Tripping Over Trouble: Where Have Falmouth’s Rays Gone?

Blonde rays (Raja brachyura) are identified by their diamond shaped body and small dots extending to the tips of their wings. Photo credit: Paul Newland

Rays used to be so common in Falmouth, divers joked about tripping over them on their way into the sea. Thornback, Blonde, Small-eyed and Undulate, are just a few of the species you could find on almost every dive. But those days are gone. Today, you’d be considered lucky to spot one without stepping foot on a boat. So what’s happened to our rays - and why?

Too Hot to Handle

On average, ray populations are declining across the UK. These cartilaginous fish belong to the superorder Batoidea, and are members of the highly-threatened Elasmobranch family which includes sharks, rays, and skates. The ‘rays’ we see here in Cornwall are often a misnomer - biologically, they are skates. The largest difference is that skates give birth via egg cases, whereas rays produce live young. For the sake of semantics, we’ll call them rays here.

Elasmobranchs are a particularly special group because they all share the ability to sense the environment through electric signals - called electroreception. They are also ectothermic, meaning their internal thermostat is determined by the surrounding environment. Temperature shifts can dramatically affect their behaviour, body functions, and movement patterns, and have undoubtedly played a part in the global decline of elasmobranchs. A recent study found a 71% decline in oceanic shark and ray populations over the last 50 years. We all know that Cornwall is no stranger to changing weather regimes, with the southwest coast experiencing numerous “unprecedented marine heatwaves” in recent years. This August, we’re experiencing “record breaking” ocean temperatures here in Cornwall.

Stealth-Mode Backfired

Temperature is just part of the story though. The UK’s rays face the greatest direct threats from recreational fishing, commercial bycatch, and ghost fishing*. Spending most of your life on the seafloor means that being well-camouflaged, sand-coloured, and flattened to the ground has its advantages. But these evolved traits also make it easy for demersal fishing gear to sweep you up, unnoticed.

*Ghost fishing occurs when discarded (or lost) gear continues to catch marine life unintentionally. With nobody coming to collect or modify it, the abandoned gear becomes a chronic threat to marine life - catching everything and anything curious enough to investigate it.

Rays have evolved this way because they use the seafloor to hide, scooping sand over their bodies like a ghillie suit. Stealthy and quick, they surprise-attack their prey whilst minimising unnecessary movements that could alert nearby predators. This skittish seafloor existence has earned rays the title “cryptic benthic mesopredators”. Broken down, this translates to:

Cryptic - hidden

Benthic - on the bottom

Meso - mid-ranking

Hidden rays blend into the seafloor, easily mistaken for a rock by fishers. Photo credit: Paul Newland

Small But Mighty Predators

A lifetime spent darting between sand and open water, rays are generally shy creatures. But with surprisingly powerful jaws and a varied diet of crustaceans, small fish and other invertebrates, they occupy an important position as predators in marine food-webs. Their diet and interactions with the seafloor provide important ecosystem services, such as top-down control of commercially important species, and nutrient cycling. Rays resuspend carbon and detritus through their movement, and as the dust slowly settles, vital nutrients like carbon, nitrogen and phosphorous become bioavailable* to scavengers and filter feeders like sea cucumbers and bivalves. But they aren’t alone! Other groups of cryptic benthic mesopredators are the dragonets, gobies, and blennies, all of which you can find here in Falmouth.

*Bioavailability refers to how accessible a substance is for uptake by living organisms. It’s often used in assessing the stability and health of an ecosystem. In open water where nutrients are rare, greater bioavailability of nutrients = greater inhabitability!

Thornback rays are famed  for the small  spines found along their back, and are the most common ray in the UK. Photo credit: ©Paul Naylor www.marinephoto.co.uk

A Slow Road to Recovery

Rays are slow-growing, low-fecundity* species. Taking between 3–10 years to reach sexual maturity, they’ve taken an evolutionary gamble by investing in just a few offspring. It’s a bit like putting your entire pension into just one or two start-up companies: you nurture them carefully and pour all your resources into their success, but once they’re out in the world, you have no control over whether they flourish or fail. If even one is lost, the impact is significant. This makes ray populations particularly vulnerable to pressures like bycatch, which often removes individuals from the population before they can reproduce. Catching a ray before its time doesn’t just affect that individual, it undermines future generations and makes population recovery far more difficult.

*Fecundity refers to the number of offspring an animal can produce over its lifetime.

Rays have two main methods of reproduction. Baby rays, called pups, either hatch externally from eggs (ovoparity) or develop in eggs inside their mother and are born as live young (ovoviviparity). Cornwall’s most common species are the Thornback ray (Raja clavata),  Cuckoo ray (Leucoraja naevus), Small-eyed ray (Raja microocellata) and the Blonde ray (Raja brachyura). All of these lay mermaids purses - those tough, leathery egg cases often found along the strandlines of Gylly and Swanpool.

Egg cases vary in size, colour, and shape. Curly tendrils indicate the egg case of a catchshark, whereas the larger, more pointed cases are produced by rays and skates. Photo credit: Eloise Holmes

Each species’ case is unique, and can be used as an identification tool. Freshly laid egg cases are usually see-through, because this allows sunlight and oxygen to diffuse inside and nourish the pup. When rays are bred in conservation, researchers can hold the cases up to sunlight and see a tiny, fully-formed ray inside waiting to spring out! The cases darken over time, thickening to provide increased protection for the growing pup. Click here to download a free identification key, produced by The Marine Institute. Next time you visit the beach, have a rummage in the strandline and see what you can find!

These catshark cases were found on Swanpool beach, you can see the difference in thickness clearly here. Photo credit: Eloise Holmes

Swanpool has long been a reliable nursery ground for young rays. It offers the sheltered shallows and sandy habitat they need to grow, but today, sightings have shifted. Divers now report seeing rays further afield in places like the Helford estuary, tucked into deep seagrass beds. This shift highlights a broader issue: as human pressures fragment coastal habitats, once-connected populations become scattered. And when populations are patchy and isolated, it threatens not just local abundance, but the genetic diversity and resilience needed for long-term survival.

Now You See Me…

How do we monitor ray populations then? Studying rays in the UK has been a long-term challenge for conservationists and scientists alike. Their cryptic nature and camouflage colouration means identifying rays from a distance requires a trained eye and lots of patience. Thankfully, new technologies like BRUVS (Baited Remote Underwater Video Systems) have made it easier to study cryptic species like rays. Leaving baited cameras to attract marine life for several hours enables us to study their behaviour at length without using scuba divers, which are often too disruptive for shyer species like rays. Unfortunately though, the most reliable way to find a ray is checking the bycatch of a commercial fishing vessel.

Charting a Course for Ray-covery

Alongside academic research, community-led initiatives are key pioneers in conservation. Over the years, several initiatives have been huge contributors to data collection on rays in Cornwall. Honorable mentions are:

●      Seaquest Southwest, run by Cornwall Wildlife Trust, has collaborated with citizen-scientists since 1997. They organise regular snorkel and scuba surveys to collect biological data on marine life, which is used to map seasonal patterns in marine megafauna like elasmobranchs. This informs local conservation efforts and feeds into outreach projects.

●      The Shark Trust is paving the way for elasmobranch conservation in Cornwall. Their Great Eggcase Hunt has been running every Easter since 2003, in collaboration with Cornwall College. Through this, they help people to identify different elasmobranch species from their mermaid’s purses in a systematic fashion. Their collected data has contributed to the protection of juvenile rays across the Devon-Cornwall border.

●      A voluntary “Ray Box” marine closure, spanning some 400km², has been in effect in North Devon since 2005. Fishermen from the North Devon Fishermen’s Association (NDFA) collectively agreed not to use mobile gear in this area during the period 1st December - 31st May, aiming to protect juvenile and brooding rays.

●      NDFA vessels also voluntarily enforce a minimum wingspan of 45 cm for all ray species. Rays smaller than this are released, allowing juveniles to grow and reach sexual maturity before they’re harvested.

Huge numbers of egg cases get counted and identified at the Shark Trust’s Great Eggcase Hunt! Photo credit: Shark Trust

A Tale of Two Coasts

In recent years, Cornwall has emerged as a key region for ray conservation and sustainable fisheries management. However, through close assessment of all this lovely data we’ve learned two vital lessons:

●      Regional discrepancies have emerged between North and South ray populations. We suspect this is due to improved data collection and the NDFA’s closure on the North Devon coast, with species like the Thornback, Cuckoo, and Small-eyed rays reaching a sustainable seafood rating for the first time in this region. Meanwhile on the South coast, we remain data-deficient and ray populations are still exposed to fishing pressure year-round. It couldn’t be clearer - monitoring marine life more closely leads to more effective and targeted conservation, with positive results. We have to put in the work if we want our ray populations to thrive here in Falmouth.

●      Ghost fishing remains a problem. Whilst conservation initiatives provide some insight into ray populations, divers and snorkelers still report “we’re not seeing these species anymore”. Localised, easily avoidable threats persist, such as increased reports of discarded fishing line at popular dive sites like Silver Steps. Prey species caught on these abandoned “ghost” lines will be attractive to elasmobranchs like rays, who love an easy meal. Local sightings of stranded thornback and cuckoo rays, perhaps due to ghost fishing, highlight the need for ongoing monitoring and habitat protection.

In Summa-ray (sorry)

Feeling compelled? There are plenty of ways to help Falmouth’s rays:

●      Fish on sandy bottoms. Counterintuitively, casting out on sandy-bottomed areas rather than rocky reefs can prevent your line from snagging and causing unwanted mortalities.

●      Use the Cornwall Good Fish Guide. This lists sustainability ratings for commercially caught species, and checking this before casting out or going shopping could help rays in the long run.

●      Ask to see what you’re buying. If you choose to buy skate, be aware that when they’ve been skinned it’s impossible to tell which species you’re buying. Make sure to ask which ray they’re selling you, to ensure it’s not unsustainable!

●      Become a citizen scientist. Joining one of the many fantastic initiatives contributing to ray conservation will strengthen our understanding of south-coast populations - leading us closer to that golden sustainable rating. Your data could even be used in future scientific publications!

●      Join us in Falmouth for a shoresearch. Come and scour the strandline and rockpools for mermaid’s purses and other treasures, collect data on our coastal biodiversity, and meet other passionate conservationists! If you’re feeling inspired, but aren’t local to Falmouth, fear not! Head to the Cornwall Wildlife Trust website, or your local Trust, and find out what's on near you.

Shout-outs go to Paul Newland and Paul Naylor for capturing some fantastic shots of these elusive creatures. Paul Newland is a widely travelled diver and member of the Totnes Subaqua Club, with a keen interest in marine life. Paul Naylor is the author of Great British Marine Animals, a fantastic ID guide and quickly becoming the British scuba diver’s bible. If you love the ocean, wildlife, or exploring our coast, you’ll love his book.

Helpful Links:

●      Shark Trust Great Eggcase Hunt

●      Seaquest Southwest | Cornwall Wildlife Trust

●      Shoresearch Cornwall | Cornwall Wildlife Trust

●      Mermaid Purse Identification Key - http://hdl.handle.net/10793/1889

Sources:

●      ‘Unprecedented’ marine heatwave hits waters around Devon, Cornwall and Ireland | Marine life | The Guardian

●      Record-breaking ocean temperatures raise alarm for Cornwall’s marine wildlife | Cornwall Wildlife Trust

●      Cornwall Good Seafood Guide (2024). New ratings announced: some major changes for rays and breams. Available at: https://cornwallgoodseafoodguide.org.uk/news/new-ratings-announced-some-major-changes.php

●      Cornwall Good Seafood Guide (2024). Thornback ray. Available at: https://cornwallgoodseafoodguide.org.uk/fish-guide/thornback-ray.php

●      Cornwall Wildlife Trust & North Devon Fishermen’s Association (2023). Ray Box initiative and voluntary landing size agreements.