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.

How can you tell a male and female humpback whale apart?

In many animals, different sexes have different appearances, with males often being larger, showier, or both: think of brightly colored male songbirds or male lions with their luscious manes. For humpback whales, however, this is not the case. Apart from females being slightly larger than males on average, humpback whale males and females look very similar to each other, making it very difficult to visually determine sex. Adding to this, all reproductive organs in both females and males are neatly tucked away behind a genital slit to help them be more hydrodynamic and sleek in the water.

Luckily for us researchers, though, we have a few tricks up our sleeves to tell the difference between the sexes, allowing us to collect additional data for our photo-identification catalog.

The easiest way to determine a female humpback whale is a close association with a calf. Mothers and calves maintain a strong bond throughout the first year of the calf’s life, so when we see an adult whale closely accompanied by a calf, we can safely assume that she is the mother of that calf.

In the absence of a calf, though, things become trickier. If the whales roll over onto their backs, often we can see the genital slit on their abdomen. The relative location of the genital slit offers some clues: For males, the genital slit is located closer to the whale’s belly, while the females’ genital slit is closer to their tail flukes. Immediately towards the tail from the genital slit, females have a grapefruit-sized lump known as a hemispherical lobe. No one knows what exactly this structure does, but we do know that it is only present on females. Females also have two mammary slits, one on either side of the genital slit, which they will use when nursing their calves.

Click through the photos in this gallery and our researchers will explain how we were able to identify the sex of these humpback whales

When we are able to determine the sex of a whale, this information is included along with the animal’s fluke photo when it is added to the catalog. Knowing the sex of different individuals enables us to more accurately determine calving rate and sex ratios of different habitat areas.

Southern right whales in Hervey Bay

This season, humpback whales haven’t been the only large baleen whale sighted in Hervey Bay. We have also had several sightings of mother-calf pairs of southern right whales, a rare species for this area. The first pair was seen in July, and there have been many additional sightings over the past several weeks, much to the surprise and delight of passengers and staff onboard Ocean Defender.

All right whales have white patches of rough skin on their heads called callosities. The pattern of callosities is unique to each individual whale, and researchers use these patterns to identify right whales much in the same way that we use fluke patterns to identify humpback whales. Using the patterns of callosities, we have been able to recognize at least three different mothers that have been sighted this season.

These mothers belong to the southeast Australia population, which is more commonly seen farther south in Victoria and New South Wales. Similar to humpback whales, southern right whales prefer relatively warmer, calmer waters for their calves, but they do not typically travel all the way to tropical areas. In fact, Hervey Bay is considered the extreme northern extent of their range. Southern right whales were hunted extensively since their slow swimming speeds and thick blubber made them the “right” whale to kill, particularly before the industrial era of whaling. The populations are recovering, though, and it is encouraging to see these mothers and calves along the east coast of Australia.

Looking back through the past several years of data from Hervey Bay, Pacific Whale Foundation researchers have only seen right whales in the area in 2006, 2007, 2009, and 2012 prior to this year. In those years, there were also fewer sightings: 2009 and 2012 each had sightings on two days, but our team only saw right whales a single time in 2007 and 2009. Although we can’t say for sure why these mothers and calves decided to visit Hervey Bay for such an extended time this season, it will certainly be interesting to see what future years bring for sightings of this amazing species.

Although Pacific Whale Foundation does not currently study southern right whales, our research team is collecting data and submitting all sightings and identification photos to the Australian Marine Mammal Centre which maintains a catalog of this population.

 

The Elusive False Killer Whale

In 2013, Jens Currie came to Pacific Whale Foundation as a data analyst from Canada’s Department of Fisheries and Oceans. With an ambition to explore more robust statistical methods of potential anthropogenic impacts on cetacean populations, Jens is now Senior Research Analyst. Here, he lends a helping hand for those of us that are new to understanding and appreciating the endangered false killer whale.

scroll below to watch video

What is a false killer whale, and can you dissect the name for me?
False killer whales are the fourth largest species of dolphin. They are characterized by their dark coloration, slender body, crescent-shaped dorsal fin, and small rounded head with no beak. Individuals of this species weigh between 1,000-3,000 lbs. Adult females reach lengths of 16 feet, while adult males are almost 20 feet long.

The name Pseudorca (pseudo-orca) comes from the similarly shaped skulls that false killer whales have to that of killer whales (Orcinus orca). The “crassidens” in their scientific name Pseudorca crassidens means “thick tooth.” They were first discovered and described by fossils.

What is their lifespan, what do they eat, how do they stand out?
These animals have a lifespan of 60 years or more.  False killer whales feed primarily on fish and cephalopods in open water habitats.  The prey items of this species include economically important fish, such as mahi-mahi and tuna, and occasionally other marine mammal species. It has been documented that false killer whales cooperatively hunt, and will share food between individuals in their group.

Where are they found in the world?
False killer whales are distributed throughout warm and temperate waters in the tropics and subtropics, with the highest abundance in warmer waters. They are typically found in the open ocean but can also occur closer to shore, particularly near tropical oceanic islands such as the Hawaiian Islands. Based on genetic and photographic data, there are three populations of false killer whales surrounding the Hawaiian Islands: the main Hawaiian Islands insular population, the northwestern Hawaiian Islands insular population, and an offshore/open-ocean population.

Do they migrate? Are they kama’aina?
They do not migrate and the main Hawaiian Islands insular population is kama’aina

Why are there so few remaining?
The endangered main Hawaiian Islands insular false killer whale population is estimated to be around 150 individuals. The historical population size is unknown; however, spotter planes from the 1980s report seeing large aggregations of 350-400 whales in a single area. Aerial data suggest that the population has declined at an average rate of 9% per year through the early 2000’s (NOAA Fisheries, 2018).

The reason why there are so few false killer whales is unknown; however, there are several factors that likely play a role. Given their endangered status, in 2010 a Biological Review Team (BRT) was established to conduct a status review of the species. In the Status Review report (Oleson et al. 2010) of the 29 identified threats identified, the most substantial threats to the population include: the effects of small population size (inbreeding depression and Allee effects), exposure to environmental contaminants, competition for food with commercial fisheries, and hooking, entanglement, and/or intentional harm by fishermen.

How can citizen scientists help us ID these elusive animals?
Citizen scientists can help us ID these animals by donating any photos they have of false killer whales in Hawaii. We can photo-identify individual Pseudorca through unique scars and markings, and by using their dorsal fin. Photo-identification is an important part of our research and how we can track changes in population size over time.

Another way to help is to notify PWF’s researchers when false killer whales are sighted in the Maui Nui region! We would greatly appreciate a phone call or text if any water users see false killer whales so we can initiate a rapid response (weather and time permitting).

Can you give me 3-5 reasons why they are awesome?
They share food with each other, and have been documented offering fish to humans that are diving or boating.

They are one of very few species known to enter menopause. Most animals continue to reproduce until they die; the only known exceptions to this are humans, killer whales, false killer whales, and short-finned pilot whales.

False killer whales were first discovered by their fossils and were thought to be an extinct species until a pod was observed in 1861.

 

All photos and videos were taken under NMFS Permit # 16479.

New research study on false killer whales

The Research Team is excited to announce that we have started a new study on false killer whales! We started field work for this study in May 2018 and will survey the leeward waters surrounding the Maui 4-island region; up to 50 miles offshore. This brings us into deep waters (> 2,500 ft) where the possibility of seeing other species is also very likely. In case this does happen, we also have authorization to collect data and photo-ID of 15 other toothed-whale species. The main objectives of this study are to assess the distribution, population structure, habitat use, body condition, and behavior of false killer whales.

The majority of false killer whales encountered within the waters of the Maui 4-island region are part of the Main Hawaiian Islands (MHI) insular stock which is currently listed as “endangered” under the Endangered Species Act. The minimum population estimate for the MHI insular stock is 151, based on the number of unique individuals photographed (Baird et al. 2013). This stock faces a number of threats such as the effects from small population size, high levels of contaminants, interactions with fisheries, and a decrease in their prey species biomass.

Given the “endangered” status of the MHI insular false killer whales, there is a need to gain a better understanding of the species in order to develop effective management plans to aid in their recovery. Our research will provide a continuous, long-term data set using new techniques and technologies to  address gaps in our knowledge of this population. In addition to photo-identification, location, and behavioral observations, we will be using unmanned aerial vehicles (commonly called ‘drones’), photogrammetry, and underwater footage to gain information on body condition, growth rates, and possibly detect pregnant females.

We are excited to begin this new study and to learn more about this endangered population. Stay tuned for updates from the field!

Research Team Launches Dolphin and Whale Tracker App

The Pacific Whale Foundation research team has been hard at work creating a new ‘Whale & Dolphin Tracker’ app that is now available for download on the App Store and Google Play. This free app allows members of the public from all over the world to participate in citizen science by recording sighting of marine mammals. Contributors are able to use their mobile phone to record the GPS location of the animals, group size, observed behaviors, as well as upload any photos they may have taken. It’s an exciting way for the public to get more involved with the monitoring and research of marine life.

The Whale and Dolphin Tracker app was initially designed as a tool for PWF’s Marine Naturalists to record marine mammal sightings in the 4-island region of Maui, Kaho’olawe, Lana’i, and Moloka’i. Launching the public app will allow for a greater range of data collection in real time and overall will contribute to the global research database of cetacean species.

Additionally, users can find an interactive live sightings map on the Pacific Whale Foundation website which displays all sightings logged on the app within the past 7 days. Viewers will be able to use species and location filters to observe changes throughout the year.

This app was able to come to life thanks to a successful fundraising venture in 2016. Jens Currie, the Senior Research Analyst at Pacific Whale Foundation, is excited about the crowdsourcing opportunities that are created by the app: “Now that more users will have access to Whale and Dolphin Tracker directly from their phones, our crowdsourcing ability, and geographical coverage will expand, and so will our knowledge of whale and dolphin distribution”. He also added “We just published a research paper on humpback whale distribution using Whale & Dolphin Tracker data, and are excited about the opportunities this app presents for opportunistic data collection.”

Are you excited to get involved with real-time monitoring of cetaceans around the world? Head to the Apple app store or Google Play now to download Whale and Dolphin Tracker and join the team.