Siebert Ursula, Grilo Miguel L, Kesselring Tina, Lehnert Kristina, Ronnenberg Katrin, Pawliczka Iwona, Galatius Anders, Kyhn Line A, Dähne Michael, Gilles Anita
Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover Foundation, Büsum, Germany.
MARE-Marine and Environmental Sciences Centre, ISPA-Instituto Universitário de Ciências Psicológicas, Sociais e da Vida, Lisbon, Portugal.
Front Physiol. 2022 Nov 23;13:880465. doi: 10.3389/fphys.2022.880465. eCollection 2022.
Evaluating populational trends of health condition has become an important topic for marine mammal populations under the Marine Strategy Framework Directive (MSFD). In the Baltic Sea, under the recommendation of Helsinki Commission (HELCOM), efforts have been undertaken to use blubber thickness as an indicator of energy reserves in marine mammals. Current values lack geographical representation from the entire Baltic Sea area and a large dataset is only available for grey seals () from Sweden and Finland. Knowledge on variation of blubber thickness related to geography throughout the Baltic Sea is important for its usage as an indicator. Such evaluation can provide important information about the energy reserves, and hence, food availability. It is expected that methodological standardization under HELCOM should include relevant datasets with good geographical coverage that can also account for natural variability in the resident marine mammal populations. In this study, seasonal and temporal trends of blubber thickness were evaluated for three marine mammal species-harbor seal (), grey seal () and harbor porpoise ()-resident in the southern Baltic Sea collected and investigated under stranding networks. Additionally, the effects of age, season and sex were analyzed. Seasonal variation of blubber thickness was evident for all species, with harbor seals presenting more pronounced effects in adults and grey seals and harbor porpoises presenting more pronounced effects in juveniles. For harbor seals and porpoises, fluctuations were present over the years included in the analysis. In the seal species, blubber thickness values were generally higher in males. In harbor seals and porpoises, blubber thickness values differed between the age classes: while adult harbor seals displayed thicker blubber layers than juveniles, the opposite was observed for harbor porpoises. Furthermore, while an important initial screening tool, blubber thickness assessment cannot be considered a valid methodology for overall health assessment in marine mammals and should be complemented with data on specific health parameters developed for each species.
根据《海洋战略框架指令》（MSFD），评估健康状况的种群趋势已成为海洋哺乳动物种群的一个重要课题。在波罗的海，根据赫尔辛基委员会（HELCOM）的建议，已开展工作将鲸脂厚度用作海洋哺乳动物能量储备的指标。目前的值缺乏整个波罗的海地区的地理代表性，并且只有来自瑞典和芬兰的灰海豹（）的大型数据集可用。了解整个波罗的海地区鲸脂厚度与地理相关的变化对于将其用作指标很重要。这样的评估可以提供有关能量储备以及因此食物可获得性的重要信息。预计HELCOM下的方法标准化应包括具有良好地理覆盖范围的相关数据集，这些数据集还应考虑当地海洋哺乳动物种群的自然变异性。在本研究中，对在搁浅网络下收集和调查的波罗的海南部的三种海洋哺乳动物物种——斑海豹（）、灰海豹（）和港湾鼠海豚（）的鲸脂厚度的季节性和时间趋势进行了评估。此外，还分析了年龄、季节和性别的影响。所有物种的鲸脂厚度都有明显的季节性变化，成年斑海豹的影响更为明显，而灰海豹和港湾鼠海豚在幼体中的影响更为明显。对于斑海豹和港湾鼠海豚，分析中所涵盖的年份存在波动。在海豹物种中，雄性的鲸脂厚度值通常更高。在斑海豹和港湾鼠海豚中，不同年龄组的鲸脂厚度值有所不同：成年斑海豹的鲸脂层比幼体厚，而港湾鼠海豚则相反。此外，虽然鲸脂厚度评估是一种重要的初步筛选工具，但不能将其视为海洋哺乳动物整体健康评估的有效方法，而应辅以针对每个物种制定的特定健康参数数据。
