Two strandings in one week: killer whale calf and an adult bottlenose dolphin

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This past week has been quite eventful in Bunbury, Western Australia with two cetacean stranding events occurring.

The last Sunday of August (30/08/2015) began with a quiet morning start until about 9:30 am when I (John Symons; PhD candidate at Murdoch University Cetacean Research Unit) was notified of a deceased adult bottlenose dolphin on Stratham Beach, just south of Bunbury. Several volunteers and I responded to this stranding. Upon reaching the location we discovered a large adult male (2.5 m long) with an octopus hanging out of its mouth. Evidence of historical shark attack on the animal were also present.

Adult male bottlenose dolphin stranded the 30th of August, 2015. Previously the animal had been attacked by a shark. The animal had an octopus hanging out of its mouth.

Adult male bottlenose dolphin stranded the 30th of August, 2015. Previously the animal had been attacked by a shark. The animal had an octopus hanging out of its mouth.

The animal was recently deceased and due to the large size of the animal (estimated to be 250-300 kg), several members of the Bunbury Dolphin Discovery Centre and the public joined us to assist in lifting the animal into our stranding trailer for transport to Perth. Two of my volunteers and I transported the animal to Murdoch University, where veterinary pathologist Dr. Nahiid Stephens conducted a full post-mortem examination assisted by MUCRU members Delphine Chabanne and myself. The cause of death was ruled to be the result of a blocked airway. The result of the octopus suctioning to the esophagus and blocking the airway.

 

Up-close image of the octopus hanging from the dolphin stranded on the 30th of August, 2015. The octopus was ruled to ultimately have been the cause of death.

Up-close image of the octopus hanging from the dolphin stranded on the 30th of August, 2015. The octopus was ruled to ultimately have been the cause of death.

Then this past Sunday (06/09/2015), began quietly with an afternoon of land-based sampling for vessel usage within the Bunbury study area (a component of my PhD research under the umbrella of the South West Marine Research Program). However, at around 12:30 in the afternoon, I received a call about a stranded animal along Back Beach in Bunbury. The animal in question was reported as a young killer whale (Orcinus orca) stranded alive. Members of the public initially attempted to get the animal back in the water and out through the surf without success.

Upon staff from WA Department of Parks and Wildlife (DPAW), Dolphin Discovery Centre and myself  reaching the site of the incident, the animal was stabilized outside of the break zone on the beach using a sling. Buckets and wet towels were used to keep the animal damp, while plans to relocate the animal to an area, without waves breaking, inside the bay were made. No sightings of other killer whales in area have been reported prior or after the stranding.

Members of Murdoch University Cetacean Research Unit, Department of Parks and Wildlife, and the public stabilize the stranded orca calf along Back Beach. Photo by Phil Coulthard, Dolphin Discovery Centre.

Members of Murdoch University Cetacean Research Unit, Department of Parks and Wildlife, and the public stabilize the stranded orca calf along Back Beach. Photo by Phil Coulthard, Dolphin Discovery Centre.

The calf (female) died at around 14:40 in the afternoon and was declared dead by a local veterinarian shortly thereafter. The young killer whale was deemed to be no more than a few days old and was 2.6 m in length. Following the animals death, standard tissue sampling and measurements were conducted to improve understanding of the species, particularly genetics. No apparent cause of death was visible, though the animal was young and had been separated from its mother.

A limited tissue sampling was conducted post-mortem of the stranded orca calf.

A limited tissue sampling was conducted post-mortem of the stranded killer whale calf.

Note to the public:

Despite research efforts along the coast, researchers are not able to cover all parts of the ocean every day. Please report any sightings of killer whales and other cetaceans, pinnipeds and sea birds using the Coastal Walkabout app available for both Android and IOS. While doing this please follow appropriate approach guidelines for these animals. Further, our ability to detect mortality events or instances of live strandings is dependent on reporting by members of the public. If you spot an animal that is either dead or distressed in the water or along the coast, please contact the local DPAW office or the department’s Wildcare Helpline.

Lars Bejder PhD
Lars Bejder PhD
Professor Lars Bejder PhD is the Research Leader of the Murdoch University Cetacean Research Unit.
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