January 17th and 18th and 25th we were fortunate to be invited to assist tagging white sharks once more for the continued study and research of their fine scale movements around the North Island. The three days were spent around the Kaipara Harbour, an area long known to be popular for encountering pointers.
We have joined expeditions on the Kaipara in past years, but apart from the occasional ‘hook-up’, success has been minimal. This has been made all the more frustrating with numerous reports being made (at times, weekly) from recreational fishermen encountering white sharks, and commercial fishermen finding them tearing through their nets in the harbour.
We have always known they are there – but they have always remained elusive to us… Till now!
Saturday 17th of Jan was the turning point and that, it has to be said, is an understatement with seven ‘hook-ups’ and an eighth shark estimated at 3.4 meters found swimming around our anchor buoy’s on return from the second successful tag deployment. The sharks ranged from approximately 2 meters total length (TL) to 3.5 meters. Two smaller juvenile sharks, a 2.1 m TL female named Caitlin, and a 2.2 m TL male named Thomas D were tagged along with a third female named Sue, estimated at 3.5m TL. Four tags were deployed in total. A SPLASH and a PAT tag on Thomas D, a SPOT tag on Catlin. and a PAT tag on Sue.
Both the SPLASH and SPOT tags started to generate data within 48 hours of deployment as can be seen on the ARGOS map images below.
The rigs being used all had re-curved barbless hooks which contributed to the low numbers successfully brought to the boat and tagged. Barbless re-curved hooks were used to ensure deep hooking could not occur and the hook could be easily extracted .
The draw-back to this rig is if tension is lost on the line the hook will usually fall out of the animal’s mouth, however this does mean if the shark bites through the leader or trace the hook will fall out causing minimal injury.
Sunday 18th of Jan was less successful with only three ‘hook-ups’ and no successful tag deployment, however in comparison to past years on the Kaipara, even this was considered a success in its own right. The following Sunday 25th we headed out again, but sadly on this day we struck out without a single hook up, however, data obtained since that first weekend showed us that Caitlin, the 2.1 m female had headed north and is about 10 km off Ninety Mile Beach on a nw heading. Since we tagged her she has travelled about 452 km, giving a rate of movement/ displacement of about 41 km per day.
Thomas D, the 2.2 m male is still going around in circles about 22 km off Manukau Harbour!
News has travelled fast and on Jan 31st the Herald published a short article about the expedition. You can read the article here!.