Mercury Bay History Series – Box Net Fishing

Recent discussions in Mercury Bay about the successful application of Ngati Hei to establish a mussel spat farm along a portion of the northern side of our beautiful bay bring to mind another similar type enterprise, back in the 1970's.

A company named JND (Japan New Zealand Developments) established a teiche net in the area, working in partnership with Sealord Fisheries. More commonly known to locals as a box net, this net was similar to some used in Japan, Portugal, and probably other countries, for many years.

The company extensively researched locations taking into account tidal and current flows, water temperatures, and fish populations, before establishing a net just off Sandy Bay in 1973. It seems this net was removed in 1974. Locals say it was then moved to Hot Water Beach where problems with the stronger currents occurred but catches seem to have improved. Much to the undoubted disgust of local recreational fishers yellowfin tuna now became part of the catch.

Construction and Sections of the Box Net

When building the net a free swimming area that ran about 200 hundred metres from the beach was established. Running out from this was a fence type net about 800 metres long. The mesh on this section varied in size, ranging from greater than 300mm on the shore end to a much finer mesh closer to the actual box net. The fish would detect the vibrations of this fence and turn outwards towards the box net itself.

The box had three sections:

• The first part the fish first entered - was a free swimming area
• The second section - had a mesh floor that sloped upwards from where the fish first entered, forcing them to swim up the slope until they reached the third part
• The third section - once in this section, which had a capacity of about two hundred tons of fish, the fish were trapped.

In addition there were detachable holding pens, which fish entered through a trapdoor. Fish were manually scooped out of the box, sorted into species and either taken for processing or put in a holding pen for later. Mackerel were the main catch, while kingfish were a much favoured species and were caught in huge numbers. Other significant species were snapper, trevalli, and kahawai. All were sold in Japan. Interestingly the kahawai were sold as Pacific salmon, apparently having a proportion of Canadian salmon oil added at the processing stage!

There were inevitably other unintended catches. Turtles were not uncommon, but perhaps the most interesting was a giant sunfish estimated to weigh three tons. Sharks were often caught, including some monsters, and occasionally orca and other marine mammals were trapped and released.

A few of the locals could see advantages from the net. Some spearfishermen discovered the benefits of a ready supply of trapped fish. A story also made the rounds of a diver who tried the delights of being towed at great speed round the net by hanging on desperately to the tail of a stingray. From the other perspective the net crew were concerned that some day they would arrive to find a diver trapped in the netting.

Boxnet layout. This example does not include detachable extra holding nets that were constructed for the Whitianga net.

Ministry Research and Official Catch Figures

Ministry research from the time stated that it was believed that only one percent of the fish population was trapped at any time. Official catch figures make that a little hard to believe. For example in December 1973, 37,600kg of kingfish were caught, while in June 1974, 26,120 kg of trevalli were recorded in the catch! Interestingly, over a twelve month period the greatest snapper catch was 1,100 kg in November 1973, so perhaps the impact on snapper stocks was not as great as for some species. Ask anyone who fished over that period what happened to their kingfish catch – they will tell you!

Environmental and Economic Considerations

It's hard to visualise the scale of this complex of nets. Although very little could be seen from the surface, making it a potential navigation hazard, under the water there was a huge structure, much larger than the area of a tennis court. It was held in place by huge kedge anchors, later replaced by sand bags when these were found to be more secure. Just imagine the forces of tide and weather the net had to withstand.

The net was serviced by Teiche boats, crewed both by locals and Japanese, and the willingness of the crews to handle quite severe sea conditions was remarkable. If the net was not monitored regularly many fish died, so the pressure was always on to venture out, especially as the legal requirement was for daily monitoring.

The box net stayed in place for quite some years, eventually being removed in 1980. It seems that, despite the net's effectiveness, the company never really made money. Perhaps it was this, or perhaps just a lack of interest from the Japanese, who no longer fished as extensively in New Zealand waters once our exclusive fishing zone was introduced, that led to its demise.

Environmentalists hated this box net, and they were not alone. Recreational and commercial fishers alike became very concerned about the detrimental effect on fishing in this area, and protests and attempts to sabotage the net became increasingly common. 

A model of the boxnet is in the Mercury Bay Museum as part of a display featuring this controversial aspect of our fishing history.

Footnote. Much of the information in this contribution relies on that given by locals who had been involved in the project at the time. However, it differs in some ways from an article written for the then Ministry of Agriculture and Fisheries in 1975. For example the word “teiche” was given by the locals where it is written “teichi” in the article. More importantly, the magazine states that two nets were originally set up, the one at Sandy Bay and the one at Hot Water Beach. I had always been told the Hot Water Beach one was established later. Maybe this just shows how difficult it is to record history accurately! (Dick Wilson)

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Article Contributor

This article was provided by Dick Wilson, Committee Mercury Bay Historical Society (2020).