Injury
Cormorants are large fish-eating birds that spend much of their time on the water or perched on rocks near the water. Three species of cormorants are typically are found within the oil spill area. Carcasses of 838 cormorants were recovered following the oil spill, including 418 pelagic, 161 red-faced, 38 double-crested, and 221 unidentified cormorants. From this sample, direct oil spill related mortality was estimated at between 2,900 and 8,800 deaths. In 1996, the U.S. Fish and Wildlife Service Alaska Seabird Colony Catalog, however, listed counts of 7,161 pelagic cormorants, 8,967 red-faced cormorants, and 1,558 double-crested cormorants in the oil spill area. These are direct counts at colonies, not overall population estimates, but they suggest that population sizes are small. In this context, it appears that injury to all three cormorant species was significant.
Counts on the outer Kenai Peninsula coast suggested that the direct mortality of cormorants due to oil resulted in fewer birds in this area in 1989 compared to 1986. In addition, there were statistically significant declines in the estimated numbers of cormorants (all three species combined) in the oiled portion of Prince William Sound based on pre and post-spill boat surveys in July 1984-85 compared to 1989-91. It is not known what the counts and trends of cormorants would have been in the absence of the oil spill.
Recovery Objective
Pelagic, red-faced, and double-crested cormorants will have recovered when their populations return to pre-spill levels in oiled areas. An increasing population trend in Prince William Sound will indicate that recovery is underway.
Recovery Status
Marine bird surveys were conducted during ten of the 16 years during1989-2005. For cormorants, trends for both summer and winter populations were increasing in the oiled area of Prince William Sound. Moreover, population estimates for cormorants in summer 2004 ranged from 9,000-11,000 birds, which falls within the range of 10,000-30,000 estimated in 1972.
Therefore, although population estimates of cormorants are highly variable throughout their range, the recovery objectives have been met and cormorants are considered to be RECOVERED.
Click HERE for more information on Trustee Council funded studies of cormorants.
