Abstract
Hard parts of squid are used in a variety of post mortem analyses, such as diet studies, which shed light on various aspects of the squid’s life. In this thesis, hard parts were reviewed. Beaks and statoliths were found to contain the most information about the squid’s life history and are the most widely used squid hard parts.
Allometric equations were created to explore the correlation between beak and body growth in Onykia ingens and Nototodarus sloanii. The resulting regressions were analysed to find the best predictors of body size for use in diet analyses. Beak weights were analysed for the first time and were found to be good predictors of squid size in O. ingens; however, rostral lengths were shown to be the best squid size predictors in N. sloanii.
The structure and composition of statoliths from both O. ingens and N. sloanii were analysed using scanning electron microscopy (SEM), Raman spectroscopy and laser-ablation-inductively-coupled-plasma- mass-spectrometery (LA-ICP-MS). Statoliths of both species were shown to consist of calcium carbonate crystals in the aragonitic polymorph. Statoliths of both species contained all 10 of the trace elements that were analysed using LA-ICP-MS (Be, Mn, Mg, Cu, Zn, Sr, Y, Zr, Ba, U) and this was the first time that Be was recorded in squid statoliths. Trace elements were compared between zones within statoliths (inner and outer zones), between locations within O. ingens and between species. There were significant differences in some trace elements between zones, locations and species. As trace element incorporation is different depending on location of capture and species, trace elements in statoliths of these two species have the potential to be used as geographic markers.
The trace element composition of beaks of O. ingens was analysed using both LA-ICP-MS and solution-based-ICP-MS and 26 trace elements were recorded. This is the first time that trace elements have been reported in squid beaks. Trace element incorporation mechanisms for these squid beaks is unknown; however, recording the presence of trace elements is the first step in gathering this information. Further directions for this research, including its possible use in fisheries forensics, are discussed.