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Climate Change and the Large-Scale Redistribution of Fish Catches

May 3, 2012

What will be the impact of climate change on fisheries?  Cheung et al. have modeled that there will be a large-scale redistribution of marine fisheries.

From the abstract:

Here, we project changes in global catch potential for 1066 species of exploited marine fish and invertebrates from 2005 to 2055 under climate change scenarios. We show that climate change may lead to large-scale redistribution of global catch potential, with an average of 30–70% increase in high-latitude regions and a drop of up to 40% in the tropics. Moreover, maximum catch potential declines considerably in the southward margins of semi-enclosed seas while it increases in pole-ward tips of continental shelf margins. Such changes are most apparent in the Pacific Ocean. Among the 20 most important fishing Exclusive Economic Zone (EEZ) regions in terms of their total landings,  EEZ  regions  with  the  highest  increase  in  catch  potential  by  2055  include Norway, Greenland, the United States (Alaska) and Russia (Asia). On the contrary, EEZ regions with the biggest loss in maximum catch potential include Indonesia, the United States (excluding Alaska and Hawaii), Chile and China.

A 30-70% increase in high latitude regions?  And a 40% drop in the tropics?  All this by 2050?  Brutal.  And this isn’t taking into account the effects of acidification.

Of course, the modeling for something this is quite tricky.  I’d be quite interested to see what they’ve got, but this model isn’t available (no win here for transparency).  Here’s what the author’s say on their method:

Future  distributions  of  these  species  are  pro-jected  using  a  dynamic  bioclimate  envelope  model (Cheung et al., 2008b, 2009) while primary production is projected by empirical models (Behrenfeld & Falkowski, 1997; Carr, 2002; Marra et al., 2003; Sarmiento et  al.,  2004).  Coupling  these  data  with  an  empirical model (Cheung et al., 2008a) allows us to project future changes in catch potential.

The Cheung et al. 2009 piece provides further details on the model:

Preference  profiles  were  calculated  by  overlaying environmental  data  (from  1980  to  2000)  with maps  of  relative  abundance  of  the  species  on  a 30¢ · 30¢   grid   (Fig. 1).   We   assume   that   the predicted current  distributions  realistically  depict the   environmental   condition   preferred   by   the species.   Thus,   the   degree   of   preference   and association to  the  environmental  condition  was represented   by   the   relative   abundance   of   the species   over   the   habitat   with   such   condition, including  sea  surface  and  bottom  temperature, coastal  upwelling,  salinity,  distance  from  sea-ice and  habitat  types  (coral  reef,  estuaries  and  sea-mounts).

With Reg Watson and Daniel Pauly part of the et al., I’m reminded of other global distribution models that are also used in a rather frank lack of transparency.  For example, see here.  I would much prefer the UBC mafia to open up a bit.  I think only worsened the divide in the fisheries community.

Anyway, here is a nice graphic depicting the changes at a CO2 concentration of 720pp in 2100, something we are well on our way to hitting:

Not a bad deal if you live in Norway...

 


William L. Cheung, Vicky W.Y. Lam, Jorge L. Sarmiento, Kelly Kearney, Reg Watson, Dirk Zeller, & Daniel Pauly (2010). Large-scale redistribution of maximum fisheries catch potential in the global ocean under climate change Global Change Biology, 16, 24-35 : 10.1111/j.1365-2486.2009.01995.x

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