Reminder shellfish and fishing warning for the Swan River update #6

The Department of Health is reminding people not to eat fish, crabs or shellfish collected from the Swan River downstream from Pelican Point to Como Jetty and upstream to Maali Bridge Park, Herne Hill due to the impact of the potentially toxic microscopic alga ‘Alexandrium spp .

This area includes the commonly known areas of Matilda Bay, Como Jetty, Perth Waters, Elizabeth Quay, Barrack Street Jetty, Claisebrook Cove, Ascot Waters, Riverside Gardens, Garvey Park, Sandy Beach Reserve, Point Reserve, Fish Market Reserve, Woodbridge Riverside Park and Middle Swan Reserve.

Acting Environmental Health Executive Director Dr Michael Lindsay said that ingestion of toxins produced by the detected microscopic algae ‘Alexandrium spp could produce a type of poisoning known as paralytic shellfish poisoning (PSP).

"These algae produce toxins that are absorbed by filter feeding shellfish and potentially consumed by crabs and finfish to a lesser extent” he said.

“It is important to note that cooking will not destroy these toxins.”

To date, Paralytic Shellfish Toxins (PSTs) have been detected in some mussels and Blue Swimmer Crabs within the area affected by the Alexandrium bloom.  Based on these results and the fact that it may take time for the toxins to pass through biota in the system the current advice not to eat fish, crabs or shellfish taken from the affected area in the Swan River remains in place.

The Department of Biodiversity, Conservation and Attractions will conduct further testing for toxins in mussels, Blue Swimmer Crabs and Black Bream in the Swan River, with assistance from the Department of Primary Industries and Regional Development, to help inform advice provided by the Department of Health.

People who consume wild shellfish, crabs or fish collected from the affected Swan River area may experience symptoms including, tingling or numbness of the lips, prickliness of the fingertips and toes, nausea or vomiting, impaired balance, dizziness, slurred speech, double vision, weakness, difficulty in swallowing or breathing, loss of fluids and diarrhoea.

In severe cases PSP may cause muscular paralysis in people who consume affected shellfish, crabs or fish.
Dr Lindsay said that anyone who had consumed shellfish, crabs or fish collected from the Swan River and experiences any of these symptoms should seek urgent medical attention, particularly if they feel any respiratory distress.

“Do not discard uneaten portions of mussels or other shellfish as these may assist with determining a likely cause of any symptoms.”
Shellfish includes oysters, mussels, clams, pipis, scallops, cockles and razor clams.

As a general rule people should avoid eating shellfish collected recreationally in rivers, estuaries or other waterways where there is an increased likelihood of contaminant or nutrient inputs that in turn can lead to increased microscopic algae growth.

Dr Lindsay said farmed shellfish purchased in supermarkets and other commercial outlets in WA are not affected as there is a strict quality-assurance program to ensure they are safe for human consumption.

“Other recreational activities including swimming, skiing and boating are not likely to be affected by this microalgae species, but as a general rule swimming should be avoided in areas of discoloured water.”

Health warning signs advising against crabbing, shellfish collection and fishing have been erected at key locations including certain jetties, boat ramps and key accessible foreshore areas within the affected region.

Not all waterways are always monitored for algal blooms and anyone who sees or suspects an algal bloom in a waterway should report this to the Department of Water and Environmental Regulation’s ALGALWATCH during office hours on 6250 8064 or to the relevant local government authority for assessment.

For further information on the Alexandrium minutum algae bloom contact the Department of Health on 9222 2000 or visit https://healthywa.wa.gov.au/algalblooms for Frequently Asked Questions.

To learn more about what DBCA and our partners are doing on this issue watch the following short video.

An Asian paddle crab (Charybdis japonica) has been found and confirmed this week via taxonomic and molecular analysis.  A single mature female crab was caught at Blackwall Reach, Swan River, Perth, by a recreational fisher on 5th December 2018.

The Asian paddle crab is an aggressive non-native crab that could outcompete native species like the blue swimmer and spread diseases to prawns, crabs and lobsters.

The Department is calling for continued vigilance from the community, recreational fishers and crabbers and sees their assistance as crucial as the five paddle crabs previously detected at Mosman Bay in 2012 and Matilda Bay in 2014, and one in Mandurah in 2010, were all caught by recreational fishers.

The pest crab varies greatly in colour but its definitive features are six sharp spines between the eyes and six spines down each side of the shell.

As part of the management response, the Department is undertaking a range of activities including public awareness and communication engagement campaign and trapping surveys in the Swan River are planned for the coming months.

The Department considers that the measures being taken are keeping the risks to WA’s aquatic environment to a low level.

Download the brochure here to find out more about this aggresive pest.

We've made it easy for you to help clean our rivers.

Together with FunCats Watersports in South Perth, we have a special board with reusable bags/buckets, grippers and instructions on how you can help!

All you need is a couple of minutes - grab a bag or bucket, gripper and pick up the rubbish along the beach and foreshore. Take your bag or bucket full of rubbish to the nearest bin, empty it and return the bag/bucket and gripper to the board - our native wildlife will thank you for it :)

Don't forget to take a pic and share it with us using the hashtag #cleanourrivers on River Guardians Facebook or Instagram. 

The Swan River is recognised as a very important area for waterbirds. There are 84 recorded species, of which 35 are seen regularly.  But there has been a loss of species and abundance especially in the last few decades in particularly caused by disturbance.

Disturbance can be caused by any human activity that alters the behaviour of birds.  In 2003 a study on the river showed disturbance events were caused by everything from jet skis to people innocently walking along the shore.

When birds are disturbed they take off and fly away. This can become a problem as eggs and chicks can be left alone and open to predation. Some beach-nesting birds are exhasuted after travelling so far and need to feed daily. 

Find out more about our beach-nesting birds project here.

Did you know the Kent Street Weir in Wilson is the point that separates the fresh water in the Canning River from the saline waters of the Canning Estuary?

The weir has been opened for the first time since a major upgrade to install automated hydraulic weir gates, a fishway and an improved walkway to enhance public access.

The opening of the weir will help alleviate winter flows and allow freshwater to push well into the estuary.

If you would like to see the water flowing through the weir, pack a picnic and visit the Explore Parks website for more info.