Thanks, I should have used different wording. I think the broader point I meant to make was that since 1990-ish, global catch has stabilized around 80 million tons (see figure 1 in that report), meaning we arent actively catching more and more every year even as population has increased by 50%. The 1990s saw a large push for fisheries reform and we are seeing lots of improvement around the world as management capacity increases. The United States collapsed many stocks in the early 90s, but now have the most sustainable stocks in the world. Much of this is due to capacity building that really ramped up in the 90s & 2000s.

The FAO report says the exact opposite of your claim:

“Based on FAO’s analysis of assessed stocks, the share of fish stocks within biologically
sustainable levels has exhibited a downward
trend, declining from 90 percent in 1974 to
68.6 percent in 2013”

1. No.

2. I never said climate change is the only issue we need to deal with, but I would argue that it is, by far, the most important one. Biodiversity loss is a big problem… and climate change is probably the greatest long-term threat to biodiversity on the planet… mitigating climate change helps biodiversity.

Global fisheries harvest fish stocks, of which 69% are sustainable. By weight, about 82% of consumed fish is sustainable. We certainly need better fishery management to get both of those numbers up to 100%, but I would not say global fisheries are “decimating” fish stocks. Fishery sustainability has been trending up for the past couple decades.

http://www.fao.org/documents/card/en/c/2c8bcf47-2214-4aeb-95b0-62ddef8a982a

Sure, an open ocean MPA can be a refuge for fish under changing ocean conditions – I don’t think that has anything to do with climate mitigation, though – that would be a climate adaptation issue.

You are absolutely right that marine life plays an important role in absorbing carbon from the atmosphere, but the “key study” that identified 8 different ways presents a false equivalence. Phytoplankton and marine plants play an outsized role in carbon uptake – to compare them to whale falls and carbonate production in bony fish is…quite a stretch. Also, a more recent paper (Howard et al. 2017) concluded that, while marine fauna cycle carbon, they do not sequester it away and thus do not contribute to carbon mitigation.

https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/fee.1451

We should recognize that many of those 8 reasons are insignificant (or plain wrong) and focus on the two main parts of the biological pump (phytoplankton & marine plants) that are orders of magnitude more important.

Marine plants were addressed in my original comment (coastal MPAs protect them, while open ocean ones do not) so let’s look at phytoplankton. Satellite mapping chlorophil concentrations as a proxy for primary productivity is the best way to tell where phytoplankton are concentrated – check out this map from NASA.

https://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MY1DMM_CHLORA&d2=MOD17A2_M_PSN

You’ll notice that phytoplankton is concentrated in coastal areas, and open ocean MPAs are mostly barren. Furthermore, there is no evidence that fishing affects phytoplankton concentrations or health.

I would restate here, again, that open ocean MPAs do nothing to mitigate carbon issues like climate change and ocean acidification and would probably be detrimental to mitigation by restricting the amount of low-carbon protein available to eat. The amount of consumed protein eaten per day should increase very slightly or remain about the same over the next few decades. It is important that consumed protein be as low-carbon as possible.

I’m not saying big open ocean MPAs are inherently bad – cultural significance, like in Hawaii, is a great reason for preservation. I’m saying that offering carbon mitigation as a reason to implement large-scale MPAs is misleading at best and actively detrimental to mitigation efforts at worst.

Open ocean MPAs may play a role in climate adaptation via refuge (as you pointed out), but Gattuso et al 2015 demonstrates that mitigation is much more important for ocean health.

http://science.sciencemag.org/content/349/6243/aac4722

Looking forward to hearing your thoughts on the above, thanks.

The case for a large scale MPA as a climate refuge (beyond nearshore seagrass/mangrove carbon sinks) was made for the Papahānaumokuākea expansion by physical oceanographers, fisheries scientists, and climate scientists based on a few key studies (citations that helped build this climate reserve argument below).

One role that big open-water MPAs serve as climate refugia involves range expansions resulting from sea temperature shifts. Scientists have documented a northward range shift in various species of fish in the northeastern U.S. with increases in surface water temperature. In the Pacific, the expansion of the Pacific Warming Pool due to climate change is expected to push fish north and east. Given this observed relationship, climate change can pose a huge threat to species that need very specific environmental conditions (e.g. temperature, prey availability, mates) in order to survive, therefore shifting their ranges could prove disastrous if they are being heavily fished. With these temperature and environmental perturbations expected to intensify in the Pacific, an expansion of Papahānaumokuākea could provide a more stable sanctuary for these marine species.

A second role hinges on the reality that marine life acts as the “biological pump” of the ocean – converting carbon dioxide into living matter – and could serve just as important of a role as a carbon sink as the physical and chemical marine processes that drive the solubility of atmospheric carbon dioxide. This biological pump accounts for about two-thirds of the flux of carbon within the ocean. A key study focuses specifcally on the role of marine life in the carbon cycle. The study identifies eight key ways that life ranging from photosynthetic primary producers – that convert sunlight into essential building blocks – to the top predators of marine ecosystems act as carbon sinks. Most notably, this work highlights the role of food web dynamics and marine life biomass in carbon storage.

Big swaths of protected, healthy ocean matter.

Booth, D. J., N. Bond, and P. Macreadie. 2011. Detecting range shifts among Australian fishes in response to climate change. Marine and Freshwater Research 62:1027–1042.

Molinos, J. G., B. S. Halpern, D. S. Schoeman, C. J. Brown, W. Kiessling, P. J. Moore, J. M. Pandol , E. S. Poloczanska, A. J. Richardson, and M. T. Burrows. 2015. Climate velocity and the future global redistribution of marine biodiversity. Nature Climate Change 6:83-88.

Sunday, J. M., G. T. Pecl, S. Frusher, A. J. Hobday, N. Hill, N. J. Holbrook, G. J. Edgar, R. Stuart-Smith, N. Barrett, T. Wernberg, R. A. Watson, D. A. Smale, E. A. Fulton, D. Slawinski, M. Feng, B. T. Radford, P. A. ompson, and A. E. Bates. 2015. Species traits and climate velocity explain geographic range shifts in an ocean-warming hotspot. Ecology Letters 18:944-953.

Perry et al. 2005.

Hazen et al. 2012.

Cheung, W. W., Watson, R., & Pauly, D. (2013). Signature of ocean warming in global sheries catch. Nature, 497(7449), 365-368. 228Sumaila, U. R., Cheung, W. W., Lam, V. W., Pauly, D., & Herrick, S. (2011). Climate change impacts on the biophysics and economics of world sheries. Nature climate change, 1(9), 449-456

Pinsky, M. L., Fogarty, M. 2012. Lagged social ecological responses to climate and range shifts in fisheries. Nature Climate Change.

D Laffoley et al. (2014). The Significance and Management of Natural Carbon Stores in the Open Ocean. IUCN.

SJ Lutz and AH Martin (2014). Fish Carbon: Exploring Marine Vertebrate Carbon Services. GRID-Arendal and Blue Climate Solutions.

D Laffoley et al. (2014). The Significance and Management of Natural Carbon Stores in the Open Ocean. IUCN; SJ Lutz and AH Martin (2014). Fish Carbon: Exploring Marine Vertebrate Carbon Services. GRID-Arendal and Blue Climate Solutions.

Atwood, T.B., Connolly, R.M., Ritchie, E.G., Lovelock, C.E., Heithaus, M.R., Hays, G.C., Fourqurean, J.W., and Macreadie, P.I. 2015. Predators help protect carbon stocks in blue carbon ecosystems. Nature Climate Change. 5:1038-1045.

Max, consumption of farmed animal protein is one of the biggest single causes of anthropogenic climate change. Granted that wild caught fish are a far smaller source but I would like to make two points.

Firstly as there are far more people on this planet than wild caught fish can feed, would it be just the wealthy who would be able to afford them?

Secondly, climate change isn’t the only issue we are having to deal with, loss of biodiversity is another big problem. Global fisheries are decimating fish stocks and so large areas where stocks can breed are very important, and will become more so in the future as consumption of animal protein has to decrease causing greater demand on ocean fisheries.

A goal of many MPAs is to bolster fish populations both inside and outside of the reserve’s boundaries. If MPAs are able to meet this goal, then there can be fully protected swaths of the ocean as well as strong fisheries.

So while Rocha has all rights to express his or her views; these do not discourage us or hinder our sight to see the values of MPAs and LMPAs.

Not to mention that wild fish are by far the least environmentally destructive animal protein to eat on the planet – no inputs, be it pesticides or freshwater, no destructive land-use change, & much lower co2 footprint (even lower than soy, nuts, & eggs). http://www.wri.org/resources/data-visualizations/protein-scorecard.

There is an argument to be made that MPAs restricting fishing are more of a detriment to climate change and ocean acidification since they limit the amount of low-carbon protein that can be eaten.