Private Hatcheries Research Articles

Experimental herpes-like viral infections in marine bivalves: demonstration of interspecies transmission.

Since 1972, herpes-like virus infections have been reported in several marine bivalve species around the world. Viral detection was often associated with high mortality rates in larvae and spat. To determine whether a single virus is able to infect different bivalve host species, we carried out experimental transmission assays. As a first step, 8 assays were performed to infect axenic Crassostrea gigas larvae with virus from infected C. gigas larvae using a previously described protocol. The protocol appeared reliable and PCR was confirmed as a powerful technique for detecting viral DNA in experimentally infected oysters. The defined protocol was then applied to infect different bivalve species. Interspecies viral transmission was demonstrated under laboratory conditions. The same phenomenon may occur in private hatcheries and may be promoted by intensive rearing conditions. This hypothesis is reinforced by reports of concomitant mortalities in the larvae of several bivalve species and by the first molecular analysis of infected larval samples.

Cost Analysis for Integrating Cryopreservation into an Existing Fish Hatchery

AbstractFish sperm cryopreservation is documented by a large body of technical research. However, there are no reports of the economic requirements for using this technology in aquatic species. This study establishes a generic analysis of the investment and operating costs required to integrate sperm cryopreservation into existing fish hatcheries and can serve as a template for implementation of cryopreservation programs. Equipment and supplies were identified in a species‐independent description of sperm cryopreservation, and capital and operating costs were documented for private and public hatcheries at three production capacities (3,000, 6,000, and 9,000 0.5‐mL straws). Compared to public hatcheries, investment costs were found to he 70% higher, and operating costs 20% higher for private hatcheries due primarily to interest on borrowed capital. Equipment costs were dependent on the scope of work. Investment in required equipment incurred costs of $5,460 to $10,458 (public) or $9,497 to $18,190 (private), depending on production level. Purchase of optional research equipment increased initial investment by 300% without increasing output. Per unit costs decreased at higher production levels for all scenarios, but greater economies of scale were associated with private research hatcheries. Production costs ranged between $6.13 and $1.86 per straw (private), to $1.59 to $1.18 per straw (public). Increased commercialization is expected to occur as research protocols for fish sperm cryopreservation are applied in the private sector and markets for cryopreserved sperm are established.

Induction of out-of-season spawning in walleye ( Stizostedion vitreum)

Simple environmental and hormonal treatments were used to induce out-of-season spawning in walleye Stizostedion vitreum up to 10 weeks prior to the normal reproductive season. Wild walleye were captured in the autumn, held in earthen ponds, and in late January, February, and March (approximately 10, 6, and 3 weeks prior to natural spawning), 16–20 female and 4–8 male walleye were recaptured and transferred to indoor tanks. Water temperature was raised from 2°C to 10°C over a one week period, and photoperiod held at 12 h light: 12 h dark. The females were injected with either human chorionic gonadotropin (hCG), des-Gly 10 [ d-Ala 6] LHRH-ethylamide (LHRHa), hCG and 17 α,20 β-dihydroxy-4-pregnen-3-one (17,20-P), or saline as a control. Each month, at least some females in each treatment group were successfully induced to ovulate. No control fish ovulated at any time. In January, hCG was the most effective treatment at inducing ovulation (3/5 fish). In February and March, all but one hormone-injected fish ovulated. In general, the eggs collected from fish treated with either hCG or LHRHa were of good quality with overall survival highest in hCG-treated fish. Eggs collected from 17,20-P-treated fish were small and had very low survival. In February and March, serum levels of estradiol-17 β and testosterone were different between fish treated with 17,20-P and those treated with either hCG or LHRHa. Out-of-season spawning could be used to provide walleye fry for intensive culture systems at multiple times of the year, thereby facilitating research on indoor fry culture. In addition, walleye fingerling production could be initiated as early as January, allowing public and private hatcheries to produce larger age-0 walleye fingerlings for stocking than would otherwise be possible.

Predation at Intermountain West Fish Hatcheries

During 1993-94, we observed predators and surveyed managers at Intermountain West fish hatcheries to quantify the extent and species responsible for depredation losses. Our field study confirmed hatchery managers' impressions that great blue herons (Ardea herodias), black-crowned night herons (Nycticorax nycticorax), ospreys (Pandion haliaetus), and California gulls (Larus californicus) were the most important predators. At 2 intensively monitored hatcheries, we calculated losses to avian predation to be 7.0 and 0.6% of annual production, in contrast to the managers' estimates of 15% at each hatchery. Feeding mostly on dead or moribund fish, feral cats (Felis catus), raccoons (Procyon lotor), and striped skunks (Mephitis mephitis) had little effect on fish production. Private hatchery managers estimated higher (13%) total depredation losses than did managers of state owned hatcheries (5%). Hatchery managers viewed netting to be the only effective nonlethal control measure.

Production and Extended Spawning of Cultured White Bass Broodstock

Abstract Our research focused on the development of domesticated broodstock of white bass Morone chrysops to reduce or eliminate the dependence of public and private hatcheries on wild-caught fish. Juveniles, obtained from spawning wild white bass, were reared to a mature size in an outdoor tank system under ambient environmental conditions. At 1 year of age, a few males were mature, and by 2 years of age all males and females were mature. Females were induced to ovulate with human chorionic gonadotropin (550 IU/kg) and then strip-spawned. Mean estimated egg production was 98,273 eggs/kg for 2-year-old fish and 127,805 eggs/kg for 3-year-old fish. Holding mature fish in reduced water temperatures extended the spawning period by 3 months. The use of cultured white bass broodstock should facilitate hatchery operations for stocking public waters and for hybrid striped bass aquaculture.

Short-and Long-term Cryopreservation of Sperm and Sperm Suspension of the Grouper, Epinephelus malabaricus (Bloch and Schneider)

Essential factors which affect the feasibility of cryopreserving sperm of the grouper, Epinephelus malabaricus (Bloch and Schneider), were determined by comparing percentage of motile spermatozoa, duration of storage life and fertilization rate of eggs when available. Fertility of sperm after thawing was maintained by using 10% dimethyl sulfoxide (DMSO) as a cryoprotectant with less than 10 minutes equilibration. An optimal ratio of 85% for sperm suspension from sliced testis or fresh milt diluted 20 times in Ringer solution for marine fish: 10% DMSO: 5% glucose is suggested. The addition of 15% Menezo Medium B2 INRA to the milt mixture resulted in the retention of higher progressive motility of cryopreserved sperm. The use of isopropanol with dry ice at -75°C or liquid nitrogen vapor at -100°C as freezing medium simplified the freezing procedure. Analysis of the motility of post-thawing sperm using the Hamilton-Thorn motility analyzer showed that the performance of one-and three-month old cryopreserved grouper spermatozoa was slightly poorer in terms of path velocity, progressive velocity, track speed and straightness. The use of microwaves in thawing frozen milt in polyethylene straws was found feasible and convenient with an optimum degree of power at 40% and conditional duration of 30-70 seconds. The post-thawing fertility of the spermatozoa was better when frozen immediately upon collection or right after transporting the material of raw milt or sperm suspension at 4°C for 1-2 hours. Fertility records of 78±18%, 83±3%, 95±0%, 75±32%, 13±1%, 95±0% and 66±12% were obtained for 1-, 17-, 41-, 54-, 128-, 278-and 291-day cryopreserved sperm. (65.58-91.92% in controls) during the spawning seasons of 1990 and 1991. Preliminary extension to a private hatchery in 1991 resulted in additional production of about 50 million fertilized eggs by using cryopreserved sperm of E. malabaricus eight times when fresh milt was not available in the field.

Economic analysis of an integrated milkfish broodstock and hatchery operation as a public enterprise

The National Bangus (Milkfish) Breeding Program of the Philippines, which was launched by the Philippine government in 1981, had succeeded in spawning milkfish in captivity and in rearing the eggs to fry that were stockable in ponds. The physical productivity and economic viability of an integrated milkfish broodstock and hatchery as a public enterprise is analyzed, using SEAFDEC research findings as bases for analysis. Discounted cash flow computations show the repayment schedule for investments in structures and equipment, and operations and maintenance expenses for both broodstock and hatchery operations covering a period of 15 years. Revenues came from the sales of fry. The analysis was based on an annual stocking of 100 milkfish (200–250 g/piece) per cage with a diameter of 10 m. Egg production started during the fifth year. Investment in the hatchery facilities started during the fourth year and expansion occurred in the subsequent years to accommodate the eggs produced for rearing to the fry stage. Economic indicators, net present value (NPV) and internal rate of return (IRR), showed negative figures. The trend, however, was upward, starting during the sixth year of operation. Sensitivity analysis was done to determine the effects of changes in operational efficiencies, such as survival rates and stocking densities to the return on investment (ROI) in private hatcheries.

Density-Dependence at Sea for Coho Salmon (Oncorhynchus kisutch)

The success of expanded salmon hatchery programs will depend strongly on the degree of density-induced diminishing returns per smolt released. Several authors have addressed the question of density-dependent mortality at sea in coho salmon (Oncorhynchus kisutch), but have come to conflicting conclusions. We believe there are compelling reasons to reinvestigate the data, and have done so for public hatchery fish, using a variety of approaches. The results provide evidence that survival of these public hatchery fish is negatively affected, directly by the number of public hatchery smolts and indirectly by the number of private hatchery smolts. These results are weak, statistically, and should be considered primarily as a caution to those who, on the basis of other published work, believe that density-dependence does not exist. The results reported here also re-emphasize the often overlooked point that inferences drawn from data are strongly biased by investigators' views of how the systems of interest work and by the statistical assumptions they make preparatory to the analysis of those data.

Application of Statistical Power Analysis to the Oregon Coho Salmon (Oncorhynchus kisutch) Problem

Nickelson (1986; Can. J. Fish. Aquat. Sci. 43: 527–535) was unable to reject the null hypothesis (Ho) of density-independent marine survival rate for Oregon coho salmon (Oncorhynchus kisutch) when wild, private hatchery, and public hatchery stocks were analyzed separately. Thus, even though there appears to have been no consistent increase in adult abundance in recent years in spite of large increases in smolt abundance, Nickelson's analysis does not support the alternative hypothesis (HA) of density-dependent marine survival. Some fishery managers are using Nickelson's results to support proposals to increase smolt production further. I calculated statistical power for these cases, i.e. the probability that the null hypothesis of density-independence could have been rejected, even if marine survival were truly density-dependent. Power was below 0.19 for all cases, which meant that Nickelson (1986) had at least an 81% chance of making a Type II error (incorrectly accepting Ho), if Ho was actually false. Therefore, Oregon fishery managers should be cautious about making decisions on increased smolt production based on current data; they run a high risk of mistakenly assuming density-independent marine survival. More generally, managers should not take action based on a failure to reject a null hypothesis unless power is high.

A Viral Disease in Larvae and Juveniles of the Japanese Flounder Paralichthys olivaceus

From 1985 to 1987, outbreaks of a disease resulting in mass mortality occurred in larvae and juveniles of the Japanese flounder Paralichthys olivaceus cultured at prefectural and private hatcheries in Hiroshima Prefecture, Japan. The disease occurred in 10-30-d-old fish that were reared at about 18–20°C, and mortality usually reached 80–90% in a few weeks. The affected fish had opaque fins and a hyperplastic epidermis on the fins and skin. Electron microscopy revealed hexagonal virus particles in the nucleus (100–140 nm in diameter without an envelope) and cytoplasm (190–230 nm with an envelope) of the affected epidermal cells. Although isolation of the causative agent by the use of five fish-cell cultures was not successful, the disease was transmitted to healthy larval flounder by exposing them to a 0.45-μm filtrate of diseased fish homogenate. The agent's morphological features and its sensitivity to ether, to a pH of 3, and to a 30min exposure to 50°C indicate it is a herpesvirus.

The economics of tilapia fingerling production and marketing in the Philippines

Abstract. These analyses of the tilapia fingerling industry in the Philippines focus on the economics of production in different hatchery systems and on fingerling marketing channels. The analyses are based on cross-sectional data from government and private hatcheries in late 1982 and from December 1983 to March 1984. The relative profitabilities of different hatchery systems (land-based and lake-based) are estimated and economies of scale are analysed. Conceptual and methodological issues inherent in analyses based on cross-sectional data are discussed in the context of the extreme difficult standardizing inputs and output from private tilapia hatcheries which are characterized by wide variation in management practices.

Influences of Upwelling, Ocean Temperature, and Smolt Abundance on Marine Survival of Coho Salmon (Oncorhynchus kisutch) in the Oregon Production Area

The relationships between the marine survival of hatchery and wild coho salmon (Oncorhynchus kisutch) in the Oregon Production Area and ocean upwelling, ocean temperature, and smolt abundance were investigated. Hatchery coho appear to be more sensitive than wild coho to changes in upwelling-related factors although this difference may be due to errors in the estimates of wild smolts and adults that were used in the analysis. Two levels of upwelling (strong and weak), which are associated with a twofold difference in survival of hatchery coho smolts, were identified. Significant relationships were identified between survival of hatchery smolts and survival of wild smolts that migrated in strong upwelling years and sea-surface temperature during that year. Similar relationships were not as apparent for smolts migrating in weak upwelling years as they were for smolts migrating in strong upwelling years. Each major component of coho production (wild, public hatchery, and private hatchery), when treated separately, as well as public and private hatchery coho combined, exhibited linear smolt-to-adult relationships. Only hatchery plus wild coho that migrated in weak upwelling years and hatchery plus wild coho in all years combined exhibited nonlinear smolt-to-adult relationships. I concluded that these nonlinear relationships were caused by a shift in the stock composition of the Oregon Production Area coho population from predominantly high-survival, wild fish when smolt numbers were low to predominantly low-survival, hatchery fish when smolt numbers were high.

Are Better Anesthetics Needed in Fisheries?

Federal, state, and private fishery workers were asked which anesthetics they used and for which fish species; how the materials were used; the disadvantages or problems associated with their use; and the desired characteristics of an ideal anesthetic. Responses were received from 66 state or provincial hatcheries, 40 federal hatcheries, 3 private hatcheries, and 74 others who did not identify themselves by category. Tricaine methanesulfonate (MS-222) was by far the most commonly used anesthetic (145 users), followed by quinaldine (41), and carbon dioxide (18). Carbon dioxide and MS-222 are the only registered fish anesthetics. The most cited limitation on the use of MS-222 was the 21-day withdrawal period required after treatment. The ideal anesthetic should permit a reasonable duration of exposure, produce anesthesia within 3 minutes or less, allow recovery within 5 minutes or less, cause no toxicity to fish at treatment levels, present no mammalian safety problems, and leave low tissue residues after a withdrawal time of 1 hour or less.

FRESHWATER PRAWN FARMING IN TAIWAN—THE PATTERNS, PROBLEMS AND PROSPECTS1

ABSTRACTIn Taiwan, large acreages of suitable freshwater ponds, streams and dams, as well as irrigation canals used for culturing various freshwater fishes, are available to shift to freshwater prawn farming because of its proven good flavor, higher price and the established propagation and cultivation techniques. Since 1974, the number of stockable juveniles supplied by Tungkang Marine Laboratory (TML) and some private hatcheries has increased year by year from 110,580 to over 5,000,000 in 1978. Therefore, several culture patterns have been set up as demonstrations in TML and in the private farms consulted by TML. Extensive and intensive culture, polyculture with fishes, as well as river ranching, are discussed. The bottom choice of mud pond, sand pond, cement pond, and polyethylene sheet pond, and the food choice, mainly of egg custard, steamed rice, fish paste in early culture stage, with trash fish, cereals and prepared feed in late culture stage are summarized. The marketing system is discussed and an estimation of total production is made on updated investigation. A speedy solving of the listed local problems would lead to steady progress in freshwater prawn farming.

Effects of Five Diets on the Growth and Mortality of Fry to Fingerling Channel Catfish (Ictalurus punctatus)

The artificial propagation of channel catfish has been done continuously by Kansas fishery workers since the early 1920's. Mr. John Murphree, now at the Durant Oklahoma Hatchery, contributed much to artificial propagation, feeding and rearing of channel catfish during his tenure with the Kansas Forestry, Fish and Game Commission. Mr. Seth L. Way, who succeeded Mr. Murphree as Superintendent of Fisheries for the State of Kansas, also contributed much to artificial propagation, hatching, feeding and rearing of channel catfish. Mr. Way invented and put into use a channel catfish incubator which is now being used by state and private hatcheries. Mr. Way's feeding and rearing techniques also have been adopted by several state and private hatcheries. This paper is a preliminary report of experiments with certain diets and concomitant growth and mortality data on channel catfish from fry to fingerling stage. It is hoped that the data may prove of value to fishery workers of other state or private hatcheries artificially producing channel catfish.

Furunculosis in Trout and the Importance of Carriers in the Spread of the Disease

1. No evidence was found of the presence of furunculosis in trout farms. Over 100 trout from four farms in S. England were examined with entirely negative results.2. Of eighteen live trout taken from the Kennet, three were carrying the B. salmonicida in their blood. All three were in poor condition but alive and active, and two of them were so-called “black fish”.3. Bacteriological analyses of Kennet water at eleven selected points were carried out in the month of August. They revealed no serious pollution nor any definite relationship between high bacterial content and the disease.4. Laboratory experiments to test pathogenicity of B. salmonicida appear to show:(a) That the bacillus is lethal to goldfish when injected into the muscle but not necessarily so when rubbed into a skin wound.(b) That in the case of gobies infection from water polluted with pure broth cultures of B. salmonicida is possible and may cause death in about fifteen days after the introduction of the culture.(c) That fish (gobies) which had survived the last experiment for a period of six weeks were capable of infecting healthy “contacts”, when kept with them in fresh running water.5. A few laboratory experiments on the behaviour of B. salmonicida in sewage appeared to indicate that the bacillus persists longer in tap and distilled water than in crude sewage and sewage effluent.6. Specimens of fish (salmon and trout) infected with furunculosis were also received during the summer from the Rivers Lledr (Wales), Lyon (Scotland) and a private hatchery on the Test at Whitchurch. The conditions in the two latter cases suggested that the outbreak was mainly due to carriers.7. Measures suggested in the case of infected streams are: avoidance of over-stocking, bacteriological scrutiny of source of fresh stocks, removal of sick and ill-conditioned fish, and sewage control.