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NZ sea lion TMP quantitative risk assessment Revised demographic assessment and MCMC Jim Roberts & Ian Doonan NIWA CSP/AEWG, 17 th August 2015 This presentation is not for publication, release or quotation in any form without prior written

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NZ sea lion TMP quantitative risk assessment Revised demographic assessment and MCMC

Jim Roberts & Ian Doonan NIWA CSP/AEWG, 17th August 2015

This presentation is not for publication, release or quotation in any form without prior written approval from the MPI Principal Adviser Fisheries Science and the author

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NZSL TMP Risk Assessment

NZSL TMP – risk assessment process

RISK ASSESSMENT MONITORING & ACTIVE MANAGEMENT POLICY

2014 2015 2016

FEB APR JUN AUG OCT DEC FEB APR JUN

WORKSHOP

Pup Mortality & Disease

NEW WORKSHOP

FIELD SEASON FIELD SEASON ADAPT MANAGEMENT APRIL JUNE AUG OCT DEC REPORT G O A L S O P T I O N S D E V E L O P E D C O N S U L T A T I O N S E E K S T A K E H O L D E R E N G A G E M E N T ACTIVE MANAGEMENT REPORT RESULTS RISK ASSESSMENT MODEL

  • Technical development
  • Peer reviewed

THREATS IDENTIFIED

ENGAGEMENT and FEEDBACK OPPORTUNITIES

· Technical Working Groups (CSP/AEWG) · National Environmental Engagement Forum (EEF) JUNE – DECEMBER Stakeholders will have opportunities to engage in the development and review of research which will inform the TMP, as well as provide feedback

  • n the TMP goals and high level objectives.

Engagement throughout the TMP will occur through the following groups: APRIL - JULY Stakeholders will have

  • pportunities to

engage in the review of the demographic work and risk assessment

  • utputs

AUGUST Experts will be invited to participate in the expert panel risk assessment SEPTEMBER - FEBRUARY IMPLEMENT Stakeholder will have

  • pportunities to review results

from the expert panel qualitative risk assessment Public consultation will occur

  • n proposed options for TMP

DEVELOPMENT PROCESS FOR THE THREAT MANAGEMENT PLAN (TMP)

EXPERT PANEL EXPERT PANEL Refine Model

Stakeholders will have

  • pportunities to review results

from the 2014 Auckland Island field season. JUNE

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Assessment methodology

For Auckland Islands & Otago Peninsula

  • 1. Demographic assessment:
  • Estimate current age distribution
  • Demographic rates for projections
  • 2. Projections from MPD run (Triage)
  • Estimate parameters with upper level of threat then project

forward 20 years

  • Screen out threats that have low impact
  • 3. Projections from MCMC run (high impact threats)
  • Apply range of threat levels over 20 years (2017-2037)
  • Relate distributions of projected mature n to criteria
  • Repeat with mitigation measures
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NZSL TMP Risk Assessment

Summary of observations

  • Pup census:

– Estimates assigned high confidence for Paul Breen’s modelling – Sandy Bay 1966-2015 (1965/66-2014/15) – Auckland Islands 1995-2015

  • Mark-resighting:

– Extract from Dragonfly database – Sandy Bay females – Marked 1990-2014 & resighted 1998-2015 – females only – Distinction by mark type (brand, chip or flipper tag only)

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NZSL TMP Risk Assessment

Summary of model at previous AEWG meeting

  • Model period from 1960-2015
  • Survival:

– Separate estimates for age classes 0, 1, 2-5, 6-14 and 15+ – Only age 0 and 6-14 survival were year-varying

  • Pupping/maturation:

– Year-varying pupping rate for age 8-14 – 5 parameters gave pupping probability at ages 4, 5, 6, 7 and 15+ relative to 8+

  • Resighting probability:

– All year-varying or year-constant resighting probability, separate estimates depending on mark type

  • Tag loss rate:

– Functional form (3 parameters) gives age-varying probability of losing 1 flipper tag in a year; another parameter gives probably of losing 2 tags in a year

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NZSL TMP Risk Assessment

Order of demographic model modification

  • Effects of alternative census CVs
  • Fitting to Auckland Islands age distribution & census
  • Parameterisation of resighting probability
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NZSL TMP Risk Assessment

Effects of alternative census CVs

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NZSL TMP Risk Assessment

Alternative census CV

  • Arbitrarily used CV of 6% for census in previous model runs
  • AEWG suggested looking at sensitivity of normalised

residuals to alternative census CV as means of selecting appropriate value

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NZSL TMP Risk Assessment

Alternative census CV

  • When using CV of 6%,

tend to overestimate pup production after 2009

  • This is improved when

CV of 3% is used

  • Adopted for all

subsequent runs

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NZSL TMP Risk Assessment

Fitting to Auckland Islands age distribution & census

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NZSL TMP Risk Assessment

Census + Age observations

  • Previous runs fit to SB MR, census and age

composition of lactating females (puppers)

  • MPI/DOC opted to change the main census series to

Auckland Islands for assessment of threats

  • Small decrease in likelihood (~4 units) when fitting

to AI instead of SB

  • AI series begins 1995 (SB was 1960s)
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NZSL TMP Risk Assessment

Age composition Sandy Bay v Dundas

Simon Childerhouse’s (2010) female ageing study indicated very different age composition at Dundas in 1998-2001

Sandy Bay Dundas

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NZSL TMP Risk Assessment

Age composition Auckland Islands

  • Combined series by multiplying proportion at age by

pup production estimate in corresponding year to get numbers at age for each rookery

  • These were then combined and proportion at-age

recalculated (AI age)

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NZSL TMP Risk Assessment

Pup survival fitting to AI census + age

  • Fitting to AI age had tiny effect on all parameters

except pup survival and relative pupping rate at age 4

  • Survival prior to 1990 greatly increased and slight

increase 1994-1997

  • Relative pupping rate at age 4 increased from ~0.1 to

~0.2

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NZSL TMP Risk Assessment

Parameterisation of resighting probability

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NZSL TMP Risk Assessment

Low resighting effort in 2013

  • Assumption of year-invariant resighting affects survival in later years
  • Recommended we use year-varying parameters
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NZSL TMP Risk Assessment

Parameterisation of resighting probability

  • Recommended actions:

– Model run with year-varying parameters

  • However:

– Greatly increases number of potentially correlated parameters – Period with highly consistent resighting effort (e.g. 2002-2012)

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NZSL TMP Risk Assessment

Parameterisation of year-varying resighting probability

  • We elected to use year

blocks: 1999, 2000-2001, 2002-2012, 2013, 2014- 2015

  • MPD estimates…
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NZSL TMP Risk Assessment

MCMC – Auckland Islands

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NZSL TMP Risk Assessment

MCMC run

Model structure as previous AEWG, expect:

  • Fit to Auckland Islands census (model start 1990) with

CV of 3%

  • Fit to Dundas/Sandy Bay age
  • Resighting probability blocked for different year-

groups

  • Relative pupping rate age 15+ fixed to 1, as MPD run

hit upper bound (same as age 8-14, effectively 8+)

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NZSL TMP Risk Assessment

MCMC sampling

  • Three chains with different starting values
  • Currently ~50,000 iterations for each chain (still

running)

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NZSL TMP Risk Assessment

Parameter correlation

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NZSL TMP Risk Assessment

Parameter correlation

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NZSL TMP Risk Assessment

MCMC outputs - Survival

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NZSL TMP Risk Assessment

MCMC outputs - Pupping

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NZSL TMP Risk Assessment

MCMC outputs – Resighting probability

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NZSL TMP Risk Assessment

MCMC outputs – Tag loss & N0 (1990)

Losing 1 tag Losing 2 tags

N0 = 1,780 (1,640 – 1,970)

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NZSL TMP Risk Assessment

Auckland Islands MCMC – Projection

λ2037 = 0.959 (0.952–0.968) N2037 (%N2017) = 47% (41–60)

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NZSL TMP Risk Assessment

Actions still to be addressed

  • Explore alternative rules for assigning pupping status
  • Model runs from start of decline with/without threats
  • Explore effects of phantom tags on parameter

estimates

  • Year subsets to assess model predictions v observed
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NZSL TMP Risk Assessment

Otago Peninsula assessment

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NZSL TMP Risk Assessment

Otago Peninsula assessment update

Added 2014/15 observations:

  • 8 pups born
  • Related to mothers (Sealion Trust family tree)

Changes to parameterisation for MCMC:

  • Year-invariant parameters
  • Survival ages 0, 1-5, 6-14 & 15+
  • Combined resighting probability for ages 1+ immature &

non-puppers

  • Pupping rate age 7+; relative pupping rate age block 4-6
  • Resight puppers fixed to 1 (MPD estimate at upper bound)
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NZSL TMP Risk Assessment

Otago Peninsula – Fit to census

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NZSL TMP Risk Assessment

Otago Peninsula MCMC parameter correlation assessment

Surv0 Surv1-5 Surv6-14 Surv15plus Pup4-6 Pupp7plus ResImNP N0

  • 0.20
  • 0.27
  • 0.14
  • 0.10

0.04

  • 0.13

0.05 Surv0

  • 0.27
  • 0.34

0.06

  • 0.14
  • 0.07
  • 0.18

Surv1-5

  • 0.38
  • 0.19
  • 0.11
  • 0.11

0.05 Surv6-14

  • 0.16

0.07

  • 0.16

0.02 Surv15plus

  • 0.08

0.07

  • 0.04

Pup4-6

  • 0.40

0.15 Pupp7plus

  • 0.00
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NZSL TMP Risk Assessment

Otago Peninsula MCMC – Fit to census (MPD) & estimates

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NZSL TMP Risk Assessment

Otago Peninsula MCMC – projection

λ2037 = 1.07 (1.05–1.09) N2037 (%N2017) = 390% (290–530)

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NZSL TMP Risk Assessment

End of demographic assessment presentation