Spurdog (Squalus acanthias) are species of shark that have experienced dramatic decline in the UK over the past few decades. In 2015 it was estimated that 5% of their original biomass remained in the NE Atlantic Stock.
Spurdog have one of the longest pregnancies of any vertebrate (2 years!) and take a long time to grow, making their recovery to fishing pressure slow.
Since 2010, commercial landings have been limited to 0 in an effort to try and allow the stock to recover. Spurdog is currently a prohibited species commercially.
While this is great for allowing stock recovery, prohibiting catch means we have no commercial landings data, a valuable source of information when trying to understand stock decline or improvement.
Recreational anglers target (and love) this species. They represent an untapped data resource to help us understand where spurdog are now being caught (and returned), how many are being caught, as well as associated size/sex information.
By collecting this information, it could help us to understand where spurdog are starting to reappear, or even where they have their pups.
Spurwatch UK is a passion project without affiliation to any group, but hopes to promote safe and responsible handling practices, sightings and catch data sharing, and general enthusiasm for spurdog in the diving and recreational angling community.
Our website has been funded for 3 years. In that time Spurwatch intends to...
Identify hotspot areas for spurdog recovery in the NE Atlantic as well as patterns in sex/size/depth
Promote safe handling techniques to anglers across the UK through club engagement and collaboration with like-minded organisations
Run seminars and outreach events online and in-person to raise awareness for the project and its goals
Publish (or be working towards publishing) the results of 3 years of records
Maintain a positive relationship with the anglers who made the project possible, ensuring their contributions are recognised and credited, always
Promote the wonderful biology and unique conservation story of spurdog
Create an online hub for spurdog-related resources (this website), including blogs, articles, videos, and literature reviews.
Frequently Asked Questions
Hello! My name is Georgie Bull and I'm a Devon-based Marine Biology & Coastal Ecology graduate and underwater photographer/filmmaker. I first developed an interest in aquatic life while fishing with my dad from the age of 3. He set an example of how recreational anglers can be stewards of the fish they catch. Since then I have loved fish, and believed in the power of angling to spark change in conservation.
I ended up focussing on spurdog in the final year of my degree, where I spent much of my time researching their ecology and historical value in societies around the world. I came to realise that this species has one of the most interesting and complicated conservation stories I've ever engaged with. Once I completed my thesis, I couldn't bring myself to stop there and started planning Spurwatch UK. I have previously worked in citizen science, managing projects on behalf of other institutions, but this project is one of my own making (with no affiliation or funding from any government or charitable body). I am doing this because I love spurdog and want to see them thrive like they once did, and I want to engage with anglers (and divers) who do too.
What are spurdog?
Spurdog, spiny dogfish, rock salmon, flake, huss, rock, hoe, rough dog, mud shark, picked dogfish, piked dogfish, blue dog, darwen salmon, spotted spiny dogfish, spring dogfish, ci pigog, victorian spotted dogfish, white-spotted dogfish... with over 190 recognised common names worldwide, it's no surprise that this question needs answering!
Spurdog, the focus species of Spurwatch UK, is a species of shark, scientifically known as Squalus acanthias. They are amazingly resilient to a range of conditions and are considered one of the most widely distributed and abundant sharks globally, found in both hemispheres in the Western Atlantic, Indo-Pacific, Mediterranean and Black Sea.
They are found in a broad range of habitats, from estuaries to open seas, between 0 to 1,500m depth, although are most common from 10 to 200m. But being so widespread and abundant can have its down sides. Archaelogical evidence suggests that spurdog were one of the first shark species to be harvested by humans, and naturally became increasingly easy targets as humans developed fishing gear and techniques.
Perhaps the most fascinating aspect of spurdog biology relates to how they reproduce. All shark species are characterised by very slow growth rates, late sexual maturation,and small reproductive output... but spurdog take this to an extreme, having one of the longest pregnancy periods of any vertebrate (2 years!). Individuals typically live for 25-40 years, and take between 7-12 years to reach sexual maturity. When a female is eventually old enough to carry a litter of pups, she will give birth to an average of 13-16 live young. Taking your time with starting a family is great, but it doesn't make for quick population recovery after over-exploitation.
Why is it important to record spurdog?
Spurdog is one of the world's most commercially exploited shark species, particularly favoured for their fins and meat. Spurdog exploitation has taken place for at least 200 years in the UK, historically being used for their liver oil, and later popularised in fish and chips as 'rock' in the 1920s. But our attitudes and interactions with spurdog haven't always been positive. The reason they are referred to as 'dogs' is because of their 'pack-like' hunting mentality, often reported as 'swarming' fishing gear and bait. These aggregations were reported in the 1700s in Canada, and eventually resulted in the government opening two harvesting plants to make glue out of the species, simply to try and alleviate their nuisance. The idea that spurdog stocks were inexhaustible was common belief until the late 1900s.
Our rocky relationship with spurdog and a complete lack of species-level recording in commercial fisheries delayed fisheries management of the stock, and eventually caused the NE Atlantic population to become critically endangered in 2006. Since 2010, the species has was been placed under a 0 total allowable catch. This means that spurdog cannot be kept by commercial fishermen, even if they are caught accidentally. While this is a great way to allow the stock to recover, and stop target fisheries, it means we have no catch information from the commercial fishing industry, a data source commonly used by fisheries scientists to understand how healthy a stock is. This leaves us with lots of questions about their recovery, such as: How do we know where/if spurdog are starting to reappear in the UK? Do we know how many? Do we know if they are forming aggregatations? Where are their nursery grounds?
The answers to these questions are complicated and nuanced in some places, and completely unknown in others. But the people who are most likely to know this information are those who encounter the species regularly. Recreational fishermen. This project aims to build connections with recreational anglers. The ones who go out to sea on a Saturday morning to try and catch spurdog. Those who love spurdog for what they offer on a catch-and-release, 'for the fight', basis. Their love for spurdog could help us understand where sites of recovery might be, the rate of recovery, and maybe even potential positions of nursery habitat. I'm confident that by encouraging anglers to report where they see and catch spurdog, we could create a very powerful tool for the species and its recovery.