New Zealand sea lion research Summer 2008/2009 B. L. Chilvers This - - PowerPoint PPT Presentation

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

• f 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 – 12 dead pups

• Dundas = 1132

– 1065 +/- 16 live pups – 67 dead pups

• South East Point = 14

– 8 live pups – 6 dead pups

• Figure of 8 = 54

– 48 live pups – 6 dead pups

Total for Auckland Islands = 1501 +/- 18 08/09 2175 +/- 46 07/08

• 31%

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

1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 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 Pup Production 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

• btained.

This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.

Pup Mortality

5 10 15 20 25 94/95 95/96 96/97 97/98 98/99 99/00 00/01 01/02 02/03 03/04 04/05 05/06 06/07 07/08 08/09 Season % mortality of pups at 1 month

This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.

Pup Mortality – Sandy Bay

5 10 15 20 25 30 35 40 45 9 7 / 9 8 9 8 / 9 9 9 9 / / 1 1 / 2 2 / 3 3 / 4 4 / 5 5 / 6 6 / 7 7 / 8 8 / 9 Season % pup mortality Mortality 1 month Mortality 2 months

This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.

8.00 9.00 10.00 11.00 12.00 13.00 14.00 2001 2002 2003 2004 2005 2006 2007 2008 2009 Year Weight (kg) Males Females Mean

Pup weight s at 1 mont h – Sandy Bay

This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.

160 210 260 310 360 410 2 9

• D

e c 3 1

• D

e c 2

• J

a n 4

• J

a n 6

• J

a n 8

• J

a n 1

• J

a n 1 2

• J

a n 1 4

• J

a n 1 6

• J

a n 1 8

• J

a n

date Number of cows ashore

2004 2005 2006 2007 2008 2009

Number of females ashore daily

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.

20 40 60 80 100 120 140 WHITE (14+)

• range (9-10)

Y w hite (8-9) pink (7-8) red (6-7) blue (5-6) yellow (4-5) AGE CLASS NUMBER O F ANIMALS 2009 PRESENT 2008 PRESENT

Red and Blue (02 & 03) bact eria year f emales

Number of ident if iable f emales seen at Sandy Bay 07/ 08 vs 08/ 09 Average drop per age class 30%

This talk is from preliminary field data and not to be referenced, distributed or used without the authors permission.

0.00 10.00 20.00 30.00 40.00 50.00 60.00 W H I T E ( 1 4 + )

• r

a n g e ( 9

• 1

) Y w h i t e ( 8

• 9

) p i n k ( 7

• 8

) r e d ( 6

• 7

) b l u e ( 5

• 6

) y e l l

• w

( 4

• 5

) 2009 % PUP 2008 % PUP

Percent age ident if iable f emales pupped at Sandy Bay 07/ 08 vs 08/ 09

Average drop per age class 6.5% 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.

10 20 30 40 50 60 70 Orange (9-10) Y White (8-9) Pink (7-8) Red (6-7) Blue (5-6) Yellow (4-5)

Age Class Number of identifiable males

2009 2008

Number of ident if iable males seen at Sandy Bay 07/ 08 vs 08/ 09 Average increase per age class 3%

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.