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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF SUSTAINABLE LAND-BASED AQUACULTURE SYSTEMS Title: Minimizing noise in fiberglass aquaculture tanks: Noise reduction potential of various retrofits

Authors
item Davidson, John - FRESHWATER INSTITUTE
item Frankel, Adam - MARINE ACOUSTICS, INC.
item Ellison, William - MARINE ACOUSTICS, INC.
item Summerfelt, Steven - FRESHWATER INSTITUTE
item Popper, Arthur - UNIVERSITY OF MARYLAND
item Mazik, Patricia - WEST VIRGINIA UNIVERSITY
item Bebak, Julie

Submitted to: Aquacultural Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 29, 2007
Publication Date: July 14, 2007
Citation: Davidson, J., Frankel, A., Ellison, W., Summerfelt, S., Popper, A.N., Mazik, P., Bebak, J.A. 2007. Minimizing noise in fiberglass aquaculture tanks: Noise reduction potential of various retrofits. Aquacultural Engineering. 37:125-131.

Interpretive Summary: Intensive aquaculture systems utilize noisy equipment such as pumps and blowers that produce underwater sound levels and frequencies within the range of fish hearing. The impacts of culture tank noise on fish are not well known, but limited research suggests that subjecting fish to noise could result in impairment of the auditory system, reduced growth rates, and increased stress. Consequently, reducing sound in fish tanks could result in advantages for cultured species and the aquaculture industry. The objective of this study was to evaluate the noise reduction potential of various retrofits to fiberglass fish culture tanks. Ten round fiberglass tanks (1.5 m3) were used in this study. Three potential avenues of sound transmission to the tanks were identified: the PVC inlet piping, effluent piping, and the gravel substrate. The following structural changes were applied to tanks to reduce underwater noise: 1) inlet piping was suspended to avoid contact with the tank, 2) effluent piping was disconnected from a common drain line, 3) effluent piping was insulated beneath tanks, and 4) tanks were elevated on cement blocks and seated on insulated padding. Four combinations of the aforementioned structural changes were evaluated in duplicate and two tanks were left unchanged as controls. Unchanged control tanks had sound levels of 120 dB re 1 µPa RMS. Each retrofit contributed to a reduction of underwater sound. As structural changes were combined, a cumulative reduction in sound level was observed. Tanks designed with a combination of retrofits had sound levels of 109 dB re 1 µPa RMS, a four-fold reduction in sound pressure level. Sound frequency spectra indicated that the greatest sound reductions occurred between 2-200 Hz and demonstrated that nearby pumps and blowers created tonal frequencies that were transmitted into the tanks. The tank modifications used during this study were simple and could be inexpensively incorporated within existing systems or considered in the design of new aquaculture facilities.

Technical Abstract: Equipment used in intensive aquaculture systems, such as pumps and blowers can produce underwater sound levels and frequencies within the range of fish hearing. The impacts of underwater noise on fish are not well known, but limited research suggests that subjecting fish to noise could result in impairment of the auditory system, reduced growth rates, and increased stress. Consequently, reducing sound in fish tanks could result in advantages for cultured species and increased productivity for the aquaculture industry. The objective of this study was to evaluate the noise reduction potential of various retrofits to fiberglass fish culture tanks. The following structural changes were applied to tanks to reduce underwater noise: 1) inlet piping was suspended to avoid contact with the tank, 2) effluent piping was disconnected from a common drain line, 3) effluent piping was insulated beneath tanks, and 4) tanks were elevated on cement blocks and seated on insulated padding. Four combinations of the aforementioned structural changes were evaluated in duplicate and two tanks were left unchanged as controls. Control tanks had sound levels of 120.6 dB re 1 µPa. Each retrofit contributed to a reduction of underwater sound. As structural changes were combined, a cumulative reduction in sound level was observed. Tanks designed with a combination of retrofits had sound levels of 108.6 dB re 1 µPa, a four-fold reduction in sound pressure level. Sound frequency spectra indicated that the greatest sound reductions occurred between 2-200 Hz and demonstrated that nearby pumps and blowers created tonal frequencies that were transmitted into the tanks. The tank modifications used during this study were simple and inexpensive and could be applied to existing systems or considered when designing aquaculture facilities.

Last Modified: 10/23/2014
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