NZ sea lion monitoring at the Auckland Islands 2014/15

Download the publication

POP2014-01: New Zealand sea lion monitoring at the Auckland Islands 2014/15 (PDF, 2,955K)

Summary

This report summarises results from work completed by Blue Planet Marine for the CSP Project New Zealand sea lion (NZSL) ground component 2014/15. The field component of the work was completed on 27 March 2015. It represents the final report for the project and replaces all previous and preliminary reports for it. This report also includes components of work that were not funded by CSP but separately by DOC and WWF. They have been included here for completeness.

In summary:

• Pup production was estimated for NZSL colonies at Sandy Bay (n=286), Dundas Island (n=1,230), Figure of Eight Island (n=60) and South East Point (n=0); with total pup production for the Auckland Islands in 2014/15 estimated as 1,576. This total represents an increase of one pup from the 2013/14 estimate from last season, and is the fourth lowest total pup production recorded for the Auckland Islands.
• With the exception of the Figure of Eight colony, estimates of pup mortality to the date of the pup production estimate are broadly comparable to previous ‘non-epidemic’ years. However, these figures do not represent full season surveys and are not directly comparable to data collected prior to 2012/13, and so should be viewed as a minimum. Pup mortality estimates are: Sandy Bay 2%, Dundas Island 5% and Figure of Eight Island 22%. This is the highest ever level of pup mortality recorded at Figure of Eight Island and is considerably higher than the long-term average annual mortality level of 9%.
• Mean pup weights at Sandy Bay were 4% and 5% lower than 2013/14 for males and females respectively. Mean pup weights at Dundas Island were 6% and 12% higher than 2013/14 for males and females respectively. Pup weights were undertaken at Figure of Eight Island for the first time and were very similar to those at Sandy Bay.
• Seven hundred and twenty nine pups were marked at the Auckland Islands including: Sandy Bay – 147 flipper tagged and microchipped, and 140 microchipped only (Note that this was a new protocol implemented in 2014/15 with only approximately 50% rather than 100% of pups being tagged at Sandy Bay); Dundas Island – 391 flipper tagged only; and Figure of Eight Island – 40 flipper tagged only.
• Of the 63 dead pups recovered at Sandy Bay, 59 were in sufficient state for necropsy. Preliminary provisional diagnosis for cause of death includes 61% bacterial infection (suspected with Klebsiella pneumoniae), 17% open diagnosis (decomposed, scavenged or no significant findings), 15% starvation, 3% trauma, 2% hookworm and 2% stillbirth/peripartum death. It is important to note that these diagnoses are provisional and will be refined and/or confirmed once full histopathology analysis has been completed at Massey University pending funding.
• Between 10 January and 27 March 2015, there were a total of 14,762 resights of marked NZSLs of which 14,295 were suitable for use (ie, contained sufficient information allowing positive identification). Flipper tags were used as the primary form of identification in these resight events (82%), followed by scanning for microchips (16%) and also viewing branding animals (2%). This season represents the most resighting records collected and is 29% more than was collected in 2013/14 but effort (ie, time spent collecting resights) was also considerably higher than previous years (eg, 586 hours in 2013/14 vs. 1,144 hours in 2014/15). Most resightings (97%) were collected on Enderby Island and most (87%) of these at Sandy Bay. A few resights were also collected from other areas of the Auckand Islands group including Dundas Island (n=364), Monumental Island (n=7) and Figure of Eight Island (n=2);BPM-15-Final Report for NZ sea lion research at the Auckland Islands 2014-15 v2.2 Page 6 of 50 
• In response to previous examples of pup mortality in holes at Sandy Bay, 12 wooden ramps were installed on streams and mud holes in order to allow pups to climb out of places where they otherwise would not be able to. A total of two pups were found dead in mud holes, however 65 were physically rescued by the NZSL team prior to ramp installation and 45 were seen exiting on ramps on review of GoPro and trail camera photos. Overall this programme of work has been very successful and has led to a direct reduction in NZSL pup mortality. This work was funded separately by DOC and WWF rather than by CSP, however, it did share resources with the CSP funded programme.
• Further investigation of Klebsiella pneumonia included the capture of 48 yellow-eyed penguins and 32 brown skuas for cloacal swabbing to ascertain disease prevalence in avians. No northern giant petrels have been caught due to their large flight distance on approach and low likelihood of safe capture with a hand net. In addition, substrate samples of mud, sand and water have been collected around the Sandy Bay sward in January and February for testing of environmental K. pneumoniae burden throughout the season.

Publication information

Childerhouse, S., Michael, S., Adams, L., Burns, T., Cockburn, S., Hamer, D., Maloney, A., and Pugsley, C. 2015. Final report: New Zealand sea lion research at the Auckland Islands 2014/15. Report prepared by Blue Planet Marine for the New Zealand Department of Conservation, Wellington. 50 p.