Definition of "demersal"

Unlike the more demersal (bottom-dwelling) cod, pollock will pursue schools of small fishes at any depth, occasionally driving them to the surface of the water where frantic splashing can be seen as the prey attempt to escape.

1991, Michael R. Ross, Recreational Fisheries of Coastal New England‎, page 156

The young tend to occupy a pelagic habitat, but shift to a more demersal lifestyle with maturity.

2003, David A. Ebert, Sharks, Rays, and Chimaeras of California‎, page 64

At a certain age, however, the Cape horse mackerel in the northern Benguela tend to adopt a more demersal lifestyle, thus entering into the bottom dead zone.

2004, Bjørn Erik Axelsen, Jens-Otto Krakstad, Graça Bauleth-D'Almeida, “7: Aggregation dynamics and behaviour of the Cape horse mackerel (Trahurus trachurus capensis) in the northern Benguela - implications for acoustic abundance estimation”, in Ussif Rashid Sumaila, editor, Namibia's Fisheries: Ecological, Economic, And Social Aspects, page 149