US-AMLR Datasets

Pinniped researchMike Goebel

CCAMLR Ecosystem Monitoring Program

• “detect and record significant changes in critical components of the marine ecosystem ……”

• “distinguish between changes due to harvesting of commercial species and changes due to environmental variability, both physical and biological.”

CEMP was established in 1984 in response to a developing krill fishery to:

•Fur seal •Elephant seal•Weddells•Leopards

Pinniped species studied by US-AMLR

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Predator performance – Fur seals

*CEMP Indices

Summer (Local/Regional scale) Foraging success (4 indices, inc. trip duration*) Trophic links – food web & diet studies (5) Reproductive success (4, inc. pup growth*)

Winter (Scotia Sea - broader geographic scale) Annual survival , natality (4 indices) Pup production (2 indices) Arrival condition – timing of reproduction (2)

Multi-year Demography - Population vital rates

• Age at first reproduction

• Net reproductive rate

• Mean generation time

• Intrinsic rate of growth

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Datasets collected – Pinnipeds

Data sets - Annual (1997/98 – Present):

DEMOGRAPHY - Mark-resight tag databaseAdult females tagged 12-15% (3% Cape-wide)Known-age 94% Pregnancy and survival rates500 pups tagged annually* (~7% of pup production)

ECOLOGYTDR deployments (Dec-Feb)PTT/GPS deployments – (Dec, Jan, Feb)Trip duration (CEMP)Pup growth* (CEMP)

TROPHIC LINKS (Scats, Fatty acids, & Stable isotopes)

* In collaboration with Chile* In collaboration with UCSC (NSF – funded)

OTHER PINNIPEDS: Mark resight data – leopards & elephant sealsWeaning mass – elephant seals

Data sets - Periodic: ECOLOGY – Regional surveys (SSMUs) (1986, 1991, 1995, 2001, 2006)

OCEANOGRAPHY - large seals as samplers – CTD* (2005-2009)

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Fur seal population vital rates

•Age-specific mortality•Net reproductive rate•Mean generation time•Intrinsic rate of growth•Age at 1st reproduction (AFR)

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Juveniles• first year survival:Low• ~90% mortality by AFR

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Adult females• survival: High• pregnancy rate:High

Fur seal year class success 1982-2006

Recruitment and/or survival are variable

….that characteristic has not changed over three decades

1999/00

Tooth data:

1982-1997 year classes

Mark-resight data:

1998-2006 year classes

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Krill demographics & fur seal performance

Krill length in fur seal diet Krill maturity & sex ratio

Fur seal trip duration

Trip durations are shortest when:

• Krill length is >47mm• Low proportion of juvenile krill• High proportion of female krill

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JuvenileMaleFemale

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Fur seal performance

Assessing overall fur seal performance:

an ordination approach using 17 indices

Fur seal performance was best 2000-2002 & 2006 when:

• Krill length was >47mm• Low proportion of juvenile krill• High proportion of female krill

Top-down impact on fur seal populations:

28-50% of all fur seal pups consumed by mid-Feb

Fur seal phenology: Climate change effects?

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Mean age

Median date of births

Mean date of arrival

Arrival and date of birth are becoming earlier.

Trends in arrival and parturition for female fur seals

Uniqueness of US-AMLR pinniped datasets

• Number of indices, length of time series, having a large known age population, and a large mark-resight database

• Demography & vital rates for an Otariid

• Data are collected simultaneously with offshore data

• Leopard seal data

• Data sets are collected in a rapidly changing environment

• Colonizing events