Changes in the timing of otolith zone formation in North Sea cod from otolith records: an early indicator of climate-induced temperature stress?
Millner, R.S.; Pilling, G.M.; McCully, S.R.; Hoie, H. (2011). Changes in the timing of otolith zone formation in North Sea cod from otolith records: an early indicator of climate-induced temperature stress? Mar. Biol. (Berl.) 158(1): 21-30. http://dx.doi.org/10.1007/s00227-010-1539-9
In: Marine Biology: International Journal on Life in Oceans and Coastal Waters. Springer: Heidelberg; Berlin. ISSN 0025-3162; e-ISSN 1432-1793, more
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| Authors | | Top |
- Millner, R.S.
- Pilling, G.M.
- McCully, S.R.
- Hoie, H.
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| Abstract |
We examine the seasonal variation in otolith increment formation in southern North Sea cod as a means of monitoring how changes in sea temperature over the past 20 years have affected cod in the wild. Seasonal opaque zone formation was related to winter and early spring. Timing of opaque zone formation was not influenced by either temperature or fish length, but increasing age led to slightly earlier but slower opaque zone formation. In contrast, there was a clear shift in the timing of translucent zone formation with temperature. In warm years, translucent growth occurs up to 22 days earlier than in colder periods. Increasing age and smaller size-at-age resulted in an earlier transition from opaque to translucent edge formation. Translucent zone formation appears indicative of increasing metabolic stress, and the earlier onset provides direct evidence of the impact of increasing sea temperatures on wild North Sea cod stocks. |
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