MEPS 317:225-236 (2006)  -  doi:10.3354/meps317225

Temperature-induced regional and temporal growth differences in Baltic young-of-the-year sprat Sprattus sprattus

Hannes Baumann1,*, Tomas Gröhsler2, Georgs Kornilovs3, Andrej Makarchouk3, Valerie Feldmann4, Axel Temming1

1Institute of Hydrobiology and Fisheries Science, Olbersweg 24, 22767 Hamburg, Germany
2Institute for Baltic Sea Fisheries Rostock (IOR), An der Jaegerbaek 2,18069 Rostock, Germany
3Latvian Fish Resources Agency, Daugavgrivas Street 8, Riga 1007, Latvia
4Atlantic Research Institute of Marine Fisheries and Oceanography (AtlantNIRO), 5, Dmitry Donskoy Street, 236000 Kaliningrad, Russia

ABSTRACT: We examined spatial and temporal differences in growth patterns of young-of-the-year (YoY) sprat Sprattus sprattus synchronously sampled in October 2002 from 4 different regions of the Baltic Sea (western, central, eastern, northeastern Baltic). The microstructure of the sagittal otoliths of 427 individuals from 64 sampling sites were analysed to determine the day of first feeding (DFF) and the growth history of YoY survivors. DFF distributions differed markedly between Baltic areas, with a shift to later mean DFFs and narrower distributions from west to northeast. This was consistent with the shift in mean seasonal spawning effort of Baltic sprat, derived from long-term observations (1973 to 2002) of sprat egg abundance in these areas. Otolith growth trajectories (i.e. increment width-at-age) had a characteristic shape related to sampling area and, more importantly, to the time of the year at which the individual started feeding (DFF). During the larval stage, individuals from the north-eastern area and those born later in the year had higher growth rates than their earlier born conspecifics, while the pattern was reversed during the juvenile stage. Weekly means of satellite-based sea-surface temperature were used to approximate the potential temperature history of YoY survivors, which significantly influenced the shape of the otolith growth trajectory. We conclude that different DFFs and therefore different temperature histories were primarily responsible for the large-scale spatial growth variability between newly recruited Baltic YoY sprat in 2002.

KEY WORDS: Young-of-the-year sprat · Otolith microstructure analysis · Satellite data · Sea-surface temperature · Growth patterns · Day of first feeding · Egg abundance

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