Thursday, August 11, 2016

Research @ Otago - Rob Lewis

Rob is working on a system to identify individual Sevengill sharks so New Zealand's Sevengill shark populations can be catalogued for future study and analysis.

Many of our local species of sharks are lesser known or unheard of in New Zealand as is the case in the Sevengill shark (Notorynchus cepedianus).  Sevengill sharks are important coastal predators that help regulate the health our local marine ecosystems. There are, however, large gaps of knowledge pertaining to the basic parameters of Broadnose Sevengill population size, composition, life span, growth rates, sexual maturity and vulnerability to fishing pressures in New Zealand.

Through the use of baited underwater camera stations we can identify each individual Sevengill encountered and start getting to know some of these missing characteristics of the NZ population. Rob's study focuses on a population of Sevengill sharks in Paterson Inlet, Stewart Island, that exhibits an all-year-round presence. The use of baited remote video systems to sample this population is ideal as they are a non-invasive, repeatable, cost-effective and easy to deploy. 

Once there is a catalogue of individuals it will be possible to start characterising the Paterson Inlet population demographics including abundance, estimated population size, sex ratio, size ranges and maturity. Only with these data present and accurate can sensible and effective future management decisions be made regarding the species.

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