Cameras provide insight into changing fisheries
Scientists are starting to get a better picture of how recreational fisheries change over time, thanks to a few web cameras and a bit of help from the public.
NIWA scientists have installed eight web cameras at boat ramps in the upper North Island and are about to install another four in the lower North Island as part of an ongoing project to monitor trends in recreational fishing effort over the long term.
The web cameras record one image each minute, 24 hours a day. Scientists then select 60 individual days at random, view the images and count the number of boats returning to the ramps.
Recreational fishers are also interviewed at the ramps on randomly preselected days so that scientists can also monitor trends in catch rates.
"We ask where and how they have been fishing, for how long, and we then count and measure their catch," NIWA's recreational fisheries scientist Bruce Hartill said.
The web camera images supplement aerial surveys carried out about once every five to seven years. These aerial surveys involve four planes working between the North and East Capes, counting fishing boats at midday.
Randomly preselected days are surveyed throughout summer and winter, on weekdays and at weekends, in conjunction with interviews conducted at various boat ramps.
"We then combine the two sources of information which can give us an estimate of the harvest on each survey day, for commonly caught species," Mr Hartill said.
He said the public had been incredibly supportive of the research and the data enabled unprecedented insight into some of New Zealand's largest recreational fisheries over a long period of time.
The project, funded by the Ministry for Primary Industries, is to be showcased at an international marine and freshwater sciences conference in Hamilton from August 19-23.
NIWA scientists are presenting about 75 papers at the conference being held at Waikato University and the organisation is one of the main sponsors of the event.
Other highlights of NIWA science being presented at the conference include:
- Undersea New Zealand – what's hidden beneath the waves
- Tidal gates and the effects on freshwater fish communities
- Temperature trends in rivers and lakes
- The changing structure of the Hauraki Gulf from 1000AD to the present day
- New, web-based data management system for New Zealand's freshwater fish data.
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