Luke A. Roy

• PhD
• Extension Professor (Full) at Auburn University

Temperature is one of the most relevant factors influencing the development of aquatic species, making it a key parameter to consider for aquaculture. Largemouth bass (LMB; Micropterus spp.) are highly relevant for human consumption and sport fishing, representing one of North America’s most important freshwater fisheries. Yet, questions remain on...

Background The innovations of the “Omics Era” have ushered in significant advancements in genetic improvement of agriculturally important animal species through transforming genetics, genomics and breeding strategies. These advancements were often coordinated, in part, by support provided over 30 years through the 1993–2023 National Research Suppor...

Over the years, the intensification of shrimp Penaeus vannamei production has brought challenges such as disease outbreaks and increases in the nutrient loading of effluents. To be more environmentally friendly as production systems intensified, it became necessary to create systems with a high degree of biosecurity and toward efficiency in water a...

Economics is the study of the allocation of scarce resources to meet human wants and needs and has a critical role to play in addressing challenges related to environmental sustainability, community resilience, and food security. In the context of aquaculture, the key to such a discussion is understanding the linkages of aquaculture farming busines...

Transgenic canola oil has been created to naturally produce essential fatty acids (EFAs) needed for shrimp, namely DHA (Docosahexaenoic acid, C22:6n-3) and EPA (Eicosatetraenoic acid, C20:5n-3). This experiment was designed to evaluate the efficacy of genetically modified Latitude oil in shrimp diets. Treatments were designed with the goal of obser...

Extension professionals have used research verification programs to evaluate the effectiveness of research-based management recommendations in several different aquaculture species. In addition to providing a platform on which to examine current best management practices and Extension recommendations from Land Grant Universities, research verificat...

Objective: In West Alabama, catfish Ictalurus spp. producers routinely face the challenge of fish that exceed market size (aka “Big Fish”) in their commercial ponds. These fish are skilled at evading seine nets during harvest and can increase in size significantly before subsequent harvests occur. This is problematic for catfish producers because p...

Economics is the study of the allocation of scarce resources to meet human wants and needs and has a critical role to play in addressing challenges related to environmental sustainability, community resilience, and food security. In the context of aquaculture, the key to such a discussion is understanding the linkages of aquaculture farming busines...

Objective The objective of this study was to quantify the economic costs and impacts of off‐flavor on U.S. catfish farms. Methods A survey was conducted to quantify the costs and economic methods using enterprise budget techniques to enumerate the costs of off‐flavor on catfish farms. Result Diuron was the most popular‐choice algicide for off‐fla...

Feed conversion ratio (FCR) is widely used as a measure of feed use efficiency in commercial aquaculture production and research. Surprisingly, little work has focused on the factors that affect FCR in plankton‐based, commercial ponds despite the widespread use of FCR as a production metric. Proposals to use FCR as a numeric standard for environmen...

With current advancements in technology allowing for genetic modification of crops, canola has been modified to contain n3 long-chain polyunsaturated fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The purpose of this study was to determine the efficacy of using genetically modified canola oil as a DHA and EPA replac...

Intraspecies variability in sperm quality is common among aquaculture species, thus necessitating an urgent need to establish reliable molecular biomarkers to screen for males with high-quality sperm. The channel catfish (Ictalurus punctatus) ♀ × blue catfish (I. furcatus) ♂ hybrid accounts for >50% of United States catfish production. Blue catfish...

Current practices used in commercial shrimp farms

Aquaculture farms in Arkansas, USA routinely battle columnaris disease caused by Flavobacterium covae. Columnaris is prevalent during stressful events such as feed training and when fish are stocked at high densities in holding vats before sale. Kaolin clay was effective in laboratory trials as a treatment for columnaris in catfish. As a result, fi...

Two prevalent bacterial diseases in catfish aquaculture are enteric septicemia of catfish and columnaris disease caused by Edwardsiella ictaluri and Flavobacterium covae, respectively. Chronic and recurring outbreaks of these bacterial pathogens result in significant economic losses for producers annually. Determining if these pathogens can persist...

Aquaculture of the Pacific white shrimp Litopenaeus vannamei in low-salinity water is a viable industry and production strategy in the southeastern United States. A major challenge facing this industry is a phenomenon called late-term mortality which is thought to be driven by thermal stress at the end of the growing season when water temperatures...

Virulent Aeromonas hydrophila (vAh) is a major bacterial pathogen in the U.S. catfish industry and is responsible for large-scale losses within commercial ponds. Administering antibiotic feeds can effectively treat vAh infections, but it is imperative to discern new approaches and better understand the mechanics of infection for this bacterium. As...

The objectives of this study were to determine statewide production losses caused by diseases, identify the most incident catfish diseases affecting Alabama (AL) farm-raised catfish production in freshwater ponds and their annual pattern, and determine disease-related economic impacts. The Alabama Fish Farming Center (AFFC) conducted seven annual r...

The ionic profile of inland low salinity water sources can be dramatically different with variable concentrations of magnesium (Mg²⁺). Inland shrimp farmers in Alabama, USA, supplement Mg²⁺ at the start of each production cycle to reach concentrations >20 mg/L at 1 to 11 g/L salinities. However, this concentration may not be high enough for larger...

We used an online survey to document challenges experienced by aquaponic hobbyists (n = 81), producers (n = 117), and educators (n = 75). Responses were distilled into the following categories: 1) operations and management; 2) facilities, location, and system design; 3) knowledge and educational resources; 4) funding; 5) economic viability; 6) plan...

As the northern Largemouth bass (LMB) (Micropterus nigricans) industry shifts toward fingerling production, implementing practical feeding strategies to ensure efficient growth during high water temperatures is paramount. Twenty (12.7 ± 0.2 g) (Trial 1) and fifteen (7.2 ± 0.1 g) (Trial 2) LMB fingerlings were stocked in two recirculating systems (e...

Aquaponics is an agricultural practice incorporating aquaculture and hydroponic principles. This study assesses the current system design and production practices of the aquaponic industry, compares these metrics by stakeholder group, identifies trends, and provides recommendations for future development. An electronic survey of aquaponic stakehold...

The US catfish industry has undergone significant technological advancements in an attempt to achieve cost efficiencies. This study monitored the progress of the adoption of alternative and complementary technologies in the US catfish industry. A 2019–2020 multi‐state in‐person survey in Alabama, Arkansas, and Mississippi (n = 68), revealed increas...

The Double-crested Cormorant is the primary avian predator on catfish farms causing significant economic losses primarily due to 1) on-farm expenditures related to bird-management activities and 2) value of the catfish lost to cormorants. This comprehensive economic study quantified these two economic effects by surveying catfish farms in the delta...

The catfish industry is the largest U.S. aquaculture sector and a major contributor to the rural economies of the Southern states of Alabama, Arkansas, and Mississippi. Economic contributions of this industry to the tristate region were estimated using an input-output modeling approach with the IMPLAN database and software (Impact Analysis for Plan...

This study assessed growth, feed conversion efficiency, and fatty acid composition of three size classes of northern largemouth bass Micropterus salmoides salmoides (80 g, 105 g, and 137 g) subjected to a 35 °C water temperature for 28 days. A completely randomized design was conducted, with ten fish per tank and treatments triplicated. The trial w...

Lesser scaup (Aythya affinis) and greater scaup (A. marila), hereafter scaup, consume a variety of aquatic invertebrates, plants, and occasionally small fish. Scaup have foraged on commercial aquaculture farms in the southern United States for decades. However, the types, abundance, and rate of fish exploitation by scaup on baitfish and sportfish f...

Commercial producers raising centrarchids in Arkansas routinely report winter mortality. Juvenile centrarchids are susceptible to harsh winter conditions. Coppernose Bluegill (Lepomis macrochirus purpurescens) is a popular sportfish for recreational fishing and there are no recommended best management practices for winter feeding of this species. A...

Processing plants prefer live catfish ranging from 0.45 to 1.81 kg as they are readily processed and sold to established markets. Catfish routinely escape harvest, become Big Fish (> 1.81 kg) in one to two production cycles, receive a reduced price, and can reduce farm profitability. This study determined age structure of Channel Catfish (Ictalurus...

While Flavobacterium columnare is a well‐known fish pathogen that has been studied for over 100 years, columnaris disease remains poorly controlled and in need of improved management solutions for United States catfish producers. Outside of therapeutants, the disease remains relatively unchallenged in the commercial catfish industry. Attempts to im...

There has been an increasing global demand for large bluegill (Lepomis macrochirus) to supply the food‐fish market. Current bluegill diets resemble those for largemouth bass and contain a high percentage of marine fish meal (FM). Research into the use of alternative protein ingredients for bluegill diets need to be conducted to not only conserve fi...

Fish‐eating birds have been found to consume baitfish and sportfish raised on farms in the United States. Understanding the on‐farm economic effects of such wildlife conflicts is essential for wildlife management agencies to make informed decisions. Lesser scaup, while not widely considered a fish‐eating bird, will consume farmed fish. Baitfish and...

Numerous approaches can be implemented to carry out on-farm Extension demonstrations in aquaculture. The design and approach used are often governed by the problem or question that needs to be addressed as well as budgetary constraints within Extension programs. West Alabama is home to a unique inland marine shrimp industry that uses a low-salinity...

Given its ubiquity, it is not surprising that agriculture, including finfish aquaculture, contributes to food webs worldwide and is used by numerous wildlife for foraging and meeting other needs. Double-crested Cormorants (Phalacrocorax auritus) impact United States commercial aquaculture and are considered the primary avian predator in catfish (Ic...

Arkansas' bait- and sportfish facilities are commonly used by various piscivorous bird species, including lesser scaup (Aythya affinis) and greater scaup (A. marila) that consume substantial quantities of fish. To mediate this predation, farmers implement extensive bird harassment programs that create additional costs to fish loss, thus research in...

The suitability of inland saline groundwater as a medium to culture juvenile cobia, Rachycentron canadum, was assessed. In the first experiment, juvenile cobia stocked in raw (unamended) saline groundwater at salinities of 5, 10, and 15 g/L exhibited complete mortality after 108, 176, and 195 hr, respectively. The second experiment evaluated the re...

The current study evaluates the effect of different Mg levels in low-salinity (3 g/L) water on growth, survival, haemolymph osmolality, cationic composition in haemolymph, carapace and whole body of Pacific white shrimp, Litopenaeus vannamei. A low-cost salt mixture (LCSM) comprised of Na, K, Ca and Mg concentrations of 298, 9, 17 and 39 mg/L, resp...

Substantial economic losses of farmed catfish to fish-eating birds such as the double-crested cormorant, Phalacrocorax auritus, continue to be reported on U.S. catfish farms. An economic analysis was conducted of the on-farm effects of both the increased expenditures to scare fish-eating birds from catfish farms and of the value of the catfish that...

U.S. catfish producers have been exploring the adoption of alternative-production technologies (intensive-aeration, in-pond raceways, and split-pond systems) in recent years for achieving cost efficiencies. A multi-state (Alabama, Arkansas, and Mississippi) survey was conducted to identify specific reasons influencing the decisions of producers whe...

Although not typically associated with eating fish, lesser scaup (Aythya affinis) and greater scaup (Aythya marila) have recently been reported consuming large quantities of bait- and sportfish produced on Arkansas commercial aquaculture facilities. During winters 2016–2017 and 2017–2018, we collected 529 lesser scaup and 19 greater scaup foraging...

Aquaculture verification programs are designed to demonstrate and test research‐based recommendations on commercial‐scale operations. From 2010‐2013, three management protocols were followed on two Channel Catfish Ictalurus punctatus farms in west Alabama. They were an owner defined multiple‐batch (MB) system, an Extension defined single‐batch (SB)...

Pacific white shrimp, Litopenaeus vannamei, exhibit a remarkable ability to tolerate low‐salinity environments, facilitating its culture far from coastal areas using various production systems at salinities less than 15 g/L. Recirculating aquaculture systems (RAS) and biofloc systems are usually operated using reconstituted sea salt (RSS), which is...

The current study evaluates the efficacy of a low‐cost salt mixture (LCSM) to replace expensive reconstituted sea salt (RSS) in the salinity acclimation and nursery phase of Pacific white shrimp under laboratory and farm conditions. LCSM was formulated to yield sodium, potassium, calcium and magnesium concentrations closely comparable to that of di...

Shrimp farmers in Alabama are seeking to increase efficiency and intensify production. Semi‐intensive earthen ponds are the traditional production system used by Alabama shrimp farmers, however, there is interest to evaluate intensive pond‐based production systems such as split ponds. These alternative systems are more intensive and require higher...

Catfish aquaculture is an important agricultural commodity in Mississippi with most of the production. occurring in the Delta region of the state. A vital factor in managing these farms is reducing fish loss from bird depredation. The most notable bird species that consume catfish are Double-crested Cormorants. These migratory waterbirds arrive in...

Two feeding trials were conducted to investigate the effect of replacing fishmeal with a combination of soy and corn protein concentrate (1:1 ratio) on growth performance of the Pacific white shrimp (Litopenaeus vannamei). A basal diet containing 200 g/kg fishmeal was systematically reduced (200, 150, 100, 50 and 0 g/kg) with protein concentrate on...

This publication is a fact sheet that summarizes results from an SRAC-funded project to measure the impacts on baitfish farms of two avian predators: Lesser and Greater Scaup.

This study evaluated three different pond‐based production systems for raising largemouth bass, Micropterus salmoides, for the food fish market, using nine 0.04‐ha ponds. Treatments included traditional ponds (TP), intensively aerated ponds (IAP), and split‐pond systems (SPS). TP and SPS ponds were aerated at 9.3 kW/ha, while IAP was aerated at 18....

Shrimp farmers in Alabama who produce the Pacific white shrimp, Litopenaeus vannamei, have recently reported abnormally low survival at harvest. Farmers have hypothesized that this phenomenonmay be due to disease, toxic algae, shrimp source, or reduced shrimp robustness in later stages of production. To compare performance of shrimp from different...

Winter mortality is a common problem for baitfish farmers in Arkansas that produce Fathead Minnows (FHM) Pimephales promelas and Golden Shiners (GS) Notemigonus crysoleucas. Winter feeding programs are a potential avenue to improve survival, condition, and reduce weight loss of baitfish. Methods of winter feeding vary widely among producers and cur...

This study evaluates the production and economic feasibility of a fixed-floor, in-pond raceway system (IPRS) to supply processor and niche live catfish markets while also highlighting production issues that arose by targeting these two markets. A west Alabama catfish producer grew hybrid catfish (♀ Ictalurus punctatus x ♂ Ictalurus furcatus) to mar...

Winter mortality is a problem for producers in temperate regions of the US, including Arkansas. Hybrid Crappie, Pomoxis nigromaculatus x Pomoxis annularis, and Redear Sunfish, Lepomis microlophus, are popular among recreational anglers. Methods of winter feeding vary widely among existing commercial farms. The impact of different winter‐feeding reg...

Stearine fish oil (SFO) and palm oil (PO) have emerged as promising alternatives for the replacement of fish oil (FO) in aquafeeds. This study evaluated the replacement of FO with alternative oils in practical diets for Litopenaeus vannamei. In a clear brackish water study (14.1 g/L) utilizing shrimp (0.29 ± 0.02 g, initial weight), FO was replaced...

The fathead minnow, Pimephales promelas, is widely used as a bait, forage, and research fish in the United States. A hardy and fecund fish, this species has many attributes that are excellent for culture. Unfortunately, despite the widespread use of fathead minnows in toxicity testing and thousands of resulting publications, relatively little aquac...

The US catfish industry has shown increasing trends toward intensification of production as a means of achieving cost efficiencies on farms. Previous studies depicted the potential for cost efficiencies in alternative technologies such as split‐pond systems, intensively aerated ponds, and in‐pond raceway systems. This study provides an economic com...

Fish Farming News, Alabama Fish farming Center.

Low‐salinity inland ponds in west Alabama were used to determine if soil composition and water ionic profiles influenced shrimp growth. Soils from four farms were collected and placed into individual tanks equipped with airlift biofilters and 2.5% reconstituted seawater. Pacific White Shrimp Litopenaeus vannamei were cultured for 42 d. Growth, surv...

There has been an increasing global demand for large bluegill (Lepomis macrochirus) and its hybrid (female Lepomis cyanellus × male L. macrochirus) to supply the food-fish market. However, production of market-size bluegill requires producers to overwinter them in temperate regions. Winter fish mortality is widely cited by fish farmers in temperate...

This study was carried out to test the suitability of biofloc technology to improve the productivity of the fathead minnow, Pimephales promelas, a commercially important baitfish in North America. Biofloc growth was induced in treatment tanks by periodic additions of a carbon source (glucose) to maintain a C : N ratio of 12:1. Control tanks (no aer...

The golden shiner, Notemigonus crysoleucas, is a major bait and forage fish species in the USA. Farmers produce millions of golden shiners annually that are distributed live, many across state boundaries. Native over much of the eastern and central USA, this species is often present but rarely abundant in natural systems, as fish density is apparen...

A length–weight relationship was developed for pond-raised hybrid catfish fingerlings, Ictalurus punctatus × Ictalurus furcatus. A total of 4663 fish were sampled ranging from 20 to 240 mm total length. Predicted weight (g) from length (mm) is based on the equation: Y = 0.000017311X2.868474309 (r2 = 0.996) where Y is the estimated individual fish w...

The baitfish industry is an important economic enterprise for many aquaculture producers in Arkansas. The industry generates approximately $30 million annually in farm-gate sales of these small fish that include fathead minnows, goldfish and golden shiners. Diving ducks known as scaup, or “Bluebills,” spend late fall through early spring in Arkansa...

The main objectives of this study were to approximate the maximum yield and evaluate size dispersion of stocker size largemouth bass, Micropterus salmoides reared in a semi-closed recirculating system for 60 days. Fingerlings with an average body weight of 36.7 g were utilized for the study. An experimental system consisting of 18 square plastic ta...

Aquaculture research verification programs are designed to demonstrate and test research-based practices recommended by extension services on commercial-scale operations. From 2010 to 2013, in western Alabama, three management protocols were followed over three crop cycles on a farm producing hybrid catfish (female Channel Catfish Ictalurus punctat...

This study evaluated the effects of biomass density on size variability and growth performance of feed-trained largemouth bass, Micropterus salmoides, fingerlings in a semi-closed recirculating system for 60 d. Average individual body weight and length of fingerlings were 9.04 g and 9.07 cm, respectively. Experimental biomass densities were set at...

A 60-d growth trial was conducted with the black tiger prawn, Penaeus monodon (ca. 0.8 g juveniles) at CIFE Rohtak Centre to evaluate the effects of salinity and Na+/K+ ratio of inland saline water on shrimp growth, survival, and osmoregulation. Three different salinities (5, 10, and 15 ppt) and five different Na+/K+ ratios (25:1, 45:1, 65:1, 85:1,...

The present study assessed the presence of hemocytic enteritis in Litopenaeus vannamei from a shrimp farm which uses semi-intensive culture with underground low salinity water, located at an urban zone of Reynosa, Tamaulipas, Mexico. Histopathological analyses showed characteristic lesions of hemocytic enteritis with a prevalence of 4.0% (12/300)....

The split-pond system (SPS) has been proposed as an alternative culture method to increase the efficiency of pond aquaculture production. This study evaluated the performance and the engineering models of paddlewheel circulators on commercial catfish SPSs. The power requirement and the water flow rate by the circulators increased as the rotational...

global aquaculture advocate Production approaches such as in-pond raceway systems (IPRS) and split ponds are providing an alternative to traditional pond culture for raising catfish in the southeastern United States. Currently, approximately 600 ha of commercial split ponds are in production in Mississippi, Arkansas and Alabama, and the area contin...

Interest in the commercial culture of White Seabass Atractoscion nobilis on the western coast of the United States has been increasing in recent years. Despite this interest, there is a scarcity of knowledge on the dietary requirements of this species, particularly as it relates to basic nutrient requirements and selection of feeds. Hence, we evalu...

Yellow coloration of catfish fillets has always been a problem. Recently increased consumer scrutiny has brought this to the forefront as a major industry concern. As catfish cannot synthesize xanthophyll, commercial feeds and natural prey items are the initial sources of the yellow color. To better understand the contribution of natural foods, a f...

Three sources of soybean meal (SBM) were biochemically characterized and evaluated in diets for juvenile Litopenaeus vannamei. Three biological techniques were utilized to evaluate the nutritional quality of the meals including an outdoor growth trial as well as determination of in vivo apparent digestibility and in vitro digestibility including pe...

A series of experiments were conducted to examine the effects of salinity (1–48 g/L) on the biological performance, as evaluated by growth and survival, of the Pacific white shrimp, Litopenaeus vannamei, and the Atlantic white shrimp, Litopenaeus setiferus, reared at temperatures of 20, 24 or 28 C. Poor growth and survival of L. vannamei was observ...