Til að framleiða eitt kíló af eldislaxi þarf fóður gert úr þremur til fjórum kílóum af villtum fiski samkvæmt nýjustu rannsóknum. Fyrir tveimur áratugum var þetta hlutfall enn hærra en hefur minnkað vegna aukinnar notkunar plöntupróteins í fóðrinu. Það hefur haft í för með sér aðrar alvarlegar afleiðingar fyrir umhverfið, eins og kemur fram í nýrri rannsókn sem sagt er frá í meðfylgjandi frétt fagmiðilsins Salmon Business.
Á því tímabili sem rannsóknin nær yfir óx losun gróðurhúsalofttegunda tengd fóðri fyrir eldislax um 314%, landnotkun um 594% og vatnsnotkun um 236%. Ofauðgun sjávar jókst um 630%, á meðan ofauðgun ferskvatns jókst um 468%.
Þetta eru sláandi tölur og allt aðrar en fulltrúar iðnaðarins hafa haldið fram.
Margfalt meira þarf af próteini og næringarefnum í laxeldi en framleiðslan gefur af sér.
Laxeldi er því ekki fæðuframleiðslukerfi heldur beinlínis fæðuminnkunnarkerfi sem dregur úr framboði næringarefni fyrir hungraðan heim.
Hér er önnur rannsókn þar sem er farið ofan í saumana á gríðarlegri þörf laxeldis fyrir fiskiolíu og fiskimjöl sem unnið er úr villtum fiskistofnum.
Fagmiðillinn Salmon Business fjallar um ósjálfbærni laxafóður:
… The research, led by Björn Kok and Dr Wesley Malcorps of the university’s Institute of Aquaculture, examined developments between 2000 and 2020 and found that the European aquaculture sector cut its overall use of wild-caught fish in feed by 13%, despite nearly doubling in production over the same period. Growth was largely driven by the expansion of Atlantic salmon farming in Norway.
While lower inclusion of fishmeal and fish oil has reduced dependence on marine resources, the study found that total environmental impacts increased substantially. Over the period analysed, greenhouse gas emissions associated with aquafeed rose by 314%, land use by 594%, and water consumption by 236%. Marine eutrophication increased by 630%, while freshwater eutrophication rose by 468%.
…
On a per-kilogram basis, wild fish use in European aquaculture fell by 59%. However, this reduction was accompanied by increases in greenhouse gas emissions of 103%, land use of 336%, and water consumption of 65%. Marine eutrophication increased by 285%, and freshwater eutrophication by 167%.
Kok said that an overreliance on single sustainability indicators can distort assessments of aquaculture performance.
“Reducing dependence on marine resources has been treated as the main environmental sustainability goal in aquaculture. However, if environmental sustainability assessments focus on a single headline metric, they risk telling an incomplete, and sometimes misleading, story. We need a comprehensive view on environmental sustainability,” he said.
Malcorps added that greater use of fish processing by-products could help improve outcomes, given their nutrient density and comparatively low environmental footprint. He also noted that novel feed ingredients show long-term potential but currently face constraints related to cost, scale, and consistency.