Note that the data published in the 2002 State of the Nation’s Ecosystems Report as well as the 2003 and 2005 Web-Only Updates have been superseded by the 2008 Report and thus should be used with caution. For the most recent data, purchase the 2008 Report from Island Press.

The Indicator

A deliberate choice was made to focus this indicator on unusual mortalities rather than all marine mortalities. The latter includes death from old age, predation, and human-related causes such as entanglement with fishing gear. Unusual mortalities were selected so that only extraordinary instances of animal deaths would be included; a death from old age is within normal functioning of an ecosystem and should not be treated as a signal of changing ecosystem status.

In response to a major dolphin die-off during 1987–88, the National Marine Fisheries Service (NMFS) established a Working Group on Unusual Marine Mammal Mortality Events (WGUMMME) to create criteria for determining when an unusual mortality event is occurring and then to direct responses to such events (see http://www.nmfs.noaa.gov/prot_res/PR2/Health_and_Stranding_Response_Program/WGUMMME.html). The Working Group consists of a multidisciplinary team that makes judgments based on the following: (1) there is an increased number of mortalities when compared with historical data; (2) animals are stranding at an unusual time of year; (3) strandings occur in a localized area, throughout the geographical range, or they spread geographically with time; (4) the species, age, or sex composition of the stranded animals is different from what is normally seen; (5) stranded animals exhibit similar or unusual pathological findings or general physical condition; (6) mortality is accompanied by abnormal behavior among living individuals in the wild; and (7) critically endangered species are dying.

The Data

Data Source: U.S. Department of Commerce, National Oceanographic and Atmospheric Administration (NOAA), NMFS, Office of Protected Resources, Marine Mammal Health and Stranding Response Program; and Dierauf and Gulland (2001).

Data Quality/Caveats: The data for 2001 are preliminary as these unusual mortality events (UMEs) have not been officially closed and the total number of affected animals tallied. Also, there was a single UME for gray whales that spanned three years (1999–2001). A total of 678 animals were lost to a UME, with 273 in 1999. NOAA has not yet finalized the accounting for this event, so the remainder was simply split between 2000 and 2001. Given that there is no apparent trend to the data, this gross simplification should not distort the interpretation of this indicator.

Data Access: The 2001 data for two UMEs and the total number of gray whales lost in the 1999–2001 UME were obtained directly from NMFS. All other UME data were obtained from Dierauf and Gulland (2001).

The Data Gap

There is no program for sea birds, fish, and shellfish similar to that in place for marine mammals run under the auspices of the WGUMMME. It will be necessary to establish guidelines for what constitutes a UME for these animals, which typically perish in much larger numbers than mammals. For example, a guideline for fish may be that 1,000 deaths of members of two or three species would be necessary to qualify for a UME. This guideline may vary by species and by location and will certainly be different from the guidelines appropriate for shellfish and sea birds. Because these UMEs would all involve large numbers of animals, only the number of events will be reported. In addition, it is unclear if data exist on UMEs for sea turtles; however, these mortalities would be reported by the number of animals lost as is done for mammals.

References

Dierauf, L.A., and F.M.D. Gulland, eds. 2001. CRC handbook of marine mammal medicine: Health, disease, and rehabilitation. 2nd ed. Boca Raton, FL: CRC Press, Inc.