My Research: Christopher Bird
The intensification and industrialisation of commercial fishing during the 20th century has caused depletions in many fish populations around the globe. As coastal and open water fisheries began to struggle, many fisheries expanded operations into deeper waters in search of new profitable fish stocks. Whilst most deep-water fishing operations only target a few species, such fishing gears are often associated with high levels of incidental by-catch of non-targeted species. Within some fisheries, these by-caught species have no commercial value and are usually discarded back overboard, dead.
Deep-sea fish populations are particularly sensitive to fishing pressures due to a culmination of slow growth rates, late maturation, extreme longevity and low fecundity. Some of the most vulnerable populations to such fishing pressures are the chondrichthyans or cartilaginous fish. Chondrichthyans are a class of fish that includes the elasmobranchs (sharks, skates and rays) and the holocephalans (chimaeras) and are characterised by having cartilaginous skeletons, instead of bony ones.
Deep-water sharks have been targeted, in the past, for their meat and large oily livers. The oil from their liver contains a chemical compound called squalene that is used to make cosmetic products and dietary supplements. The loss of apex predators, such as sharks, from marine environments can have cascading effects that reverberate throughout an ecosystem. Understanding the intricate dynamics within deep-water ecosystems and how they function will be fundamental in assessing the sustainability of their exploitation.
Historically our understanding of deep-sea environments has been hampered by the technical and logistical difficulties in sampling such depths. Whilst traditional techniques such as “satellite tracking” and “catch-and-release” are not plausible for studying deep-water chondrichthyans, the application of techniques such as stable isotope analysis (SIA) may be able to improve our understanding of certain aspects.
Isotopes are variants of particular elements that contain the same number of protons and electrons but differ in the number of neutrons that they contain; essentially they are the same element, just heavier. They behave in a predictable manner within marine ecosystems and can be used to make inferences on trophic ecology (what they are eating) and movements (where they are eating). 
Image from
http://icanhasscience.com/fun-stuff/a-deuterated-mouse-isotopes-and-phys-org/
My research uses a combination of methods in order to uncover migration movements, distributions and the trophic dynamics of deep-sea chondrichthyans throughout Northeast Atlantic. I am mainly interested in the assemblages found on the continental slope between the depths of 500-2000m. We still know relatively little about the fish that occur at these depths. Through collaborations across Europe, I hope to gain a greater insight into the ecology about these important yet vulnerable fish populations.
