Halpern, Benjamin S, Melanie Frazier, Jamie Afflerbach, Julia S Lowndes, Fiorenza Micheli, Casey O’Hara, Courtney Scarborough, and Kimberly A Selkoe. “Recent Pace of Change in Human Impact on the World’s Ocean.” Scientific reports 9, no. 1 (2019): 11609–8. Link: https://escholarship.org/content/qt3t31m632/qt3t31m632_noSplash_ea8824bad96c72c9511dc8267af20cdd.pdf?t=qaogsi

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., Parma, A. M., Pitcher, C. R., McConnaughey, R. A., & Jennings, S. Comment on “Tracking the global footprint of fisheries”. Science, 361(6404), 2018. eaat6713. Link: https://www.science.org/doi/full/10.1126/science.aat6713

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

Hilborn, R., Amoroso R. O., et al. “Effective fisheries management instrumental in improving fish stock status”, PNAS, 117(4), 2020. 2218-2224. Link: https://www.pnas.org/doi/abs/10.1073/pnas.1909726116

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

Pitcher Roland, C., Hiddink, J.G., Jennings, S., Hilborn, R., et al. “Trawl impacts on the relative status of biotic communities of seabed sedimentary habitats in 24 regions worldwide”, PNAS, 119(2), 2022. e2109449119. Link: https://www.pnas.org/doi/abs/10.1073/pnas.2109449119

Seabed status is high in regions where fisheries are exploited sustainably
Conversely, low status highlights regions needing improved management
Good fishery management contributes to better ecosystem outcomes and environmental benefits

Hilborn, Ray, Daniel J. Hively, Nicole Baker Loke, Carryn L. Moor, Hiroyuki Kurota, Johannes N. Kathena, Pamela M. Mace, et al. “Global Status of Groundfish Stocks.” Fish and fisheries (Oxford, England) 22, no. 5 (2021): 911–928. Link: https://onlinelibrary.wiley.com/doi/full/10.1111/faf.12560

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

Pons, M., Watson, J.T., Hilborn, R., “Trade-offs between bycatch and target catches in static versus dynamic fishery closures”, PNAS, 119(4), 2022. e2114508119. Link: https://www.pnas.org/doi/abs/10.1073/pnas.2114508119

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

Hiddink, Jan Geert, Sebastiaan J. van de Velde, et al. 2021.“Quantifying the Carbon Benefits of Ending Bottom Trawling”, Figshare, 2021. Link: https://figshare.com/articles/preprint/Quantifying_the_carbon_benefits_of_ending_bottom_trawling/16722808

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

Bindoff, N.L., Cheung, W.W.L., Kairo, J.G., “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

Cabral, R.B., Bradley, D., Mayorga, J., et al. “A global network of marine protected areas for food”, PNAS, 117(45), 2020. 28134-28139. Link: https://www.pnas.org/doi/abs/10.1073/pnas.2000174117

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

Barrientos, S., Barreiro, R., Piñeiro-Corbeira, C. “Paradoxical failure of Laminaria ochroleuca (Laminariales, Phaeophyceae) to consolidate a kelp forest inside a Marine National Park”, European Journal of Phycology, 2022. Link: https://www.tandfonline.com/doi/full/10.1080/09670262.2022.2065365?casa_token=dm2ukp7RFCYAAAAA%3AqnSE-Sl8QuRhha0XYnOKDcjW_nCAiBiedaLLb92wK1sPvp7I-hzpg1ozKc5lMnHXdUMHIkK1KGr9

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

A D Rijnsdorp, J G Hiddink, P D van Denderen, 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. Link: https://doi.org/10.1093/icesjms/fsaa050

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, Jan G Hiddink, Simon Jennings, Roland Pitcher, Michel J Kaiser, Petri Suuronen, Marija Sciberras, 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. Link: https://onlinelibrary.wiley.com/doi/full/10.1111/faf.12431

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