Whales divided: how adults and calves use Hervey Bay differently

If you go whalewatching in Hervey Bay after mid-September, you may notice that there is a calf in nearly every pod you see. Mothers with calves are typically the last to arrive in the bay, and they may be the group that benefits most from the shallow, protected waters near Fraser Island.

Our research on the East Australia population of humpback whales allows us to ask questions about long-term trends in behavior and habitat use within the area. Using sighting data collected by our research team from 2004 – 2016, we looked at whether pods with a calf preferred different areas of the bay compared to pods without a calf. As it turns out, mothers with calves do show a preference for an place just inside the U-shaped coastline of Fraser Island, known colloquially by whalewatch operators as “the pocket”. Pods without a calf show an opposite preference for waters a bit farther offshore.

Although depth and distance to shore do not vary much throughout the bay due to the overall shallow waters and the U-shape of the coastline, mothers may prefer that area because it might be the most protected from rougher weather conditions. They may also use it as a place to avoid pursuing males and competition pods. Pods that do not have a calf may prefer the area slightly farther out of the pocket if they are seeking mating or socializing opportunities from other adults or subadults.

The study provides a baseline to compare future observations of whale distribution within the Hervey Bay area, particularly as this population continues to coexist with human activities in the bay including recreational boating, commercial whalewatching, and swim-with-whales tourism.

Coral Reef Survey

Pacific Whale Foundation (PWF) was recently contacted by WHALE Environmental Services LLC and asked if we were interested in a collaboration, as this Oahu-based company was planning to undertake a pilot project to survey the West Maui coral reefs. PWF was very keen to take part, and so we made arrangements to take our research vessel, Ocean Protector, out as a diving vessel for a change.

Using a standardized method, we made very short dives at 14 coral reefs along the coast of West Maui, between Ma’alaea Harbor and Honolua Bay. While scuba diving, we took note of various factors which would be used to indicate reef health, such as:

  • the number of coral species observed
  • the number of fish species observed
  • signs of pollution
  • signs of erosion
  • signs of coral disease or bleaching
  • signs of fishing pressure
  • signs of stormwater entry at the site

It was interesting to see the stark differences between a healthy reef and an unhealthy reef. This project is a baseline study – meaning that we are recording the current state of these reefs so we have a measurable starting point and can monitor the reef and detect any changes in the future. In science it is very important to record a baseline so you know when changes are happening. You then have data on how fast or slow changes are occurring, or in what locations.

While we await the results of the report that is being prepared, the research department is back to its usual summer routine of carrying out transect surveys for dolphins and marine debris.