Mengunin sem norskt sjókvíaeldi losar í firði Noregs er á við óhreinsað skólp frá 17,2 milljón manns þegar litið er til köfnunarefnis, 20 milljónum manns af fosfórs í losuninni og 30 milljón manns hvað varðar lífrænt kolefni. Í öllum tilfellum er mengunin margfalt magn skólps íbúa landins, sem eru 5,5 milljón talsins.
Þetta kemur fram í sláandi frétt sem var að birtast í The Guardian og byggir á nýrri rannsókn norsku gagnarannsóknastofnuninni Sunstone.
Sjókvíaeldi á laxi losaði á síðasta ári óhreinsað skólp á við 816.000 manns í firði Íslands.
Til viðbótar við fosfór, köfnunarefni og lífrænt kolefni er í skólpinu frá sjókvíaeldi gríðarlegt magn af örplasti, þungmálmar, lyf og skordýraeitur.
Sjókvíaeldi á laxi er óboðleg aðferð við matvælaframeiðslu.
Í frétt The Guardian segir m.a.
…
Norway is the largest farmed salmon producer in the world, and nutrients in fish feed are excreted directly into coastal waters. Analysis from the Sunstone Institute found that Norwegian aquaculture released 75,000 tonnes of nitrogen, 13,000 tonnes of phosphorus and 360,000 tonnes of organic carbon in 2025.
The nutrients are equivalent to those contained in the untreated sewage of 17.2 million people for nitrogen, 20 million people for phosphorus, and 30 million people for organic carbon, the report found, raising fears of destructive algal blooms.
…
Researchers found feed consumption had increased by 14.6% over a six-year period, in line with industry expansion, producing nutrient pollution in 2025 that equated to levels expected in the raw sewage of a country about the size of Australia. In a separate analysis, the report authors found that seasonal variation aggravated the problem, with nutrient load highest in summer months when ecosystems are least able to absorb it.
Fish sludge from nutrients can fertilise phytoplankton and lead to destructive algal blooms that deplete oxygen levels. Fjords are particularly vulnerable to such effects because they are semi-enclosed bodies of water, allowing for greater accumulation of nutrients. Their oxygen levels are already declining because of global heating.
In Sognefjord, the country’s longest fjord, increased nutrient inflows – not just from fish farms – were held responsible for about two-thirds of the oxygen depletion, a study found last year, while warmer water was blamed for the other third.
Oxygen levels in deep waters have also declined in the second-longest fjord in Norway, the Hardangerfjord, according to the country governor for Vestland.
In March, officials rejected nine applications for fish farms in the fjord on account of the increased emissions they would cause. Tom Pedersen, an environmental adviser for the region who served as an expert reviewer on the Sunstone report, said the figures in its analysis were unsurprising and even “on the conservative side”.
“The major concern we experienced in the last few years is that all these algae and plankton and whatever die and they sink down to the bottom of the floor and they decompose – and that process uses oxygen,” he said. “The end result is that the oxygen level in the fjord is going down, and has gone down.”
Við mælum með að skoða framsetningu Sunstone á gögnum úr rannsókninni. Hve marga Norðmenn þarf til að jafna mengunarfótspor sjókvíaeldisins?
Og þetta líka: Mengunin fyrir neðan yfirborðið.