The structure and spatial distribution of pelagic fish schools in multispecies clusters: an acoustic study

A temporary sign pole installation is disclosed which includes a hollow passage in a vertical pipe having a pointed bottom end. Vertical slots in the side of the hollow passage permit a handle to pass through the slots and into and/or through a pounder weight which can be moved up and down in the hollow core of the pipe. For the installation the pounder weight is moved by the handle emphatically downwards hitting the end of the vertical slot to pound the pipe into the ground. For removal of the pipe, the pounder handle constrained by the limits of the vertical slot is moved emphatically upward and drives the vertical pipe out of the ground. Various horizontal attachment pieces can be attached to the top of the vertical pipe to support an advertising sign or the like.

[1]  Werner Stuetzle,et al.  Relating the distribution of pollock schools in the Bering Sea to environmental factors , 1994 .

[2]  Pierre Freon,et al.  La variabilité des tailles individuelles à l'intérieur des cohortes et des bancs de poissons I : Observations et interprétation , 1984 .

[3]  K. Lindström,et al.  Size matters when three-spined sticklebacks go to school , 1992, Animal Behaviour.

[4]  T. Pitcher.  Behaviour of Teleost Fishes , 1986 .

[5]  O. Nakken,et al.  Target strength measurements of fish , 1977 .

[6]  Pierre Fréon,et al.  Changes in school structure according to external stimuli: description and influence on acoustic assessment , 1992 .

[7]  Jacques Masse,et al.  Acoustic detection of the spatial and temporal distribution of fish shoals in the Bay of Biscay , 1993 .

[8]  Pierre Petitgas,et al.  Precision of acoustic fish abundance estimates: separating the number of schools from the biomass in the schools , 1993 .

[9]  Ole Arve Misund,et al.  Swimming behaviour of fish schools in the North Sea during acoustic surveying and pelagic trawl sampling , 1992 .

[10]  J. M. Coudeville,et al.  INES MOVIES : A NEW ACOUSTIC DATA ACQUISITION AND PROCESSING SYSTEM , 1990 .

[11]  Kenneth G. Foote,et al.  Effect of fish behaviour on echo energy: the need for measurements of orientation distributions , 1980 .

[12]  Robert J. Wootton,et al.  Ecology of Teleost Fishes , 1989, Springer Netherlands.

[13]  W. C. Leggett,et al.  Hydroacoustic Signal Classification of Fish Schools by Species , 1988 .