Marine species of commercial interest
Global ocean warming is causing marine species to move northwards in terms of depth and phenology. This indicator includes the egg-laying distribution and phenology of two marine species of commercial interest in the Bay of Biscay: mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus).
- Ocean warming has caused changes in the abundance, distribution, phenology and reduction in size of numerous marine species over the last few decades.
- In years when the north-east Atlantic sea temperature is warmer, the mackerel spawning season moves slightly forward, while the mackerel move slightly northwards.
Relationship of the indicator to climate change
Global ocean warming is causing shifts of marine species northwards in terms of depth, phenology (Poloczanska et al., 2013) and in particular marine fishes (Cheung et al., 2013, Perry et al., 2005). The egg-laying distribution of the north-eastern mackerel stock has shifted northwards over the last three decades, probably in response to global warming of the sea in that area (Hughes et al., 2014; Bruge et al. 2016).
The abundance of eggs
Maps showing the abundance of eggs for both species over the years can be seen in Figures 2 and 3. Statistical analysis of the relationships between distribution and phenology with inter-annual sea temperature show different responses to warming. In years when sea temperatures are warmer, mackerel move their spawning season forward by about 12 days per degree of warming, while the mackerel's range and distribution moves about 370 km northwards per degree of warming (Chust et al., 2023).
Figure 2. Time series of the spatial distribution of mackerel egg abundance (eggs/m2) in the north-east Atlantic.
Figure 3. Time series of the spatial distribution of cicada egg abundance (eggs/m2) in the north-east Atlantic.
Appearance of the eggs of mackerel (left) and horse mackerel (right) as identified in the plankton samples.
The data were compiled from the oceanographic campaigns on mackerel and horse mackerel eggs that have been carried out every 3 years since 1992 in north-east Atlantic waters. The campaigns start in January/February and run until July. The detailed sampling methodology can be found in the ICES (2019).
The study of trends over the years in terms of latitudinal distribution and the timing of egg-laying throughout the year includes: 1) an analysis in relation to sea temperature and 2) processing of the data observed to standardise them over the years in order to avoid biases arising from irregular sampling in space and time.
Bruge, A., P. Alvarez, A. Fontán, U. Cotano, and G. Chust. 2016. Thermal Niche Tracking and Future Distribution of Atlantic Mackerel Spawning in response to Ocean Warming. Frontiers in Marine Science 3:86.
Cheung, W. W. L., R. Watson, and D. Pauly. 2013. Signature of ocean warming in global fisheries catch. Nature 497:365-368.
Chust, G., F. G. Taboada, P. Alvarez, and L. Ibaibarriaga. 2023. Species acclimatization pathways: Latitudinal shifts and timing adjustments to track ocean warming. Ecological Indicators 146:109752.
Hughes, K., L. Dransfeld, and M. Johnson. 2014. Changes in the spatial distribution of spawning activity by north-east Atlantic mackerel in warming seas: 1977–2010. Marine Biology 161:2563-2576.
ICES, 2019. Manual for mackerel and horse mackerel egg surveys, sampling at sea. Of ICES Survey Protocols SISP 6. 82 pp. http://doi.org/10.17895/ices.pub.5140.
Perry, A. L., P. J. Low, J. R. Ellis, and J. D. Reynolds. 2005. Climate Change and Distribution Shifts in Marine Fishes. Science 308:1912-1915.
Poloczanska, E. S., C. J. Brown, W. J. Sydeman, W. Kiessling, D. S. Schoeman, P. J. Moore, K. Brander, J. F. Bruno, L. B. Buckley, M. T. Burrows, C. M. Duarte, B. S. Halpern, J. Holding, C. V. Kappel, M. I. O’Connor, J. M. Pandolfi, C. Parmesan, F. Schwing, S. A. Thompson, and A. J. Richardson. 2013. Global imprint of climate change on marine life. Nature Climate Change 3:919-925.
Bay of Biscay
Mackerel (chicharro):spawning season 12 days before
Per each ºC of sea tempertature increase
Mackerel (Verdel): movement of 370 km northwards
Per each ºC of sea tempertature increase