Density of wintering sand eel in the sand recorded by grab catches

Buried wintering sand eel Ammodytes marinus was sampled by van Veen grab on two coastal localities off Norway, and on a fishing ground in the central North Sea. Areas with assumed suitable sandy substrate were located by interviewing fishermen, hydroacoustic observations, and grab sampling. On the two coastal localities sampled in November and January, there were no significant differences between the day and night catches of sand eel; the mean catches were 5.6 and 7.4 specimens/m 2 at the respective sites. On the North Sea locality sampled in January 1998, the mean catch rate was 60.9 specimens/m 2, and single catches of 200 specimens/m 2 occurred. When the same locality was re-sampled in January 1999, no sand eels were caught. The results suggest that spatial and temporal variation in winter density can be studied by grab sampling. The utility of the method for local studies of sand eel abundance is discussed.