Concerns over the environmental and ethical impacts of fishing are driving calls to replace wild-caught seafood with agricultural or plant-based alternatives.
However, a new paper by Duncan Leadbitter of the Australian National Centre for Ocean Resources and Security, University of Wollongong claims that a shift away from ocean-caught protein may inevitably worsen biodiversity loss.
According to the paper, the prevailing assumption is that agriculture is inherently more sustainable than marine fishing.
“The underlying assumption is that the comparative impacts of agriculture versus fisheries favour agriculture, but this may not be the case, especially when biodiversity is the basis for the comparison.”
The paper called out documentaries such as Seaspiracy and Oceans for popularising claims that sustainable fishing is not possible, leading consumers to consider changing their diets thinking it is more sustainable.
The paper was based on a workshop funded by the international non-profit The Marine Ingredients Organisation (IFFO).
“This peer-reviewed article underscores the essential role of responsibly managed fisheries in sustainable food systems and biodiversity protection. Despite their impacts, agricultural systems remain vital for feeding a growing population.
“However, more tools are needed to enable objective, localised comparisons between the biodiversity impacts of land-based animal protein production and marine fishing. With this in mind, IFFO has started a pilot project to transition current discussions to a biodiversity framework outlining indicators to measure impacts and guide decision-making,” said said Dr Brett Glencross, IFFO’s Technical Director.
Too much to replace sustainably
Today, around half of the Earth’s arable land has already been converted from natural habitats to food production, driving major terrestrial biodiversity loss.
Approximately 83 per cent of the expansion of global agriculture in the 1980s and 1990s replaced tropical forests.
About 77 per cent supports livestock production and the remainder is dedicated to crops, some of which for animal feed.
Aquaculture also increasingly relies on fed systems, often using fishmeal derived from wild capture. However, the paper also noted that the use of plant-based replacements like soy are rising.
The paper claims that replacing animal protein from marine fisheries could require an additional 5 million km2 of land – an area larger than the extent of intact rain forest in Brazil.
Additionally, replacing all fish products in aquaculture diets would result in the need for over 47,000 km2 of new land converted to agricultural production.
The paper highlighted the importance of integrated food systems.
Without holistic assessments of feed ingredients and food systems, environmental impacts risk being shifted from oceans to land, the paper warned.
“Well-managed fisheries do not rely on fundamental changes to ecosystems in the way that agriculture does and there is lots of progress in improving fisheries management underway,” said the researchers.
The paper concluded: “There are choices to be made as to how more food will be produced in the coming decades and what unintended land use and biodiversity consequences will be produced from these decisions.”
Reviews in Fisheries Science & Aquaculture, 1–13.
Biodiversity Consequences of Replacing Animal Protein From Capture Fisheries With Animal Protein From Agriculture.
Leadbitter, D. et al
https://doi.org/10.1080/23308249.2025.2585414
