Cover climate now
To feed the world more sustainably than sheep and cattle farming, aquaculture will have to find a way to thrive in a warm sea, reports Marc Daalder
When the sea gets warm, like during a marine heat wave, cold-blooded salmon move to cooler waters. It can be a simple descent to the same place or a longer migration to another place.
However, farmed salmon does not have such an option. And fish farmers cannot easily move beads when temperatures are higher than expected.
At 14 degrees salmon thrive.
At 16 degrees they survive.
At 18 degrees, the enzymes that help them digest food begin to die off. When water temperatures are at 18 degrees for several weeks, the salmon’s immune system breaks down. They get sick. They die.
At higher temperatures, for long periods, the heat alone can kill them.
This is what happened this summer, when a marine heat wave killed about two out of every five salmon in New Zealand’s King Salmon’s Marlborough Sounds farms. More than 1000 tons of fish waste was sent to landfill.
“It was one of the hottest we’ve ever seen. It started early and it ended later. It was often a degree and a half warmer than normal,” Grant Rosewarne, CEO of NZ King Salmon, told Newsroom said. “There was a very long period of more than 18 degrees in the Pelorus Sound and in the Queen Charlotte as well.”
The company reported a $ 73 million loss for the year ended January and is closing most of its farms in the Marlborough Sounds.
Climate hits farms
Marine heatwave conditions – when ocean temperatures are above the 90th percentile for at least five days – were common over the summer, driven by the La Niña phenomenon.
“What we’re starting to see is that we do have a changing environment and unfortunately New Zealand King Salmon is suffering from the consequences,” said Serean Adams, aquaculture group manager at the Cawthron Institute.
This is not the first time that climate change has hit New Zealand’s fish farms. Ocean temperatures have been rising for decades, although the pace has accelerated more recently.
“You hear Niwa and others talking about marine heat waves. For the first seven years of my job, I never heard the term marine heat wave and now it’s every second year. And it looks like we’re going to have three La Niñas in a drive now, which is again quite unheard of, ”said Rosewarne.
Other salmon farmers and fishing companies say they are also seeing the impact of climate change, although NZ King Salmon’s losses this year are unique in their scale.
It has driven a spate of research into ways to increase resilience by moving to cooler waters or changing species.
Maren Wellenreuther is an evolutionary ecologist at the University of Auckland and a seafood scientist at Plant and Food Research in Nelson. The top of the South Island may soon be inhospitable to salmon, but other fish could replace them, she said.
“This is quite an interesting area because many species show their southernmost range here, such as snapper. For them, when you think of climate change, they increase their range in New Zealand, while other species, such as salmon, are found. as far north as Nelson and the Marlborough Sounds, they are struggling. ”
Wellenreuther was working on a project to breed snapper and get ready for aquaculture.
“If you just look at the Marlborough Sounds, this suddenly becomes an area where we might want to farm with species like snapper. If you think ahead, it’s something that’s just going to accelerate. In 10 years you’ll stop using salmon in the “Marlborough Sounds to farm. Completely. What are we going to do with that space? With climate change, you always think of winners and losers.”
This does not mean a wholesale end to salmon farming in New Zealand. Other companies farm the species further south and NZ King Salmon is still the single largest producer of the king salmon species worldwide.
open ocean
In recent years, therefore, the focus has shifted to open-sea aquaculture, which could unlock a new scale of fish farming while also increasing climate resilience.
Climate change, Rosewarne said, is “the best reason” his company is looking at open-sea farms. In 2019, NZ King Salmon applied for permission to build a 12-acre farm in Cook Street called Blue Endeavor. A decision on this application is expected later this year.
“We think it will lead to less stressed fish because the temperature will be cooler. Also in that area there is something called a thermocline where it gets cooler and cooler as you get closer to the bottom. We do not see it in the sounds, ”he said.
“Of course we can grow on a larger scale, but we can also possibly increase our unit value. We can grow bigger, more valuable fish out there. We think we can get a good environmental outcome – we think we can possibly get an increase in natural biodiversity associated with the farm, rather than a decrease that you can see in most farming methods.
Wellenreuther said next-generation offshore technology could make it possible to move beads as a matter of course, year-round, to track the optimal temperatures for the cultivated species. It will also limit environmental impacts because the farm will not be concentrated over a single space.
At least three other offshore salmon farms are being investigated. Fishing company Sanford, which also operates a few salmon farms, submitted a permit application for an open sea farm in the South in 2020. Ngāi Tahu also has plans for his own open-sea salmon farm in the South, called Hananui Aquaculture. That program referred to the government’s rapid Covid-19 consent process, according to documents released to Newsroom under the Official Information Act.
A report commissioned by Fisheries New Zealand last year found that the government’s most valuable intervention would be a new consent process that provides more security more quickly.
Feedback from applicants and others on the resource consent application process and outcomes was almost unanimous – it is fraught with risks and uncertainties that have a real impact on development schedules, costs and operational flexibility. obtain a permit; costs that can be spent more productively on the work needed to provide viability in the case of open sea farms. “
Rosewarne agreed, saying that if activated, offshore farming would play a critical role in achieving the Government’s target of a $ 3 billion aquaculture industry by 2035. It will also help with the country’s climate goals, which will enable us to supplement high-emission dairy products and low-emission meat production, large-scale source of protein. One hectare of land could generate $ 30 million in revenue on an open-sea farm, compared to about $ 11,000 on a dairy farm.
“We firmly believe that offshore aquaculture can become New Zealand’s most valuable industry. At the same time, it can be the greenest primary sector we have,” he said.
“The Norwegian salmon industry is now more or less equal to our dairy industry, depending on where those two commodities are in their price cycle. There is no new primary producing industry that can be set up that can deliver such great value from a relatively small amount of space and with an environmental footprint that is very acceptable. “
This article is part of Newsroom’s contribution to the Covering Climate Now joint coverage week on food and water.