Durning the last few years I have had the pleasure of hosting several overseas scientists as part of my position at Massey University.

There is a downside though, in that I dread the inevitable embarrassing explanations I have to give describing New Zealand's numerous failures when it comes to protecting our unique environment and its biodiversity.

The scientists come to study our biodiversity and its management so I cannot hide the facts.

The difficulties begin when I relate that we have the highest proportion of threatened plant and animal species globally, and, included in this statistic, we have almost certainly the highest proportion of threatened and declining freshwater fish species.

Not surprisingly, they are stunned at this admission and typically their response is to question how this could happen given our world-famous environmental legislation, the Resource Management Act (RMA).

"Surely in 'clean-green New Zealand' there is strong protection for your unique biodiversity, especially native fish?"

I then have to explain that no, on the contrary, the RMA has largely been compromised, our freshwater environmental protection weakened over the last few years and our native fish have no formal legal protection, while absurdly introduced game fish species (many of which impact on native fish biodiversity), have complete protection.

My next cringe is when I describe our freshwater fisheries legislation enacted in 1983.

Like something from a Monty Python script the first paragraph gives total protection to just one of the native fish species: the grayling - which became extinct in the 1930s!

The next paragraph of the act continues the Pythonesque theme, giving complete protection to the rest of New Zealand's native fish with one massive exception: if the fish are taken for "human consumption" or for "scientific purposes" then there is no protection. So, in reality there is no practical, legal, or functional safeguard at all for our native fish.

A typical stunned response from visitors is an incredulous, "So you mean to say in 1983 you passed a law to protect a fish that went extinct 50 years earlier, but gave no protection to the rest of the not yet extinct native species, and then, to top it off, you gave total protection to introduced game fish species?"

I have to sheepishly admit that all that is true, but that it gets worse. Not only do we not protect in law or practice our native and mostly endemic threatened freshwater fish species, we commercially and recreationally harvest some of them! I explain that annually hundreds of tonnes of our endemic and threatened longfin eels are harvested and exported.

In addition, a favourite pastime is whitebaiting - the recreational and commercial catch of an unmeasured annual tonnage of the juveniles of five species of native fish.

Four of the five whitebait species are listed as threatened.

All these threatened native fish species are sold in supermarkets, restaurants and online (via Trade Me), and for the whitebait there is no assessment or limit on the catch.

Meanwhile, it is illegal to buy or sell introduced trout and this restriction is strictly policed.

Deluded by the "clean-green" image of New Zealand, the visitors who came to learn from us instead find that environmental and biodiversity protection is a sham.

Understandably, they are saddened and frustrated that we didn't learn from their mistakes.

They tell me that we should be leading the world in biodiversity protection and sustainable food production with our small size, geographic position and beautiful environment.

I have to agree and voice my disgust at the way our political leaders have capitulated to environmental exploiters in a naive belief in the short-term economic gains claimed from allowing environmental degradation from extractive industries.

The reality is that the once real "clean-green" image is becoming more of a deception every day with the out-of-control agricultural intensification and weakening of environmental protection.

Our No 1 priority should be making sure it is true and honest, not a parody like our freshwater fish legislation. Our "clean-green" image underpins our economic and ecological future and once it's gone, you don't get it back.

- Mike Joy is a senior lecturer in environmental science and ecology at Massey University.