The effects of aquaculture production noise on the growth, condition factor, feed conversion, and survival of rainbow trout, Oncorhynchus mykiss

Intensive aquaculture systems, particularly recirculating systems, utilize equipment such as aerators, air and water pumps, blowers, and filtration systems that inadvertently increase noise levels in fish culture tanks. Sound levels and frequencies measured within intensive aquaculture systems are within the range of fish hearing, but species-specific effects of aquaculture production noise are not well defined. Field and laboratory studies have shown that fish behavior and physiology can be negatively impacted by intense sound. Therefore, chronic exposure to aquaculture production noise could cause increased stress, reduced growth rates and feed conversion efficiency, and decreased survival. The objective of this study was to provide an in-depth evaluation of the long term effects of aquaculture production noise on the growth, condition factor, feed conversion efficiency, and survival of cultured rainbow trout, Oncorhynchus mykiss. Rainbow trout were cultured in replicated tanks using two sound treatments: 117 dB re 1 mu Pa RMS which represented sound levels lower than those recorded in an intensive recycle system and 149 dB re 1 mu Pa RMS, representing sound levels near the upper limits known to occur in recycle systems. To begin the study mean fish weights in the 117 and 149 dB tanks were 40 and 39 g, respectively. After five months of exposure no significant differences were identified between treatments for mean weight, length, specific growth rates, condition factor, feed conversion, or survival (n=4). Mean final weights for the 117 and 149 dB treatments were 641 3 and 631 10 g, respectively. Overall specific growth rates were equal, i.e. 1.84 +/- 0.00 and 1.84 +/- 0.01%/day. Analysis of growth rates of individually tagged rainbow trout indicated that fish from the 149 dB tanks grew slower during the first month of noise exposure (p<0.05); however, fish acclimated to the noise thereafter. This study further suggests that rainbow trout growth and survival are unlikely to be affected over the long term by noise levels common to intensive aquaculture systems. (C) 2008 Elsevier B.V. All rights reserved.