Pelagic fishes: Sprat (Sprattus sprattus)

 

The most important pelagic fish in the Baltic Sea fisheries are herring and sprat. Their distribution varies with season, food availability, hydrography etc., but in general the concentrations of the clupeids are largest in the zone of intense mixing of the homo- and heterohaline layers.

 

Baltic sprat do not form separate populations to the same extent as herring. The sprat are not as closely connected with the coast as the herring and they mix more easily, especially in the wintering period and during spawning time in the open sea.

 

The spawning area of sprat is determined by salinity and temperature. The pelagic eggs are spawned in the open sea or near the coastal slopes of basins at salinities down to 5 psu and temperatures around 5 to 12 ^o C.

 

The main food of the sprat is plankton and benthos. Depending on the seasonal and spatial composition as well as the abundance of species, the diets may differ. Cod eggs as well as sprat eggs (cannibalism) are part of the sprat diet during spawning.

 

State of sprat in Subdivisions 22-29+32

 

Sprat is assessed as one stock (Subdivisions 22-29+32) and an analytical assessment is available based on landing statistics and survey data. The scientific parameters used to evaluate the biological status of the stocks include the spawning stock, recruitment , fishing mortality and species interactions.

 

The fishing mortality this stock can sustain depends on the natural mortality, which is linked to the abundance of cod. At present the sprat spawning stock biomass is well above the long term average due to strong recruitment and low predation. Under these conditions the stock can sustain a high fishing mortality, but as the cod stock recovers a much lower exploitation on sprat is implied.

 

Management of sprat fishery

 

Sprat catches are mainly taken by pelagic trawling (both single- and pairtrawls) and mainly used for industrial purposes in EU and for human consumption in Eastern Baltic Countries.

 

IBSFC manages Sprat as one stock. Annual TACs are set at a higher level than expected catches. This allows for higher catch quota to certain Contracting Parties who fully utilise their quota without altering traditional allocation keys between Contracting Parties.

 

IBSFC in 2000 adopted the Resolution on the Long Term Management Strategy for the Sprat Stock in the Baltic Sea with the goal to maintain a level of Spawning Stock Biomass greater than 200 000 tonnes. In order to protect the Sprat stock IBSFC has reduced the TAC from 1998 (550 000 tonnes) to 2001 (355 000 tonnes) by 30%.