Estimating cause-specific mortality rates using recovered carcasses.
Stranding networks, in which carcasses are recovered and sent to diagnostic laboratories for necropsy and determination of cause of death, have been developed to monitor the health of marine mammal and bird populations. These programs typically accumulate comprehensive, long-term datasets on causes of death that can be used to identify important sources of mortality or changes in mortality patterns that lead to management actions. However, the utility of these data in determining cause-specific mortality rates has not been explored. We present a maximum likelihood-based approach that partitions total mortality rate, estimated by independent sources, into cause-specific mortality rates. We also demonstrate how variance estimates are derived for these rates. We present examples of the method using mortality data for California sea otters (Enhydra lutris nereis) and Florida manatees (Trichechus manatus latirostris).
Joly
Damien O
DO
Global Health Programs, Wildlife Conservation Society, 1008 Beverly Drive, Nanaimo, British Columbia, Canada, V9S 2S4. djoly@wcs.org
Heisey
Dennis M
DM
Samuel
Michael D
MD
Ribic
Christine A
CA
Thomas
Nancy J
NJ
Wright
Scott D
SD
Wright
Irene E
IE
D000818:Animals; D000835:Animals, Wild; D002423:Cause of Death; D005260:Female; D020387:Food Chain; D016013:Likelihood Functions; D008297:Male; D009026:Mortality / Q000639:trends*; D009792:Oceans and Seas; D010041:Otters / Q000293:injuries / Q000382:microbiology / Q000469:parasitology; D012307:Risk Factors; D018571:Sentinel Surveillance / Q000662:veterinary*; D012754:Sharks; D020457:Trichechus manatus / Q000293:injuries / Q000382:microbiology / Q000469:parasitology