(April, 2009) The 2009 NC Aquaculture Development Conference was held Jan. 30-31 in
North Carolina Aquaculture for 2008, as reported by Dr. Tom Losordo (NCSU), is valued at approximately $55-$60 million. The breakdown of freshwater producers by species is: trout (86), catfish (28), striped bass (14), tilapia (9), freshwater prawn (8), crawfish (5), southern flounder, yellow perch, and sturgeon caviar (1 each), and ornamentals (2). The number of food fish producers increased about 5% over 2007 to 241. The average sale price of $1.40 was down about $0.01 compare to 2007. Trout production (processed product) was 1.6 million pounds, and total trout industry value (farm gate plus processed product) was about $15 million (an increase of $708,000). Catfish production was similar to 2007 at 8.4 million pounds and the total catfish industry value (farm gate, processed product and feed milling) was about $25.5 million. Hybrid striped bass industry value (hatcheries and processed product) was about $4.4 million though this is probably underestimated because not all producers reported. The tilapia industry value (fingerlings and growout) was valued at about $3.3 million. Freshwater prawn production was 26 thousand pounds (36 acres with average pond yield of 766 pounds) with a farm gate value of $332,800. Prawn sales were 60% frozen tails at $16.50 per pound and 40% whole fresh prawns at $9.50 per pound.
The NC State Aquaculture Research Update was provided by Dr. Harry Daniels. Southern flounder aquaculture is continuing to make strides; a method for commercial-scale production of female fingerlings has been developed and one fingerling producer has come online. A gift was made to NC State to provide for commercial scale research and development of sturgeon aquaculture for caviar production. Hybrid striped bass demonstrate low feed conversion efficiency and strategies to optimize feeding and growth would be useful to help reduce feed costs and nutrient wastes that influence pond water quality. One strategy is to restrict feeding resulting in higher feed conversion efficiency and compensatory growth when fed resulting in little loss in biomass production compared to fish not on a restricted feeding schedule.
Dr. Craig Tucker, Research Professor,
The keynote speaker, Mr. Philip Gadsden, Seafood Buyer for Harris Teeter grocery stores, talked about consumer preferences and importance of quality, and he discussed the recent effort by People for the Ethical Treatment of Animals (PETA) to reclassify fish as ‘seakitten’. He suggested that this effort is to target children to influence their perceptions of fish and seafood so that they are less likely to purchase these products as adults. He suggested that producers, industry, and researchers develop a unified response, though he had no suggestions as to how this might be accomplished.
Dr. Terry Hanson discussed the economics of aquaculture production, and highlighted a cost of production study of freshwater prawn production in
Dr. Steven Rawles, USDA Harry K Daniels ARC, presented results from a variety of studies on the use plant protein substitutes for fishmeal in aquaculture feeds. Other presentations of potential interest to freshwater producers were on aeration technologies (Mr.Bob Robinson, Kasco Marine), on-farm biodiesel production, (Dr. M. Veal, NCSU), and how to get started in pond aquaculture in NC (M. Parker, NCDACS and
VSU-ARS Aquaculture Research Report (2008 Activities)
Dr. Scott H. Newton & Dr. Edward N. Sismour
(April, 2009) Studies over the past two years (2007-2008) have investigated the causes of catfish fingerling mortality following cage stocking. Studies have been conducted in ponds at the Aquaculture Pond Complex on Randolph Farm,
1) Short-term Survival of Catfish Fingerlings Following Transport and Cage Stocking
Catfish fingerlings delivered from
2) Over-Winter Growth and Survival of Caged Catfish Fingerlings
Over-winter growth and survival were compared between two groups of catfish fingerlings, one group purchased in the spring and the other purchased in the fall, 2007. Fingerlings were restocked in cages for the over-winter study in October and were harvested the following April. Fish were fed a standard ration to apparent satiation when water temperature was at or above 10 oC. Growth in weight, but not length, different statistically between the two groups increasing more in the fall fingerling group, about 25%, compared to the spring fingerling group, about 17%. Mortality in both groups was very low and no indications of disease were observed. The study currently is being repeated. Fingerlings were restocked into cages in November, 2008, and will be held over winter for harvest in April, 2009. The practical significance of this study is that
3) Over-Winter Cage Culture of Brown Trout
The survival and growth of brown trout and rainbow trout were compared over winter during 2007-08. In two of three cages, brown trout survival was comparable to that of rainbow trout. However, survival of brown trout in a third cage was very poor due to irregular feeding activity resulting in cannibalism. Brown trout in this cage were observed with bite marks on fins and the caudal peduncle. Brown trout grew slower and harvest weights averaged about two ounces less than rainbow trout. In natural populations, brown trout do not begin the rapid-growth phase until about the fourth or fifth year, and this limitation accounts for the slower growth of caged brown trout observed in this study. Because of underlying behavioral and physiological constraints and unless there is a specific sales reason, the brown trout is not a good candidate for commercial cage culture. This study repeats and verifies a previous VSU study conducted in the 1980’s.
4) Effect of Glucan on Survival and Growth of Caged Catfish Fingerlings
Utilization of glucan and other immunostimulants to improve health and growth of fish and shellfish in intensive culture systems is an important and timely area of research with substantial potential industry benefit. A proposal to VDACS/VAC to investigate feed additives with immune system enhancement potential was not funded, though the Virginia Aquaculture Association expressed great interest in the project. However, sufficient resources were available at VSU, with additional industry support, to conduct a modified study of the effects of â-glucan on catfish growth and survival using fingerlings remaining from 2007 studies. The study results suggest that oral administration of â-glucan at the dosages tested and with the dosing/feeding schedule used did not produce a significant beneficial effect for catfish fingerlings. Results of this study will be provided to industry association members via newsletter. Further investigations on the efficacy of â-glucan and other immunostimulants for catfish culture will require technical capabilities and methods to assay immunological responsiveness of fingerlings and to determine the concentration of â-glucan in the body. Once these capabilities and methods are established and as follow-up to this study, the oral dosage(s) of â-glucan and a dosing/feeding schedule that stimulates and maintains an effective immunological response in catfish fingerlings need to be determined.
5) Effect of Transport Time and Stocking Method on Skin Condition of Catfish Fingerlings Assayed Using Fluorescein Dye
A single delivery of catfish fingerlings from Arkansas was made in late October, 2008 and the delivery was subdivided into two stockings, an early stocking approximately 26 hours after loading and a late stocking approximately 93 hours after loading, representing ‘short’ and ‘long’ transport times. Fingerlings were stocked by both weight and count into cages and pond-side tanks. Water quality in transport tanks was adequate and compatible with receiving pond water. Fingerlings were subsampled at the beginning of both stockings and at harvest three weeks post-stocking from all treatment conditions. One of 4000 stocked fish died during the trial. The skin condition of fingerlings was evaluated using a fluorescein-dye assay to identify damaged areas. The greatest frequency and distribution on the body of fluorescein-marked areas occurred at the first stocking and thereafter declined. Preliminary analysis of the results suggests that, with good water quality in the tanks during transport, neither transport time nor residence in cages subsequent to stocking may have detrimental effect on fingerling skin condition.
6) Species Composition and Relative Abundances of Turtles in Aquaculture Ponds at
Turtles are often captured in aquaculture cages and the effect of their presence on contained fish is not known. Turtles may have greater effect on caged fish than on those in open ponds as a consequence of stress induced by their presence, by possible harassment or predatory activity, and by consuming uneaten feed. As a result of capturing turtles in our research cages, a study was initiated in collaboration with Dr. Christian D’Orgeix (Department of Biology, VSU) to quantify and describe the composition and relative abundances of turtle species in the aquaculture ponds at Randolph Farm. The most abundant species were Slider and Painted turtles. Two subspecies of Slider were caught, the non-native Red-eared Slider and the Yellow-bellied Slider. The Red-eared Slider is the most common turtle in these ponds. The Yellow-bellied Slider is present, but in low abundance. High abundance of Red-eared Sliders suggests that they may out-compete the Yellow-bellied Slider. Whether this implies that Red-eared Sliders are more likely to impact fish in aquaculture ponds and cages is not known. An unexpected outcome was the capture of intergrades between the Red-eared Slider and Yellow-bellied Slider. These subspecies and their intergrades have not been reported previously from
7) Collaboration with VCU Department of Biology
Collaborative studies are being conducted with Dr. Michael Fine, Department of Biology,
Aquaculture Survey of 2008 Production Year Coming Up
(April, 2009) The USDA National Agricultural Statistics Service (Virginia Field Office) is preparing to conduct a statewide aquaculture survey in the spring of 2009. This survey will reference the 2008 production year and measure changes in size and scope of the industry since the last state aquaculture survey was conducted in 2003. The survey is conducted once every five years and the information helps with legislative, regulatory and marketing decisions at the state level. The distribution of the survey to producers will begin in late December to early January with a deadline set for the spring of 2009. To participate in the survey, or to request a copy of the 2003 survey report, contact: Herman Ellison, State Director 1-800-772-0670; nass-va@nass.usda.gov.
Caged Fish Culture in Virginia Farm Ponds
Scott H. Newton, Virginia State University
(April, 2008) Virginia State University research has shown that small-scale caged fish culture production in ponds is practical and biologically feasible. Uses of fish harvested from cages include: personal consumption, stocking of ponds, and food fish sales. Primary species for cage culture are rainbow trout, channel catfish, and bluegill sunfishes and their hybrids. Various combinations of the above fishes with companion species are also possible. Other species may be cage cultured or held temporarily in cages under certain situations or for special applications. Poor candidates for cage culture include brown trout, striped bass, hybrid striped bass, largemouth bass, and large pond-reared catfish. Tilapia is a good fish for cage production in ponds; however, in Virginia, tilapia must be reared in closed systems and the producer must be permitted by VDGIF.
Climatic conditions in Virginia’s Central Piedmont and Coastal Plains Regions are well suited for two distinct production seasons. Research, industry results, and over 40 years of experience with caged fish culture shows that double cropping of warm season fish with winter rainbow trout production is a viable option for small producers using farm ponds. Channel catfish, sunfishes, and koi carp are the preferred fishes for spring to fall (warm season) production, and rainbow trout, golden trout and, in some cases, brook trout, are the best choices for fall to spring (winter season) production. Overlaps in fish crops (either during spring or fall seasonal transition times) may occur but seldom create major problems. Seasonal fish production is similar to grain crops as with soybeans and wheat production cycles (basically frost to frost seasons). In ponds where only one fish crop may be practical (due to pond size, fertility, watershed, etc.), then rainbow trout is the preferred species. In small, multi-use ponds, winter production of trout would be the best choice since this would reduce conflicts with other uses (irrigation) and result in fewer adverse effects on caged fish.
Winter Production
Trout averaging four to five fish per pound are stocked in the fall and harvested the following spring. The best trout growth is obtained when fish are fed a quality floating (slow-sink) feed of the proper size. Initially, trout should be fed 1/8-inch (3 mm) size pellets because the 3/16-inch pellets are too large for stocker size trout. The shift to larger size pellets may not be necessary until mid-winter or early spring, thus feed purchases should be planned accordingly. Remember, water temperature (ideal trout range is 55 to 65 Fahrenheit) is the primary environmental factor in fish production and this is true regardless of fish species or season of the year. Trout harvested in late spring must be dressed or sold on ice because live trout stockings/transfers are not possible due to warm water conditions. All sizes of trout are marketable. The most desirable harvest size for trout as food fish is 14 to 15 ounces.
Present recommendations regarding winter cage culture in Virginia include the following. Brook trout can be stocked in the same cage with rainbow trout at the ratio of 1 brook trout for each 10 rainbow trout. Because they feed at cooler water temperatures, brook trout may stimulate rainbow trout to feed more often during the colder winter months. Secondly, brook trout may be reared in cages for either specialty restaurant sales, which can command a higher sales price because they are native to Virginia and are the official state fish, or for live fish sales for fee fishing and sporting club stockings. Thirdly, small rainbow trout usually less than 8 inches total length may be legally sold for recreational fishing bait. Finally, golden trout is an interesting species to produce. Though considered a separate species, for culture purposes it is basically a color variation of rainbow trout. Golden trout are considered by the author to be a novelty fish used mainly in fee fishing operations because for pond or cage culture situations. The lighter color of golden trout is simultaneously an advantage and a disadvantage. Observing them during feeding is much easier for the farmer, but it also causes golden trout to be a prime target of predators, mainly the great blue heron. In all cases, regardless of species, sales of live trout should be made during early spring due to intolerance of handling and transporting at warmer water temperatures.
Summer Production
The warm growing season for cage culture in Virginia is typically from the frost-free spring to fall frost period, or April through October. Catfish stocked into cages should be healthy fish that average 8 to 10 fish per pound. Feeding should be daily with attention given to summer heat and storm conditions. Feeding should be reduced or temporarily stopped when signs of possible low oxygen conditions are suspected. Emergency management measures, especially pertaining to aeration, must be considered and plans made in advance for cage culture in farm ponds. At harvest, caged catfish should average over a half pound and some will reach one pound by fall. However, at harvest, there will likely be a range of fish sizes to be dealt with from both production and sales perspectives. Management options for smaller fish include either over-winter feeding for spring sales or fall sales of fish over 8 inches for live stocking into farm ponds.
A solid business reason that Virginia farmers should consider for growing catfish in cages is to sell them live for stocking farm ponds. Fish too small for food sales may be as valuable, or more so, when sold for farm pond stocking. Charges may be made for the fish and for delivery service as well. Since a two pound largemouth bass can consume an 8-inch catfish, stocking of smaller size fish in older ponds is not recommended. On the other hand, stocking of catfish weighing one-half pound or more also produces “immediate fishing opportunities”.
Other warm-season caged culture opportunities include fish species that are generally sold live for stocking ponds or water gardens for recreational purposes. Bluegill and hybrid sunfishes do well in cages, but they must be fed pellets of the appropriate sizes and should be disturbed as little as possible to reduce mortalities. For short-term sales, koi carp, goldfish, and several other species may be held in cages. Large catfish (over one-half pound) that have been pond reared should not be placed into cages for short-term holding nor for further grow out because they will fight and cannibalize each other. There may be certain situations whereby some cool-season fishes, such as hybrid striped bass and yellow perch, may be reared in cages, but production risks are higher for these species. Some fish require greater experience and advanced management practices to generate successful crops. For culture purposes, cage mesh size, and perhaps shape, should be considered for different fish species and/or sizes.
Farm ponds may provide opportunities to supplement small farm incomes and to enhance the rural lifestyle. More opportunities for farm-raised fish products may arise as consumer interest in locally produced products and emphasis on freshness and wholesomeness, etc. continues to increase. However, farm pond owners’ expectations should not exceed the reality of the actual production capacity of small multiple-use, watershed farm ponds. In summary, many, but not all, Virginia farm ponds are suitable for caged fish aquaculture and the species chosen for production should match existing pond conditions and farmer knowledge, experience, and related capabilities (physical and fiscal).
Over-Winter Cage Culture of Brown Trout
by Scott H. Newton and Edward N. Sismour
Agriculture Research Station, Virginia State University
(February, 2008) In order to maximize efficiency of project funds and to continue to provide fish farming information to industry, studies are conducted with trout during the fall to spring season in VSU ponds. Also, we usually conduct winter studies with catfish left from previous summer season experiments. It was established many years ago that the Central Piedmont and Coastal Plains regions of Virginia are well suited for two seasons of caged fish production in farm ponds. Channel catfish may be reared from spring to fall and rainbow trout may be reared from fall to spring. With experience and management, two crops may be reared in larger size ponds, while ponds less than 2-acres may only allow for the annual production of one of the two species. In smaller ponds, caged rainbow trout during winter would be the best option, with possibly channel catfish loose in the pond for recreational fishing or harvests.
During the 2007 fall to 2008 spring season, we have three cages of brown trout being reared alongside rainbow trout in a comparison trial. Fish stocked this past fall were slightly larger than normally recommended for several reasons. Less feed may be required to grow fish to an acceptable food market size. And, brown trout grow to such a large adult size, their period of fastest growth does not occur in fish less than two pounds.
This is our second attempt to cage rear brown trout because they failed to survive during the first attempt. Brown trout grown in cages in Nottoway County during the early 1990s died during April when water temperatures began to fluctuate. During several seasons since, some brown trout mixed with rainbow trout were observed to survive and grow well. However, market sales of brown trout should be explored beyond live sales to fee fishing operations. Brown trout may not be stocked in public streams or waters managed by VDGIF without a written permit, because brown trout are predaceous upon other trout, especially native brook trout.
NOTE: Results of caged brown trout versus rainbow trout will be provided in shortly.
