Weddell Seal Pup Production in relation to harvesting pressure and the B-15 iceberg
| dc.contributor.author | Briars, Lacey | |
| dc.date.accessioned | 2017-08-21T00:22:53Z | |
| dc.date.available | 2017-08-21T00:22:53Z | |
| dc.date.issued | 2011 | en |
| dc.description.abstract | The Ross Sea, one of two large embayments on the Antarctic continent, provides scientific opportunity to study marine ecosystem processes. The Weddell Seal Leptonychotes weddelli resides in the Ross Sea, with breeding colonies in Erebus Bay, McMurdo Sound. The Weddell Seal‟s life-history is well documented in the literature; females congregate in „pupping colonies‟ along cracks in the sea ice and give birth to their pups in October. Since the austral summer of 1968/69 every pup born into the Erebus Bay population has been tagged and the tag number, sex, year of tagging, location, and age at tagging recorded, creating a database containing datum for over 20,000 individual seals. Weddell Seals produce one pup per year. The age at which first reproduction occurs is an important life-history decision, mediated by several trade-offs. Age at first reproduction also has potential impacts for fitness and reproductive output/pup production – a fact also well documented in the literature. The Ross Sea has a history of exploitation; when permanent research stations were established in McMurdo Sound, adult Weddell Seals in Erebus Bay were harvested to feed resident dog teams. Additionally, in the year 2000 a large tabular (~10,000km2 ) iceberg named B-15, calved off the Ross Sea Ice Shelf, blocking the usual advection of sea ice from McMurdo Sound until the winter of 2006. Several earlier studies have documented the large scale effects that both harvesting and iceberg calving had on the size of the Erebus Bay population of Weddell Seals, and the effects on age at first reproduction, however, no studies have focused on pup production. This study investigated pup production in the Erebus Bay population of Weddell Seals to determine if harvesting pressure and iceberg calving affected the number of pups produced in Erebus Bay from 1969 to 2009. The results of the current study illustrate that both harvesting pressure and environmental disturbances (iceberg calving) affected pup production in Erebus Bay. Pup production reached very low levels in the years that harvesting occurred but increased following the cessation of harvesting in 1985. A similar trend was witnessed from 2000 to 2006 when the B-15 iceberg was blocking McMurdo Sound. Pup production decreased between 2000 and 2006 inclusive, but rapidly increased once the effects of B-15 were removed. While harvesting of Weddell Seals no longer occurs in the Ross Sea, iceberg calving still does. If this was to continue in the future, it is likely that Weddell Seal pup production in Erebus Bay will be somewhat negatively impacted. Other Antarctic seal species such as the Crabeater seal may be negatively affected also | en |
| dc.identifier.uri | http://hdl.handle.net/10092/14169 | |
| dc.language | English | |
| dc.language.iso | en | |
| dc.rights | All Rights Reserved | en |
| dc.title | Weddell Seal Pup Production in relation to harvesting pressure and the B-15 iceberg | en |
| dc.type | Theses / Dissertations | en |
| thesis.degree.discipline | Science | en |
| thesis.degree.grantor | University of Canterbury | en |
| thesis.degree.level | Postgraduate Certificate | en |
| thesis.degree.name | Postgraduate Certificate in Antarctic Studies | en |
| uc.college | Faculty of Science | en |