[MARMAM] New publication: Importance of squid as prey of NZ sea lions and NZ fur seals at The Snares, subantarctic NZ
trudi.webster at otago.ac.nz
Tue Mar 11 13:10:53 PDT 2014
Dear list members,
We are happy to announce our recent publication:
Lalas, C. and Webster, T. 2014. Contrast in the importance of arrow squid as prey of male New Zealand sea lions and New Zealand fur seals at The Snares, subantarctic New Zealand. Marine Biology, 161(3): 631-643.
New Zealand sea lions (Phocarctos hookeri) are threatened by incidental bycatch in the trawl fishery for southern arrow squid (Nototodarus sloanii). An overlap between the fishery and foraging sea lions has previously been interpreted as one piece of evidence supporting resource competition for squid. However, there is currently no consensus about the importance of squid in the diet of New Zealand sea lions. Therefore, we investigated this importance independently of spatial and temporal differences in squid availability through a simultaneous study with sympatric New Zealand fur seals (Arctocephalus forsteri), a species known to target arrow squid. Diet sampling at The Snares (48°01′S 166°32′E), subantarctic New Zealand, in February 2012 coincided with peak annual catch in the nearby squid fishery. Diets were deduced by analyses of diagnostic prey remains from scats (faeces) and casts (regurgitations). The contribution of each prey species to the diet was quantified using the per cent index of relative importance (% IRI) that combined frequency of occurrence, mass and number of prey items. Arrow squid was a minor component in sea lion scats (2 % IRI), and none was found in their casts. In contrast, arrow squid was the major component in fur seal scats and casts (93 and 99 % IRI, respectively). This study found that New Zealand sea lions ate minimal squid at a time when squid was clearly available as evidenced by the diet of New Zealand fur seals; hence, there was no indication of resource competition between sea lions and the squid fishery.
A PDF may be obtained from Marine Biology: http://link.springer.com/article/10.1007/s00227-013-2366-6<http://booksandjournals.brillonline.com/content/journals/1568539x/advance>
or requests for reprints can be sent to: trudi.webster at otago.ac.nz
Marine Mammal Research Group
Department of Marine Science
University of Otago
Dunedin, New Zealand
Ph: +64 (0)3 479 5476
Cell: +64 (0)21 264 4432
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