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

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 northeastern 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 satellitebased 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 largescale 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 Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 317: [225][226][227][228][229][230][231][232][233][234][235][236] 2006 throughout the larval and early juvenile stages of sprat . Because survival in the field is often coupled with growth (Houde 1989), a better understanding of the processes that influence growth patterns in larval and juvenile Baltic sprat is desirable. However, an inherent limitation of growth studies on larvae and early juveniles is that 'average' patterns do not reflect the small fraction of individuals that will eventually emerge as survivors of these stages (Sharp 1987). It is thus meaningful to obtain samples from successful sprat recruits and investigate their growth histories, which can later be compared to individuals sampled earlier from the population.Growth histories of sprat survivors are best inferred from otolith microstructure analysis of newly recruited, young-of-the-year (YoY) or 0-group sprat because, until their first winter, sprat are known to form readily discernible, daily increments that correspond in width to daily somatic growth rates and allow a direct backcalculation until the day of first feeding (DFF) (Baumann et al. in press). In sprat, DFFs comprise the best available proxy for hatch date, beca...

The fate of eggs and larvae of three pelagic species, mackerel (<i>Scomber scombrus</i>), horse mackerel (<i>Trachurus trachurus</i>) and sardine (<i>Sardina pilchardus</i>) in relation to prevailing currents in the Bay of Biscay: Could they affect larval survival?

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Physiologically based limits to food consumption, and individual-based modeling of foraging and growth of larval fishes

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Recruitment variability in Baltic Sea sprat (Sprattus sprattus) is tightly coupled to temperature and transport patterns affecting the larval and early juvenile stages

“…The authors presented evidence that the late larval stages critically relied on the abundance of larger copepodites and adult copepods, which were scarce in April-May but significantly more abundant in June-July 2002. In addition, Baumann et al (2006a) inferred distributions of days-of-first-feeding (DFF, a proxy for hatch date) from otolith microstructure analyses in newly recruited 0-group sprat caught in October 2002 in the Baltic Sea. Depending on the Baltic region, DFF distributions of sprat survivors peaked between the end of June and mid-July 2002, which is consistent with the present conclusion.…”