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Dolphin populations likely to be impacted by climate change

Freshwater Skin Disease (FWSD) is due to the detrimental effects of freshwater exposure in coastal bottlenose dolphins, and is an emerging cause of morbidity and mortality in many regions. We, for the 1st time, provide a case definition of this disease entity based on two Australian mortality events. The 1st affected Burrunan dolphins (Tursiops australis) in Victoria’s Gippsland Lakes in 2007 (a similar event is currently unfolding - see https://www.abc.net.au/.../burrunan-dolphin.../12900270). The 2nd event occurred in 2009 and affected the resident Indo-Pacific bottlenose dolphins (T. aduncus) in WA's Swan-Canning Riverpark. Simultaneously with the Gippsland Lakes event, the first outbreak of FWSD in US waters was recorded for common bottlenose dolphins (T. truncatus) entrapped in Lake Pontchartrain, Louisiana, USA, following Hurricane Katrina in 2007. However, the dermatopathology was not described for the US event, as post-mortem examinations were not conducted.

By contrast, the Australian events occurred where the resident populations were well documented by long-term and ongoing field ecology, population, and behaviour studies (including Citizen Science projects e.g. WA's River Guardians and Dolphin Watch programs); the waters inhabited by the dolphins were intensively monitored for physical and chemical parameters before, during and after the events; and when mortalities occurred, thorough and systematic post-mortem examinations were carried out. Based on these data, FWSD occurs when there is a sudden (over days) and precipitous (>25ppt to <5ppt) decrease in salinity, persisting for weeks to months. The skin lesions initially appear as patchy pale areas that progress to raised targetoid areas of ulceration and opportunistic colonisation by algae, diatoms, fungi and bacteria. In our paper we detail the gross and histological appearance of the characteristic skin lesions of FWSD. Death may ensue from fluid loss and electrolyte imbalance - because the ulcerative skin lesions are akin to severe third degree burns and often affect a large % of the body surface.

In Australia, the outbreaks followed resumption of seasonal rainfall following a prolonged drought that flooded the Gippsland Lakes (normally brackish to marine saline) with fresh water. In WA, unusually high winter-spring rainfall in the river catchments similarly turned a normally marine/brackish habitat to freshwater. In the Gulf of Mexico, USA, events have followed the heavy rainfall and storm surges in the aftermaths of Hurricanes Katrina and Harvey. Common to all events is a preceding extreme weather event - which are predicted to increase in frequency and severity with Climate Change. Therefore, FWSD is an emerging disease of cetaceans which we are likely to see increasing in frequency in vulnerable estuarine and coastal habitats that continue to be affected by worsening Climate Change.

The research paper is titled ‘Fresh water skin disease in dolphins: a case definition based on pathology and environmental factors in Australia’ published in Nature Scientific Reports. Read the full paper here.

Photo: Case 3 from the paper, a dolphin from Perth’s Swan-Canning Riverpark that died in 2009 (photo credit – Douglas Coughran, AM, DBCA)

Alexandrium algal bloom caution

Alexandrium algal bloom caution
Following two consecutive years of significant Alexandrium algal blooms impacting the Swan and Canning Rivers, the Department of Primary Industries and Regional Development (DPIRD), Department of Biodiversity, Conservation and Attractions (DBCA) and the Department of Health (DoH) are adopting a proactive management approach prior to the opening of the blue swimmer crab season in the Swan and Canning rivers on 1 December 2020.

A new harmful algae caution sign has been installed at popular jetties, boat ramps and fishing locations around the Swan and Canning rivers. The sign advises recreational fishers not to eat mussels and  to clean any blue swimmer crabs caught in the Swan and Canning rivers by removing the head, guts, mustard and gills prior to freezing, cooking and eating.

DPIRD and DBCA will run an ongoing Alexandrium education campaign and have created some Frequently Asked Questions, a brochure and a video to help inform recreational fishers and the general public of this public health issue. Alexandrium does not affect swimming and other aquatic activities in the rivers but you are advised not to swim in discoloured or smelly water.

What is Alexandrium?

Alexandrium is a group of microalgae that has been previously detected at elevated levels in the Swan and Canning rivers.

It has impacted waterways and fisheries around the globe, and is expected to be an annual occurrence in the Swan and Canning rivers.

These algae can produce Paralytic Shellfish Toxins (PSTs) that can impact mussels and crabs. At worst, poisoning by PSTs can be fatal to humans and there is no antidote, with treatment being supportive care and artificial respiration. A meal of 3-4 whole crabs can cause symptoms.

How can I reduce my risk?
To reduce your risk of ingesting PSTs:

• do not eat mussels from the Swan and Canning rivers
• clean any blue swimmer crabs caught in the Swan and Canning rivers by removing the head, guts, mustard and gills prior to freezing, cooking and eating

How can I find more information?
The Department of Biodiversity, Conservation and Attractions (DBCA) and the Department of Primary Industries and Regional Development (DPIRD) have developed an ongoing Alexandrium education program to alert the public and recreational fishers to the dangers of PSTs.

More information is available in the following publications available for download at the bottom of this page:
• 'How to clean blue swimmer crabs' brochure
• Frequently asked questions
Alexandrium video

Look out for new 'harmful algae' caution signs that have been installed at key Swan Canning Riverpark locations including jetties, traffic bridges, boat ramps and popular fishing locations.

For further information on Alexandrium, please contact DoH on 9222 2000 or refer to the web pages provided on the DBCA and DPIRD websites.
www.dbca.wa.gov.au/algal-bloom
www.fish.wa.gov.au/alerts

Volunteers needed for new Reel it in bins

With the recent installation of Reel it in bins in City of Joondalup and City of Wanneroo, we are now searching for enthusiastic local volunteers to adopt-a-bin and help keep our wildlife safe and rivers and coastal areas clean.

By registering as a volunteer for the Reel it in campaign, you will be provided with the training and equipment needed to audit a local fishing line bin. This opportunity provides a great way to care for and look after your local environment.

If you are interested in adopting a bin and want more information head to our Reel it in page. To register your interest please email us at community@dbca.wa.gov.au.

Point Roe Embankment Stabilisation Project


DBCA and the Town of Mosman Park (the Town) collaborated to fund the Point Roe Embankment Stabilisation Project in 2019. The project involved bioengineering, revegetation and weed control to stabilise and protect the previously degraded embankment. Approximately 400m2 of steep embankment has been restored, improving stability, ecological function and amenity for the surrounding community. The Town will continue with weed control and in-fill planting to ensure the success of the project site. The collaboration between DBCA and the Town continues at Point Roe with a new foreshore restoration project and the construction of a bird hide currently underway.

Figure 1 & 2. Bioengineering and revegetation at the Point Roe Embankment Stabilisation Project

7 new coastal Reel it in bins installed in Joondalup and Wanneroo

The Cities of Joondalup and Wanneroo are the latest local government authorities to join the Reel it in campaign aimed at preventing discarded fishing line and other harmful waste from ending up in our marine environment and posing a threat to wildlife.

Seven new fishing line bins have been installed at the following popular coastal fishing locations:

Joondalup (3 x bins)

• Ocean Reef boat harbour (complementing the fish cleaning station and de-rigging areas)
• Burns beach
• Marmion foreshore

Wanneroo (4 x bins)
• End of Alexandra View (Mindarie)
• Groyne 2, Groyne 3 and Groyne 4 running parallel with Ocean Drive (Quinns Rocks)