Expectations for population growth at new breeding locations for the vulnerable New Zealand sea lion (Phocarctos hookeri) using a simulation model

• Published in: Biological Conservation
• Main Authors: Lalas, C., Bradshaw, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Sci Ltd 2003
• Subjects: New Zealand sea lions; Phocarctos hookeri; Colonisation; Establishment; Leslie matrix model; Survival; Maximum lifespan; Population management plan; Campbell Island; New Zealand; Auckland Islands
• Online Access: http://hdl.handle.net/2440/48202; https://doi.org/10.1016/S0006-3207(02)00421-4

Copyright © 2003 Elsevier Ltd. All rights reserved. Management plans for threatened or recovering large vertebrate species that are increasing in population size and range focus on the establishment of viable populations within set temporal limits. New Zealand (Hookers) sea lions (Phocarctos hookeri) were declared a threatened species in 1997, and New Zealand legislation requires that threatened species of marine mammals must be managed to reduce human-induced mortality and achieve a non-threatened status within 20 years. The present breeding distribution of P. hookeri is highly localised, with over 95% of total annual pup production located at Auckland Islands and almost all of the remainder at Campbell Island. Breeding elsewhere has been ephemeral or restricted to <10 adult females. The only recorded sustainable breeding at a new location has been at Otago, South Island, New Zealand. This breeding population consisted of a total of four breeding females in 2002 and is derived from one immigrant female that gave birth to her first pup in the 1993/1994 breeding season. The New Zealand Department of Conservation management plan specifies that to achieve a non-threatened status P. hookeri (1) at Otago must increase in the number of breeding females to greater-or-equal, slanted10, and (2) must establish greater-or-equal, slantedtwo new breeding locations within the 20-year time frame, each with greater-or-equal, slanted10 breeding females. This study 1) projects the population growth trends at a new location (Otago) to see if it will achieve greater-or-equal, slanted10 breeding females within the legislated time frame, and (2) examines the likelihood that other breeding locations will establish elsewhere given the demographic information available for this species. We present 20 deterministic and three stochastic Leslie matrix model scenarios for female population growth for the initial years following the start of breeding at a new location. Our results indicate that (1) a new breeding population derived from ...