Melissa Nehmens



Thesis Project summary:

The Food and Agricultural Organization of the United Nations held a workshop in 2009 to address the lack of species and ecosystem knowledge we have of the deep-sea. Since then, efforts have increased to better understand these deep water environments and the species that inhabit them. My thesis aims to contribute information to the efforts of characterizing deep-sea environments by looking at life history parameters of deep-sea sharks.

The nine deep-sea squaloid species in my thesis were caught as bycatch on seamounts in the Southwestern Indian Ocean (SWIO). This region lies beyond any nation’s jurisdiction to implement management strategies. Furthermore, if there were a way to enforce species and ecosystem management in this area, it would lack the robustness needed to make a lasting change due to missing information. Some of the most important pieces of information needed for effective management are age, growth, and reproduction. Age and growth are necessary parameters as they provide information that allow for calculations of other biological factors, where understanding a species’ reproductive history is useful because it tells how likely they will be able to withstand fishing pressure, based on their rebound potential. Reproductive strategies can be assessed outside of traditional fecundity and age at maturity studies, where effective population size and female reproductive fitness are measured. This can be addressed using genetic studies.

For my thesis, I will estimate the age and growth of all nine deep-sea squaloid species and assess multiple paternity for one species, whose reproductive strategy has not previously been genetically assessed. Due to limited knowledge, and vulnerability of both species and location of my study, the addition of the information from my thesis to the scientific body of knowledge will increase understanding of the deep-sea environment; adding the FAO initiative that began in 2009. Additionally, the age, growth, and multiple paternity findings from my thesis research will provide crucial information to characterize the Chondrichthyan community on this remote chain of seamounts and may be useful in developing better management plans for this and other remote seamounts around the world.