Marine Life & Conservation Blogs
Divers asked to look after Cornwall’s Crawfish after dramatic comeback
A Cornwall Wildlife Trust initiative introduced by Jeff Goodman
I always thought it was OK to take one for the pot. Diving in the early seventies we hardly ever climbed out of the water without something for our tea. But as the eighties approached I saw less and less marine life as full ‘goody’ bags from divers got bigger and more frequent. I started to feel uneasy about what we were doing to our seas.
Of course commercial fishing and angling have always taken an horrendous toll on marine life but now we as divers were in a position to find and take what was left. There is no finer example to this than the wonderful Crawfish. Along with them the Lobsters and Scallops were equally depleted. Scallops reproduce far quicker than Crawfish and so had a better chance to recover. Lobsters were and are reintroduced by hatcheries in their hundreds of thousands. The Crawfish was ignored and left to simply vanish from the marine ecosystem.
Finally against all the odds, Crawfish are starting to re-appear in Cornish waters and already fishermen and divers are eager to take them.
I spoke with Matt Slater, Marine Awareness Officer for Cornwall Wildlife Trust and as a result he sent me the following article on their new initiative to give these incredible animals a fighting chance. Whether you live in Cornwall or Timbuktu, I urge, no implore you to read this and give it all the support you can.
Matt Slater:
After nearly forty years crawfish have made a dramatic comeback as large numbers of young crawfish have reappeared on wrecks and reefs all around the Cornish shores.
The crawfish or spiny lobster is a spiky and ornate relative of the common lobster, with incredible long antennae and a powerful finned tail. This species was overfished back in the 1970’s and 80’s by both fishermen and divers but in recent years marine conservationists have been thrilled to see their return.
However Cornwall Wildlife Trust is now calling on divers to show that they care about crawfish by pledging not to catch them through a new national campaign called #HandsOffOurCrawfish
Image: David Morgan
They hope through education to get a high proportion of divers supporting this campaign with the eventual aim to see crawfish better protected in our waters, ensuring a sustainable fishery for the species. Dive schools, dive boats and dive clubs will be provided with stickers saying ‘no crawfish on this boat’ and the Trust hopes to provide a much needed clear message for the benefit of these creatures.
Crawfish can live to up to 60 years and are very slow growing. They have long antennae which are used to taste the water to help them look for food as they scavenge on the sea bed.
They also communicate by generating a strange creaking sound by rubbing the bases of their antennae against their shell. This sound can travel for long distances and may play a role in attracting mates.
Matt Slater, Marine Awareness officer for Cornwall Wildlife Trust describes his first encounter with these creatures:
“We dropped down to the seabed on a rocky reef off Newquay that I have dived many times over the years. Where previously I had never seen any crawfish, on this dive within just a few minutes we found 18 beautiful crawfish.”
“Through our Seasearch citizen science project our volunteer divers have recorded huge numbers of crawfish over the past few years in Cornish waters. And we now carry out repeat survey dives for this species at several locations in Cornwall.”
Image: Matt Slater
“Divers all around the south west are reporting crawfish at their favourite dive sites and everyone is really pleased to see them back. However, there is a strong concern from many that we must ensure that they are back for good and that fisheries for this species are carried out at sustainable levels to ensure that history does not repeat itself and they become over fished again.”
“The majority of recreational divers appreciate all the marine creatures they encounter and very few collect marine life to eat, preferring to enjoy peaceful encounters and underwater photography. Having said this, many popular dive sites appear to have groups of resident crawfish. If even small numbers of divers start collecting them, it would not take long for them to disappear once again.”
“We already have the support of many of Cornwall’s dive operators and dive schools but we would ask everyone to get involved and to pledge not to take crawfish on their dives – that’s why we started the ‘Hands Off Our Crawfish’ campaign.”
Dive Newquay were the first company to sign up to the campaign. Paddy Maher of Dive Newquay says, “Since we first set up our dive company five years ago we have always made our customers return any collected crawfish back into the sea. No one wants to see these creatures wiped out again as they were in the 1980’s. It makes absolute sense to educate divers and to ask people to think more about their impacts on the underwater world.”
To pledge please visit www.cornwallwildlifetrust.org.uk/crawfishproject Look out for the hash tag #HandsOffOurCrawfish on social media as the Trust hopes divers will share their photos and crawfish news to help spread the word about the project!
This campaign will also be promoted through the national Seasearch programme in Devon, Dorset and the Channel Islands.
Further information
Crawfish or spiny lobster
Palinurus elephas
- These ancient crustaceans are usually found on exposed rocky reefs at depths of at least fifteen meters.
- They are heavily armoured, with sharp spines for defence.
- Unlike lobsters crawfish don’t have large claws instead having spikey front legs.
- Crawfish grow slowly, and can grow to a maximum size of 1 meter living for at least 60 years.
- They take at least three years before they are old enough to breed. Larger females produce far more eggs than smaller ones.
- Crawfish use their spectacular, long antennae to taste tiny amounts of chemicals in water allowing them to detect predators and other mates as well as food.
- Crawfish can communicate using strange creaking sounds that they produce by rubbing the base of their long antennae against each other. This sound can travel for long distances underwater. Some Cornish fishermen actually call crawfish ‘creakers’
Seasearch
- Seasearch is a national citizen science project that trains recreational divers to record marine life and habitats they encounter on their dives.
- The project is led by the Marine Conservation Society and in Cornwall it is coordinated by and funded by Cornwall Wildlife Trust.
Aims of Seasearch
- To encourage the participation of volunteer recreational divers in marine conservation through gathering data, particularly for areas where little data exists or where there is a conservation need,
- To provide training in recording skills to enable volunteer recreational divers to participate in Seasearch,
- To make quality assured Seasearch data available to partner organisations and the general public,
- To raise public awareness of the diversity of marine life and habitats in Britain and Ireland through the dissemination of information gathered and the identification of issues arising from it.
Matt Slater, Marine Awareness Officer CWT
A Cornish Marine biologist and educator, experienced in aquarium and community engagement work. I am passionate about our marine world and love sharing this passion and encouraging us all to take better care for the oceans.
In this series, the Shark Trust will be sharing amazing facts about different species of sharks and what you can do to help protect them.
This month we’re looking at the Undulate Ray. Easily identified by its beautiful, ornate pattern, the Undulate Ray gets its name from the undulating patterns of lines and spots on its dorsal side.
This skate is usually found on sandy or muddy sea floors, down to about 200 m deep, although it is more commonly found shallower. They can grow up to 90 cm total length. Depending on the size of the individual, their diet can range from shrimps to crabs.
Although sometimes called the Undulate Ray, this is actually a species of skate, meaning that, as all true skates do, they lay eggs. The eggs are contained in keratin eggcases – the same material that our hair and nails are made up of! These eggcases are also commonly called mermaid’s purses and can be found washed up on beaches all around the UK. If you find one, be sure to take a picture and upload your find to the Great Eggcase Hunt – the Shark Trust’s flagship citizen science project.
It is worth noting that on the south coasts, these eggcases can be confused with those of the Spotted Ray, especially as they look very similar and the ranges overlap, so we sometimes informally refer to them as ‘Spundulates’.
Scientific Name: Raja undulata
Family: Rajidae
Maximum Size: 90cm (total length)
Diet: shrimps and crabs
Distribution: found around the eastern Atlantic and in the Mediterranean Sea.
Habitat: shelf waters down to 200m deep.
Conservation Status : As a commercially exploited species, the Undulate Ray is a recovering species in some areas. The good thing is that they have some of the most comprehensive management measures of almost any elasmobranch species, with both minimum and maximum landing sizes as well as a closed season. Additionally, targeting is entirely prohibited in some areas. They are also often caught as bycatch in various fisheries – in some areas they can be landed whilst in others they must be discarded.
IUCN Red List Status: Endangered
For more great shark information and conservation visit the Shark Trust Website
Image Credits: Banner – Sheila Openshaw; Illustration – Marc Dando
Protecting (Dutch) Caribbean Reefs from Unomia stolonifera
Recent reports highlight the concerning spread of the invasive soft coral, Unomia stolonifera, currently devastating Venezuela’s marine ecosystems and detected in Cuba. With the potential threat of its expansion to the (Dutch) Caribbean islands, urgent action and awareness are essential to safeguard marine biodiversity and local economies from possible catastrophic consequences.
Invasive species are animals or plants from another region of the world that don’t belong in their new environment. These species can have major ecological effects by decimating native flora or fauna. They can also cause large economic losses and impact human health. Invasive species also pose a significant threat to marine ecosystems worldwide, including the Dutch Caribbean. Among these invaders is the octocoral species Unomia stolonifera or “Pulsing Xenia”, originally from the Indo-Pacific. With its rapid growth and lack of natural predators, this species can outcompete native species and disrupt fragile marine habitats such as seagrass beds and coral reefs.
Background
The invasive soft coral U. stolonifera was first identified in 2014, off the coast of Venezuela. It is believed to have been introduced via the illegal aquarium trade. Since this species can reproduce sexually and asexually (or fragment), even small pieces can regenerate to spread. Once introduced it quickly took over shallow reefs and hard substrate at depths of 0-50 meters, outcompeting local corals and seagrass for space. Follow on surveys found that this coral species exhibited average percentage cover as high as 80%, vastly outcompeting native corals. In highly colonized areas, fish are disappearing due to loss of habitats.
In 2022, during a survey conducted in Cuba by the University of Havana, an unknown octocoral was discovered which was later identified as the invasive Unomia stolonifera. It is suspected that the coral larvae arrived in ballast water from fossil fuel ships originating from Venezuela, as nearby sites adjacent to Venezuelan ports have been heavily affected by the invasion.
How to help
Prevention through continuous monitoring, particularly in high-risk areas such as marine harbors and oil facilities, is paramount. Early detection plays a pivotal role in mitigating the threat posed by Unomia stolonifera.
The public’s involvement and awareness are also vital. Local communities, recreational divers, tourists, and all stakeholders are urged to participate in early detection efforts by reporting sightings (photo, location and date) of this invasive coral to their respective Protected Area Management Organization (PMO’s)- the Fundacion Parke Nacional Aruba (FPNA), STINAPA Bonaire, CARMABI Curaçao , Saba Conservation Foundation (SCF), Nature Foundation St. Maarten (NFSXM) and St. Eustatius National Parks (STENAPA). If an invaded area is confirmed, follow the recommendations by the local PMO’s.
Keys to Success
Despite the challenges, early detection is key to mitigating the threat posed by Unomia stolonifera. With continued vigilance, research, and community engagement, there is hope for containing this potential issue before it becomes a major threat.
About the DCNA
The Dutch Caribbean Nature Alliance (DCNA) supports (science) communication and outreach in the Dutch Caribbean region by making nature related (scientific) information more widely available through amongst others the Dutch Caribbean Biodiversity Database, DCNA’s news platform BioNews and through the press. This article contains the results from several scientific studies but the studies themselves are not DCNA studies. No rights can be derived from the content. DCNA is not liable for the content and the in(direct) impacts resulting from publishing this article.
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