Document ID: chunk:federal_register_of_legislation:F2024L00930:reg:2:p39
Version: federal_register_of_legislation:F2024L00930
Segment Type: reg
Provision Reference: reg 2 (pt 39/48)
Character Range: 168516–171523

foraging grounds, and reduced prey availability has been linked to depressed calving intervals for breeding female southern right whales (Leaper et al. 2006, Seyboth et al. 2016). However, the ability to reliably identify and separate the effects of climate change on female calving rates and breeding success from other threats, such as habitat degradation and disturbance within calving areas, is difficult. Irrespective, if both threats potentially impact on breeding success, then the cumulative effects from both could result in the species decline. Due to the life history characteristics of southern right whales, any cumulative effects are unlikely to be detectable over short timescales (i.e., 1 - 3 years).
Consideration of the spatial and temporal patterns of exposure to stressors and threats is necessary when assessing the potential for cumulative effects of these combined stressors. The occurrence of individual stressors may demonstrate strong spatial and/or temporal variation. Their effects depend on the extent and timing that whales use BIAs and the whales' proximity to these stressors. As a migratory species, southern right whales can be exposed to a wide range of threats. However, they also demonstrate philopatry and site fidelity to reproductive areas for calving and nursing, which may lead to cumulative exposure to stressors within these areas. Although threats to southern right whales operate across the entire species range, they can be spatially biased and usually occur close to more populated coastal areas. Consequently, the eastern population may be at higher risk to threats than the western population given their lower abundance and rate of recovery (Stamation et al. 2020) and greater proximity to higher human density coastal areas and human activities.
The challenge with assessing cumulative effects on animals is that combined effects may not always be reliably predicted from the individual effect of each stressor, because the way each stressor operates in isolation may change or be modified in the presence of other stressors (Pirotta et al. 2022). At present, the quantitative prediction of cumulative effects of stressors on marine mammals has not been achieved and consequently conceptual frameworks for assessing the population consequences of multiple stressors are developed (National Academies of Sciences 2017). A key component of this framework is an assessment of the health of individuals. The Population Consequences of Multiple Stressors (PCoMS) model is a framework proposed for exploring pathways from exposures to stressors through their effects on physiology, behaviour, and health of an individual, to their effects on vital rates and population dynamics (National Academies of Sciences 2017). An important component to this is the use of early warning indicators for adverse impacts, including health and population measures (e.g., changes in southern right whale calving intervals), given that reliably measuring trends in marine mammal