Sea urchins don’t look very appetising.
In fact, they look downright scary; a ball of black or purple covered in sharp needles that can easily puncture any foot that accidentally stands on it.
- The purple sea urchin is responsible for a 90 per cent reduction of kelp in Port Phillip Bay’s marine sanctuaries
- Scientists and the government want people to start catching and eating sea urchin themselves to help with population control
- Kelp forests can take up to three years to start growing back after sea urchins are culled from an area of reef
But the real threat comes from the sea urchin’s ability to destroy kelp beds and turn coastal reefs into barren ocean deserts.
Which is exactly what the native pest has done to Port Phillip Bay.
Deakin University’s Paul Carnell is leading a sea urchin culling project in two marine parks in the bay where recreational fishing is not allowed.
For the past 20 years, he said kelp and other seaweed in the bay had slowly declined, brought on largely by the millennium drought that stripped the bay of vital nutrients, leaving less food for urchins.
Under healthy conditions, sea urchins sit idly on the sea floor, eating kelp and other sea life that floats near it and is caught on its spine.
But when kelp densities began to drop, other sea life, like the urchin’s predators, moved on, and sea urchin populations not only boomed but began moving to seek out food.
“They are moving in dense fronts almost like little armies, and they are clearing everything in their path,” Dr Carnell said.
He said sea urchins were destroying reefs all along Port Phillip Bay, having already wiped out 90 per cent of kelp forests, creating “ocean deserts” and “barren rock”.
“The urchins move together in droves, they can move about 25 metres a year, but in a front about 500 metres long.”
He said only 10 sea urchins per square metre were required to create an urchin barren, and some areas of Port Phillip Bay had become home to 50 urchins per square metre.
“So you see nothing but sea urchins,” he said.
“Our kelp forests are the forests of the ocean and so if you lose the kelp you lose the biodiversity and fish species in there as well.
“You see less abalone out there, less fish and biodiversity.”
Dr Carnell has restored some kelp forests but said it took 18 months for recovery to begin and up to three years for kelp to come back.
“If you want to restore the reef we need to reduce that number [of urchins] down very close to zero,” he said.
That’s where you come in.
Alongside other researchers and the Victorian Fisheries Authority, Dr Carnell wants people to start catching and eating sea urchins from the bay themselves, to help with population control.
While it’s not a staple food in the Australian diet, sea urchin roe (the gonads of the urchin) is considered a delicacy in some Asian countries and can fetch roughly $40 a teaspoon in restaurants in Melbourne.
Taylor Hunt, acting manager at the Victorian Fisheries Authority, said while sea urchins were detrimental to the environment, they were also a native species that provided a commercial fishery.
“We have looked at options at culling them and they do look like they work but it’s labour intensive, it’s a lot of effort,” he said.
Culling has been achieved in particularly overpopulated areas in Port Phillip Bay and Mallacoota but Dr Hunt said it was difficult to carry out culls everywhere because of the manpower needed and the speed at which sea urchins reproduce.
Dr Hunt said it would be unrealistic to assume recreational fishing could control sea urchins populations in the bay “but it does help”.
Recreational fishers can take up to 40 sea urchins per person per day in waters beyond the intertidal zone; waters at least two metres deep.
Dr Carnell said anyone with a catch bag and a strong pair of gloves could swim out just a few hundred metres into Port Phillip Bay and catch themselves dinner.
Johnson Teoh is the chef and co-owner of Uni Boom Boom, a restaurant that specialises in sea urchin roe, also known as uni.
The menu even has three types of sea urchin cake and a sea urchin cocktail.
“In Japan, it’s a staple food, it’s one of the three biggest ingredients used there,” Mr Teoh said.
He said knowing sea urchins were a pest in Australian waters made him think up creative ideas for dishes.
“Sea urchins are a very comforting food, especially in this cold. We can cook it multiple ways, we cook it steamed, fried, even dehydrated on popcorn so there’s a lot of potential.”
Mr Teoh said many people were sceptical of trying sea urchin for the first time, which is why he thought up the popcorn dish.
“We do dehydrated sea urchin on popcorn so they can take it one step at a time.”
He said sea urchins had a umami taste, with subtle differences between short and long-spined species; long-spined sea urchins are “creamy” and “almost like an ocean-flavoured custard”, while short-spined urchins, like the type found in Port Phillip Bay, are “sweet with a burst in your mouth”.
Jessica Teoh works as a waiter in the restaurants and said many Australians who were taken to the restaurant “often refuse to try it”.
“So we tried sea urchin fried rice, which most people enjoy,” she said.
When diners try it for the first time, Ms Teoh said they were usually surprised that it tasted similar to fish roe or lobster.
“After they’ve tried it they usually order it again,” she said.
Dr Carnell said collecting the urchins was easy as long as you had gloves and a catch bag.
“They don’t run or swim away,” he said.
Getting the roe out is pretty easy too.
Ms Teoh said to get the roe out of the urchin, simply use a sharp pair of kitchen scissors to cut the urchin open, being careful not to pierce the roe inside.
Have a bowl of ice water nearby with a little salt added, scoop out the yellow roe and place it in the water for a few minutes. The guts of the urchin, which are usually black, can be thrown away.
Ms Teoh said the roe could be eaten like sushi with a little soy sauce and wasabi or a great winter dish was to fry the roe in butter for a few minutes and add it to scrambled eggs.