Hilborn, R., et al. (2023), “Evaluating the sustainability and environmental impacts of trawling compared to other food production systems“. ICES Journal of Marine Science, fsad115.

The article lays down how seafood produced by bottom trawling can have a lower environmental impact than chicken or pork, and that banning bottom trawling would increase negative environmental impacts by increasing terrestrial protein production. Hilborn et al. have reviewed dozens of papers about bottom trawling impact, including stock sustainability, bycatch, ecosystem impact, and carbon footprint. Benthic sedimentary habitats remain in good condition where fishing pressure is well managed and where VME and species of concern can be protected by spatial management. Though bottom trawling is generally the most impactful kind of fishing, well-managed bottom trawl fisheries produce food with a much lower environmental impact than any terrestrial animal protein.

Smith, J. G., et al., (2023). A marine protected area network does not confer community structure resilience to a marine heatwave across coastal ecosystems. Global Change Biology.

The article notes that one of the claims about the benefits of Marine Protected Areas (MPAs) is that they supposedly provide resilience against climate impacts. The paper evaluated what is probably the largest marine protected area network in the world (in California) and shows no evidence that the MPA network provided any protection against a marine heat wave.

Hiddink, J. G., et al. (2023).“Quantifying the Carbon Benefits of Ending Bottom Trawling”, Nature, 617(7960), E1-E2.

We do not know enough about the impact of trawling on seabed carbon. There are context-dependent responses of the sediment metabolism to trawling, varying between positive and negative effects depending on the studied metric and location. The volume of sediment where carbon is mineralized after trawling is greatly overestimated

Pons, M., et al., “Trade-offs between bycatch and target catches in static versus dynamic fishery closures”, PNAS, 119(4), 2022. e2114508119. 

The degree of bycatch reduction achievable for a certain quantity of target catch is related to the correlation in space and time between target and bycatch species. Dynamic area closures could reduce bycatch by an average of 57% without sacrificing catch of target species, compared to 16% reductions in bycatch achievable by static closures. Dynamic approaches will be increasingly valuable as climate change drives species and fisheries into new habitats or extended ranges

Barrientos, S., et al., “Paradoxical failure of Laminaria ochroleuca (Laminariales, Phaeophyceae) to consolidate a kelp forest inside a Marine National Park”, European Journal of Phycology, 2022. 

Implementing an MPA does not guarantee that all components of the local community will benefit from it. Restoring MPA kelp reefs will more likely require efforts to reduce herbivore activity than to bolster kelp populations. Kelp canopies recurrently failed inside a MPA in recent years.

Hilborn, Ray, et al. “Global Status of Groundfish Stocks” Fish and fisheries (Oxford, England) 22, no. 5 (2021): 911–928. 

Average stock abundance is increasing and is currently above the level that would produce maximum sustainable yield (MSY). Stocks from the Northeast Atlantic tend to have among the greatest average abundances relative to MSY-based reference points. The impact of fishing is highly variable by region and by benthic habitat structure

Bindoff, N.L., et al., “Changing Ocean, Marine Ecosystems, and dependent Communities”, IPCC Report (2021).

There is a lack of data and understanding of the complex processes that affect carbon storage in the potentially mobile fraction of marine sediments. Due to these uncertainties, there is currently low confidence that control of sediment disturbance can be used for climate mitigation. The removal of bottom trawling pressure in certain habitats might increase the organic carbon content in those habitats.

Hilborn, R., et al. “Effective fisheries management instrumental in improving fish stock status”, PNAS, 117(4), 2020. 2218-2224. 

On average, fish stocks are increasing where they are assessed. Where fisheries are intensively managed, the stocks are above target levels or rebuilding. On the contrary, where fisheries management is less intense, stock status and trends are worse. Management tools are still needed for sustaining fisheries in places where they are lacking

A D Rijnsdorp, et al. “Different bottom trawl fisheries have a differential impact on the status of the North Sea seafloor habitats”, ICES Journal of Marine Science, Volume 77, Issue 5, September 2020, Pages 1772–1786. 

Trawling is highly aggregated in core fishing grounds where the status of the seafloor is low but the catch per unit of effort (CPUE) per unit of impact is high. In the North Sea, muddy habitats are impacted the most and coarse habitats are impacted the least. Beam trawling for brown shrimps, otter trawling for industrial fish, and dredging for molluscs have the lowest impact.

Mcconnaughey, Robert A, et al. “Choosing Best Practices for Managing Impacts of Trawl Fishing on Seabed Habitats and Biota.” Fish and fisheries (Oxford, England) 21, no. 2 (2020): 319–337. 

Reducing impacts of trawling on seabed habitats and biota will be influenced by the characteristics of the fishery and the ecosystem, as well as the local, regional or national values, priorities and resources.
There is no universal best practice, and multiple management measures and industry actions are required to meet sustainability objectives and improve trade-offs between food production and environmental protection

Cabral, R.B., et al. “A global network of marine protected areas for food”, PNAS, 117(45), 2020. 28134-28139.  

Strategically expanding the existing global MPA network to protect an additional 5% of the ocean could increase future catch by at least 20% via spillover, generating 9 to 12 million metric tons more food annually. Food provisioning can be a central driver of MPA design, offering a pathway to strategically conserve ocean areas while securing seafood for the future.

Halpern, Benjamin S, et al., “Recent Pace of Change in Human Impact on the World’s Ocean.” Scientific reports 9, no. 1 (2019): 11609–8. 

A fundamental gap in understanding how humanity is affecting the oceans is our limited knowledge about the pace of change in cumulative impact on ocean ecosystems from expanding human activities. Bottom trawling is not the most damaging activity to the seabed. Climate change, shipping and pollution are far bigger threats to the ocean than fishing.

Amoroso, R. O., et al., Comment on “Tracking the global footprint of fisheries”. Science, 361(6404), 2018. eaat6713. 

There is a significant contrast between the estimated global footprint of fisheries and the actual results of tracking due to an artifact of the spatial scale of analysis. Reanalyses of global (all vessels) and regional (trawling) fisheries data at higher resolution reduced footprint estimates by factors of >10 and >5, respectively. Such analyses are unlikely to be a good proxy for the footprint of fishing or the status of species or ecosystems affected by fishing.

Bacheler, N. M., et al., (2016). No evidence of increased demersal fish abundance six years after creation of marine protected areas along the southeast United States Atlantic coast. Bulletin of Marine Science, 92(4), 447-471.

The paper concludes there is no evidence that the MPA network increased the abundance of fish, which seriously challenges the underlying theory of benefits from MPAs.