Harp seals are the most abundant marine mammal in the north Atlantic. As an ice obligatory predator, they reflect changes in their environment, particularly during a period of climatic change. As the focus of a commercial hunt, a large historic data set exists that can be used to quantify changes. There are three populations of harp seals: White Sea/Barents Sea, Greenland Sea and Northwest Atlantic. The objective of this paper is to review their current status and to identify the factors that are influencing population dynamics in different areas. Although important historically, recent catches have been low and do not appear to be influencing trends in either of the two northeast Atlantic populations. Massive mortalities of White Sea/Barents Sea seals occurred during the mid 1980s due to collapses in their main prey species. Between 2004 and 2006, pup production in this population declined by 2/3 and has remained low. Body condition declined during the same period, suggesting that ecosystem changes may have resulted in reduced reproductive rates, possibly due to reduced prey availability and/or competition with Atlantic cod. The most recent estimate of pup production in the Greenland Sea also suggests a possible decline during a period of reduced hunting although the trend in this population is unclear. Pupping concentrations are closer to the Greenland coast due to the reduction in ice in the traditional area and increased drift may result in young being displaced from their traditional feeding grounds leading to increased mortality. Reduced ice extent and thickness has resulted in major mortality of young in the Northwest Atlantic population in some years. After a period of increase, the population remained relatively stable between 1996 and 2013 due to increased hunting, multiple years with increased ice-related mortality of young seals, and lower reproductive rates. With a reduction in harvest and improved survival of young, the population appears to be increasing although extremely large interannual variations in body condition and fecundity have been observed which were found to be influenced by variations in capelin biomass and ice conditions. Each of these populations has been impacted differently by changes in their ecosystems and hunting practices. By identifying the factors influencing these three populations, we can gain a better understanding of how species may respond to changes that are occurring in their ecosystems.

中文翻译：

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竖琴海豹：监测不同生态系统的变化

竖琴海豹是北大西洋最丰富的海洋哺乳动物。作为冰上强制性捕食者，它们反映了环境的变化，特别是在气候变化时期。作为商业狩猎的焦点，存在可用于量化变化的大型历史数据集。竖琴海豹分为三个种群：白海/巴伦支海、格陵兰海和西北大西洋。本文的目的是回顾它们的现状并确定影响不同地区人口动态的因素。尽管在历史上很重要，但最近的捕捞量一直很低，似乎不会影响大西洋东北部两个种群中的任何一个种群的趋势。白海/巴伦支海海豹在 1980 年代中期由于主要猎物物种的崩溃而大量死亡。2004 年至 2006 年间，该种群的幼崽产量下降了 2/3，并且仍然很低。同一时期身体状况有所下降，这表明生态系统的变化可能导致繁殖率降低，这可能是由于猎物减少和/或与大西洋鳕鱼的竞争所致。格陵兰海幼崽产量的最新估计也表明，在狩猎减少期间，幼崽产量可能下降，尽管这一种群的趋势尚不清楚。由于传统地区的冰层减少，幼崽的集中地更靠近格陵兰海岸，而漂移的增加可能会导致幼崽从传统的觅食地流离失所，从而导致死亡率增加。在某些年份，冰的范围和厚度的减少导致了西北大西洋人口中年轻人的主要死亡。经过一段时间的上涨，1996 年至 2013 年间，由于狩猎活动增加、幼海豹因冰冻导致死亡率增加以及繁殖率降低，种群数量保持相对稳定。随着收获的减少和幼鱼存活率的提高，尽管已经观察到身体状况和繁殖力的极大年际变化，但发现这些变化受到毛鳞鱼生物量和冰条件变化的影响，但种群似乎正在增加。这些种群中的每一个都因其生态系统和狩猎习惯的变化而受到不同的影响。通过确定影响这三个种群的因素，我们可以更好地了解物种如何应对其生态系统中发生的变化。年，幼海豹与冰有关的死亡率增加，繁殖率降低。随着收获的减少和幼鱼存活率的提高，尽管已经观察到身体状况和繁殖力的极大年际变化，但发现这些变化受到毛鳞鱼生物量和冰条件变化的影响，但种群似乎正在增加。这些种群中的每一个都因其生态系统和狩猎习惯的变化而受到不同的影响。通过确定影响这三个种群的因素，我们可以更好地了解物种如何应对其生态系统中发生的变化。年，幼海豹与冰有关的死亡率增加，繁殖率降低。随着收获的减少和幼鱼存活率的提高，尽管已经观察到身体状况和繁殖力的极大年际变化，但发现这些变化受到毛鳞鱼生物量和冰条件变化的影响，但种群似乎正在增加。这些种群中的每一个都因其生态系统和狩猎习惯的变化而受到不同的影响。通过确定影响这三个种群的因素，我们可以更好地了解物种如何应对其生态系统中发生的变化。尽管已观察到身体状况和繁殖力的极大年际变化，但发现这些变化受到毛鳞鱼生物量和冰条件变化的影响，但种群似乎正在增加。这些种群中的每一个都因其生态系统和狩猎习惯的变化而受到不同的影响。通过确定影响这三个种群的因素，我们可以更好地了解物种如何应对其生态系统中发生的变化。尽管已观察到身体状况和繁殖力的极大年际变化，但发现这些变化受到毛鳞鱼生物量和冰条件变化的影响，但种群似乎正在增加。这些种群中的每一个都因其生态系统和狩猎习惯的变化而受到不同的影响。通过确定影响这三个种群的因素，我们可以更好地了解物种如何应对其生态系统中发生的变化。