Fishing club records back up signs of smaller fish

As published today in the Gisborne Herald

AVERAGE fish sizes in New Zealand could be decreasing says a genetics researcher, and records collated from fishing clubs between the East Cape and the lower North Island, back this up.

Dr Peter Ritchie, a researcher from the Allan Wilson Centre at Victoria University, presented his report — Size Does Matter, analysing the effect humans are having on fish stocks around the world — in Gisborne last week.

He said the Government needed to conduct research into fish sizes and might need to re-assess its management approach for some species because fish could be getting smaller and smaller as a result of genetic changes.

Competition fishing records gathered by clubs in the Central Fishing Management Area, which stretches from the East Cape down to Wellington and round to Wanganui, show that over the past 30 years most recreational species of fish have declined in size, some by nearly 50 percent.

This includes snapper, hapuka, blue nose, blue cod, terakihi, kahawai and kingfish.

Recreational Fishing Forum representative Linda Coulston, who is also a board member of the Gisborne Tatapouri Sports Fishing Club, says they have been presenting their findings to the Ministry of Primary Industries for years.

“The subject of fish species getting smaller has been a major contention of ours for over two years but the MPI won’t listen.

“For our fishery in area 2 (Central Fishing Management Area), they have done very little research or surveys.”

Fishing club patron Hilton Webb said for some of the species there had been very little research done by the MPI since the Quota Management System was set up in 1986.

Mr Webb is also a representative on the Recreational Fishing Forum, which meets with ministry staff three times a year to discuss fisheries management issues.

“We are essentially in the dark,” Mr Webb said.

“The majority of marine biologists we have talked to are saying the same as Dr Ritchie but the MPI will not acknowledge that we have major issues.”

Dr Ritchie, who has a background in genetics and evolution, says the records gathered by fishing clubs in area 2 which show fish sizes are declining, are consistent with what is being found in other parts of the world and highlight the need for more targeted research.

“We have not matched up the way that we manage the fishery with what we understand about fish populations,” he said.

“Our whole fisheries management mentality has grown to believe that catching the big fish is the way to go because we give the young fish the opportunity to reproduce.

“But actually the big fish are the ones that do it better and by only catching fish of a certain size and above, we are getting rid of the efficient reproducers.”

Dr Ritchie said that this could result in genetic changes when combined with increasing pressure on fish stocks.

“This means the smaller fish are producing the most offspring which causes a genetic shift and results in smaller average fish sizes within species.

“Studies conducted overseas into species such as the Atlantic cod and silverside, have proved this.”

He is calling for a New Zealand study into size-selective harvesting to determine whether average fish sizes in New Zealand are decreasing.

“There is yet to be any official approach to figure out whether we have these problems and there is uncertainty there that we really need to get a handle on,” he said.

“Fish is the only major food item that is still harvested directly from the wild and that makes the science really important.

“We need to figure out if we have similar problems as the ones we have seen overseas so that we can ensure our fishery management strategy is fit for purpose.”

Dr Ritchie wants to compare the DNA of snapper caught by Maori hundreds of years ago with snapper caught in 2015.

“One of the projects I’m trying to develop, if we can get funding, is to compare the genetic diversity of snapper pre industrialisation to the genetic diversity today,” he said.

“And test to see if we actually have got a genetic change over time which is the final piece of the puzzle.”

MPI was asked to respond but they could not meet our deadline. Their response will be in tomorrow’s paper.

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MPI denies ignoring fish size records

The Ministry of Primary Industries (MPI) denies accusations they are ignoring records which show fish are decreasing in size between the East Cape and lower North Island.

Two Gisborne representitives on the Recreational Fishing Forum said the MPI was refusing to acknowledge data collated from fishing clubs in the central management area which showed most recreational species had decreased in size over the last 30 years, some by nearly 50 percent.

This includes snapper, hapuka, blue nose, blue cod, tarakihi, kahawai and kingfish.

However, MPI fisheries management director Dave Turner said trends collated from commercial catch information confirm that fish stocks are in good condition.

“These sources indicate that the fisheries across the wider central management area that MPI monitors are healthy.

“That said, fish numbers can vary significantly within a management area due to environmental factors such as changing sedimentation, water temperature and food supply.”

He denied accusations that the MPI had not carried out enough surveys in the area since the Quota Management System was introduced in 1986. This came after a genetics researcher said at a public talk in Gisborne the government needed to conduct research into fish sizes.

Dr Peter Ritchie from the Allan Wilson Centre at Victoria University said fish could be getting smaller due to genetic changes, and that the Government might need to re-assess its management approach for some species.

“The records gathered by fishing clubs in area 2 (central management area) which show fish sizes are declining, are consistent with what is being found in other parts of the world and highlight the need for more targeted research,” he said.

For more information visit www.gisborneherald.co.nz

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