Can you eat that?

That’s one of the questions we get regularly asked about marine pest management. It’s a fair question — and wouldn’t it be great if the solution was that simple?

Undaria is also called wakame and a delicacy in many places. Photo / NRC

Unfortunately, the answer is a bit more complicated. Here’s why.

We can definitely eat some of the species that we think of as marine pests here in New Zealand. In fact, the Asian paddle crab and Japanese mantis shrimp are considered delicacies in their countries of origin. One visitor to our boat show stand told us how much he enjoys eating them when he is home in Japan.  

We’ve also heard about a distillery turning invasive crabs into whisky and a company called Salty Roe Tasmania which is turning an invasive crab into a delicious delicacy that it is exporting around the world. 

At Cambridge University there is a project to rebrand shipworms - which they have branded  Naked Clams, a pest species of saltwater clam -, proposed as an alternative food source that provides similar micronutrients to meat without the environmental cost.  

We also reported earlier this year that one iwi is attempting to raise funds for Undaria management by harvesting and selling it for food, stock food and fertiliser. 

But unfortunately as a solution to the marine pest issue, it does come with some fish hooks (excuse the pun):

A report by the Invasive Species Council in Australia finds that while invasive species are a major driver of extinction around the world, we can’t eat our way out of the invasive species issue. 

“There are no compelling examples of a commercial market successfully controlling, let alone eradicating an invasive species,” says the report. 

“At best, these strategies have made a minimal and ephemeral impact on the population due to the limited impact harvests generally have on the population size. At worst, the establishment of commercial markets to bolster invasive species management exacerbates the issue, causing more harm than good.”

It explains that for species with high reproductive rates - which is the case for the marine pest species causing harm in our local environments, commercial harvesting is rarely able to achieve sufficient removal rates to eradicate a species.

The other reason that it can’t be sustainable as a population control mechanism is because a successful business will depend on plentiful supply of the product - which is counter to the goals of reducing or eradicating the pest species.  

The report does say that commercialisation of invasive species can be a clever way of gaining public sport for control activities of some species - but is unlikely to be successful as a management approach - and in New Zealand, strict rules relating to movement of marine pests will also be obstacles. 

Styela salad dressing, anyone?