• Subscribe • Archives • For Authors • About IJRA • Links • Partners • Contact Us
 

Nutrient Retention by Fish in a Multispecies Recirculating Aquaculture Facility

R.C. Summerfelt, and C. R. Penne

Footnote
International Journal of Recirculating Aquaculture 8 (2007). All Rights Reserved
© Copyright 2006 by Virginia Tech and Virginia Sea Grant, Blacksburg, VA USA

ABSTRACT

Nutrient (N and P) content of the dry weight gain of fish relative to N and P content of the dry weight of feed was used to determine nutrient retention in a commercial recirculating aquaculture facility.  The culture system had five 39.2m3 dual-drain culture tanks, one tank each with largemouth bass (Micropterus salmoides), hybrid striped bass (aka sunshine bass, Morone chrysops  x Morone saxatilis ), and rainbow trout (Oncorhyncus mykiss), and two tanks with walleye (Sander vitreus).  On the first day, most rainbow trout (643 g) and walleye (497 g and 398 g) were market size whereas the largemouth bass (73 g) and hybrid striped bass (96 g) were fingerlings.  Measured for a 56-d interval, the range in nutrient retention was 12.0 to 44.1% for N 14.8 to 53.8% for P.  Market-size rainbow trout had the slowest growth and correspondingly low levels of nutrient retention; likewise, the larger walleye had nearly half the retention rates of the smaller walleye.  Highly significant (P ≤ 0.01) positive correlations occurred between retention of N and P, protein efficiency ratio, and net protein utilization, but inversely related to food conversion ratio.  Total ammonia nitrogen (g kg-1 feed fed) in the culture tank was inversely related to nitrogen retention.  Values for TAN production ranged from 2.9 to 6.9% of daily feeding rate, important information for sizing biofilter requirements.  This study demonstrated an interaction between fish age or size, growth rates, temperature, feeding rates, nutrient content, and protein retention.

IJRA Home