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Measurement of organic loading under an open‐ocean aquaculture cage, using sediment traps on the bottom
Author(s) -
Rapp P.,
Ramírez W. R.,
Rivera J. A.,
Carlo M.,
Luciano R.
Publication year - 2007
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1111/j.1439-0426.2007.00900.x
Subject(s) - cage , biological dispersal , benthic zone , aquaculture , biology , sediment , sink (geography) , fishery , mooring , gill , oceanography , fish <actinopterygii> , geology , paleontology , population , demography , mathematics , cartography , combinatorics , sociology , geography
Summary Organic loading under a submerged fish cage in commercial operation has been quantified for the first time in the open ocean. Sediment traps out to 100 m sampled the loading continuously over the 15 months of a complete grow‐out cycle for cobia ( Rachycentron canadum ). Typically 4% or 5% of the feed arrived directly to the sediment, although this benthic percentage became much higher in the last two months of this study. Almost all the loading (90%) lands within 30 m of the cage mooring block. The loading consists of fragments of feed pellets that wash out from the mouths and gills of the fish. The fragments sink rapidly and almost vertically; they are not carried horizontally into large dilution volumes. Dispersal on the sediment surface is much more extensive than dispersal in the water. This study developed expeditious and cost‐effective techniques for sampling and analyzing organic loading, using a minimum of technological resources.