British shark life: are spurdog siblings sticking together?

  • Sharks
Years funded
  • 2021
  • Active
Project types
  • Conservation
  • Research

Fenella is studying British spurdog, a small shark found across the temperate regions around the world. She wants to know how related populations of spurdog are around the British Isles. While commercial targeting of spurdog has been banned after major population declines, whole aggregations can be caught as bycatch. Fenella’s team is asking how related an aggregation might be, using individuals caught from an accidental bycatch event. Her project’s work can look at genetic connectivity of spurdog within a single aggregation and between populations across the British Isles

British shark life: are spurdog siblings sticking together?

Fenella Wood

Project leader
About the project leader

For as long as I can remember, I have felt an affinity with water. As a youngster, I spent every summer along the South Wales coast, exploring rock pools and swimming as much as I could. For the rest of the year, I would fill up on nature documentaries, longing to get back into the water the following summer. I was determined to turn my summer experience into my every day, instead of once a year. To do that, I moved to South Wales and started my BSc (Hons) in zoology at Cardiff University. Despite living relatively...

Project details

Social networks: how related are Scotland’s spurdogs?

Key objective

To investigate the family relationships between individuals within a single spurdog aggregation and estimate their genetic connectivity with the wider Northeast Atlantic population.

Why is this important

Spurdog are an aggregating species, making them particularly vulnerable to being caught in large quantities by commercial fisheries as bycatch. There has been limited research into this aggregating behaviour and the impact bycatch may have on the population. This project has the rare opportunity to assess genetic relatedness within a single aggregation, to reveal the impact that removing these aggregations may have on the Northeast Atlantic gene pool.


Spurdog, also known as spiny dogfish, are a wide-ranging, highly mobile, small shark that can be found in temperate seas across the globe. Like most elasmobranchs spurdog exhibit slow life-history traits including a long generation time of 25 – 35 years and an 18 – 24 month gestation period. Once a commercially important species, they are now listed as Endangered in the Northeast Atlantic by the IUCN red list due to a 77% decline in biomass between 1955 and 2010.  The aggregating nature of the species means that when they are caught by commercial fisheries, a large number are caught. Not only is this an issue for a reduction in population size, but there could be unknown effects on genetic diversity. Previous research suggests these aggregations may contain a high proportion of closely related individuals (perhaps as siblings) and losing these family groups can decrease genetic diversity, reducing their ability to adapt to environmental change. Understanding the genetic composition of spurdog aggregations is crucial to assess the potential impact of bycatch on population sustainability in the Northeast Atlantic.  This is the first time family relations will have been assessed for an elasmobranch aggregation on such a scale. However, previous work using relatedness information has proven key in understanding the ecology and life-history of elasmobranchs.

Aims & objectives
  • Obtain the genetic profile of each individual from a single bycatch event.
  • Identify relatives within the aggregation, assess the overall relatedness levels and genetic diversity.
  • Compare the genetic diversity and connectivity between the aggregation samples with additional samples collected elsewhere in the Northeast Atlantic.