Sprat

The European Sprat (Sprattus sprattus) is a small, abundant member of the herring family found throughout coastal waters of the northeastern Atlantic, the North Sea, Baltic Sea, and Mediterranean. Closely resembling a young herring, it is one of the most numerous forage fish in European seas, forming enormous schools that support a major commercial fishery and sustain populations of larger predatory fish, seabirds, and marine mammals. Sprats are short-lived, fast-growing, and highly productive, with populations fluctuating in response to environmental conditions and predator abundance. Distinct regional subpopulations exist, including a distinct Baltic form, reflecting the species' adaptability across varied salinity and temperature regimes.

Sprats are small, slender, silvery fish easily confused with juvenile herring or sardines at a glance.

• Single dorsal fin positioned roughly at the midpoint of the back, slightly forward of the pelvic fins
• Sharp, saw-toothed keel of scutes along the entire belly, more pronounced than in juvenile herring
• Deeply forked tail and a blue-green iridescent back fading to bright silver flanks
• Typical adult length 10-16 cm
• Distinguished from herring by the belly keel extending further forward and a shorter overall body

Sprats inhabit shallow coastal and shelf waters of the northeastern Atlantic, North Sea, Baltic Sea, and Mediterranean, typically at depths from the surface to around 100 meters. They tolerate a broad range of salinities, thriving in fully marine as well as brackish Baltic waters, and often move closer inshore and to shallower depths at night. Preferred habitat includes open water over the continental shelf where dense plankton blooms provide abundant food. Seasonal movements track water temperature and prey availability, with schools often concentrating near estuaries and bays during warmer months.

Sprats form dense, fast-moving schools that filter zooplankton, including copepods and fish larvae, from the water column using closely spaced gill rakers. Schooling behavior provides protection from numerous predators, including larger fish, seabirds, and marine mammals that rely heavily on sprats as a food source. Spawning occurs over an extended season, typically spring through summer, with females releasing buoyant pelagic eggs that drift with currents until hatching. Sprats grow quickly and mature within one to two years, with short average lifespans reflecting their role as a fast-turnover forage species. Population sizes fluctuate significantly, making them a key indicator of broader marine ecosystem health.