Ringed seals, which are small phocid seals, range across the circumpolar Arctic, and have evolved in close association with sea ice and depend on it for all aspects of their life history. This research study compares age structure, reproductive parameters, body size and condition during three time periods—1981–82 (n = 277), 2002–04 (n = 272) and 2012–18 (n = 212)—to study potential changes in demography in ringed seals in western Svalbard, Norway, an area that has undergone dramatic changes in sea-ice conditions during recent decades. Age distributions for the three time periods were similar, with the exception that the most recent period had a higher proportion of young animals. Age at sexual maturity for both sexes was similar for the two most recent periods, both being lower than in the 1980s. Ovulation rates did not vary significantly among the three periods (range 0.86–0.94). Pregnancy rates were only available for the most recent study period (0.71); this value falls within the range reported from other Arctic regions. Body length showed no clear temporal patterns; males were slightly longer in the most recent period, while females were slightly longer in the first period. Data from May in all periods suggest that body condition has not varied significantly through time. In conclusion, although the ringed seal breeding habitat in Svalbard has declined significantly in recent decades, demographic parameters appear to be largely unaffected. Life-history plasticity in combination with a small-scale regional variation in environmental conditions might explain the lack of changes in demography over time.

环状海豹是小型幽闭海豹，分布在北极的极地，并与海冰密切相关，在其生活史的各个方面都依赖于海冰。此研究中三个时间段-1981-82（比较年龄结构，生殖参数，身体大小和状况Ñ  = 277），2002-04（Ñ  = 272）和2012-18（Ñ = 212），以研究挪威斯瓦尔巴特群岛西部环斑海豹的人口统计学潜在变化，该地区近几十年来海冰条件发生了戏剧性变化。三个时期的年龄分布相似，不同的是最近时期的年幼动物比例更高。最近两个时期，男女的性成熟年龄都相似，均低于1980年代。在这三个时期之间，排卵率没有显着变化（范围在0.86-0.94之间）。妊娠率仅适用于最近的研究时期（0.71）；该值落在其他北极地区报告的范围内。体长没有明显的时间规律。男性在最近时期略长，而女性在第一时期略长。5月份所有时期的数据表明，身体状况并未随时间显着变化。总之，尽管最近几十年来斯瓦尔巴群岛的环斑海豹繁殖栖息地已大大减少，但人口统计学参数似乎未受影响。生命历史可塑性与环境条件的小范围区域性变化相结合，可以解释人口结构随时间推移缺乏变化的情况。