Recommendations

The Arctic Species Trend Index (ASTI): 2011 update.

1.1 Average abundance of Arctic vertebrates increased from 1970 until 1990 then remained fairly stable through 2007, as measured by the ASTI 2011.

1.2 When species abundance is grouped by broad ecozones, a different picture emerges, with low Arctic species abundance increasing in the first two decades much more than high Arctic and sub Arctic species abundance. The low Arctic index has stabilized since the mid-1990s while the high Arctic index appears to be recovering in recent years and the sub Arctic index has been declining since a peak in the mid-1980s.

1.3 The trend for Arctic marine species is similar to that of the overall ASTI, while the trend for terrestrial species shows a quite different pattern: a steady decline after the early 1990s to a level below the 1970 baseline by 2005.

Tracking trends in Arctic marine vertebrates.

2.1 The trend for marine fish is very similar to the trend for all marine species, increasing from 1970 to about 1990 and then levelling off. This indicates that the ASTI is strongly influenced by fish trends. Overall, marine mammals also increased, while marine birds showed less change.

2.2 The three ocean regions, Pacific, Atlantic, and Arctic, differed significantly in average population trends with an overall decline in abundance in the Atlantic, a small average increase in the Arctic and a dramatic increase in the Pacific. These differences seem to be largely driven by variation in fish population abundance—there were no significant regional differences for birds or mammals.

2.3 Pelagic fish abundance appears to cycle on a time frame of about 10 years. These cycles showeda strong association with a large-scale climate oscillation.

2.4 The ASTI data set contains population trends for nine sea ice associated species. There were mixed trends among the 36 populations with just over half showing an overall decline.

2.5 The Bering Sea and Aleutian Island (BSAI) region of the Pacific Ocean is well studied, providing an opportunity to examine trends in more detail. Since 1970, BSAI marine fish and mammals showed overall increases, while marine birds declined. However, since the late 1980s, marine mammal abundance has declined while marine fish abundance has largely stabilized.

Tracking trends through space and time.

3.1 Spatial analysis of the full ASTI data set (1951 to 2010) started with an evaluation of vertebrate population trend data from around the Arctic. The maps produced from this analysis provide information useful for identifying gaps and setting priorities for biodiversity monitoring programs.

3.2 Mapping trends in vertebrate populations provides information on patterns of biodiversity change over space and time, especially when examined at regional scales.

3.3 Understanding of the causes of Arctic vertebrate population change can be improved by expanding the spatial analysis of ASTI data to include spatial data on variables that represent driversof biodiversity change.