Why a giant carp has appeared at Argal reservoir

A 4ft carp has appeared at Argal reservoir. It did not swim there. The model, built by Greenspace, is part of a week of activity drawing attention to a problem that costs the country billions and threatens wildlife across the South West.

A week built around the invaders

This week, 22 to 28 June, is Invasive Non-Native Species (INNS) Week. The annual event is led by the GB Non-Native Species Secretariat to raise awareness of the alien species harming native wildlife.

South West Water ran activities throughout the week, following on from hosting the South West Invasive Species Forum’s 10th birthday celebrations in Bristol. Alongside surveys and data collection on marine species across its sites, the company marked the week both in person and online.

The carp at Argal reservoir was created with South West Lakes Trust. A 6ft crayfish model is set to appear at Wildwood on Friday 26 June.

What counts as an invasive species

Non-native animals and plants carried into Great Britain by humans can damage native wildlife. They arrive as new predators, compete for food and introduce disease. Once a species starts causing harm, it is classed as a non-native invasive.

These species are one of the top five drivers of global biodiversity loss and have played a part in 60% of plant and animal extinctions.

New non-native species arrive in the UK every year. Most are harmless. But around 10 to 15% go on to become invasive and cause damage.

How they get here

Invasive species can arrive by accident, hitching a ride as plants or insects on cargo ships or on imported materials like timber. Others were brought in deliberately as exotic pets, or in the past for ornamental or hunting purposes, then released or escaped into the wild.

That route led to an influx of American mink and grey squirrels. Mink became a major threat to water voles. Grey squirrels wiped out red squirrels.

South West Water frames it as a man-made problem that needs man-made solutions. Species that are valuable in their own native habitat become part of a much bigger problem once humans move them somewhere new.

The cost of getting it wrong

Invasive species are hard to manage and cost the economy nearly £2 billion a year through control costs, lost agricultural productivity and damage to public utilities.

For water companies the impact is direct. Zebra mussels can clog water pipes and cause operational disruption. Invasives can also disrupt ecosystems and reduce water quality, and some affect human health.

Ten years of the forum

The South West Invasive Species Forum (SWISF) marked its 10th birthday in Bristol. The work of environmental charities, companies and individuals across the UK was put under the spotlight, with the Environment Agency, the Waterlife Recovery Trust and Conservation K9 Consultancy among those presenting how they identify invasives and then act to manage them.

Open to the public, the event was held at Bristol’s Grand Hotel on Sunday. Guest speaker Dave Slater, Regional Director of Natural England, was among those reviewing the last 10 years and looking ahead to the next 10.

The agenda was full of data and project plans, with a shared sense among the speakers that removing invasives is an urgent but achievable goal.

‘A wonderful whirlwind’

Kate Hills, Biosecurity and Invasive Non-Native Species Manager at South West Water, said: “The last ten years of hosting the Invasive Species Forum have been a wonderful whirlwind. We have seen new invasive species arrive in Great Britain, but we have also seen partnerships and new forums work to prevent the spread of INNS and to protect our native species. Substantial efforts have been made to improve new technologies such as biocontrol, the use of detection dogs and eDNA. However, we still need better longer-term funding and a strategic approach to be more effective.

“During this ten-year period the yellow-legged Asian hornet was discovered near Bristol. Although this hornet has proved an aggressive predator of honeybees and other pollinators, its appearance is a testimony to how we hope to react to invasive species going forward by raising public awareness and delivering a clear nation-wide agenda.

“I look forward to hosting many more forums and fostering this knowledgeable community we have built to learn how we can best prepare ourselves for future invasions.”