| Abstract |
The structure of an intense deep scattering layer off the southwest coast of Baja California, Mexico, is described using Isaacs-Kidd net trawl samples, Bongo samples and hydroacoustic records. Results demonstrate the dominance of three organisms: an euphausiid, Euphausia eximia Hansen 1911, a decapod of the family Galatheidae, Pleuroncodes planipes (Stimpson, 1860); and a fish of the family Photichthyidae, Vinciguerria lucetia (Carman, 1899). Using a SIMRAD EY-200 echosounder, with a working frequency of 200 kWz, and a Hydro Acoustic Data Acquisition System (HADAS), echoes were separated according to their target strength. Euphausiids were associated with the -56 to -62 dB target strength group, the red crabs with the -51 to -55 dB group, and fishes with the -32 to -50 dB group. Results indicate that organisms within the layer were not randomly distributed, but that they have an internal structure both in a horizontal and vertical dimension. |
Robinson, C.J., J. Gomez, and V. Arenas (1997) On the structure of a deep scattering layer on the coastal shelf off Bahia Magdalena, Baja California, Mexico. Ciencias Marinas 23(1): 141–154. 