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HPL Finfish Aquaculture Program
| Recirculating System Efficiency
An engineering and economic evaluation of selected commercial recirculating aquaculture production systems
Project leader:
Fred Wheaton, UM Biological Resource Engineering Department;
Co- P.I.'s: Andy Lazur, UMCES/HPL
Doug Lipton, UM Agriculture and Resource Economics
Don Webster, Wye Research and Education Center
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Overview:
Recirculating aquatic systems (RAS) are the dominant culture system used in Maryland for the culture of food fish species. This technology uses a combination of solids and biological filters with pumps to maintain good water quality. Although there are some successful recirculating systems, many have failed for a variety of reasons, many of which are economic. Proposed here is a detailed analysis of both the ability of the RAS to maintain water quality at an acceptable level to support the fish load within the systems and an economic analysis of the systems to determine the break-even point, profitability, and return on investment. Two identical Tilapia culture systems, each operated by a different manager, will be monitored over one fish production cycle. Water quality is monitored and controlled at desirable levels. Economic data will be collected to delineate all of the capital and operating costs for each system. Profitability and water quality will both be a function of management and RAS. Major costs and common management errors will be determined to help researchers focus their research efforts on reducing the largest cost items. It will also enable the extension agents to provide data on commercial systems, and to educate aquaculturists in the state-of-the-art and the best management practices.
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Historic landings of Atlantic sturgeon on east coast |
Sturgeon Restoration
Feed training of Atlantic sturgeon broodstock and sex determination/induced spawning technology transfer
Project Leaders: Andrew Lazur and Erin Markin
Sturgeon fossil records date back more than 150 million years making them among the oldest vertebrates. There are 26 species of sturgeon, eight being found in North America. T wo species of sturgeon are native to the Chesapeake Bay, the shortnose and Atlantic sturgeon. Historically, Atlantic sturgeon were of significant commercial importance on the East Coast being harvested primarily for their highly prized roe or caviar. In the late 1880's harvest peaked at about 7 million pounds, of which approximately 10% was harvested from the Chesapeake Bay. Commercial catch declined rapidly after the turn of the century, primarily due to over fishing, with annual harvests from 1905 to the 1990's amounting to less than 5% of the record catch. Populations were unable to rebound despite reduced fishing pressure because of a loss of spawning grounds and reduced water quality. A moratorium on all US commercial harvest was established for Atlantic sturgeon in 1997. Currently, the population of Atlantic sturgeon in the Chesapeake Bay appears to be extremely low with no young of year fish being caught during surveys between 1950 and 2003. However, in the Spring of 2004, young of year sturgeon were observed in the James River providing an indication that though rare and given the right environmental conditions, spawning ang hatching is possible. The unique life fishery of sturgeon, requiring 10-15 years to reach sexual maturity and only spawning every 2-3 years, contributed to its population decline and presenting challenges to its recovery. |
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As a key initial step in developing an Atlantic sturgeon restoration program, Maryland Department of Natural Resources Fisheries Service and its partners, Mirant at the Chalk Point Power Plant, Delaware Department of Natural Resources and Environmental Control, U.S. Fish and Wildlife Service, and UMCES Finfish Aquaculture Program at Horn Point Laboratory are in the process of establishing the necessary broodstock population as recommended by the Atlantic States Marine Fisheries Commission (ASMFC, 1996). Among the ASMFC sturgeon restoration protocols are recommendations to ensure maximum genetic diversity and include a minimum broodfish population of 100 animals of six year classes and preferably utilizing animals from the same or adjacent river system. Currently over 200 Atlantic sturgeon of 1992 or younger year class are being maintained by the partners, but all of this stock is from the Hudson River and the sex and maturity of these fish are unknown. To establish the desired broodstock population in Maryland several objectives mush be achieved and include: 1) identify the genetic diversity of existing stock through genetic profiling of all animals; 2) conduct studies to identify methods to train wild fish collected from the Bay to consume commercial feed.
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 Historical landings of sturgeons in the U.S. Atlantic coast |
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Feed training of wild-caught Atlantic sturgeon
Captured wild fish do not readily train onto commercial diets (and in some cases, natural food) often resulting in excessive weight loss, reduction in fish condition factor and mortality. Preliminary efforts to force feed sturgeon resulted in mixed results, yet some had success force feeding captured Atlantic sturgeon by inserting gelatin encapsulated natural foods into the alimentary tract. For feeding trials conducted at HPL, sturgeon were captured from the Delaware River and Chesapeake Bay over the Summer of 2003 and 2004. In our study, two methods of feeding are evaluated: passive introduction of natural foods and forced feeding of a natural-food A "slurry" of shrimp, shad roe, squid, and bloodworms. After several weeks, commercially available pellet feed is added to the mixture and ultimately commercial diets. |
Striped Bass
Studies on the Effects of Harmful Algal Blooms on Excretion of Nitrogen Compounds by Fish
Harmful algal blooms (HABs) may stress or kill fish due to direct toxic effects, hypoxia, or diurnal shifts in pH. Algal blooms change the acidity of the water by using carbon dioxide during the day, causing the pH to rise, and adding carbon dioxide at night (through respiration) causing the pH to fall. Large diurnal variations in pH may change the rate and species of nitrogen excreted by fish, and may, in turn, stimulate algal growth. While fishes excrete primarily ammonia, transfer of ammonia across the gills can be substantially reduced during periods of high environmental pH. Urea is energetically costly to produce but when ammonia excretion becomes impaired, the production of this non-toxic, electrically neutral compound may be beneficial to the fish.
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| The goal of this study was to characterize the stress responses of fish exposed to HABs and to better understand the relationship between compounds excreted by fish and their role in stimulating HABs. Huge schools of juvenile menhaden invade Chesapeake Bay tributaries in the summer and striped bass are becoming more abundant each year. Fish stressed by algal blooms that cause large pH shifts may react by increasing the rate of excretion and/or excreting more urea and less ammonia. Some HAB species preferentially incorporate urea over ammonia, and the possibility exists that increased urea excretion by large schools of fish during algal blooms can enhance production of these algal species.Striped bass used in these experiments were reared in the HPL fish hatchery. We performed three experiments during the summer of 2003 to measure the effects of pH change on fish stress responses. Eighteen tanks were used for each experiment with four fish per tank. Three replicate tanks were sampled at each time interval and serum from three fish was pooled for analysis. In each experiment fish were acclimated to tanks at pH 8.5 for one week and then pH was changed slowly from 8.5 to 9.5 and back to 8.5 over a period of several hours to mimic changes that would occur with a HAB in nature. We measured Ammonia and Blood Urea Nitrogen (BUN) in samples of blood drawn at 0, 1, 3, 6, 24 and 48 hours after pH change. Ammonia and urea were also measured in the water. |
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Effect of pH cycling on nitrogen excretion
When fish were subjected to pH cycling over a period of hours ammonia and urea that accumulated in the blood as pH increased was excreted into the water as pH declined.
(Figures 1 (top)and 2(bottom).
Figure 1. Water pH was changed from 8.5 to 9.5 over a 4 hour period, then reduced to 7.5 during the next 4 hours and finally increased to 8.6 during the final two hours. Ammonia accumulated in the fish blood as pH increased and was excreted when pH was decreased.
Figure 2. Water pH was changed from 8.5 to 9.5 over a 4 hour period, then reduced to 7.5 during the next 4 hours and finally increased to 8.6 during the final two hours. Urea accumulated in the fish blood as pH increased and was excreted when pH was decreased.
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Conclusions:
~ At high pH (9 - 9.5) both ammonia nitrogen and urea concentrations increase in the blood of striped bass and the fish do not survive for 24 hours. When subjected to short term pH changes such as the diurnal changes in pH that could be caused by an algal bloom, urea and ammonia accumulate in the blood at high pH and are released into the water as pH declines.
~ Assuming that menhaden are similar to striped bass in their response to pH change, urea and ammonia nitrogen accumulated during the day as pH rises are excreted as pH decreases at night. Large schools of menhaden and striped bass may contribute to the continuation of algal blooms by dumping urea and ammonia nitrogen as pH declines at night.
Acknowledgements
We are grateful for the assistance of Megan O' Conner, Bart Rogers, and summer students Colin Middleton, Jennifer Williams, and Brittany Thorsteinsson. Funding was provided by NOAA through the ECOHAB program.
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Marine Ornamental Fish
The global trade of marine ornamental species for the aquarium industry is valued at over $7 billion annually. In the United States, ornamental fish are the second largest pet industry with over $660 million worth of live freshwater and marine fish imported in 1998. There are estimated to be 13 million aquaria in U.S. households, of which 1.1 million hold marine ornamentals. This constitutes an annual trade valued at $300 million that includes over 25 million individual specimens. Of these, 95% are still obtained from the wild Worldwide, there are roughly 1,471 species traded with top ten species amounting to 36 % of the total number traded. Species from 5 families (Pomacentidae- clownfish 43 %, Pomacentridae- angelfish 8%, Acanthuridae- surgeonfish 8%, Labridae-wrasses 6 %, and Gobiidae-gobies 5 %) account for 70 % of total market volume. The reliance on wild harvest as the primary source of marine ornamental fish is unsustainable and has led to both over-fishing and the use of environmentally destructive harvest techniques. Culturing aquarium species in closed systems minimizes environmental impact and leads to the production of hardier specimens that survive longer in captivity. Aquaculture of these species has the potential to supply a superior product that is in high demand while relieving pressure on threatened populations. |
Research Objectives:
A. Evaluate effect of broodstock nutrition on clownfish and flame angelfish reproduction and egg quality;
B. Evaluate the effect of copepod nauplii as a supplemental diet during the period of first feeding;
C. Determine the effect of juvenile diet on coloration, growth and survival;
D. Compile experimental results into an optimized production protocol for the species and use them to conduct an economic feasibility analysis; and
E. Dissemination of information learned from experiments to industry and public by tours, workshops, presentations and publications. |
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Aquatic Plants and Nutrient Management
Aquatic plant production is the largest sector of Maryland's aquaculture industry with annual sales over $2 million. Several hundred plant species or varieties are cultured and sold primarily as ornamentals for the expanding water garden industry. Many of these shallow water species such as arrow arum, arrowhead, bulrush, duck potato, iris, pickerelweed, and rushes are also used for restoration or mitigation projects for planting in the littoral zones of stormwater or wetland ponds. The importance of aquatic plants in absorbing nutrients and trapping sediments is widely recognized by resource managers in water treatment ponds or constructed wetlands and in agricultural settings for treating livestock wastes. In most urban watersheds, stormwater ponds serve as the primary treatment method for mitigating housing and commercial nutrient and sediment runoff. The Chesapeake 2000 Agreement specifically states that improvements in stormwater performance are needed to meet its goal of deceased nutrient loading to the Bay by 2010. The potential application of aquatic plants for nutrient management in stormwater ponds is extensive since they are used throughout Maryland, with over 17,700 ponds accounting for 175,720 acres in 16 Maryland counties alone. They are also widely used throughout the Chesapeake Bay watershed and United States.
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Despite the broad understanding and published recommendations of the value of aquatic plants in nutrient uptake, specific uptake potential has only been identified for a few of these plant species. Our research is aimed at determining the effectiveness of numerous marginal plant species for nitrogen and phosphorus uptake and evaluating various applications of aquatic plants for enhancement of nutrient capture within stormwater and other treatment settings. |
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More plants and nutrient managment research: SARE  |
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