Effects of stocking density on production traits of channel catfish Ictalurus punctatus x blue catfish Ictalurus furcatus hybrids

Authors: Bosworth, Brian; Ott, Brian; Torrans, Eugene

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2015
Publication Date: 8/7/2015
Citation: Bosworth, B.G., Ott, B.D., Torrans, E.L. 2015. Effects of stocking density on production traits of channel catfish Ictalurus punctatus x blue catfish Ictalurus furcatus hybrids. North American Journal of Aquaculture. 77:437-443.

Interpretive Summary: Stocking density is an important consideration for catfish farmers because it influences production and economics. Past research has focused on effects of stocking density on channel catfish production, but little information is available on the effects of stocking density on production traits of channel catfish x blue catfish hybrids. Hybrids are becoming increasing popular with farmers and therefore information specific for hybrid management is important. In this study, hybrid catfish fingerlings were stocked at 3,000; 5,000; 7,000; 9,000 and 11,000 head/acre to determine the effects of stocking density on production traits. There were no differences in survival, feed conversion ratio, or processing yield at any density. Average harvest weight and percent of sub-marketable size fish (<1 lb) were not different from 3,000 through 9,000 head/acre (overall averages 1.9 lbs and 2.3%, respectively) but fish were smaller (1.5 lbs) and there were more were sub-marketable (8.9%) at 11,000 head/acre. Hours of aeration increased and minimum oxygen levels decreased as stocking density increased. Past research has demonstrated a ‘threshold’ relationship between minimum dissolved oxygen levels and catfish feeding and growth. The data from this study (no density effect from 3,000 through 9,000 head/acre, with a decline at 11,000 head/acre) suggest that the observed effect of density on growth was at least partially due to minimum oxygen levels being below levels needed to maintain optimal growth at 11,000 head/acre.

Technical Abstract: Channel catfish (Ictalurus punctatus) x blue catfish (I. furcatus) hybrid fingerlings were stocked in 0.4 ha ponds in April at densities of 7,410; 12,350; 17,290; 22,230; and 27,170 head/ha in 3 replicate earthen ponds per density. Fish were fed to apparent satiation once daily with a 28% protein floating pellet. Ponds were equipped with electric paddle wheel aerators which were turned on at dissolved oxygen (DO) levels < 5.0 ppm and additional aeration was provided by PTO-driven paddlewheels at DO < 2.5 ppm. Feeding was terminated at the end of October and fish were harvested and weighed. Stocking density had no effect on feed conversion (overall average 1.97); survival (> 93% in all treatments); or processing yield (carcass yield = 66.2%, fillet yield = 34.8%, nugget yield = 10.5%). Average harvest weight was not different between 7,410 and 22,230 head/ha (average 0.87 kg) but was smaller at 27,170 head/ha (0.70 kg). Net production increased with increased density from 7,410 to 22,230 head/ha but was not different between 22,230 and 27,170 head/ha. The percentage of sub-marketable fish (< 0.45 kg) was not different from 7,410 through 22,230 head/ha (average 2.3%), but was higher at 27,170 head/ha (8.9%). Hours of aeration increased and minimum oxygen levels decreased as stocking density increased. Past research has demonstrated a ‘threshold’ relationship between minimum dissolved oxygen levels and catfish feeding and growth. The data from this study (no density effect from 7,410 through 22,230 head/ha, with a decline at 27,170 head/ha) suggest that the observed effect of density on growth was at least partially due to minimum oxygen levels being below levels needed to maintain optimal growth at 27,170 head/ha.