Increased harbor porpoise mortality in the Pacific Northwest, USA: understanding when higher levels may be normal

Diseases of Aquatic Organisms

Jessica L. Huggins¹  John Calambokidis¹  Joseph K. Gaydos¹  Steven J. Jeffries¹  James M. Rice¹  Stephen A. Raverty¹  Kristin Wilkinson¹  Stephanie A. Norman¹  Dyanna M. Lambourn¹  Brad Hanson¹  Deborah A. Duffield¹  Lynne Barre¹  Brent Norberg¹ 

关键词:   Phocoena phocoena;    Stranding;    Pacific Northwest;    Unusual mortality event;   

DOI  :  10.3354/dao02887

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: In 2006, a marked increase in harbor porpoise Phocoena phocoena strandings were reported in the Pacific Northwest of the USA, resulting in the declaration of an unusual mortality event (UME) for Washington and Oregon to facilitate investigation into potential causes. The UME was in place during all of 2006 and 2007, and a total of 114 porpoises stranded during this period. Responders examined 95 porpoises; of these, detailed necropsies were conducted on 75 animals. Here we review the findings related to this event and how these compared to the years immediately before and after the UME. Relatively equal numbers among sexes and age classes were represented, and mortalities were attributed to a variety of specific causes, most of which were categorized as trauma or infectious disease. Continued monitoring of strandings during 4 yr following the UME showed no decrease in occurrence. The lack of a single major cause of mortality or evidence of a significant change or event, combined with high levels of strandings over several post-UME years, demonstrated that this was not an actual mortality event but was likely the result of a combination of factors, including: (1) a growing population of harbor porpoises; (2) expansion of harbor porpoises into previously sparsely populated areas in Washington’s inland waters; and (3) a more well established stranding network that resulted in better reporting and response. This finding would not have been possible without the integrated response and investigation undertaken by the stranding network.

【 授权许可】

Unknown