The by-catch of witch flounder (Glyptocephalus cynoglossus) was studied in the
Spanish deep-sea fishery for Greenland halibut, which developed in the NAFO Regulatory
Area in Div. 3LMNO over the period 1991–94. A total of 32 483 hauls were sampled.
Some data from the Div. 3NO Spanish bottom trawl survey in 1995 and 1996 were also
included in this study. Witch flounder yield was estimated for this period. The yield showed
an annual seasonality where yield was greater in spring. Through the period 1992–96, the
overall annual yield showed a general increase.
The length frequency and the length/weight relationship were obtained from samplings
performed at depths ranging from 800 m to 1500 m. The length range of the individuals
was 26–60 cm in males and 22–72 cm in females. The mean length decreased throughout
the period analyzed, and was higher in the large vessel catches. The individuals were also
larger in Div. 3M. The sex ratio showed seasonal variation in the large vessel catches,
while no clear trend appeared in the small vessels.
In addition to Greenland halibut, which was the target species, the main fish species
accompanying the witch flounder catches were redfish, grenadiers, skate and American
plaice as incidental catch