Climate and population density drive changes in cod body size throughout a century on the Norwegian coast.
Understanding how populations respond to changes in climate requires long-term, high-quality datasets, which are rare for marine systems. We estimated the effects of climate warming on cod lengths and length variability using a unique 91-y time series of more than 100,000 individual juvenile cod lengths from surveys that began in 1919 along the Norwegian Skagerrak coast. Using linear mixed-effects models, we accounted for spatial population structure and the nested structure of the survey data to reveal opposite effects of spring and summer warming on juvenile cod lengths. Warm summer temperatures in the coastal Skagerrak have limited juvenile growth. In contrast, warmer springs have resulted in larger juvenile cod, with less variation in lengths within a cohort, possibly because of a temperature-driven contraction in the spring spawning period. A density-dependent reduction in length was evident only at the highest population densities in the time series, which have rarely been observed in the last decade. If temperatures rise because of global warming, nonlinearities in the opposing temperature effects suggest that negative effects of warmer summers will increasingly outweigh positive effects of warmer springs, and the coastal Skagerrak will become ill-suited for Atlantic cod.
School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USA. larogers@u.washington.edu
Lauren A
LA
Rogers
Leif C
LC
Stige
Esben M
EM
Olsen
Halvor
H
Knutsen
Kung-Sik
KS
Chan
Nils Chr
NC
Stenseth
D000818:Animals; D049628:Body Size; D002980:Climate; D048389:Gadus morhua; D009664:Norway; D011156:Population Density
Proc Biol Sci. 2007 Apr 22;274(1613):1015-22
17264058
Mol Ecol. 2003 Feb;12(2):385-94
12535089
Evol Appl. 2008 Aug;1(3):524-33
25567733
Biol Lett. 2008 Dec 23;4(6):693-5
18782730
Nature. 2003 Dec 11;426(6967):661-4
14668864
Proc Natl Acad Sci U S A. 2007 Dec 11;104(50):19709-14
18077405
Science. 1995 Aug 4;269(5224):676-9
17758812
Proc Biol Sci. 2009 Dec 7;276(1676):4163-71
19740875
Nature. 2010 Jun 3;465(7298):609-12
20520713
Nature. 2002 Mar 28;416(6879):389-95
11919621
Proc Natl Acad Sci U S A. 2008 Sep 9;105(36):13492-6
18757740
Science. 2002 Apr 26;296(5568):707-11
11976447
Ecol Lett. 2009 Jul;12(7):622-31
19453620
Mol Ecol. 2011 Feb;20(4):768-83
21199035
Proc Biol Sci. 2006 May 7;273(1590):1085-92
16600885
Ecology. 2010 Oct;91(10):2918-30
21058552