New Zealand sea lion research Summer 2008/2009 B. L. Chilvers This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
NZ sea lion research objectives Auckland Islands • Measure Auckland Islands pup production • Tag pups produced during 2008/09 • Data to estimate survival and reproduction of previously marked female NZ sea lions • Maintain and update the NZ sea lion database • Characterise and analyse the at- sea distribution of poorly known age and sex classes of NZ sea lions This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
Pup production - methods and date of estimate • Sandy Bay (Enderby Island) - Mark/Recapture estimate (16/1/09) • Dundas Island - Mark/Recapture estimate (21/1/09) • S.E. Point (Enderby Island) - Direct count -daily counts • Figure of 8 Island - Single direct count - (9/1/09) This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
Pup production 2008/09 - Results • Sandy Bay = 301 – 289+/-2 live pups Total for Auckland – 12 dead pups Islands = • Dundas = 1132 – 1065 +/- 16 live pups 1501 +/- 18 08/09 – 67 dead pups 2175 +/- 46 07/08 • South East Point = 14 – 8 live pups - 31% – 6 dead pups • Figure of 8 = 54 – 48 live pups – 6 dead pups This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
AUCKLAND ISLANDS PUP PRODUCTION 1997-2009 3200 3000 2800 Pup Production 2600 2400 2200 2000 1800 1600 1400 1200 1996/97 1997/98 1998/99 1999/00 2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 Season This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
Pup tagging – Satellite tagging • 701 pups were double tagged for population studies. • Eleven juvenile sea lions (4 male / 7 female) aged between 2 and 5 years were captured and satellite tagged at Sandy Bay, Enderby Island. Deployment lasted between 11 and 40 days. • Enderby, Rose, Dundas, Ewing, Fig. of 8, Adams, Campbell, Snares and Stewart Islands, Ross and Carnley Harbours, NE Auckland Islands and Catlins / Otago searched or reports obtained. This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
08/09 This talk is from preliminary field data and not to be referenced, distributed or used without 07/08 06/07 05/06 04/05 03/04 Pup Mortality 02/03 01/02 Season 00/01 99/00 98/99 97/98 96/97 the authors permission. 95/96 94/95 25 20 15 10 5 0 % mortality of pups at 1 month
Pup Mortality – Sandy Bay 45 40 Mortality 1 month 35 % pup mortality Mortality 2 months 30 25 20 15 10 5 0 8 9 0 1 2 3 4 5 6 7 8 9 9 9 0 0 0 0 0 0 0 0 0 0 / / / / / / / / / / / / 7 8 9 0 1 2 3 4 5 6 7 8 9 9 9 0 0 0 0 0 0 0 0 0 Season This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
Pup weight s at 1 mont h – Sandy Bay 14.00 13.00 12.00 Weight (kg) 11.00 Males 10.00 Females 9.00 Mean 8.00 2001 2002 2003 2004 2005 2006 2007 2008 2009 Year This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
Number of females ashore daily 410 360 Number of cows ashore 2004 2005 310 2006 2007 260 2008 2009 210 160 n n n n n c c n n n n e e a a a a a a a a a D D J J J J J J J J J - - - - - - - - - - - 2 4 6 8 0 2 4 6 8 9 1 1 1 1 1 1 2 3 date 31% drop in pup product ion due t o 30% decrease in # f emales ashore This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
Number of ident if iable f emales seen at Sandy Bay 07/ 08 vs 08/ 09 Average drop per age class 30% 140 NUMBER O F ANIMALS 2009 PRESENT 120 2008 PRESENT 100 80 60 40 20 0 WHITE (14+) orange (9-10) Y w hite (8-9) pink (7-8) red (6-7) blue (5-6) yellow (4-5) AGE CLASS Red and Blue (02 & 03) bact eria year f emales This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
Percent age ident if iable f emales pupped at Sandy Bay 07/ 08 vs 08/ 09 Average drop per age class 6.5% 60.00 2009 % PUP 2008 % PUP 50.00 40.00 30.00 20.00 10.00 0.00 y W o Y p r b e r e i l H a w n d u l l o n k e I h T ( g w i ( 6 ( E e t 7 5 e - ( - 7 - 4 ( ( ( 8 6 ) 1 9 - 8 ) ) 5 - 4 - 1 ) 9 + 0 ) ) ) Red and Blue (02 & 03) bact eria year f emales This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
Number of ident if iable males seen at Sandy Bay 07/ 08 vs 08/ 09 Average increase per age class 3% 70 2009 60 Number of identifiable males 2008 50 40 30 20 10 0 Orange (9-10) Y White (8-9) Pink (7-8) Red (6-7) Blue (5-6) Yellow (4-5) Age Class This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
Conclusion 31% drop in pup product ion due t o 30% decrease in f emales Why drop in f emales? Not likely bact erial * No sign in t issue samples so f ar analysed * Low mort alit y in pups * No signif icant decrease in f ecundit y * Spread low occurrence in wint er due t o sparse dist ribut ion * Wint er dist ribut ion, abundance and appearance report ed normal * Did not af f ect males * Normal pup weight s * Normal number of dead bodies af t er wint er * Not inf luence f rom previous bact erial out breaks Not likely dispersal * Philopat ric species * No increases in numbers elsewhere This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.
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