granulomas within the pulmonary lymph node and stomach indicate sites of prior parasitic infestation. Skin lesions collected from SC0802 and SC0803 were characterized by fibrosis and 30 Southeastern Naturalist Vol. 11, No. 1 epithelial hyperplasia with ballooning degeneration, which is characteristic of poxviral dermatitis. Histopathological findings from the Atlantic White-sided Dolphin were rather limited, as no evidence of systemic infection or disease was observed. The aforementioned punctures and lacerations were determined to have been inflicted post-mortem given the lack of superficial inflammation or fibrin exudation at the site of the lesions. Life history Previous studies have demonstrated that Melon-headed Whales prey primarily on mesopelagic squid and fish species found in waters up to 1500 m deep (Jefferson and Barros 1997) and that Atlantic White-sided Dolphins prey on Illex illecebrosus LeSeur (Short-finned Squid), Clupea harengus L. (Atlantic Herring), and Merluccius bilinearis Mitchill (Silver Hake) (Sergeant et al. 1980). Gastric analyses in this study revealed minimal stomach contents. The stomachs of SC0801 and SC0814 were empty, and the stomachs of SC0802 and SC0803 contained two squid beaks each, demonstrating that the whales and dolphin did not appear to have been actively feeding prior to death. Due to the advanced state of decomposition and severe degree of abdominal and peritoneal scavenging in SC0804 and SC0805, the sex of these two individuals could not be determined upon initial gross investigation. A molecular sexing method (Rosel 2003) targeting the ZFX and SRY genes was used to determine the sex of individuals that could not be sexed morphologically. Molecular methods successfully identified one individual that could not be sexed morphologically as a female (SC0804). The remaining unknown sample (SC0805) could not be sexed using molecular methods, presumably due to extensive DNA degradation. Gross anatomical observation indicated that SC0801 was sexually immature as characterized by small, smooth ovaries that lacked any external signs of scarring and no internal evidence of corpora or follicles (Akin et al. 1993). The sizes of the testes and undeveloped vas deferens and epididymi observed in SC0802 and SC0803 suggest both animals were also sexually immature, as would be expected due to the young ages of the animals (Akin et al. 1993). Gonads from SC0804, SC0805, and SC0807 were not available for analysis due to condition of the carcasses. Life-history characteristics and data collected from each animal reported herein are presented in Table 2. Samples from cross sections of both the left and right testis of SC0802 and SC0803 were examined through routine histology. The sections were consistent with testes with minimal activity characterized by prominent germ cells and the presence of few spermatogonia within the tubular lumina. No development into spermatocytes or other latter developmental stages of spermatogenesis were observed. SC0814, the Atlantic White-sided Dolphin specimen, was determined to be sexually maturing, as indicated by histological findings. Seminiferous tubules in samples from both the left and right testis were lined by a single layer of 2012 J.W.B. Powell, D.S. Rotstein, and W.E. McFee 31 well-developed germ cells. In random tubules, maturation of spermatagonia into spermatids was observed; however, overall, the number of mature spermatids was relatively low, and only rare tubules contained clumped sperm. Interestingly, the Atlantic White-sided Dolphin specimen displayed physical maturity, as evident by fusion of the epiphyseal discs, prior to being sexually mature, suggesting testicular recrudescence. Incomplete ossification of the exoccipitals was observed in SC0801, SC0802, and SC0803, potentially due to normal development, as these were the youngest individuals. No additional cranial lesions were observed in any individual. Vertebral epiphyses were unfused in all three Melon-headed Whales from the mass stranding event (SC0801, SC0802, and SC0803) and completely fused in SC0807. Vertebrae were not available for SC0804 and SC0805. The epiphyseal discs were completely fused in the Atlantic White-sided Dolphin specimen, and the first 5 cervical vertebrae were completely fused to one another, exhibiting complete skeletal, or physical, maturity. Discussion Causes of death could not be determined in any of the Melon-headed Whale or Atlantic White-sided Dolphin specimens through gross necropsy or histopathology. The specimens were characterized by systemic pulmonary distress and lymphadenopathy, as well as drastically limited feeding, pathological characteristics not atypical of common maladies observed in other stranded cetaceans. The unique occurrence of these individuals coincided in relative temporal proximity to strandings of other species rarely observed in South Carolina, including a mass stranding of three live Feresa attenuata Gray (Pygmy Killer Whale) in August 2007 and a live Mesoplodon densirostris de Blainville (Blainville’s Beaked Whale) in September 2007. Geographical ranges of most small cetacean species, while rather widespread, are typically limited to specific water temperatures. The correlation between oceanic water temperatures and the geographical distribution of a particular species is thought to be driven by many factors, including prey distribution (Learmonth et al. 2006) and ecological competition (MacLeod et al. 2008). Any long-term changes to oceanic temperature could lead to a shift in geographical distribution of a given species with varying effects on the individuals based on their biological tolerance for such ecosystem alterations. MacLeod (2009) proposed that global climate change and the resultant increase in oceanic water temperatures could change the geographical range of certain cetacean species and, in some species, ultimately lead to extinction. MacLeod hypothesizes that certain characteristics, such as the restriction to non-tropical waters observed in Atlantic White-sided Dolphins, predispose some species to greater risk from such changes. An increase in oceanic water temperature ultimately leads to a negative effect on the conservation of these species. Changes in oceanic water temperature and the resultant shift in range is expected to have 32 Southeastern Naturalist Vol. 11, No. 1 either a positive or no effect on other species such as Melon-headed Whales and Pygmy Killer Whales, due primarily to their increased resilience exhibited by being found in a wider temperature range than species limited to non-tropical and polar waters (MacLeod 2009). Initial studies reported the southernmost limit for Atlantic White-sided Dolphins as 41°N, just below Cape Cod, based on a harpooned specimen in 1954 (Schevill 1956). The range was expanded further south to 38°N when a specimen stranded dead immediately south of the Virginia–Maryland border in 1977, extending the range into the Middle Atlantic Bight (Testaverde and Mead 1980). Palka et al. (1997) extended the known distribution of Atlantic White-sided Dolphins to 35°N. SC0814 stranded dead, in relatively good body condition, at 33°N, providing evidence to support a further extension of the known geographical range to at least the border between North Carolina and South Carolina. The strandings reported herein are the first records of Melon-headed Whales and Atlantic White-sided Dolphins in South Carolina. Additionally, the Melonheaded Whale mass stranding is only the second of its kind on the Atlantic coast of the United States. Continued monitoring of free-ranging stocks of these species, as well as strandings investigations, will help to identify patterns of occurrences and elucidate possible causes of mortality. Acknowledgments The authors would like to thank the South Carolina Marine Mammal Stranding Network and additional volunteers and agencies who assisted with stranding response, carcass retrieval and transport, and subsequent necropsies of the cases reported herein. Biotoxin analyses were provided by Dr. Zhihong Wang of the NOAA/NOS Marine Biotoxins Program, and molecular analyses were performed by Lara Adams of the NOAA/ NOS Marine Forensics Program. The authors are grateful for contributions from Dr. Aleta Hohn and Mr. William A. McLellan, as well as NOAA internal reviewers Scott Cross, Spencer Fire, and Tom Greig, in enhancing the quality of this manuscript. This research was made possible through NOAA’s responsibility under the Marine Mammal Health and Stranding Response Act, Section 109(h). 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