Increase in Extralimital Records of Harp Seals in Maine. Peter T. Stevick; Thomas W. Fernald

Transcription

1 Increase in Extralimital Records of Harp Seals in Maine Peter T. Stevick; Thomas W. Fernald Northeastern Naturalist, Vol. 5, No. 1. (1998), pp Stable URL: Northeastern Naturalist is currently published by Humboldt Field Research Institute. Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. The JSTOR Archive is a trusted digital repository providing for long-term preservation and access to leading academic journals and scholarly literature from around the world. The Archive is supported by libraries, scholarly societies, publishers, and foundations. It is an initiative of JSTOR, a not-for-profit organization with a mission to help the scholarly community take advantage of advances in technology. For more information regarding JSTOR, please contact support@jstor.org. Mon Mar 31 13:23:

2 1998 NORTHEASTERN NATURALIST 5(1): INCREASE IN EXTRALIMITAL RECORDS OF HARP SEALS IN MAINE ABSTRACT - Between 1994 and 1996 we identified 26 harp seals (Phoca groenlandica Erxleben) between the western shore of Penobscot Bay (44" 05' N, 69" 05' W)and Calais, Maine (45" 11' N, 67" 16' W). This represents a dramatic increase in sightings for this area, from which only three previous records have been published. Most sightings occurred between late January and early April. One individual was an adult with a pup, the first evidence for probable whelping in the region. All other individuals were juveniles, with males more abundant than females. Most individuals appeared to be in good health. A single tagged individual was subsequently reported from Fortune Bay, Newfoundland after having traveled at least 1,250 kilometers in an interval of 34 days. INTRODUCTION Harp seals (Phoca groenlandica Erxleben) are abundant in the northern Atlantic and Arctic Oceans, with estimates of more than half a million pups born each year off Canada (Stenson et al. 1993). They rarely stray far from pack ice at any season of the year (Lavigne and Kovacs 1988, Sergeant 1991). Virtually all whelping activity in the western North Atlantic is restricted to ice in the Gulf of St. Lawrence, and off southeastern Labrador and northeastern Newfoundland (Lavigne and Kovacs 1988; Sergeant 1965, 1991). In summer, this northwest Atlantic group moves north to feed off West Greenland, the Canadian archipelago and northern Labrador (Sergeant 1965). Extralimital records have been scarce (McAlpine and Walker 1990). Prior to 1994, harp seals were virtually unknown along the coast of Maine. McAlpine and Walker (1990) reviewed the extralimital records of the harp seal for the western North Atlantic. They reported only 16 records from New Brunswick south to Virginia between 1841 and Only one of these was a recent sighting from Maine, a 1988 record from Mt. Desert Island. They also included a second Maine record from Penobscot Bay, dated approximately 1892, with few supporting details (citing Norton 1930), and a poorly supported report from Passamaquoddy Bay on the Maine - New Brunswick border (citing Boardman 1903). No additional harp seals were reported through * College of the Atlantic, 105 Eden Street, Bar Harbor, Maine 04609

3 76 Norrheastem Naturalist Vol. 5, No. 1 We report here on the evidence of a dramatic increase in recent sightings in eastern coastal Maine. METHODS The study area extends from Calais, Maine (45" 11' N, 67" 16' W), to the western shore of Penobscot Bay, Maine (44" 05' N, 69" 05' W). This study includes all sightings handled by College of the Atlantic personnel representing the Northeast Regional Stranding Network. The Stranding Network coordinates response to all stranded dead, injured or out-ofhabitat marine mammals. Photographs were taken of most seals to confirm species identification. Sightings for which neither photographs nor specimens were obtained were only considered confirmed if made by staff from College of the Atlantic with experience in identification of harp seals. Response varied with the condition and location of the animal. An external examination was generally performed to assess the health of the individual. Most individuals appeared healthy and were left at the site. Dead animals, or those with obvious signs of trauma or illness were taken to College of the Atlantic or the New England Aquarium (Boston, Massachusetts) for necropsy or treatment. In 1995 and 1996 a total of four harp seals were tagged in the hind flipper using numbered 3 cm x 5 cm white plastic "Allflex" livestock identification tags. Figure 1. Juvenile harp seal (Phoca groenlandica) in spotted coat, from Hulls Cove, Maine, March 18, Photo by Robert Bowman

4 P. T. Stevick and T. W. Fernald RESULTS Reports of harp seals increased dramatically beginning in Twenty-six harp seals were identified between 1994 and 1996 (Table I). No two sightings were confirmed to have been of the same individual, either through tagging or, within a season, through photographs of natural markings. Twenty-four animals were in spotted pelage, indicating an age of at least three or four weeks, but less than about 4 years (Figs. 1 and 2; Lavigne and Kovacs 1988; Sergeant 1991). These individuals were similar in size and patterning and all were classified as juveniles. A single, much larger adult harp was seen with a pup, which was still molting from the lanugo coat. The sex of 11 individuals was determined by examination. Eight were males and two were females. Most individuals appeared to be in good health, were not emaciated, and showed no external symptoms of trauma or disease. Eight individuals were found dead or died shortly after being sighted. Three of these were emaciated, one was decapitated, and one badly decomposed. Two individuals suffered from apparent injuries. On 27 January 1996, a Table 1. Harp seal records between Calais and Penobscot Bay, Maine during 1994, 1995 and Date Location Age Class Notes; Sex /Tag# Bar Harbor Juvenile Bar Harbor Juvenile Dead male, emaciated Bar Harbor Juvenile Hulls Cove Juvenile Small individual Trenton Juvenile Bass Harbor Juvenile Irregular molt Seal Cove Juvenile Dead female, emaciated, infected Somesville Adult / Ragged Jacket (2) Mother / Pup Brooklin Juvenile Bar Harbor Juvenile Tag# 638 Sorrento Juvenile Male, Tag#637 Southwest Harbor Juvenile Dead male, decomposed Lamoine Juvenile Small individual Trenton Juvenile Dead male, head missing Bar Harbor Juvenile Irregular molt Pen-Y Juvenile Male, shot Bar Harbor Juvenile Belfast Juvenile Seal Harbor Juvenile Dead male, emaciated Isle Au Haut Juvenile Southwest Harbor Juvenile Dead male Stonington Juvenile Dead female Southwest Harbor Juvenile Sullivan Juvenile Male, Tag# 629, irregular molt Brewer Juvenile Tag# 628, return to Newfoundland

5 78 Northeastern Naturalist Vol. 5, No. 1 single young male harp seal was found along the coast near Perry, Maine (44" 59' N, 67" 03' W). It was suffering from open infections on several regions of the head. X-ray images showed that it had 10 buckshot pellets in the head and the animal was euthanized. On 8 February 1995, a young harp seal was reported on the ice in Seal Cove, Maine (44" 17' N, 68" 25' W). It had an open wound and extensive infection on the upper jaw and died the following day. Irregular molt was the most common non-fatal abnormality. Three individuals exhibited patches of exposed skin varying from a few cm2 to most of the body. Four seals were tagged, two in 1995 and two in 1996 (Table 1). One tagged seal was subsequently re-identified. On 18 April 1996, an immature harp seal was reported from 44" 47' N, 68" 46' W on the shore of the Penobscot River in Brewer, Maine. A white tag, number 628, was applied to the left rear flipper. On 24 May 1996 the animal was caught in a gillnet set for lumpfish (Cylopterus lumpus Linnaeus) five miles west of Fortune, Newfoundland, Canada (47" 00' N, 56" 00' W). The shortest distance by water between the two sites is approximately 1,250 kilometers (675 nautical miles). On 2 March 1995, two harp seals were reported hauled out on the ice at the mouth of the harbor near Somesville, Maine (44" 21' N, 68" 19' W). The pair consisted of an adult and a young pup. The pup had numerous patches of loose white fur typical of the ragged jacket stage (Stewart and Lavigne 1980, Sergeant 1991). Local residents reported that the animals had been in the area for two days or more before the sighting was confirmed. A third individual, apparently an adult, was Figure 2. Harp seal (Phoca groenlandica), Bar Harbor, Maine, March 8, The spotted pelage is apparent, as is the flexion of the foreflipper typical of the ice breeding seals. Photo by Peter Stevick

6 1998 P. T. Stevick and T. W. Femald 79 reported by a local resident to have hauled out on the ice nearby at one time, but no details were observed of the third individual. DISCUSSION The increase in harp seal numbers was sudden and dramatic. No confirmed reports of harp seals were received between May 1988 and January 1994 in spite of an active and well publicized stranding network. In 1994, five individual harp seals were identified, followed by 11 in 1995 and 10in This increase is unlikely to reflect an increase in effort. While a similar increase in reports of hooded seals (Cystophora cristata Erxleben), another ice breeding species, occurred during the same time period, there was no corresponding increase in reports of strandings of other species during this time or of any increase in winter sightings generally (College of the Atlantic, unpublished data). Reports of sick or abandoned harbor seal (Phoca vitulina Linnaeus) pups have increased steadily over the past 20 years, but this appears to reflect an increase in abundance of this species (Kenney and Gilbert 1994) and has been gradual rather than rapid. When harp seals occurred in the region, they were commonly found on the mainland or larger inhabited islands, where they frequented ledges, sea walls, and even lawns, in contrast to the more commonly occurring harbor and gray seals (Halichoerus grypus Fabricius) which are rarely found in such proximity to inhabited areas. In these locations the harp seals were easily encountered and reported by coastal residents. When response was made, residents were queried on previous sightings of seals in the area and any previous winter sightings. None reported seeing seals in these areas in winter prior to The increase in sightings in Maine probably reflects dispersal from traditional wintering areas in waters off Canada or Greenland, possibly associated with increases in population size or changes in oceanographic conditions. While methodological considerations have complicated analysis of abundance and productivity trends in harp seals (Stenson et al. 1993), recent estimates place the Canadian harp seal population at about 5 million animals (Anonymous 1995) and the population appears to have been increasing since the 1970s (Anonymous 1995, Roff and Bowen 1986, Stenson et al. 1993). The temporal distribution of the Maine sightings corresponds with the timing of migrations to and from traditional whelping areas. While harp seal sightings occurred as early as December 29 and as late as May 6 (Table l), all but three records occurred during a interval of about ten weeks, beginning abruptly in late January. Harp seals normally migrate south from Greenland in the fall and early winter, moving just ahead of the advancing ice. They arrive in the Gulf of St. Lawrence in late December or

7 80 Northeastern Naturalist Vol.5, No. 1 early January (Sergeant 1965). Juveniles generally do not move with the bulk of adults, wandering more widely, arriving later in the Gulf of St. Lawrence, and earlier off eastern Newfoundland (Sergeant 1991). Thus harp seals arrived in Maine at a time consistent with the normal southward movement of juvenile seals. Sightings occurred on a sporadic, but regular basis through February and March, then ended rapidly in early April. This period coincided with the primary whelping period for the Gulf of St. Lawrence from late February through late March (Sergeant 1991). Rapid departure in April corresponded with the normal molt period, when juveniles and adults converge at the southern extremity of the pack ice in preparation for the northerly migration in May (Sergeant 1991). The single tag return was from southern Newfoundland. This is consistent with three previous tag returns from Massachusetts to traditional harp seal feeding areas. In 1989, two tags from releases in Wellfleet, Massachusetts were returned. One individual had traveled to Placentia Bay, Newfoundland, and the other to Paamuit, Greenland (McAlpine and Walker 1990). In 1995, a single individual released in Massachusetts was recaptured in Hermitage Bay, Newfoundland (pers. comm, G. Early, Boston, MA). Three of the four returns were from April releases to May returns. Only one of the 26 individuals identified in Maine during the three years was an adult, while the preponderance were juveniles. These findings are in contrast with those of McAlpine and Walker (1990) who reported a ratio of five juveniles to four adults in their study, and whose only Maine sighting for which age class could be determined was an adult female. Of the 11 individuals where sex was identified by examination, nine were males and only two were females. This also contrasts with the findings of McAlpine and Walker (1990). Of seven individuals reported by them for which sex was recorded, four were females and three were males. The majority of individuals reported here appeared healthy. This further contrasts with the findings of McAlpine and Walker (1990). Of the sixteen individuals in their study, only one was reported to be in good health, while the only recent record reported by them from the geographical area covered here was of a dead individual. The sighting of an adult with a pup in the region was unexpected. Harp seals almost invariably whelp on ice, and sea ice is uncommon, temporary and unpredictable in the Gulf of Maine. The review by McAlpine and Walker (1990) is inconclusive as to the probability of previous breeding in this area. They report skeptically on the undated sighting of a whitecoat pup from Saint John, New Brunswick (citing Squires 1968). They also present the finding of a pup estimated to be between 21 and 28 days from Wellfleet, Massachusetts on 26 February 1988.However, the pup was in beater coat, the stage at which movement

8 1998 P. T. Stevick and T. W. Fernald 81 from the ice to the water is most common. The age of the pup reported here could not be determined with certainty. Pups are normally in ragged jacket stage between 16 and 24 days old (Stewart and Lavigne 1980). That would imply that this individual was born between February 6 and 14. Whelping dates vary considerably from region to region, apparently in relation to ice conditions. In the Gulf of St. Lawrence whelping normally occurs during the first week in March (Sergeant 1991). Thus, if the pup was the typical age for a ragged jacket, it was born about three weeks earlier than normal for the species. It was still in ragged jacket stage when last sighted on March 4. As this stage normally lasts no more than 24 days, it would have been no older than 19 days when first reported in the area. Harp seal pups are generally weaned between 12 and 15 days old, before onset of the ragged jacket stage. However, Kovacs (1987) reported some instances of continued nursing in ragged jackets of undetermined age. No nursing behavior was observed during the three days of intermittent observation. However, weaning is generally characterized by the abrupt departure of the mother, and other individuals do not remain in attendance with pups (Kovacs 1987), so the close association of the two animals over a period of at least five days, and the continued return of the adult, strongly suggested that it was the mother. ACKNOWLEDGMENTS We gratefully acknowledge all of the many individuals who reported sightings to the Stranding Network, especially to Helen Tyson for reporting the adult and pup. Numerous College of the Atlantic staff, students and volunteers were involved in responses to strandings. Wayne Miller of the F/V Bonnie and Denise, Fortune, Newfoundland thoughtfully reported the tag return. This manuscript was greatly improved by comments from James Eddington, Steven Katona, David Sergeant and two anonymous reviewers. Financial support was provided by Allied Whale, College of the Atlantic. LITERATURE CITED ANONYMOUS Report on the status of harp seals in the northwest Atlantic. Department of Fisheries and Oceans Atlantic Fisheries Stock Status Report 95/7. LAVIGNE, D. M., and K. M. KOVACS Harps and Hoods: Ice-breeding Seals of the Northwest Atlantic. University of Waterloo Press, Waterloo. Ontario. 174 pp. KENNEY, M. K., and J. R. GILBERT Increase in harbor and gray seal populations in Maine. Report to National Marine Fisheries Service, Northeast Fisheries Science Center, Woods Hole. MA. 19pp. KOVACS, K. M Maternal behavior and early behavioral ontogeny of harp seals, Phoca groenlandica. Animal Behav. 35:

9 82 Northeastern Naturalist Vol. 5, No. 1 McALPINE, D. F., and R. H. WALKER Extralimital records of the harp seal, Phoca groenlandica, from the western North Atlantic: a review. Mar. Mammal Sci. 6(3): ROFF, D. A,, and W. D. BOWEN Further Analysis of population trends in the northwest Atlantic harp seal (Phoca groenlandica) from 1967 to Can. J. Fish. Aquat. Sci. 43(3): SERGEANT, D. E Migrations of harp seals, Pagophilus groenlandicus (Erxleben), in the Northwest Atlantic. J. Fish. Res. Board Can. 22(2): SERGEANT, D. E Harp Seals, Man and Ice. Can. Spec. Publ. Fish. Aquat. Sci Department of Fisheries and Oceans, Ottawa. 153 pp. STENSON, G. B., R. A. MYERS, M. 0. HAMMILL, I.-H. NI, W. G. WAR- REN, and M. C. S. KINGSLEY Pup production of harp seals, Phoca groenlandica, in the Northwest Atlantic. Can. J. Fish. Aquat. Sci. 50(11): STEWART, R. E. A,, and D. M. LAVIGNE Neonatal growth of northwest Atlantic harp seals, Phoca groenlandicus. J. Mammal. 61(4):