Mariculture Production Research Articles

Dynamics of dissolved nutrients in the aquaculture shrimp ponds of the Min River estuary, China: Concentrations, fluxes and environmental loads

Dissolved inorganic nutrients (NO2−-N, NO3−-N, NH4+-N, and PO43−-P) play a critical role in the effective management of water quality and prevention of fish and shrimp diseases in aquaculture systems. In this study, dissolved inorganic nutrient concentrations in the water column and sediment porewater, and the fluxes across the sediment-water interface (SWI) were investigated in three intensive shrimp ponds with zero water exchange to examine nutrient cycling during the different growth stages of shrimps. Distinct changes in the dissolved inorganic nutrient concentrations in both the water column and sediment porewater were observed among the three growth stages. Average NO2−-N, NO3−-N, NH4+-N, and PO43−-P concentrations in the sediment porewater were 3.53, 2.81, 29.68, and 6.44 times higher, respectively, than those in the water column over the study period, indicating that the pond sediment acted as a net source of nutrients to the water column. This was further supported by the net release of nutrients from the sediments to the water column observed during the incubation experiment. Nutrient fluxes were dominated by NH4+-N, while NOx−-N (NO2−-N and NO3−-N) and PO43−-P fluxes remained low. The high rates of NH4+-N release from the sediment highlight the need of taking into account the biogeochemical role of sediments in mitigating the problem of water quality degradation in coastal shrimp ponds. Based on a total water surface area of mariculture ponds and a total mariculture production of 2.57×106ha and 2.30×109kg, respectively, we estimated conservatively that approximately 4.77×104tons of total nitrogen and 3.75×103tons of total phosphorus are being discharged annually from the mariculture ponds into the adjacent coastal zones across China. Results demonstrated the importance of aquaculture pond effluent as a major contributor of water pollution in the coastal areas of China, and called for actions to properly treat these effluents in alleviating the eutrophication problem in the Chinese coastal zones.

A Quantitative Management Tool Reflecting Impact of Nutrient Enrichment from Mariculture in the Levantine Basin

Mariculture production increased significantly in recent years due to global rise in human population. However, in addition to providing food, fish farms are also a source of nutrients and antibiotics to the water column. Here, we research the nutrient pollution originating from fish cages in the Eastern Mediterranean by utilizing a Lagrangian modeling approach that followed trajectories of the water parcels. The effects of farm size and the farm’s distance from the shoreline were included in the model, and biological uptake and sinking of nutrients were incorporated into the analysis. By using computations of back-trajectories examining the water origin of strategically important shoreline areas, such as desalination plants, we were able to identify which of the proposed farm locations were potentially harmful. The results suggest that remotely-located, smaller and spatially distant farms are more preferable to limit the nutrient and antibiotic effluent resulting from mariculture activity.

Potential environmental drivers of a regional blue mussel mass mortality event (winter of 2014, Breton Sound, France)

In the context of global change, increasing mariculture production has raised particular concerns regarding its environmental impact and sustainability. Molluscs and particularly blue mussel account for a significant part of this total production. Although blue mussels are considered to be pretty resilient to environmental disturbances, we report in this study an unprecedented mussel mortality event that occurred during the winter of 2014 in the Breton Sound. 9000metrictonnes of mussels were lost and mortality rates up to 100% were recorded at some farming areas. Through a coupling approach, the present work aims to better understand the potential environmental drivers associated with those mortalities. Firstly, we analysed long-term in situ and satellite data from environmental monitoring networks (available since 1998) to characterize the variability of seawater masses of the sound during the winter of 2014. Secondly, we used modelling simulations to study the possible relationship between seawater hydrodynamics and observed spatio-temporal patterns of mussel mortalities. From January to April 2014 at the long-line culture site where mortalities started, seawater temperatures ranged from 8.3 to 13.3°C (10.2±0.8°C). Salinity and turbidity values showed successive and short drops (below 16; 29.3±2.3) and numerous peaks (above 70 NTU; 17.4±13.4 NTU) respectively. Winter conditions of 2014 were encountered along the entire French Atlantic coastline and linked to the sixth highest positive North Atlantic Oscillation (NAO+) index recorded since 1865. These particular environmental variations characterized the winter of 2014 but also others whereas no comparable mussel mortality rates were reported. Exact causes of the 2014 mortality event are still unknown but we showed these environmental variations could not alone be responsible. These have likely affected the sensitivity of the blue mussel populations that were already weakened by early spawning. Meanwhile, these may have facilitated the apparition of a pathogenic strain of Vibrio splendidus isolated on moribund mussels at that time. Our modelling simulations suggested that this pathogenic strain could spread through hydrodynamic patterns and drive the observed mussel mortalities. If this pathogenic strain recurs in future years, particularly with the added stress associated with climate change, mussel mass mortality events may exceed the resilience of this species.

Effects of CO2 levels and light intensities on growth and amino acid contents in red seaweed Gracilaria lemaneiformis

The seaweed Gracilaria lemaneiformis is largely maricultivated in China, for use as food and as a material in the agar industry. This alga experiences ocean acidification caused by rising atmospheric CO2 levels, and experiences changing light levels caused by self-shading during the later period of mariculture. In this study, growth and amino acid (AA) content responses of G. lemaneiformis to different CO2 levels (the present and the predicted increased levels) and varying light levels at 28 (±1)°C temperature conditions were investigated. The results showed that a higher light level enhanced algal growth and decreased water loss, but reduced AA accumulation. Decreased pH levels (as a result of CO2 elevation) also enhanced algal growth and reduced AA contents, but the decreases in the AA score at the lower pH levels were not significant under the two light level treatments. In this study, the light treatments had greater influences on growth and AA contents than CO2 levels. The results suggest that G. lemaneiformis quality will be negatively affected during the later mariculture production period as levels of CO2 rise and global temperatures increase.

Development of three-valent vaccine against streptococcal infections in olive flounder, Paralichthys olivaceus

Streptococcus iniae and S. parauberis types I and II are major bacterial pathogens affecting the olive flounder, Paralichthys olivaceus. With the introduction of formalin-killed vaccine for S. iniae, recent epidemiological studies have indicated that S. parauberis infections are becoming increasingly severe and frequent in the olive flounder farming industry. Here, the formalin-killed bacterins were used to develop a three-valent vaccine against three streptococcal infections, and its efficacy was assessed in laboratory- and field-challenge trials. In the laboratory-challenge test, it obtained 75%, 75% and 90% relative percent survival (RPS) values in vaccinated olive flounders challenged with S. iniae, S. parauberis type I, and S. parauberis type II, respectively. For the field-challenge trial, the three-valent vaccine was administered to over 100,000 olive flounders, which were compared to non-injected control fish. An RPS of 74% was observed when S. parauberis infection naturally occurred at 11 fish farms. Serum antibody measurements using olive flounder immunoglobulin-specific antibodies indicated that immunized fish had significantly higher serum antibody levels than control fish up to 6months post-vaccination. These results demonstrate that the three-valent vaccine using formalin-killed bacterins could effectively protect olive flounders against three major streptococcal infections. Statement of relevanceThe olive flounder, P. olivaceus, is an economically important fish species in Northeast Asia and the most valuable fish species in South Korea, corresponding to 56.5% of the total mariculture production in 2010 (Baeck et al., 2006). However, streptococcal infections often break out among farmed olive flounders subjected to certain conditions (e.g., high stocking density, poor water quality and high water temperature), leading to mass mortality and severe economic losses (Baeck et al., 2006; Cho et al., 2008) Antibiotic treatments are usually recommended to address such outbreaks, but the prevalence of multi-drug-resistant bacteria means that antibiotic compounds are not always able to eradicate the infections (Creeper and Buller, 2006).The Gram-positive bacteria, Streptococcus iniae and S. parauberis, cause streptococcosis and have severe effects on aquaculture of the olive flounder, barramundi, channel catfish, European sea bass, rainbow trout, striped bass, tilapia, turbot and yellow tail (Gudmundsdóttir and Björnsdóttir, 2007; Han et al., 2011). In the olive flounder, fish infected with S. iniae usually show severe pathological changes, such as darkening, exophthalmia, rectal hernia, abdominal distension, ascites and congestion of intestinal organs, whereas fish infected with S. parauberis rarely exhibited any remarkable pathological finding except for darkening of the skin (Kim et al., 2006).Some vaccines have been reported to prevent S. iniae infection, showing high relative percent survival (RPS) among olive flounders in laboratory trials; such vaccines are now commercially available (Cheng et al., 2010a). However, recent epidemiological studies have suggested that S. parauberis infection has increased and become more severe and frequent as much as infections of S. iniae, which was previously considered the major bacterial pathogen among olive flounder (Park et al., 2012; Park, 2009; Perera et al., 1998). S. parauberis can be divided into two serotypes (types I and II) based on serological testing of a distinctive capsular polysaccharide layer (Bromage and Owens, 2002; Plant and Lapatra, 2011). Since the two serotypes possess specific antigenic characteristics, a vaccine should be able to address both types in order to effectively prevent S. parauberis infection.The present study was undertaken to develop a three-valent vaccine against both serotypes of S. parauberis plus S. iniae using formalin-killed vaccine preparation method. The efficacy of this vaccine against the major streptococcal infections of olive flounder was calculated as RPS and conducted in both laboratory trials and large-scale field trial. This vaccine will be highly useful and more advantageous since the use of this does not require several antibiotics which means safer food production and more sustainable environment.

Cultivo de Bijupirá (Rachycentron canadum) em Cananeia, SP, Brasil. Avaliação da viabilidade utilizando geoprocessamento

Cultivation of cobia (Rachycentron canadum) in Cananeia, SP, Brazil. Feasibility assessment using GIS The Food and Agriculture Organization of the United Nations (FAO) frequently publishes reports about world fisheries production. These reports state wild fish stocks increasingly depleted and mariculture production growth in the past decade. The mariculture emerged then as an alternative to food production and generating income. Cobia, Rachycentron canadum, has been highlighted in recent years and is being studied in different aspects aiming its commercial production in Brazil. As mariculture has expanded, the development of management instruments for coastal zone is shown increasingly necessary. As establishing a sustainable basis to select the proper location to install fish farming it is possible to maximize the efficiency mariculture, producing raising the maximum number of organisms with minimal costs. This viability occurred through the understanding of the relationship between the physiological requirement of the aquatic organism selected and the environmental conditions. Data were obtained through literature searches, documents from government agencies, restitution of satellite images and field sampling organized in a manager geodatabase and analyzed using geostatistical interpolation, distance and density analysis to define ideal areas of Cananeias estuary and coastal zone to cultivate Cobia. The current

Cryptophyte bloom in a Mediterranean estuary: High abundance of <em>Plagioselmis</em> cf. <em>prolonga</em> in the Krka River estuary (eastern Adriatic Sea)

During the June 2010 survey of phytoplankton and physicochemical parameters in the Krka River estuary (eastern Adriatic Sea), a cryptophyte bloom was observed. High abundance of cryptophytes (maximum 7.9×106 cells l–1) and high concentrations of the class-specific biomarker pigment alloxanthine (maximum 2312 ng l–1) were detected in the surface layer and at the halocline in the lower reach of the estuary. Taxonomical analysis revealed that the blooming species was Plagioselmis cf. prolonga. Analysis of the environmental parameters in the estuary suggested that the bloom was supported by the slower river flow as well as the increased orthophosphate and ammonium concentrations. The first record of a cryptophyte bloom in the Krka River estuary may indicate that large-scale changes are taking place in the phytoplankton community. Such changes could have a major impact on the natural ecosystem dynamics and the mariculture production in the area.

A genetic linkage map of kelp grouper (Epinephelus bruneus) based on microsatellite markers

Kelp grouper (Epinephelus bruneus) is an important aquaculture species in Japan, Korea and China. Mariculture production of the species has increased due to its high demand and market price. However, some problems affect kelp grouper aquaculture such as the low growth rate, high mortality due to diseases and low ability to survive the larval stage. To analyze economically important traits, genetic linkage maps are an effective tool. We constructed sex-specific linkage maps of kelp grouper using 222 microsatellite markers. The male map consisted of 23 linkage groups with 161 markers and the female map consisted of 25 linkage groups with 173 markers. The total lengths of the male and female maps were 650.5cM and 944.4cM, respectively, and the average intervals were 5.0cM and 6.7cM, respectively. The average ratio of recombination between males and females was 1:1.5. Moreover, syntenic sequence comparisons provided basic information of several potential candidate genes affecting organism physiological and biochemical reactions. Based on the linkage map, further quantitative trait loci (QTL) or candidate gene(s) detection can be anticipated to contribute to assist breeding programs of kelp grouper. In addition, by providing basic genome information of kelp grouper, the map provides a first step towards comparative QTL as well as comparative genome analyses with other groupers in the future.

Mariculture: A global analysis of production trends since 1950

Abstract Aquaculture is one of the fastest growing global food animal production industries and, according to the United Nations Food and Agriculture Organization (FAO), now accounts for nearly half of global food fish supply. This proportion is anticipated to grow in the coming decades as global capture fisheries continue to stagnate and global demand for seafood continues to rise. As the significance of aquaculture grows, the marine and brackish (‘mariculture’) subsector is of particular interest for analysis because of its growing influence on the development of global aquaculture and its known negative impacts on marine biodiversity and coastal health. In this context, and based on known global data limitations and past experience with fisheries and aquaculture statistics reported to the FAO, there is reason to independently verify the FAO's global database of mariculture production statistics. These data were therefore re-estimated and global mariculture production from 1950 to 2010 was GIS-mapped at a higher spatial resolution than available thus far. This new database indicates that, unlike for capture fisheries, the current understanding of historical global mariculture trends is reasonably accurate; however, some uncertainty remains in the accuracy of reported mariculture production statistics at the country level, most notably in China. Thus, mariculture statistics should still be used with caution. Finally, the new database independently confirms global ‘farming up the foodweb’, and briefly evaluates whether it is really the case that nearly half of all ‘fish’ consumed nowadays originate from aquaculture.

MARICULTURE DEVELOPMENT IN INDONESIA: Prospects and Constraints

Mariculture is an important component of Indonesian fisheries and aquaculture production, directly contributing an estimated US$ 320 million in 2008. Because most mariculture production is focussed on producing for export markets, mariculture production is an important source of foreign earnings for the Indonesian economy. This paper reviews the current status and prospects for continuing development of mariculture in Indonesia. Currently the major mariculture commodity in Indonesia is seaweed for carrageenan production. Seaweed production accounts for 98% of total Indonesian mariculture production and 84% of value. The other major commodity groups are marine finfish and pearl oysters. Commodities being developed for mariculture in Indonesia include abalone and spiny lobsters. Prospects for continued development of mariculture in Indonesia appear positive. Indonesia has several advantages for mariculture development, including many potential mariculture sites, a stable tropical climate, and does not suffer from cyclonic storms. The Government of Indonesia is planning to increase aquaculture production substantially over the next four years, including mariculture production. Globally, demand for seafood products is expanding due to increasing population and increased per capita consumption of fish products. Constraints to the continued development of mariculture in Indonesia include: limited seed supply, particularly of species which cannot be economically produced in hatcheries, such as spiny lobsters; need to develop more efficient production systems for some marine finfish; the need to improve environmental sustainability by improving feeds and reducing environmental impacts; and market issues relating to environmental sustainability.

Development of mariculture and its impacts in Chinese coastal waters

China has a long history of aquaculture. Since the 1980s, mariculture has been considered by the government as an increasingly important sub-sector of aquaculture. Mariculture provides nutritional and economic benefits, and decreases the intensity of exploitation on declining wild living resources. China now has the highest mariculture production in the world. Kelp made up 50–60% the total Chinese mariculture production in 1967–1980. Production of Laminaria japonicaAresch, the leading species, reached 252, 907 t (dry wet) in 1980. The percentage of kelp production decreased after 1981 because of proportionally greater production of molluscs, shrimps and finfish. Marine finfish and mollusc production increased sharply after 1990. In 2001, the total mariculture production reached 11,315,000 t from a production area of 1,286,000 ha. The rapid development and changes in mariculture species have aroused increasing concern about mariculture’s impact on the coastal environment. The impact of coastal aquaculture, such as water quality deterioration and contaminants, will have a significant bearing on the expansion of mariculture. The key of improving and maintaining the long-term health of mariculture zones lies in adopting sustainable culture systems. It is imperative that the density of stocking fish and other economically important organisms such as oysters, and scallops, be controlled, in addition to restricting the total number of net-cages in the mariculture zones. The authors suggest moving rafts (cages) periodically and to development of a fallow system in which area fish culture will be suspended for 1–2 years to facilitate recovery of the polluted sediment. Moving fish culture offshore into deeper waters is also suggested. The authors also believe that large-scale seaweed cultivation will reduce eutrophication in coastal culture zones in China.

A comparative study on morphological differences in the olfactory system of red sea bream ( Pagrus major) and black sea bream ( Acanthopagrus schlegeli) from wild and cultured stocks

The improving technology in artificial propagation of aquatic animals is having a direct effect on increasing aquaculture fishery production of many aquatic food species throughout the world. High-valued fish species are being produced en masse and released into the wild to augment populations depleted due to over-fishing and habitat degradation. This study was conducted to determine the effect of procedural conditions in mariculture hatcheries on the olfactory systems of fish in Kagoshima Prefecture, Japan, and to compare the results with fish from wild stocks. Red sea bream ( Pagrus major) and black sea bream ( Acanthopagrus schlegeli) were suitable candidates for this study because of their economic importance and history in mariculture production, especially ongoing restocking of natural populations via stock enhancement programs in Japan. An extensive survey revealed a high percentage of fish with an abnormal single olfactory nasal opening. The single abnormal nasal opening contrasted strongly with a pair of natural nasal openings, an anterior and a posterior nares, in normal fish of both species whereby olfactory water is sampled when the fish swims. Ultrastructural observation of lamellar topography demonstrated not only a substantial variation in sensory epithelial distribution patterns in red sea bream of cultured stock but also showed that the sensory epithelial area in abnormal cultured fish was significantly smaller ( P<0.005) than the lamellar area in wild fish. The densities/mm 2 of microvillous and ciliated olfactory receptor neurons in both species were not significantly different when normal fish were compared with abnormal fish. Nonetheless, there were some notable irregularities in distribution patterns of the two receptor neurons on the lamellar surface. In abnormal red sea bream, the density of ciliated nonsensory cells was relatively higher than the normal fish. The kinocilia in cultured fish (normal red sea bream with anterior and posterior nares; CNR, 6.45±0.83 and abnormal red sea bream with a single nasal opening; CAR, 8.05±1.39 μm SD) were significantly longer ( P<0.05) than the ones observed in wild fish (5.46±1.39 μm SD). Further, ciliary beat cycle and metachrony were evident in normal fish olfactory epithelia but were usually not evident in abnormal fish. The results indicated that gross and micromorphological abnormalities in the olfactory systems of fish are a consequence of certain procedural condition(s) in mariculture facilities. The physiological and behavioral implications of morphological deformities in fish olfactory systems are discussed, especially in the context of ensuring production of healthy, normal fish for marine ranching programs and ecological preservation.

The use of hydrous iron (III) oxides for the removal of hydrogen sulphide in aqueous systems

The potential for iron (hydr)oxides to remove dissolved hydrogen sulphide from seawater has been examined under flow-through conditions. Ferrihydrite (a hydrous iron (III) oxide) was stabilised by precipitation onto zeolite pellets, and rates of sulphide removal were determined under laboratory conditions at pH 8.5. Sulphide removal kinetics were dependent on the initial sulphide concentration, substrate mass and flow rate. The experimental data suggest that these parameters can be optimised to result in the rapid and effective removal of hydrogen sulphide. The results from laboratory experiments compared favourably with sulphide removal kinetics determined in a series of experiments performed online in a recirculating mariculture production system. However, the presence in solution of ligands such as phosphate may also significantly affect reaction rates; a 50% reduction in sulphide removal rate for substrate removed from an online system was partly attributed to phosphate adsorption. The formation of a more crystalline, less reactive iron (hydr)oxide in recharged substrate was the likely result of FeS oxidation, which may also have contributed to the observed reduction in sulphide removal rates. Ferrihydrite-coated zeolite would appear to provide an efficient, low-cost method for sulphide removal, which is particularly suited to relatively small-scale aqueous flow-through systems. The reaction of iron (hydr)oxides with dissolved sulphide is also accompanied by a distinct colour change due to the formation of black FeS (s) which, under appropriate conditions, may be used as a rapid indicator of sulphidic conditions.

Summary of mariculture production in countries neighbouring the European Union

Summary of mariculture production in countries neighbouring the European Union

Fin-fish Fisheries' Potential in the Territorial Waters of Kuwait

Fishing has been a part of the traditional heritage of Kuwait for centuries. Nearly 130 fish species are known to occur in Kuwait waters. The fin-fish fisheries are licensed to be caught by gill nets, gargoor traps and hand lines using dhow wooden and fibreglass boats. A complete ban on fishing within the 3-mile limit off the Kuwait coast and Kuwait Bay has been maintained as part of conservation of fish breeding and nursery areas. However only Hadra stake nets are allowed to be operated for fin-fish catches within the coastal zone. Annual 1995 fin-fish catch comprised nearly 80% of the total marine fisheries' harvest. Recent catch composition of highly palatable fish, namely the silver croaker, Otolithes argenteus, the shad, Hilsa ilisha, the silver pomfret, Pampus argenteus, the brown spotted grouper, Epinephelus tauvina and the silvery grunt, Pomadasys argenteus has been found to be 23, 17, 16, 5 and 3% of the total fin-fish catch respectively. It has been noticed that edible fish preference varies from state to state as species-specific preferences appear to differ among Gulf tribes. The consumer demand for fish and the price stability equilibrium have been evaluated. The pattern of regional fin-fish import and export has been discussed. Although mariculture production potential has been estimated to be high, only 90 tons/annum of sea bream has been cultivated in floating cages. Kuwait Institute of Scientific Research in collaboration with the Public Authority for Agriculture Affairs and Fish Resources have initiated cultivation of tilapia and other fish species in the local brackish water fish farms. Suggestions and recommendations have been made for sustainable fin-fish development in Kuwait.

Inheritance of size as estimated by principal component analysis at two temperatures in Penaeus vannamei

Five species of penaeid shrimp are being considered for mariculture production in the southern United States. Four of these, Penaeus aztecus, P. setiferus, P. stylirostris, and P. vannamei, are the subject of an investigation of genetic differentiation among wild stocks using the electrophoretic technique. Preliminary results indicate a low level of genetic variation and little geographic differentiation within species. The implication of these findings for the creation of a foundation population for the selective breeding program is discussed.Many questions have resulted from the initial efforts to employ a quantitative criterion in the selection of future broodstock from pond-reared adults. One response has been morphometric studies to evaluate other possible selection criteria. Several morphological measures are identified as potential selection criteria and discussed with regard to the handling necessary to make each measurement and the correlation between these measurements and tail weight.An overview of the penaeid mariculture methodology used in Texas is presented as a justification for a program using mass selection rather than other methods to improve tail weight grow-out.

Strontium is required for statolith development and thus normal swimming behaviour of hatchling cephalopods.

When cephalopod eggs were incubated in artificial sea water it was found that they sometimes resulted in hatchlings with defects of the statocyst suprastructure, leading to the severe behavioural defect of uncontrolled swimming. Experiments in defined media (seven basic salts mixed in deionized water) with seven species of cephalopods demonstrated clearly that there is 100% normal development of the aragonite statoliths when strontium levels were 8 mg l-1. Conversely, statoliths did not develop when strontium was absent. In cuttlefish, the growth of the cuttlebone was also affected adversely when strontium was absent. In mariculture production tanks, supplementing commercial artificial sea water with strontium to normal levels of 8 mg l-1 almost eliminated the occurrence of abnormal hatchlings. Circumstantial evidence indicates that there is a critical window in development during which strontium is required for normal development. The role of strontium in biomineralization during embryogenesis is unknown, but it appears to be important in the Mollusca.

Ocean ranching of abalones and scallops in northern Japan

Ezo abalone, Haliotis discus hannai, is one of the most important species for ocean ranching along the rocky shores of Hokkaido. The number of juveniles produced from hatchery and natural seed in 1980 is estimated at 1,150,000 and 798,000 respectively. The juveniles are released in rocky areas of the Sea of Japan around Hokkaido every year. At Otaru, Yoichi, and Furubira, for example, 5,000 to 20,000 juveniles are released annually and they grow to 75 mm in shell length in 2 to 3 years. The recapture rates for abalone are 5–10% for hatchery and 20–25% for natural seed. The giant ezo scallop, Patinopecten yessoensis, is one of the most important species on gravel-bottomed habitats in Hokkaido. This species is maricultured on a large scale in Funka Bay and Lake Saroma and is propagated in the Okhotsk Sea, the Nemuro Channel, and at other areas on Hokkaido's coasts. The propagation has been especially successful in Sarufutsu on the Okhotsk Sea. Mariculture production of this species in Hokkaido has increased rapidly, from 5,625 tons in 1971 to 69,532 tons in 1977. This rapid increase, however, has resulted in a number of problems, such as reduced growth rates, diseases, and higher death rates. Toxins produced by plankton, Protogoniolax sp. and Dinophysis fortii, resulted in a sharp decrease in the production in 1979 and 1980. On the other hand, propagation of the species has developed with the availablity of large-scale seedbeds, nursery culturing, and improvements in transportation. The production by propagation showed a rapid increase from 8,231 tons in 1971 to 68,774 tons in 1980. Propagation, however, has recently faced problems similar to those encountered in mariculture: tardiness in growth, underdevelopment of the gonad, and generation of parasites.

Developing a selective breeding program for penaeid shrimp mariculture

Five species of penaeid shrimp are being considered for mariculture production in the southern United States. Four of these, Penaeus aztecus, P. setiferus, P. stylirostris, and P. vannamei, are the subject of an investigation of genetic differentiation among wild stocks using the electrophoretic technique. Preliminary results indicate a low level of genetic variation and little geographic differentiation within species. The implication of these findings for the creation of a foundation population for the selective breeding program is discussed. Many questions have resulted from the initial efforts to employ a quantitative criterion in the selection of future broodstock from pond-reared adults. One response has been morphometric studies to evaluate other possible selection criteria. Several morphological measures are identified as potential selection criteria and discussed with regard to the handling necessary to make each measurement and the correlation between these measurements and tail weight. An overview of the penaeid mariculture methodology used in Texas is presented as a justification for a program using mass selection rather than other methods to improve tail weight grow-out.

Legal and institutional factors affecting mariculture in texas

Abstract Aquaculture and its specialized cousin, mariculture, provide some potential additional food sources and economic revenues. Technological barriers to increased mariculture production are being removed, but many legal and institutional barriers remain. Examples of the current and potential regulation of mariculture in Texas by state and federal authorities are examined. The effect of various state and federal regulations on the development of mariculture is discussed from a legal and institutional viewpoint. The potential for growth of mariculture is considered questionable without regulatory reforms, particularly at the federal level.