Ringed seals (Phoca hispida) in Thesiger Bay (about 71 °45'N, 125°00'W), in northwestern Amundsen Gulf in the western Canadian Arctic, suffered a failure of pup production in the years before 1987, starting probably in 1984. Pups taken in the summer hunt in the years before 1987 were reported scarce, and in 1987 were only 2.8% of the total 4+ and older. This low reproduction was associated with poor body condition in females and with an age distribution of adults that was weighted toward older animals (the modal year class was the 8+ class). An unusually high proportion of adult females had never reproduced; the median age of first birth was estimated at 8.6 years. By the summer of 1988 the age distribution had changed toward younger animals (modal age 5+), in better condition (by 20%), which had almost all ovulated. Pups were more numerous in the catch. In 1989 pups were very numerous in the catch (142% of the 4+ adults) and the estimated mean ageof first birth had decreased to 5.3 years; almost all 5-year-olds sampled had borne pups. A similar occurrence of low pup production had been documented in the early 1970s, and resumption of reproductive activity had then also been associated with an apparent turnover of the population, the mean age of adults decreasing from 16-17 years when reproduction was low to 10.9 years in the year before reproduction resumed. Long-term data on ringed seals in the western Canadian Arctic has shown an average age at first ovulation of about 5.55 years and first birth just before age 7, about 1 year older than seen in this sample in 1989. Our 1989 sample may have been able to mature earlier because food was temporarily more abundant, or breeding densities temporarily lower, than long-term average values.
The northern fulmar Fulmarus glacialis is a medium-sized seabird with a broad, circumpolar range in the northern hemisphere, and is the only petrel that inhabits the High Arctic. We used stomach analysis and stable isotopes (δ 15 N, δ 13 C) of muscles to examine the diet of 179 fulmars during the breeding season at 4 locations in Arctic Canada, to compare diet to those from studies conducted in these regions > 2 decades earlier. Across sampling locations, cephalopods, polychaetes and crustaceans dominated dietary remains in fulmars, although there was some regional variation. Both stable isotopes and stomach dissections showed that a seasonal shift in diet occurred in May, after which fulmars fed at a higher trophic level, suggesting a difference in winter/migration diet and breeding season diet. After migration, fulmar digestive organs decreased markedly in size, and by the time chicks were hatching, these organs were still 17 to 39% smaller than their size when birds arrived at the colony. Despite ongoing changes in the marine environment in much of the Arctic due to global warming, recent fulmar diet samples were similar to samples collected in the 1970s and 1980s, except that a higher proportion of recent collections contained fish. KEY WORDS: Arctic · Cephalopod · Crustacean · Procellariiformes · Reproduction Resale or republication not permitted without written consent of the publisherAquat Biol 10: [181][182][183][184][185][186][187][188][189][190][191] 2010 fulmar diet in the High Arctic, although it appears to rely more on invertebrates in this region, particularly early in the breeding season, than farther south (Hatch & Nettleship 1998, Mallory 2006.We examined the diet of fulmars at several locations in the Canadian High Arctic. This region is experiencing environmental changes, including less extensive and thinner sea ice cover, earlier ice breakup, later ice formation and in some cases warmer sea surface temperatures (ACIA 2005). Most High Arctic marine birds use ice edges, leads and polynyas as important foraging locations because these sites are often highly productive and provide the only open water areas where prey are accessible (Brown & Nettleship 1981, Stirling 1997. In fact, in the Canadian Arctic, most polynyas and recurrent ice leads have been identified as key marine habitat sites for migratory birds (Mallory & Fontaine 2004). Thus, long-term changes in marine environmental conditions may influence the timing and availability of prey for breeding marine birds. For example, Gaston et al. (2003) found that the diet of thick-billed murres Uria lomvia at one Arctic colony switched from ice-associated Arctic cod Boreogadus saida to warmer-water capelin Mallotus villosus over a 20 yr period. Such changes in marine food webs could potentially influence reproduction of marine birds through changes in prey availability or diet quality. Consequently, our study sought to: (1) establish a baseline of dietary information for fulmars at locations where this had not been investigated previ...
ABSTRACT. A subsistence hunt for eiders by Inuvialuit of Holman, Northwest Territories, was observed over three spring harvest seasons from 1996 to 1998 to determine rates of crippling loss and to assess the sustainability of the harvest. King eiders (Somateria spectabilis) are the dominant waterfowl species harvested. The number of king eiders estimated to migrate past Holman in spring varied from 40 696 ± 4461 (95% confidence interval) in 1996 to 70 018 ± 14 356 in 1998, averaging 53 000 per year. Common eiders (Somateria mollissima v-nigra) were much less abundant, varying from 2728 ± 631 to 6017 ± 770 birds, averaging 4400 annually. Peak numbers of king eiders moved through the study area in 1-8 days during the second to third week of June in all years, and common eiders peaked in 1 -8 days during the first to second week of June. Strong winds may have hindered migration for a few days. Crippling loss rates during the hunt were low (3 -9%) in the first two years of the study, but increased to 13 -20% in the early open-water spring of 1998, when hunters were forced to shoot over open water rather than shorefast ice. On the basis of these estimates and harvest data from the Inuvialuit Harvest Study, we determined that Holman hunters removed 3.7 -6.9% of the king eider subpopulation and less than 1% of the common eiders over the three-year study period. The present level of harvest of eiders available to Holman hunters is likely sustainable. However, more information on natural mortality and recruitment rates, particularly for king eiders, is needed to confirm this.
Sightings of killer whales (Orcinus orca) are increasing in the eastern Canadian Arctic, but trends in the western Arctic have not been thoroughly examined. We summarise killer whale observations from the Canadian Beaufort Sea, primarily from traditional ecological knowledge interviews and group workshops conducted in 1993 and 2006–2007. After correcting for duplicative reports, we documented 31 observations occurring from the 1940s to 2000s (18 of the 31 observations could be attributed to a particular decade whereas others could not). Killer whales are rare in the Canadian Beaufort Sea, with only 1–5 reported sightings per decade since the 1940s (median = 3). In 1993 only 15% of Inuvialuit hunters in three communities had observed them, including some sightings in Alaska. Recent mapping workshops (2006–2007) collected only eight sightings from 128 participants in all six regional communities. Local observations indicate no apparent increase in killer whale presence in the western Canadian Arctic. Sightings were widely distributed across the region, although concentrated in the Mackenzie Delta area with few to the east. Killer whales are annually observed as far north as Barrow, Alaska, but do not appear to make regular eastward movements and are rare in Canadian waters.
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