Potential of invasive carp as a source of fish meal and fish oil in Channel Catfish diets

Animal protein, generally fish meal, has traditionally been used in the diet of channel catfish. However, our previous research indicates that animal protein is not needed for growing stocker-size catfish to food fish when the fish are stocked at densities typical of those used in commercial catfish culture. Whether this holds when fish are stocked at high densities is not known; thus, we conducted an experiment to evaluate the effect of feeding diets with and without fish meal to channel catfish stocked in earthen ponds at different densities. Two 32% protein-practical diets containing 0% or 6% menhaden fish meal were compared for pond-raised channel catfish, Ictalurus punctatus, stocked at densities of 14,820, 29,640, or 44,460 fish/ha. Fingerling channel catfish with average initial weight of 48 g/fish were stocked into 30 0.04-ha ponds. Five ponds were randomly allotted for each fish meal level × stocking density combination. Fish were fed once daily to satiation for two growing seasons. There was a significant interaction between stocking density and fish meal for net production; net production increased in fish fed a diet containing fish meal compared with those fed an all-plant diet at the highest stocking density, but not at the two lower stocking densities. Net production of fish fed diets with and without fish meal increased as stocking density increased. Viewing the main effect means, weight gain decreased and feed conversion ratio increased for fish stocked at the two highest densities, and survival was significantly lower at the highest stocking density. Visceral fat decreased in fish at the two highest stocking densities. Body composition data were largely unaffected by experimental treatment except for a reduction in percentage filet fat in fish at the highest stocking density, and fish that were fed diets containing fish meal had a lower percentage fillet protein and a higher percentage fillet fat. It appears that at stocking densities two to three times higher than generally used, animal protein (fish meal) may be beneficial in the diet of channel catfish. In regard to stocking densities, high stocking results in higher overall production, but the average fish size decreased as stocking density increased.

Animal protein, generally fish meal, has traditionally been used in the diet of channel catfish. However, our previous research indicates that animal protein is not needed for growing stocker-size catfish to food fish when the fish are stocked at densities typical of those used in commercial catfish culture. Whether this holds when fish are stocked at high densities is not known; thus, we conducted an experiment to evaluate the effect of feeding diets with and without fish meal to channel catfish stocked in earthen ponds at different densities. Two 32% protein practical diets containing 0% or 6% menhaden fish meal were compared for pond-raised channel catfish, Ictalurus punctatus, stocked at densities of 14,820, 29,640, or 44,460 fish/ha. Fingerling channel catfish with average initial weight of 48 g/fish were stocked into 30, 0.04 ha ponds. Five ponds were randomly allotted for each fish meal level × stocking density combination. Fish were fed once daily to satiation for two growing seasons. There was a significant interaction between stocking density and fish meal for net production; net production increased in fish fed a diet containing fish meal compared with those fed an all-plant diet at the highest stocking density, but not at the two lower stocking densities. Net production of fish fed diets with and without fish meal increased as stocking density increased. Viewing the main effect means, weight gain decreased and FCR increased for fish stocked at the two highest densities, and survival was significantly lower at the highest stocking density. Visceral fat decreased in fish at the two highest stocking densities. Body composition data were largely unaffected by experimental treatment except for a reduction in percentage of filet fat in fish at the highest stocking density, and fish that were fed diets containing fish meal had a lower percentage of fillet protein and a higher percentage of fillet fat. It appears that at stocking densities two to three times higher than generally used, animal protein (fish meal) may be beneficial in the diet of channel catfish. In regard to stocking densities, high stocking results in higher overall production, but the average fish size decreased as stocking density increases.

The Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis are two species of invasive bigheaded carp currently invading North American rivers and watersheds. Bigheaded carp were accidentally introduced into the lower Mississippi River basin in the early 1970s and have since invaded many water bodies in the Midwestern United States. Evidence of bigheaded carp reproduction and recruitment in the upper Mississippi River upstream of Lock and Dam 19 (LD19) at Keokuk, Iowa, thought to be a critical constriction point to their upstream establishment, has been limited to a few isolated detections of eggs, larvae, and juvenile life stages since 2012. Therefore, a more comprehensive assessment of bigheaded carp reproduction in this critical management zone was needed. We used quadrafoil light traps (n = 1,387) deployed during May–September 2016–2018 in Pools 17–19 of the Mississippi River to monitor for advanced larval bigheaded carp in low-velocity habitats. Throughout the sampling period, we captured 1,747 larval and 35 postlarval bigheaded carp (N = 1,782). Bigheaded carp were collected on 15 sampling events that spanned from May 31, 2016, to September 13, 2018, with associated hatch dates estimated to represent 10 unique reproductive events from May 2016 to September 2018. The individual captures and backdated hatch estimates revealed a protracted spawning period of up to seven events in 2016, one event in 2017, and two events in 2018. Bigheaded carp were only captured in Pool 19, possibly due to the drifting requirements for egg maturation and the low-velocity downstream reach of Pool 19. This research provides confirmation that bigheaded carp spawned upstream of LD19 are capable of transitioning past the yolk sac stage upstream of this bottleneck to more advanced larval stages. Knowledge of reproduction and larval retention and the field-based evidence of protracted spawning fill critical research gaps needed for the management of bigheaded carp.

Invasive carp populations have purported a negative influence on native biota at high densities. These invasive fishes (i.e., bighead carp Hypophthalmichthys nobilis, silver carp Hypophthalmichthys molitrix, grass carp Ctenopharyngodon idella, and black carp Mylopharyngodon piceus) each exhibit similar life history characteristics. In the Neosho River‐Grand Lake system (i.e., John Redmond Reservoir, Kansas, downstream to Grand Lake O’ the Cherokees, Oklahoma), only bighead carp and grass carp have been documented to date. The distribution and status of bighead carp throughout this system were previously unknown due to limited historical data and low abundance. While few bighead carp are encountered within this system, grass carp exhibited relatively higher abundance a were used to provide insights into bighead carp. Captures of both species were used to inform management and suppression efforts. Sampling locations (n = 18) were established for environmental DNA analyses throughout the Neosho River‐Grand Lake system. We sampled 13 sites using a suite of gears for standardized targeted fish sampling. All invasive carp were measured, sexed, and otoliths removed for ageing and microchemical analysis. Grass carp were processed for ploidy testing following the U.S. Fish and Wildlife Service protocol. Environmental DNA analyses generated positive results for the eDNA presence of bighead carp and silver carp. Otolith age estimates suggest fish are long lived and supported by multiple year classes. Additionally, a sampled two‐year‐old grass carp demonstrates spawning and recruitment potential. Otolith microchemistry suggests largescale broad movement patterns. Ploidy testing confirmed the first documented evidence of diploid grass carp in the Neosho River‐Grand Lake system and revealed reproductive viability. Our results may provide future insights into locations for containment, removal, and/or eradication.

Partial substitution of soybean meal with animal protein sources in diets for channel catfish

Intensive tank rearing of channel catfish (Ictalurus punctatus Rafinesque) fry can be successfully accomplished with commonly available ‘salmonid’ starter diets. Ingredient substitution in starter diets is less important from the cost perspective but growth, survival and health of fish are major concerns. Several combinations of fish meals and animal protein substitutes were evaluated in diet formulations for hatchery rearing of catfish fry. Sub-optimal thermal conditions were used which are characteristic for the north-central USA where catfish culture is important for stocking purposes and live-fish markets. A diet formulated on the basis of menhaden fish meal (29.1%), herring fish meal (25.1%) and animal by-product mixture (16.38%) gave numerically the highest growth rate after 13 weeks of feeding, although growth reductions in fish fed diets exclusively with mehaden meal (77.6%) as protein or substituted with 50% animal by-product protein were not significant. Instantaneous mortality rates were the highest between weeks 2 and 4 of rearing and increased almost proportionally with the increased fish meal protein substitution. A diet based on menhaden fish meal had the highest concentration of phosphorus and several other essential minerals, but these were not reflected in the mineral composition of the fish body at the termination of feeding. Among activities of digestive enzymes, trypsin was depressed in fish offered diets with 75–100% fish meal protein replacement. A diet superior in terms of fish performance was defined in the present study and it was concluded that the initial feeding can greatly affect physiological status of juvenile channel catfish.

Invasive carp in China's plateau lakes.

In the 1970s, the introduced silver carp Hypophthalmichthys molitrix (which is indigenous to eastern Asia) escaped from southern U.S. aquaculture to spread throughout the Mississippi River basin, and since has steadily moved northward. This large, prolific filter-feeder reduces food availability for other fishes. It now has reached the threshold of the Laurentian Great Lakes, where it likely will significantly impact food chains and fisheries. Our study evaluates population genetic variability and differentiation of the silver carp using 10 nuclear DNA microsatellite loci, and sequences of two mitochondrial genes–cytochrome b and cytochrome c oxidase subunit 1, along with the nuclear ribosomal protein S7 gene intron 1. We analyze population samples from: two primary Great Lakes’ invasion fronts (at the Illinois River outside of Chicago, IL in Lake Michigan and in the Wabash River, which leads into the Maumee River and western Lake Erie), the original establishment “core” in the Lower Mississippi River, and expansion areas in the Upper Mississippi and Missouri rivers. We analyze and compare our results with bighead and other invasive carps, and cyprinid relatives. Results reveal that the silver carp invasion possesses moderate levels of genetic diversity, with more mtDNA haplotypes and unique microsatellite alleles in the “core” Lower Mississippi River population, which also diverges the most. The two invasion fronts also significantly genetically differ. About 3% of individuals (including all populations except the Illinois River) contain a unique and very divergent mtDNA haplotype, which likely stems from historic introgression in Asia with female largescale silver carp H. harmandi. The nuclear microsatellites and S7 sequences of the introgressed individuals do not differ from silver carp and are very distant from bighead carp. These sequence variation data are employed to design and evaluate a targeted high-throughput metabarcoding sequence assay that identifies and distinguishes among species of invasive carps (i.e., silver, bighead, grass, black, and common carps, along with goldfish), as well as native cyprinids, using cytochrome b. Our assay further differentiates among selected silver carp haplotypes (including between H. molitrix and H. harmandi), for use in population genetics and future analyses of spread pathways. We test and evaluate this assay on environmental (e)DNA water samples from 48 bait shops in the Great Lakes’ region (along the Lake Erie, Lake St. Clair, and Wabash River watersheds), using positive and negative controls and custom bioinformatic processing. Test results discern silver carp eDNA in four of the shops–three in Lake Erie and one in the Wabash River watershed–and bighead carp from one of the same Lake Erie venues, suggesting that retailers (who often source from established southerly populations) comprise another introduction vector. Our overall findings thus provide key population genetic and phylogenetic data for understanding and tracing introductions, vectors, and spread pathways for silver carp, their variants, and their relatives.

Comparison of diets containing various fish meal levels on growth performance, body composition, and insulin-like growth factor-I of juvenile channel catfish Ictalurus punctatus of different strains

Various seafood processing wastes were collected, analyzed, and evaluated for their use as primary protein sources in catfish diets. Finfish wastes (flounder racks and mixed finfish) were higher in crude protein content (60 versus 40%) than blue crab (Callinectes sapidus) wastes. Practical diets containing menhaden (Brevoortia spp.) fish meal or one of four seafood processing wastes (flounder racks, mixed finfish, blue crab, and blue crab without carapace) amounting to 10% of the diet were fed to fingerling channel catfish (Ictalurus punciatus) for 7 weeks under controlled, laboratory conditions. Weight gain and feed efficiency did not differ among treatments. Similar diets containing Atlantic herring (Clupea harengus) or blue crab meal were compared with a standard production diet containing fish meal in a 139-d field cage culture experiment. Caged channel catfish fed the control or Atlantic herring diets had greater daily gain and net production than those fed the crab diet.

Absorption of amino acids from intact dietary proteins and purified amino acid supplements follows different time-courses in channel catfish ( Ictalurus punctatus)

Three species of invasive carp—Grass Carp Ctenopharyngodon idella, Silver Carp Hypophthalmichthys molitrix, and Bighead Carp H. nobilis—are rapidly spreading throughout North America. Monitoring their reproduction can help to determine establishment in new areas but is difficult due to challenges associated with identifying fish eggs. Recently, random forest models provided accurate identification of eggs based on morphological traits, but the models have not been validated using independent data. Our objective was to evaluate the predictive performance of egg identification models developed by Camacho et al. (2019) for classifying invasive carp eggs by using an independent data set. When invasive carp were grouped as one category, predictive accuracy was high at the following levels: family (89%), genus (90%), species (91%), and species with reduced predictor variables (94%). Invasive carp predictive accuracy decreased when we only considered observations from newly sampled locations (family: 9%; genus: 22%; species: 30%; species with reduced predictor variables: 70%), suggesting potential differences in egg characteristics among locations. Random forest models using a combination of previous and new data resulted in high predictive accuracy for invasive carp (96–98%) when invasive carp were grouped as one class for all models at the family, genus, and species levels. The two most influential predictor variables were average membrane diameter and average embryo diameter; the probability of predicting an invasive carp egg increased with these metrics. High predictive accuracy metrics suggest that these trained and validated random forest models can be used to identify invasive carp eggs based on morphometric variables. However, decreased performance at new locations suggests that more research would be beneficial to determine the models’ applicability to a larger spatial region.

A laboratory study was conducted to compare different animal protein sources in diets containing 32% protein for channel catfish Ictalurus punrtatus. The experimental diets were practical‐type diets and formulated to meet or exceed all known nutrient requirements for channel catfish. Twenty juvenile channel catfish (initial weight: 6.4 g/fish) were stocked into each of 25 110‐L flow‐through aquaria (five aquaria/treatment). Fish were fed twice daily to approximate satiation for 9 wk. Fish in each aquarium were counted and weighed collectively every 3 wk. No significant differences were observed in feed consumption, weight gain, feed efficiency, survival, percentages visceral fat and fillet yield, or proximate composition of fillets among channel catfish fed diets containing either 5% menhaden fish meal, meat and bone/blood meal, catfish by‐product meal, poultry by‐product meal, or hydrolyzed feather meal with supplemental lysine. The data indicate that these animal protein sources can be used interchangeably in diets for channel catfish without affecting fish growth, feed efficiency, or body composition.

Evaluation of growth performance, condition indices and body composition of juvenile red drum (Sciaenops ocellatus) fed fishmeal- and fish-oil-free diets

One hundred and seventy five pigs (initially weighing 14.1 lb and 17 + 2 d of age) were used in a 21-d growth assay to compare performance of pigs fed two sources of Menhaden fish meal. Overall, there was no difference in growth performance between the two fish meal sources. For the first 14 days ADG and F/G were improved by including fish meal in the diet and as the level increased from 2.5 to 5%. However, in the third week (day 14 to 21) of the trial there was no benefit in adding fish meal to the diet. These results indicate that IPC 740 fish meal can be an effective replacement for Special Selectâ„¢ Menhaden fish meal in nursery diets.; Swine Day, Manhattan, KS, November 15, 2001