Osinga N, Shahi Ferdous M M, Morick D, García Hartmann M, Ulloa J A, Vedder L, Udo de Haes H A, Brakefield P M, Osterhaus A D M E, Kuiken T
Seal Rehabilitation and Research Centre, Pieterburen, The Netherlands.
J Comp Pathol. 2012 Nov;147(4):550-65. doi: 10.1016/j.jcpa.2012.04.001. Epub 2012 May 24.
Pathological examination of stranded marine mammals provides information on the causes of mortality in their populations. Patterns of stranding and causes of death of dead-stranded seals on the Dutch coast were analyzed over a 30-year period (1979-2008). Stranding data (n=1,286) and post-mortem data (n=379) from common seals (Phoca vitulina) and grey seals (Halichoerus grypus) found dead, or that died before admission to rehabilitation, were obtained from the Seal Rehabilitation and Research Centre database. Data for the years 1988 and 2002, when mass mortality occurred due to phocine distemper virus epidemics, were excluded. Common seal stranding increased from one to nearly 100 per year over this period. This coincides with the increase in the number of common seals in Dutch waters over recent decades. Grey seal stranding increased gradually from one to about 40 per year over the period, reflecting recolonization of Dutch waters by this species. For both species, the trend in stranding of dead seals was found to be in line with that of seals observed in Dutch waters during aerial surveys and did not provide any indications of a relative change in the stranding rate of dead seals. The total monthly stranding rates peaked at more than 120 in June and July for common seals and at nearly 60 in January for grey seals. This coincides with the pupping periods of the two species. Besides phocine distemper, the most common causes of death in investigated common seals (n=286) were by-catch (confirmed and inferred) (19%), pup starvation (7%), intestinal volvulus (7%) and parasitic bronchopneumonia (6%). The most common causes of death in investigated grey seals (n=93) were by-catch (confirmed and inferred) (15%), pup starvation (11%) and trauma (5%). The relative occurrence of by-catch significantly decreased over time for grey seals, but not for common seals. Common seals were affected by infectious disease significantly more often than grey seals, mainly because of a higher occurrence of parasitic pneumonia. Phocine distemper caused mass mortalities among common seals, but not among grey seals. These findings in dead-stranded seals differ in part from those reported elsewhere in live-stranded seals, for which pup starvation and parasitic bronchopneumonia were the main causes of stranding. A substantial proportion of seals in Dutch waters die from causes related to human activity. Continued monitoring of stranding patterns and causes of death is warranted for early detection of changes and the possibility of taking timely management actions.
对搁浅海洋哺乳动物进行病理检查可提供有关其种群死亡原因的信息。我们分析了荷兰海岸30年期间（1979 - 2008年）死胎海豹的搁浅模式和死亡原因。从海豹康复与研究中心数据库获取了普通海豹（港海豹）和灰海豹死亡时或在送往康复机构前死亡的搁浅数据（n = 1286）和尸检数据（n = 379）。1988年和2002年因海豹瘟热病毒流行导致大规模死亡的数据被排除。在此期间，普通海豹的搁浅数量从每年1只增加到近100只。这与近几十年来荷兰水域普通海豹数量的增加相吻合。在此期间，灰海豹的搁浅数量从每年1只逐渐增加到约40只，反映了该物种在荷兰水域的重新定居。对于这两个物种而言，死胎海豹的搁浅趋势与空中调查中在荷兰水域观察到的海豹趋势一致，并且没有提供任何死胎海豹搁浅率相对变化的迹象。普通海豹的每月总搁浅率在6月和7月达到峰值，超过120只，灰海豹在1月达到近60只。这与这两个物种的产仔期相吻合。除了海豹瘟热外，在接受调查的普通海豹（n = 286）中，最常见的死亡原因是误捕（确认和推断）（19%）、幼崽饥饿（7%）、肠扭转（7%）和寄生性支气管肺炎（6%）。在接受调查的灰海豹（n = 93）中，最常见的死亡原因是误捕（确认和推断）（15%）、幼崽饥饿（11%）和外伤（5%）。随着时间的推移，灰海豹误捕的相对发生率显著下降，但普通海豹没有。普通海豹比灰海豹更容易受到传染病的影响，主要是因为寄生性肺炎的发生率更高。海豹瘟热在普通海豹中导致大规模死亡，但在灰海豹中没有。这些死胎海豹的研究结果部分不同于其他地方报道的活胎海豹的研究结果，在活胎海豹中，幼崽饥饿和寄生性支气管肺炎是搁浅的主要原因。荷兰水域相当一部分海豹死于与人类活动相关的原因。有必要持续监测搁浅模式和死亡原因，以便早期发现变化并及时采取管理行动。
