Human-mediated extirpation of the unique Chatham Islands sea lion and implications for the conservation management of remaining New Zealand sea lion populations.
While terrestrial megafaunal extinctions have been well characterized worldwide, our understanding of declines in marine megafauna remains limited. Here, we use ancient DNA analyses of prehistoric (<1450-1650 AD) sea lion specimens from New Zealand's isolated Chatham Islands to assess the demographic impacts of human settlement. These data suggest there was a large population of sea lions, unique to the Chatham Islands, at the time of Polynesian settlement. This distinct mitochondrial lineage became rapidly extinct within 200 years due to overhunting, paralleling the extirpation of a similarly large endemic mainland population. Whole mitogenomic analyses confirm substantial intraspecific diversity among prehistoric lineages. Demographic models suggest that even low harvest rates would likely have driven rapid extinction of these lineages. This study indicates that surviving Phocarctos populations are remnants of a once diverse and widespread sea lion assemblage, highlighting dramatic human impacts on endemic marine biodiversity. Our findings also suggest that Phocarctos bycatch in commercial fisheries may contribute to the ongoing population decline.
Department of Zoology, Allan Wilson Centre, University of Otago, Dunedin, New Zealand.|Canterbury Museum, Christchurch, New Zealand.
Nicolas J
NJ
Rawlence
Department of Anatomy, Allan Wilson Centre, University of Otago, Dunedin, New Zealand.
Catherine J
CJ
Collins
Scripps Institution of Oceanography, University of California, San Diego, CA, USA.
Christian N K
CN
Anderson
Department of Anthropology and Archaeology, University of Otago, Dunedin, New Zealand.
Justin J
JJ
Maxwell
Department of Anthropology and Archaeology, University of Otago, Dunedin, New Zealand.
Ian W G
IW
Smith
Department of Zoology, Allan Wilson Centre, University of Otago, Dunedin, New Zealand.
Bruce C
BC
Robertson
Department of Anatomy, Allan Wilson Centre, University of Otago, Dunedin, New Zealand.
Michael
M
Knapp
Department of Anthropology, Southern Methodist University, Dallas, TX, USA.|School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Wits, 2050, South Africa.
Katherine Ann
KA
Horsburgh
Department of Anatomy, Allan Wilson Centre, University of Otago, Dunedin, New Zealand.
Jo-Ann L
JA
Stanton
Canterbury Museum, Christchurch, New Zealand.
R Paul
RP
Scofield
Museum of New Zealand Te Papa Tongarewa, Wellington, New Zealand.
Alan J D
AJ
Tennyson
Department of Anatomy, Allan Wilson Centre, University of Otago, Dunedin, New Zealand.
Elizabeth A
EA
Matisoo-Smith
Department of Zoology, Allan Wilson Centre, University of Otago, Dunedin, New Zealand.
Jonathan M
JM
Waters
D000818:Animals; D044822:Biodiversity; D003247:Conservation of Natural Resources; D000072441:DNA, Ancient / Q000032:analysis; D004272:DNA, Mitochondrial / Q000235:genetics; D053476:Extinction, Biological; D005398:Fisheries; D006802:Human Activities; D006801:Humans; D062312:Islands; D009520:New Zealand; D046070:Sea Lions / Q000235:genetics*
D000072441:DNA, Ancient; D004272:DNA, Mitochondrial
Chatham Islands; New Zealand sea lion; Phocarctos hookeri; ancient DNA; extinction; fisheries bycatch; human impact