Environmental determinants of fecundity and pup growth in fur seals

This indicator is no longer maintained, and is considered OBSOLETE.

INDICATOR DEFINITION
The 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 INDICATOR
There 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: CONDITION

RATIONALE FOR INDICATOR SELECTION
A 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 PROGRAM
Spatial 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 ISSUES

LINKS TO OTHER INDICATORS

本指标已停止维护，视为废弃（OBSOLETE）。

## 指标定义
本指标聚焦麦夸里岛（Macquarie Island）周边海域海表温度（sea surface temperature, SST，局地初级生产力）变化与雌性毛皮海豹（fur seal）的繁殖力（fecundity，产仔率（pupping rates））及其幼崽生长速率之间的关联关系。

## 指标类型
本报告中共采用三类指标：
1. 描述系统关键组成要素的状态（CONDITION）；
2. 展示作用于系统的主要压力（PRESSURES）程度；
3. 衡量系统状态或状态变化所引发的响应（RESPONSES）。
本指标属于【状态】类指标。

## 指标选取依据
研究已在麦夸里岛周边海域海表温度与毛皮海豹繁殖力及幼崽生长之间检测到显著负相关关系。长达十余年的数据集显示，秋季海表温度与次年繁殖季的雌性繁殖力呈高度负相关。
该指标并非仅将以繁殖力与幼崽生长衡量的繁殖成功率简单视为海表温度及潜在海洋生产力的关联因子，其价值远不止于此。麦夸里岛毛皮海豹种群的数据集具备独特性：它揭示了环境变异如何在年度及终生尺度上影响动物的繁殖成功率。这一点尤为关键，因为当前我们已能够明确南极绕极波（Antarctic Circumpolar Wave）、全球变暖等环境/气候现象对毛皮海豹的影响，以及环境变化如何作用于种群存续能力。在此场景下，数据清晰表明海洋温度升高会显著损害毛皮海豹的繁殖成功率。因此，持续的海洋升温将对种群施加人口统计学层面的约束。

## 指标监测方案设计与策略
空间尺度：海表温度数据取自该岛以北1平方度的海域，该区域覆盖绝大多数雌性毛皮海豹在泌乳期的觅食范围。
监测频率：毛皮海豹繁殖成功率数据需按年度采集。
测量方法：每个繁殖季（11月至次年1月），对佩戴标记的雌性个体的繁殖成功率（包括产仔成功率）及其幼崽的生长速率进行监测。

## 研究议题

## 与其他指标的关联