Scientific Hatcheries
Huntington Beach, Ca
Bottom Trawling
Bottom trawling is a fishing method that drags a net and other equipment along the ocean bottom to catch fish, shrimp, and other marine life. As this fishing method will effective catch everything that is large enough to get caught in the net, the ratio of by-catch, that is pure waste and usually discarded, to useful product may run about 10 lb. of bycatch per lb. of product.
Along with effectively clear-cutting the ocean bottom, this mobile fishing gear also stirs up the sediments on the bottom. The magnitude of the suspended solids pollution and associated turbidity created by this fishing method makes bottom trawling the largest source of man made pollution in the coastal environment. This suspended solids pollution from mobile fishing gear can then move with the currents and create environmental impacts remote from the site of the actual trawling.
A study of these remote impacts on giant Kelp forests is available as a word document (Notes: On Remote Impacts of Soft Bottom Trawling on Kelp Forests). This document is an evolving document in that readers can make changes, addition and comments and then send the market up version back to Dallas Weaver. These changes may or may not be incorporated into an updated version of the document.
The above document is based upon the calculations and model that is contained in an excel file (Bottom_Trawling.xls). This is a rather simple model with the variables, such as trawling speed, that the user can change being in yellow. The user is welcome to play with the model and see what happens with his local assumptions. If someone whants to add vertical dispersion or a better horizonal dispersion to the model, feel free and send me the results.
For United Anglers of Southern California whom funded the above studies, click below
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