Title: Probable discards of cod in the Barent sea and adjacent waters during Russian bottom trawl fishery

Unaccounted discarding of small-sized fish is an important and acute problem in many fisheries because it affects the condition of stocks and reduces the reliability of fishery statistics. Such discards are regarded as a threat to intensively exploited species, such as the North-East Arctic cod (Gadus morhua morhua L.) which inhabits the Barents Sea and adjacent waters. In the present study an attempt is made to estimate of the quantity of small-sized cod discarded in the Russian bottom trawl fishery in 1996-2001. This work is based on cod length measurements onboard Russian commercial vessels in the period 1996-2001 and distributional features, such as density and size composition inferred from catch statistics.

The calculated annual discards of small cod were estimated to be in the range of 3-80 million individuals. Discards appeared to be highest in 1998 and lowest in 1996 and 2001. This was found to be related to the abundance of cod recruits and the portion of total catch taken in the Eastern-Central part of the Barents Sea. The features of spatial and seasonal distribution of small-sized cod, the depth and duration of trawling and catch of cod influence the catch of small cod per unit of effort and, as a consequence, discards of such fish.