New Zealand Sea Lions Historic and Present Day Threats.

New Zealand Sea Lions

Historic and Present Day Threats

Past Distribution

Present Distribution

Life history• Estimated maximum age:

females 28yrs, males 23yrs

• Age at first reproduction:

females 4 yrs, males 9+ yrs

• Reproductive rate:

females 64%

• Adult survival not well defined – juvenile survival highly variable

• Population estimate 2008/09:

9880 (95% CI, 8604-11297)

Breeding

• Sexually dimorphic:

females 160 kgs, males 400 kg

• Dominant males hold territories, females move between territories

• Polygynous breeders: December - January

• Females nurse 8+ months

• Females are highly philopatric

• Colonial during breeding but disperse widely outside breeding season

• 68 % of all NZ sea lion dives at Auckland Islands exceed estimated ADL (4-10% for other otariids)

Mean aerobic dive limit

Feeding

Parameter Auckland Islands Otago

Age at first breeding 4yrs < 5% of all females 4yrs >85% of all females

Female mass (8-13yrs) 112 kg 152 kg

Foraging trip distance up to 175 km (ave 102km) up to 25 km

Foraging trip duration 66 hours <24 hours

Dive Depth ave 130m, max 600m ave 50m, max 110

Interaction with people• Sea lions are

sometimes curious and playful and are usually unafraid

IUCN red list 2009:

Vulnerable due to low population in decline

DoC Threat classification 2005:

Range restricted – conservation dependent

Current Population Status

•Bacterial outbreaks

•Fisheries bycatch

•Fisheries competition

Present Threats

Fisheries – Direct By-catchEstimated by-catch SQUID 6T 1999 - 2009

Season

FRML(revised)

Estimated total number NZ sea lion mortalities

% observer coverage

Number NZ sea lion captures on observed boats

% females caught

TotalTows

1999 64 14 37 5 80 401

2000 65 71 35 25 44 1208

2001 75 67 100 38 58 582

2002 79 84 33 22 73 1647

2003* 70 39 23 10 60 1466

2004* 62 (124) 118 31 16 88 2595

2005 115 115 29 9 67 2693

2006+ 96 (150) 110 28 11 91 2459

2007 91 56 41 8 75 1318

2008 81 46 47 5 60 1247

2009 113 (95) 72 38 4 75 1916

Total 780 153 Ave. 70% 17205* Court ruling allowed fishing to continue after FRML reached

+ Minister of Fisheries increased FRML at request of fishery

Diet of the New Zealand sea lion occurrence (%O), number (%N) and mass (%M)

TOTAL (121 stomachs) DIGESTED (112 stomachs)

1 to 2+ days before death

FISH %O %N %M %O %N %M

Jack Mackerels 8.2 0.7 3.0 7.1 0.7 2.6

Warehou 4.1 0.2 1.0 2.7 0.1 1.2

Pigfish 11.5 0.7 0.1 9.7 0.6 0.1

Barracouta 7.4 0.5 4.6 5.3 0.5 5.8

Javelin fish 9.0 3.3 0.4 7.1 4.3 0.7

Hoki 11.5 2.2 9.6 12.4 3.1 15.5

Red cod 32.0 3.1 3.2 30.1 3.8 4.3

Ling 13.1 0.9 4.4 14.2 1.5 8.8

Opalfish 48.4 35.5 2.4 50.4 50.1 4.7

CEPHALOPODS

Octopus 38.5 3.1 14.4 28.3 2.1 27.8

Arrow squid 86.9 33.4 43.0 33.6 14.1 17.9

Total number of taxa/species 35 29

Protection measures

• Marine mammal protection act:- it is an offence, amongst other things, to harass or disturb marine mammals;- offences carry penalties of up to 6 months imprisonment or fines up to $250,000 and further fines of up to $10,000 for every marine mammal in respect of which the offence is committed;- marine mammals caught accidentally or incidentally in fisheries must be reported

• Marine mammal sanctuary:since 1994 there has been a 12 n.mile marine mammal sanctuary around the Auckland Islands

Protection measures• Fisheries Act:

- the Minister may take measures considered necessary to avoid, remedy, or mitigate the effect of fishing-related mortality on any protected species (ie Fisheries Related Mortality Limit, FRML)

• FRML:- in place since 1992- FRML supposed to allow population growth- bycatch estimated using historical catch data when observer coverage was low and has not been adjusted to account for 50% longer tows- model used to calculate FRML severely limited (unable to fit estimated reproductive rate)- FRML does not include other fisheries (just SQ 6T)- legal challenges have allowed continuation of fishing after FRML has been passed.

Protection measures• Sea Lion Exclusion Device (SLED):

- impact on sea lions/rate of survival unknown- 35% discount factor attributed to boats using approved SLED based on poor data

• DoC Population Management Plan:- would allow DoC to set mortality limit but currently abandoned