Environmental determinants of fecundity and pup growth in fur seals

This indicator is no longer maintained, and is considered OBSOLETE.INDICATOR DEFINITIONThe fecundity (pupping rates) of female fur seals and the growth rates of their pups relative to changes in sea surface temperatures (local primary production) in the vicinity of Macquarie Island.TYPE OF INDICATORThere are three types of indicators used in this report:1.Describes the CONDITION of important elements of a system;2.Show the extent of the major PRESSURES exerted on a system;3.Determine RESPONSES to either condition or changes in the condition of a system.This indicator is one of: CONDITIONRATIONALE FOR INDICATOR SELECTIONA highly negative correlation has been detected between sea surface temperatures in the vicinity of Macquarie Island and fur seal fecundity and pup growth. A dataset of over ten years has shown that autumn sea-surface temperatures are highly negatively correlated with female fecundity in the following breeding season.Rather than the reproductive success in terms of fecundity and pup growth being seen simply as a correlate of SST and presumably ocean productivity, the measure is much more than this. What the dataset from the Macquarie Island fur seal populations is rather more unique, in that they indicate how environmental variability effects the reproductive success of animals at annual and lifetime scales. This is especially important as we can now show what impacts environmental/climatic phenomena such as the Antarctic Circumpolar Wave, and global warming will have on fur seals, and how changes in the environment may impact on the viability of populations. In this situation, the data clearly suggest that warmer ocean temperatures significantly effect the reproductive success of fur seals. Sustained warmer temperatures would therefore impose demographic constraints on populations.DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAMSpatial scale: SST data are obtained from a 1 degree square just north of the island that represents the region in which most females obtain food throughout their lactation period.Frequency: Data on the reproductive success of fur seals is to be collected annually.Measurement technique: Each breeding season (November-January), the reproductive success of tagged females is monitored, including their pupping success, and the growth rates of their pups.RESEARCH ISSUESLINKS TO OTHER INDICATORS