Shark re­search hauls in knowl­edge

Central Leader - - NEWS - By RANI TI­MOTI

One day of fish­ing has turned up a wealth of new in­for­ma­tion for shark re­searchers on the Kaipara Har­bour.

The great white is re­mark­ably elu­sive but Depart­ment of Con­ser­va­tion ma­rine tech­ni­cal ad­viser Clin­ton Duffy says he was part of a group that man­aged to hook six on Jan­uary 17.

The Three Kings res­i­dent is study­ing the species in north­ern New Zealand as part of his PhD re­search as a stu­dent in ma­rine science at the Univer­sity of Auck­land.

He says the six sharks, which were all re­leased, ranged in size be­tween 2 and 3.4 me­tres.

The group also filmed a 3m fe­male and saw a 2m white shark re­leased by an­other boat.

Duffy says the sharks were all in a very small area not far down Kaipara River from Shelly Beach.

A 2.5m white shark was also ob­served on the sur­face out­side the har­bour – about 9km off South Head by an­other fish­er­man.

Duffy’s group man­aged to tag three of the six sharks whose move­ments have since been tracked around the North Is­land.

Bruce Goor­ney of the White Shark Con­ser­va­tion Trust was also on the boat and says the day was a turn­ing point af­ter min­i­mal suc­cess over the years in the Kaipara.

He says the group was ini­tially buoyed by nu­mer­ous re­ports from recre­ational fish­er­men en­coun­ter­ing white sharks in the area and com­mer­cial fish­er­men whose nets were de­stroyed by the species.

‘‘We have al­ways known they are there but they have re­mained elu­sive to us – till now!’’

The crew caught three more white sharks be­tween 1.8m to 3.5m in the same area the next day but lost them all be­fore they could be tagged.

Duffy’s PhD looks at the move­ments and spa­tial ecol­ogy of the species and is part of a larger col­lab­o­ra­tive re­search pro­gramme be­tween the univer­sity, DOC and NIWA which be­gan on the Chatham Is­lands 10 years ago.

His field work in the Kaipara and Manukau har­bours in­volves fish­ing for white sharks, mainly ju­ve­niles be­tween 1.8m to 3.5m types them.

Pop-off archival trans­mit­ting (PAT) satel­lite tags are used to study long dis­tance move­ments and div­ing be­hav­iour of the sharks, whereas SPOT satel­lite tags pro­vide more ac­cu­rate in­for­ma­tion on their lo­cal trav­els.

‘‘My hope is that the dif­fer­ent types of data ob­tained from these tags will en­able me to build up a pic­ture of how these sharks use the and de­ploy­ing two of satel­lite tag on coastal waters along the north­west North Is­land, in­clud­ing the har­bours, and how they re­late to other white shark pop­u­la­tions within New Zealand, Aus­tralia and else­where in the south­west Pa­cific,’’ Duffy says.

Duffy tagged his first white shark, a 1.8m male, in 2012 in the Kaipara, helped by Scott and Sue Tin­dale.

‘‘That shark was tagged with a PAT tag which Scott and I re­cov­ered from a beach near Ta­pora nine months later.

‘‘The data on that tag in­di­cated that although it hadn’t ven­tured far from Kaipara Har­bour it had dived to more than 200 me­tres depth on sev­eral oc­ca­sions.’’

Last year, the trio SPOT tagged a 1.5m male.

‘‘The small­est white shark I have ever seen in Kaipara Har­bour, but un­for­tu­nately the tag failed to trans­mit,’’ he says.

Photo: VERONIKA RENTSCH

Thrash­ing work: Clin­ton Duffy with a crew on Scott Tin­dale’s boat Red Oc­to­ber plac­ing a PAT tag on a 1.8 me­tre male white shark in 2012.

Pho­tos: SCOTT TIN­DALE

Sleek sight­ing: A 3mfe­male white shark is filmed glid­ing along Kaipara Har­bour on Jan­uary 17.

Re­search sup­port: A SPOT tag on the first dor­sal fin of a 2.1 me­tre fe­male white shark at Kaipara Har­bour on Jan­uary 17.

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