Whales as sentinels in a changing environment
Building on 10 years of previous GAP data, GAP 2009 seeks to document and compare seasonal shifts in the distribution of three mysticete species to identify temporal shifts in habitat use that may indicate changes in prey availability. We will continue to photo-identify individual whales of all three species as a means of following long-term patterns in their residency, habitat use, and reproductive history. Measurable changes in stable carbon and nitrogen isotope ratios in whale tissues reflect shifts in the proportion of fish and zooplankton in the diets of these whales. Therefore, we will continue to collect skin biopsies from humpbacks and fin whales in the Kodiak and Shumagin areas and analyze them isotopically as a means of monitoring trophic-level diet shifts over time and between areas.
New in GAP 2009, we propose to explore the fine-scale response of whales to a physical change in their environment: point-source noise generated by acoustic deterrent devices. In collaboration with Kodiak commercial fishermen, we will measure the response of tagged humpbacks to noise-making devices used by fishermen to deter whales from entangling in their fishing gear. By monitoring whales’ response to abrupt acoustic change in their environment, we hope to identify effective means of avoiding entanglement while minimizing the introduction of additional noise into coastal waters.
The goal of GAP 2009 is to monitor the measurable response of three mysticete whale species to changes in their physical and acoustic environment. Our specific objectives are to
- Monitor trophic-level shifts in prey use via isotopic ratios in fin and humpback whale skin
- Monitor distribution, diet, and residency of a sentinel species (gray whales in Ugak Bay)
- Monitor the seasonal distribution of Kodiak whales as an indicator of changing prey/environment
- Document fine-scale response of humpback whales to acoustic deterrents