Variation in Reproduction and Body Condition of the Ringed Seal (<i>Phoca hispida</i>) in Western Prince Albert Sound, NT, Canada, as Assessed Through a Harvest-based Sampling Program

Abstract

ABSTRACT. Between 1992 and 1998, 869 ringed seals taken in the subsistence harvest in western Prince Albert Sound were sampled by two Inuvialuit seal monitors from Holman, Northwest Territories. Considering the 1992-98 data along with data from 1971 -78, we found that the mean body-mass index (BMI) values for females (≥ 7 yr) were significantly lower in 1974 than in all other years examined. At the same time, ovulation rates fell from 100% in 1971 and 1972 to lows of 42. 9% (1974) and 64.3% (1975), with a return to 93.8% in 1976. Mature females that had ovulated had significantly higher BMI values than those that had not ovulated. In eastern Amundsen Gulf, 1974 was the most severe ice year on recent record, with the latest date of clearing of the landfast ice (6 September), the earliest date of new ice formation (4 October), and the fewest number of open water days (28 days). There were no years between 1992 and 1998 that compared to 1974 in reduced ovulation rates, reduced body condition, or severity of ice conditions. Between 1992 and 1998, mean BMI values for adult females and males were lowest in 1994 and highest in 1998, and all annual mean BMI values were between the extremes of the 1970s. This variation in condition in the 1990s did not coincide with a reduction in ovulation rates of mature females, which remained high (93.5-100%) from 1992 to 1998. In 1998, the landfast ice cleared 43 days earlier than the average clearing date for the 1990-98 period, apparently interrupting the lactation period for seal pups located at the periphery of the core breeding habitat. The apparent effects on growth and condition of unweaned pups came at a time when marine food appeared to be abundant and available to all age classes of ringed seals.

Arctic Marine Mammals and Climate Change: Impacts and Resilience

“…Similarly, examination of dietary variability and individual animal health by way of isotopic, fatty acid, and contaminant analyses (e.g., Burek et al 2008) can provide a wealth of information about marine ecosystem trophic pathways. Human subsistence communities provide a strong link here, in that, as consumers of marine mammals, they are the first-line investigators of this system (Harwood et al 2000, Metcalf and Robards 2008. A coordinated research response to climate change could more effectively use Arctic marine mammals as sentinels for the ecosystem.…”

Effects of Climate Change on Arctic Marine Mammal Health

“…For example, stranded harbor seals with higher circulating cortisol levels (as an indication of physiologic stress) are more likely to die of endemic herpesvirus than animals with lower cortisol levels (Gulland et al 1999). Poor nutrition is also a well-known factor in reduced reproductive success, affecting age of onset of puberty, fertility, and success in maintaining pregnancies in domestic animals (Gerloff and Morrow 1986), all of which could have major effects at the population level (Harwood et al 2000).…”

Seasonal Movements and Diving of Ringed Seals, <i>Pusa hispida</i>, in the Western Canadian Arctic, 1999–2001 and 2010–11

“…However, attempts to relate changes in the environment (Melling et al, 2005;Serreze et al, 2007;Walsh, 2008) to a marine mammal's responses to those changes, are often constrained by lack of baseline information about the species, its life history, prey, and critical habitats (Moore et al, 2014). Although the distribution, reproduction, and biology of the ringed seal (Pusa hispida) in the western Canadian Arctic have been the subject of scientific study for four decades (Stirling et al�, 1977(Stirling et al�, , 1982Smith, 1987;Kingsley and Byers, 1998;Harwood et al, 2000Harwood et al, , 2012bStirling, 2002), the seasonal movements and habitat use of ringed seals in Amundsen Gulf have not been explicitly examined to date.…”