Wildfowling advice on blue-green algae

Countryside Alliance Ireland has been monitoring the level of blue-green algae and the threats it poses as you prepare for the wildfowling season, should the issue continue to persist.

Under favourable conditions, blue-green algae can double in number in just 24 hours and these blooms can turn waters from blue to brownish green.

Generally, toxic algae blooms last only a few days, but as in our case they continue to persist for several weeks.

What is Blue/Green Algae?

Algae occurs when the right nutrient and temperature conditions allow for overgrowth of algae. With July being the wettest month on record, it has washed excess nutrients into our waterways and, coupled with the unusually high water temperatures, has provided ideal conditions for algae blooms to occur.

Cases usually occur in late summer or early autumn, normally in stagnant ponds however, this year we have seen it in lakes, rivers, lochs and even along coastal waters.

Toxicity within the blue-green algae can change rapidly and increase as it ages or starts to die. Some toxins can persist for more than three months before being degraded by sunlight and microbial activity. 

Water can be toxic to stock even after the bloom has disappeared. Sun-dried algal scum can remain toxic to you and other animals including dogs, ducks, geese, rabbits, frogs, fish, sheep and cattle for up to five months.

In the case of dogs, symptoms can appear within a few minutes or sometime hours after exposure, and commonly include vomiting, diarrhoea, drooling, disorientation, trouble breathing, seizures, and blood in faeces. While there is no known antidote for the toxins, prompt veterinary treatment is critical to give any chance of recovery. It is vital that you continue to be vigilant, especially with dogs as they are very susceptible to these toxins. A number of canine deaths have been attributed to dogs entering the water near algae blooms.

Small ponds that don’t drain into other waterways or bodies of water can be treated with copper sulphate or an algicide. However, toxin levels increase immediately after treatment, so livestock and other animals should not be allowed to drink in line with manufacturers recommendations.

Whether you’re preparing your hide for the season ahead or going out to harvest some ducks for the pot during the season, if you suspect the water to be contaminated or that it has recently been contaminated with blue-green algae, make sure you consider taking the following precautions:

• Avoid areas where blue-green algae is known to be in the water and use/seek alternative hunting areas
• Avoid contact or entering the water even if you are wearing undamaged waders
• Do not consume the water or allow your dog to do so. Seek emergency treatment if you are concerned this may have happened.
• Do not eat, discard, or feed to your dog the internal organs (particularly the liver) of ducks. Rinse the duck with clean water prior to cooking and eating if taken from contaminated wetlands, lakes or other waterways as toxins may have accumulated within the quarry.
• Do not let your dog submerse itself in the water and, if it does, wash your dog thoroughly in clean water (wearing gloves) before it starts to groom or lick itself.
• Be aware that boiling water where algae is present does not remove toxins from the water.