eDNA Ground-Truthing and Six Gill Sharks Survey

University College Dublin, Queens University Belfast, Trinity College Dublin, Marine Institute
Government BodiesResearch Institutions
FjordStrong were subcontracted to gain additional ecological information on the reported presence of Six Gill sharks off the coast of county Clare, to characterise their habitat (physical and environmental parameters) and to provide visual validation for eDNA analysis obtained from water samples.
Many elasmobranchs play a huge role in mediating our ecosystems as apex predators at the top of the food chain. But they are also highly vulnerable in large part due to their large size (old age) at sexual maturity, slow growth and small number of offspring.
Six Gill sharks are no exception. Often referred to as “living fossils”, these enormous sharks (up to 6.1 meters in length) reach maturity at around 18 years in the case of the females, and take two years to give birth. Unlike some species of fish who release millions of offspring, sixgill sharks only give birth to about 20 pups, of which researchers believe only a handful will survive the first year.
Using BRUVs, we confirmed the presence of a female six-gill shark, and characterised the habitat it was associated with. Notably, this individual was located at a depth of approximately 70 meters, which is significantly shallower than the reported preferred depths for adults, which is between 180 and 1,100 meters. Based on other findings, it seems that only females are using this area, and it is therefore possible that these warmer, shallower waters are leveraged by pregnant individuals to speed up the gestation process and perhaps act as a nursery area. Indeed, juveniles are reported to use waters as shallow as 12 meters, however more research is ongoing to test this theory.
During each BRUV deployment, we coordinated simultaneous Rosetta deployments to obtain environmental parameters throughout the water column and water samples at 1 m from the bottom.
These samples were then processed by the genetics department at UCD with the aim of developing assays for detecting the presence of Six Gill Shark, for which our visual records are required for validation.

Explore the range of services we provided for this project: 

Marine Surveys

Using bait to attract wide-roaming wildlife into the survey platform, our bespoke Baited Remote Underwater Video (BRUV) systems are tailored to perform under the high current speeds encountered in the North East Atlantic. Rated to a depth of 250 meters, they are a rapid and cost effective tool for surveying marine biodiversity, with dual independent lights facilitating round the clock surveying.

Our stereo-imaging techniques are optimised for moderate turbidity levels, allowing our analysts to take accurate measurements through a technique known as photogrammetry without removing specimens from their habitat. Covering both the demersal and pelagic regions, our BRUVs can provide reliable data on:

  • Species Inventories
  • Accurate Measurements and Biomass Estimates
  • Relative Abundances
  • Species Interactions
  • Temporal Changes and Patterns
  • Growth Rates and Overall Condition
Marine Surveys

At FjordStrong, our expertise covers taxonomic identification of species and communities, alongside characterisation of the abiotic and physical environment they live in using nationally recognised classification protocols such as JNCC and EUNIS. By collecting data using non-destructive methods such as ROVs and tow-fish cameras, we can systematically identify, predict and compare habitat distribution and ecosystems using a standardised methodology, while preserving the integrity of the area. Such knowledge underpins MPA monitoring, assessing conservation-value of sites, and licensing of industry activities.

Marine Surveys

FjordStrong provides a suite of non-destructive tools and methodologies for assessing marine biodiversity, tailored to your requirements. In light of the ongoing biodiversity crisis caused by anthropogenic pressures and climate change, there is an increasing urgency to understand local biodiversity and population dynamics, including demographic trends and biomass estimates. We provide a range of robust, non-destructive biodiversity surveys to suit your needs, providing a rapid and cost-effective alternative to traditional destructive techniques. With an in-house elasmobranch expert team, benthic ecologists and fisheries scientists, our team can work with you to bridging the knowledge gap and taking the first steps towards a better ocean.

Marine Surveys

Climate change is already impacting the environmental conditions in the ocean which in turn has seen changes in ecosystems, species, habitats, tourism, coastal communities and fisheries. Understanding our oceans, and the variables that affect our oceans’ biodiversity are fundamental for protecting and supporting recovery. Accurate and reliable environmental data facilitates understanding and monitoring the drivers of change. At FjordStong, we have the flexibility to integrate a full suite of oceanographic and environmental measurements into your project, including temperature, dissolved oxygen, pH and turbidity.

Consultancy & Data Processing

FjordStrong is deeply committed to Elasmobranch Conservation, employing advanced techniques to study and safeguard these vital components of the oceanic web. Drawing on the expertise of the QUB Marine Lab, Regional Flapper Skate Working Group and Elasmobranch Strategy Group, our team comprises specialists in elasmobranch fisheries interactions, bycatch reduction and monitoring, distribution modelling, and acoustic tagging and biotelemetry. Our commitment extends beyond assessment to proactive strategies, ensuring sustainable practices that protect elasmobranch populations and enhance our understanding of these sentinel species and their crucial role in our oceans.


At FjordStrong, we understand the importance of thoroughly testing, validating, optimising, and improving new approaches to ensure their reliability and effectiveness. Our team is committed to pushing the boundaries of innovation, using cutting-edge technology and methodologies in the marine environment. Our expertise and experience includes ground truthing methods such as eDNA sample collection, video survey for acoustic detections, elasmobranch tagging, and identification of egg-laying grounds. FjordStrong will not only keep pace with the latest advancements but also contribute to shaping the future of sustainable marine solutions with passion and expertise.

Fisheries Engagement and Conservation Research at the Marine Institute

Orkney Egg Case Survey

Tender for North Coast Elasmobranch Survey

Discover how FjordStrong’s expert consultancy services can elevate your marine projects, tailored specifically to your unique requirements.
Scroll to Top