Global Short Term Trend: Decline of 30-70%
Comments: The time frame for short-term trend is long; three generations is roughly 60-120 years); on this basis the trend is a large decline.
For 42 sites rangewide for which recent trend (within the last 20 years) could be determined, 24 percent were increasing, 7 percent were stable, and 69 percent were declining (NMFS and USFWS 2007). For 11 sites for which quantitative continuous data for approximately 20 or more years were available, 6 were increasing, 4 were decreasing, and 1 was stable; however, these data are not representative of the global pattern because the sites are better protected than most areas. In general, trend is least favorable in the Pacific Ocean and most favorable in the Atlantic (NMFS and USFWS 2007).
Global Long Term Trend: Increase of 10-25% to decline of 70%
Comments: Extent of occurrence has been reduced to a small degree over the long term, but much larger reductions have occurred in population size and condition of occurrences (NMFS & USFWS 2007). For 58 sites rangewide for which long-term trend (>20 to 100 years) could be assessed, all showed a declining trend (NMFS and USFWS 2007).