Stable isotope analysis of New Zealand fur seal (Arctocephalus forsteri) pup vibrissae used to explore dispersal and isotopic niche widths : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University, Palmerston North, New Zealand
| dc.contributor.author | Galbraith, Diana | |
| dc.date.accessioned | 2024-10-16T01:19:58Z | |
| dc.date.available | 2024-10-16T01:19:58Z | |
| dc.date.issued | 2024 | |
| dc.description.abstract | The New Zealand fur seal/kekeno (Arctocephalus forsteri, NZFS) is a mobile, top predator native to Aotearoa/New Zealand, that was almost extirpated by hunting. Knowledge of life history (demographics), abundance, distribution, and movement patterns is essential to understanding the ecological implications of NZFS dispersal and recolonisation. Intrinsic markers are increasingly being used to identify individuals. Stable isotope analysis (SIA) is used to study diet, trophic level, and movement patterns in many marine mammal species. Otariid pup vibrissae are metabolically inert, relatively easy to sample, and provide a sequential record of nutrient uptake from gestation onwards. Vibrissae from NZFS pups were collected from seven established breeding colonies around the coast of New Zealand. δ¹³C and δ¹⁵N values in the proximal vibrissa were used to calculate isotopic niche widths for each colony. Isotopic separation was not sufficient to identify the colony of origin of pups. Vibrissae from stranded (deceased) NZFS young-of the-year were collected opportunistically from areas not known to have breeding colonies in Northland and Hawkes Bay, New Zealand. δ¹³C and δ¹⁵N values were measured in the proximal vibrissa and in a section two-thirds of the length from the base corresponding to the time that individuals would have been at their natal colony. Values from young-of-the-year overlapped with pups at colonies. Isotopic niche widths were greater for young-of-the-year than for pups at colonies and greater for samples at the base of the vibrissa than at two-thirds. Vibrissa growth rates and estimated vibrissa lengths at birth were calculated using linear regression on colony and stranded samples. The mean vibrissa growth rate was 0.21 mm/day for colony samples and 0.24 mm/day for all samples. The estimated vibrissa length at birth was 55 ± 11 mm. Mean δ¹⁵N decreased by 4.7 ‰ between two-thirds of the vibrissa and the base. The estimated maximum age at weaning was 223 to 247 days; less than any published lactation lengths for the NZFS. SIA is a practical and economical way to monitor the isotopic niche width of NZFSs, providing indirect information on foraging. | |
| dc.identifier.uri | https://mro.massey.ac.nz/handle/10179/71738 | |
| dc.language.iso | en | |
| dc.publisher | Massey University | |
| dc.rights | The author | en |
| dc.subject.anzsrc | 310303 Ecological physiology | |
| dc.title | Stable isotope analysis of New Zealand fur seal (Arctocephalus forsteri) pup vibrissae used to explore dispersal and isotopic niche widths : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University, Palmerston North, New Zealand | |
| dc.type | Thesis |