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1.
Miguel Vazquez Archdale Cherry Pilapil Aasco Yoshihito Tahara 《Fisheries Research》2008,91(2-3):291-298
Fishing trials were conducted in a pond using collapsible pots containing fish mince inside a “teabag” or cut fish baits. Scomber japonicus was minced (100 g) and packed in a teabag or cut in half; non-baited pots served as controls. Baits were placed inside box-shaped pots (2.3 cm mesh size) with two slit entrances. Trials consisted of 100-pot hauls/bait type using a 1-day soaking time. The crab catches of Charybdis japonica and Portunus pelagicus from “fish” and “mince teabag” baits were not significantly different, but differences were found for total catch and damselfish Chromis notata. Trials using 80 g of mince and 20 g of sugar as the “teabag” bait lowered the catch of C. japonica, Thalamita sima and Thalamita prymna but not P. pelagicus when compared with fish bait. Results indicate that the mince in teabags is as suitable as fish bait, and that adding substances to the mince might be used to make selective crab baits. 相似文献
2.
A comparative hatching study has been carried out with Reference Artemia Cysts as well as cysts from Argentina, Australia, Brazil, Canada, France, Italy, the People's Republic of China, the Philippines and the U.S.A. Hatching rate, percentage and efficiency vary considerably from one cyst source to another. These hatching criteria are, however, not strainspecific since significant variation is found among cyst batches from the same geographical origin.
The limitations of the “hatching efficiency” concept are discussed and a new criterion “hatching output”, i.e. the biomass of nauplii expressed in mg dry weight produced per gram cyst product, is proposed for evaluation of the hatching quality of Artemia cyst brands.
The hatching quality of Reference Cysts and cysts from Canada and Argentina can be significantly improved by incubation of the cysts at low salinity.
For almost all commercial sources the use of decapsulated cysts results in a significant increase of the hatching output. 相似文献
3.
Off flavor characterization and origin in French trout farming 总被引：1，自引：0，他引：1
Joël Robin Jean-Pierre Cravedi Anne Hillenweck Cyrille Deshayes Dominique Vallod 《Aquaculture (Amsterdam, Netherlands)》2006,260(1-4):128-138
The results of a study on off-flavor problems in four French trout (Onchorynchus mykiss) farms are presented. Methodological aspects on sensory analyses and volatile compounds quantification in fish are discussed. Detection of odorous compounds by gas chromatography–mass spectrometry shows that significant concentrations of geosmin (up to 18 μg/kg in fat) are found in trout. The sensory evaluation, the presence/absence of geosmin in the flesh and the identification of off-flavor compounds producers demonstrate the implication of Microcoleus in the appearance of earthy/musty off-flavors. The presence of this particular cyanobacterium is linked to the deterioration of water quality during the water recirculation period. Correlations between chemical and sensory detection in the flesh indicate that the taste evaluation enables the differentiation of the four categories “non-tainted”, “slightly-tainted”, “tainted” and “strongly-tainted”. However, the average concentrations of geosmin found for these different intensities are relatively limited, from 0.2 to 4.9 μg/kg. Finally, recommendations are made to allow a more effective control of off-flavor occurrences. 相似文献
4.
Dora Zouiten Ines Ben Khemis Raouf Besbes Chantal Cahu 《Aquaculture (Amsterdam, Netherlands)》2008,279(1-4):166-172
This work describes the ontogeny of the digestive tract in thick lipped grey mullet (Chelon labrosus) larvae reared until day 36 post-hatching with the semi-extensive technology in mesocosms. Diet was constituted by live preys, rotifers, Artemia and wild zooplankton, then compound diet was added from day 20 (p. h.). Linear growth, weight growth and digestive enzymes specific activities were studied during larval ontogeny. Pancreatic enzymes (trypsin and amylase) and intestinal enzymes (leucine-alanine peptidase “Leu-ala”, aminopeptidase N “AN” and alkaline phosphatase “AP”) were assayed in larvae sampled throughout the rearing trial to evaluate gastrointestinal maturation along the development.The trypsin specific activities were very high during the first two weeks and then declined as observed in marine fish species. A following increase in trypsin specific activity from day 20 was attributed notably to ingestion of particle compound diet. In contrast to the pattern generally described in fish larvae, amylase specific activity showed a continuous increase. This could be attributed to the fact that C. labrosus is an omnivorous species and suggests that the fish might be able to use efficiently diets containing higher levels of starch or other carbohydrates since the end of larval development.Relative expression of intestinal brush border membrane enzymes (AP and AN) and cytosolic enzyme (Leu-ala), showed an abrupt increase of both AP/leu-ala and AN/leu-ala ratios at day 8 (p. h.), indicating that maturation of intestinal tract in C. labrosus larvae is particularly precocious. It is assumed that larvae of C. labrosus might support early co-feeding and weaning strategies, which could reasonably be initiated since mouth opening. 相似文献
5.
Ninety sexually mature Cherax quadricarinatus females were exposed to various combinations of photoperiod and temperature for 2 months during the summer. Females were randomly assigned to either “winter” “semi-winter” or “summer” simulation treatments. In the “winter” treatment, crayfish were exposed to a simulated winter photoperiod (gradual decrease from 14L:10D to 10L:14D, 4 weeks at short day length followed by gradual increase to 14L:10D) and temperature (gradual decrease from 27 to 15 °C, held for 4 weeks, and then gradual increase to 27 °C). In the “semi-winter” treatment, crayfish were exposed to a simulated winter photoperiod and a summer temperature (27–29 °C). In the “summer” treatment, the crayfish were exposed to summer water temperatures and a photoperiod of 14L:10D. Following the 2 months of conditioning, the females were stocked for 7 months in small groups with males under environmental conditions similar to those of the “summer” treatment. All females were individually tagged and molting and spawning events were monitored. Females exposed to “semi-winter” conditioning in the summer, demonstrated a threefold increase in the rate of first spawning during the winter (December–February) compared with the other females. Crayfish breeders can easily implement these findings since shifting the breeding season into the winter only requires shortening of the photoperiod in the summer. The stocking of ponds in the spring with large nursed juveniles that hatched from eggs spawned in the winter, would allow the attainment of market size at the end of the limited growout season in temperate zones. 相似文献
6.
Roger W. Doyle Somsuk Singholka Michael B. New 《Aquaculture (Amsterdam, Netherlands)》1983,30(1-4):237-247
“Indirect selection” is exerted on a trait indirectly, by means other than artificial selection for the trait itself. Expressions are derived for calculating the intensity of indirect selection in aquaculture environments. The calculations are illustrated with growth-rate data on M. rosenbergii from farm ponds in Thailand, and with computer-generated data which simulate measurements made during a multiple mark-recapture experiment. Indirect selection for growth is probably negligible in Thai prawn farms and hatcheries at present, but small changes in management practice could exert strong indirect selection on growth rate. One very effective change appears to be collecting broodstock as early in the production cycle as possible. Control of indirect selection may be useful for the genetic improvement of aquaculture stock, especially in developing countries and other situations where an intensive artificial selection program is not economically or biologically desirable. Like all selection programs, the probability of success is critically dependent on the genetics of the traits being selected. 相似文献
7.
Jorge Chvez-Villalba Jean Barret Christian Mingant Jean Claude Cochard Marcel Le Pennec 《Aquaculture (Amsterdam, Netherlands)》2002,210(1-4):171-186
Gametogenesis, emitted gametes and larval yield (D larvae) of the oyster, Crassostrea gigas (Thunberg), were simultaneously examined in laboratory under two different conditions of temperature and photoperiod. One batch (“natural” cycle, NC) followed the equivalent cycle of average conditions of these parameters measured in La Tremblade (Charente-Maritime, France) during the last 15 years. The second batch (“accelerated” cycle, AC) was maintained under a variation two times faster of these parameters. Three conditioning experiences were performed during October, November and December 1998 with oysters from both NC and AC conditions. “Accelerated individuals” produced oocytes in growing stage from October and mature oocytes were noticed from December. In contrast, oysters from NC produced growing oocytes until January. Animals in AC produced 42% (October), 56% (November) and 96% (December) of mature oocytes after conditioning. Only the “natural” lot conditioned in December showed growing (23%) and mature oocytes (8%). Higher Walne–Mann index (WMI) values were recorded for “accelerated oysters” and significant differences (P<0.05) between treatments were noticed during October and November, suggesting nutrient accumulation before conditioning in the “accelerated” condition. Gamete emission and D larval yield results were equivalent to those reported in literature during early spring for the same species. The effect of temperature and photoperiod is discussed in order to understand their relationship with gametogenesis under these particular experimental conditions. It was demonstrated that internal clocks regulating gametogenesis can be change if stimulating factors (environmental cues) also change. 相似文献
8.
The blue swimmer crab, Portunus pelagicus, is an emerging aquaculture species in the Indo-Pacific. Two experiments were performed to determine the effects of salinity on survival, growth and haemolymph osmolality of early juvenile P. pelagicus crabs. The salinities tested for the first experiment were 10, 15, 25 and 40 ppt, and for the second experiment 5, 20, 30, 35 and 45 ppt. Each salinity experiment was triplicated, with each replicate consisting of 10 stage 4 juveniles. Each experiment lasted 45 days. Mortalities and incidence of “molt death syndrome” were recorded daily, while the intermolt period, carapace length, carapace width and wet weight were measured at each molt. At the end of the experiments the haemolymph osmolality and dry weights were measured.
Results demonstrate that salinity significantly affects both the survival and growth of early P. pelagicus juveniles. Mortality was significantly higher (p < 0.01) for juveniles cultured at salinities ≤ 15 ppt and at 45 ppt. At a salinity of 5 ppt a complete mortality occurred on day 20. In all salinity treatments, the majority of mortalities were due to “molt death syndrome”. In experiment 1, immediate effects of salinity on growth and development were seen at 10 ppt as the intermolt period was significantly longer (p < 0.01) and the mean carapace size increase was significantly less (p < 0.01) at the first molt compared to the other treatments. Meanwhile, the specific growth rates (carapace length, width and wet weight) were significantly lower (p < 0.05) at high salinities (≥ 40 ppt) due to longer intermolt periods and significantly lower (p < 0.05) carapace size or wet weight increases.
The haemolymph osmolality exhibited a positive linear relationship with the culture medium with an isosmotic point of 1106 mOsm/kg, equal to a salinity of approximately 38 ppt. Based on the osmolality graph, high metabolic cost for osmoregulation due to increased hyper- and hypo-osmotic stress appeared to cause lower survival and specific growth rates of the crabs. The results demonstrate that a salinity range of 20–35 ppt is suitable for the culture of early juvenile P. pelagicus. 相似文献
9.
10.
Aline Gangnery Cdric Bacher Dominique Buestel 《Aquaculture (Amsterdam, Netherlands)》2004,230(1-4):323-347
A population dynamics model was used to simulate variations in the standing stock of the Pacific oyster, Crassostrea gigas, to assess the marketable production in Thau Lagoon (France) and to evaluate the sensitivity of this production to environmental conditions. The model is based on a continuous equation of the oyster abundance as a function of individual growth rate, inter-individual growth variability and mortality rate. The growth model depends on water temperature, particulate organic matter concentration and total individual mass. Inter-individual growth variability was introduced into the general population dynamics equation by a diffusion coefficient K that was set to 0.05. The population dynamics model took into account the two culture methods (i.e. “collées” and “pignes” oysters) and rearing strategies of oyster farmers by using timetables of seeding and harvesting obtained through interviews of oyster farmers. Distributions of standing stocks were obtained through assessments conducted in the lagoon in March 2000, October 2000 and March 2001 and were used to calibrate the model. The model estimated the total marketable production at ca. 17,900 t between March 2000 and March 2001. The major part of the production (ca. 70%) was in spring. Seventy percent of the annual production came from “collées” oysters. Sensitivity analyses showed that the key parameters are those related to harvesting. The model was used to evaluate the effects of different environmental conditions (e.g. a decrease in the oyster growth rate, a harvesting closure due a toxic algae bloom, a massive summer mortality due to an anoxic crisis) on short- and long-term variations in the standing stock and the production for both culture methods. A decrease in the growth rate of ca. 20% resulted in losses of 18% in the first year of production for both culture methods. Long-term simulations showed that the production of “pignes” oysters was more affected than that of the “collées” oysters (reductions of 26% and 4%, respectively). Simulated scenarios included a 2-month long harvesting closure (i.e. November and December) or a massive summer mortality (i.e. 45% and 20% for “collées” and “pignes” oysters, respectively). No long-term effect was predicted for either event, although losses of ca. 10% were estimated in the first year of production for both culture techniques. The model can be a useful tool for predicting marketable production of oysters as a function of rearing strategy and environmental conditions. 相似文献
11.
Christophe Lambert Philippe Soudant Lionel Dgremont Maryse Delaporte Jeanne Moal Pierre Boudry Frdric Jean Arnaud Huvet Jean-Franois Samain 《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):276-288
High variability among individuals is often encountered when hemocyte characteristics are measured in bivalves. Such variability is suspected to result partly from genetic factors. In this study, hemocyte characteristics of six families of Crassostrea gigas were compared by flow cytometry at one sampling date in October 2001. These families were obtained from a nested, half-sibling cross design, and reared from July to October 2001 at three sites distributed along the French Atlantic coast from north to south: Baie des Veys (Normandy), Rivière d'Auray (Brittany) and Ronce (Marennes-oléron Basin, Poitou Charentes).
Among the 15 measured hemocyte characteristics, production of reactive oxygen species (ROS) of untreated hemocytes (maintained in filtered sterile seawater) and treated hemocytes (zymosan at 20 particles per hemocyte, and with Vibrio sp. S322 at 50 bacteria per hemocyte) was the most notable differences between families. This supports the existence of a genetic basis, at least partly, for the hemocyte characteristics of oysters, and especially for ROS production.
Among the six families analyzed, three have shown high survival during summer (named as “resistant”, mean mortality 5.2%) and three experienced high mortality during summer (named as “susceptible”, 30.6% mean mortality). Families showing high or low survival to summer mortality had similar hemocyte characteristics, regardless of the environmental conditions or reproductive state. Resistant families were observed to have higher total hemocyte counts and lower production of ROS than susceptible families. Moreover, ROS production of hemocytes from susceptible families was diminished significantly more by pathogenic Vibrio than that of resistant families. However, this study demonstrates also that rearing site strongly affected the hemocyte characteristics of all families of oysters, most notably hemocyte concentration and morphology (size and granularity), production of reactive oxygen species (ROS), and susceptibility to the cytotoxic activity of the pathogenic Vibrio sp. S322 (50 bacteria/hemocyte). Food availability and reproductive state are the most probable explanations for the site differences observed. Finally, it appeared difficult to link oyster survival during summer mortality to hemocyte profiles evaluated at one sampling date; other relevant indicators would probably help explaining oyster survival during summer mortality events. 相似文献
12.
The taxonomic composition of the metazoan parasites found in the stomach of 629 specimens of the “Patagonian toothfish” Dissostichus eleginoides Smitt, 1898, from two localities in southern Chile (Lebu 36°00′S; Quellón 48°49′S), is recorded. More than 58,000 parasite specimens belonging to 9 taxa were registered. Adult worms were represented by the hemiurids Gonocerca phycidis Manter 1925, Lecithochirium genypteri Luhe 1905, Brachyphallus crenatus (Rudolphi 1802), and Derogenes varicus (Muller 1784) and the nematode Hysterothylacium sp. Ward & Magath 1917. Larval forms of anisakid nematodes, an acanthocephalan (Corynosoma sp.), a trypanorhynch cestode (Hepatoxylon trichiuri (Holten 1802)) and an unidentified pseudophyllidean cestode were also obtained. Parasitological evidence, based on univariate and multivariate analysis, does not support either the existence of discrete stocks, migratory movements between areas or seasonality in pattern of infection. 相似文献
13.
Spring and fall chinook (Oncorhynchus tshawytscha), steelhead (Oncorhynchus mykiss) and hatchery spring chinook in the Tucannon River, Washington, USA are listed as “threatened” under the Endangered Species Act of 1973. Restoration and management of both species can be facilitated by understanding how biotic and abiotic factors affect their smolt trap efficiency. In this paper, we examine the effects of the rate of water flow, water temperature, the level of staff gauge, debris load, and Secchi disk readings on their weekly smolt trap efficiency from 1998 to 2003 using a generalized linear model (GLM) with a binomial response (link function – logit). The nonlinear relationships between the smolt trap efficiency and abiotic variables are also analyzed using a generalized additive model (GAM) with a binomial response (link function – logit). Both GLM and GAM analyses showed that the trap efficiency varied among years for fall chinook, steelhead, and wild spring chinook, but not for hatchery spring chinook, and that the level of staff gauge and the rate of water flow were the most important factors altering trap efficiency. The partial residuals from GAM analyses were used to determine the optimal number of sampled fish with a known efficiency and to detect possibly misleading results from GLM analyses. 相似文献
14.
Analysis of nutrient flows in integrated intensive aquaculture systems 总被引：12，自引：0，他引：12
This paper analyses nutrient conversions, which are taking place in integrated intensive aquaculture systems. In these systems fish is cultured next to other organisms, which are converting otherwise discharged nutrients into valuable products. These conversions are analyzed based on nitrogen and phosphorous balances using a mass balance approach. The analytical concept of this review comprises a hypothetical system design with five modules: (1) the conversion of feed nutrients into fish biomass, the “Fish-Biomass-Converter”; (2) the separation of solid and dissolved fish waste/nutrients; the “Fish-Waste-Processor”; (3) the conversion of dissolved fish waste/nutrients, the “Phototrophic-herbivore-Converter”; (4 and 5) the conversion of solid fish waste, the “Bacterial-Waste-Converter”, or the “Detrivorous-Converter”. In the reviewed examples, fish culture alone retains 20–50% feed nitrogen (N) and 15–65% feed phosphorous (P). The combination of fish culture with phototrophic conversion increases nutrient retention of feed N by 15–50% and feed P by up to 53%. If in addition herbivore consumption is included, nutrient retention decreases by 60–85% feed N and 50–90% feed P. This is according to the general observation of nutrient losses from one trophic level to the next. The conversion of nutrients into bacteria and detrivorous worm biomass contributes only in smaller margins (e.g. 7% feed N and 6% feed P and 0.06% feed N 0.03 × 10−3% feed P, respectively). All integrated modules have their specific limitations, which are related to uptake kinetics, nutrient preference, unwanted conversion processes and abiotic factors. 相似文献
15.
The Magnuson-Stevens Fishery Conservation and Management Act defines essential fish habitat (EFH) as “the waters and substrate necessary to fish for spawning, breeding, feeding, and growth to maturity” and the protection of nursery areas has become a key element in US Federal fisheries management. Distribution and abundance by habitat for age-0, young-of-the-year (YOY) winter flounder, Pseudopleuronectes americanus, were compared for 28 Maine estuaries to help define essential fish habitat for this life history stage. The Maine coast was divided into three broad geographic zones based upon geological features and sampled over 5 consecutive years; during April–November of 2000 in the Mid-coast, in 2001 and 2002 along the Southwest coast and in 2003 and 2004 along the Eastern Maine coast. One beam trawl (2.0 m width, 3 mm mesh) sample was collected in one to four habitats in estuaries: eelgrass (Zostera marina), kelp (Laminaria longicruris), drift algae (Phyllophora sp.) and unvegetated sand/mud. Fish were sampled every 2 weeks, April–November 2000–2004. Abundance of YOY winter flounder was greatest in Mid-coast estuaries between Casco and Penobscot Bays and was significantly lower in Southwest and Eastern estuaries. Abundance was similar across all four habitats in Mid-coast estuaries in 2000. In the other years, YOY were found in higher abundance in eelgrass relative to other habitats. A logistic regression model based on nearshore habitat characteristics was developed to predict the distribution of this species along the three broad geological zones of the Maine coast with the physical and biological variables most important in discriminating between habitats with and without individual fish identified. This logistic regression model correctly classified winter flounder 72.4% of the time based on the year, zone, the physical habitat variables (temperature, salinity, depth) and the presence–absence of submerged aquatic vegetation (eelgrass, kelp or algae). These results indicate that the type of habitat most important to YOY winter flounder varies among estuaries and EFH for this species and life stage must be defined with care. 相似文献
16.
Shiro Itoi Noriyuki Takai Satomi Naya Keitaro Dairiki Akira Yamada Seiji Akimoto Kiyoshi Yoshihara Haruo Sugita 《Fisheries Science》2008,74(3):503-510
ABSTRACT: Gnomefish Scombrops boops and Scombrops gilberti are commercially important fishes in Japan, but these species are often confused in the markets because of their morphological similarity. To identify these two species, we performed nucleotide sequencing and restriction fragment length polymorphism (RFLP) analysis on 16S ribosomal RNA (rRNA) gene and the control region in mitochondrial DNA. Five and 12 nucleotide substitutions were observed between species in the 777-bp 16S rRNA gene and 471-bp control region, respectively. Diagnostic restriction sites for discriminating between S. boops and S. gilberti were found in the 16S rRNA gene, but not in the control region. Polymerase chain reaction (PCR)–RFLP analysis using two enzymes, Eco NI and Mva I, clearly discriminated between S. boops and S. gilberti identified by meristic characters. The PCR–RFLP analysis identified most of the 168 Scombrops young caught in the coastal waters of the Izu and Miura peninsulas as S. boops , suggesting that S. gilberti juveniles are rare in this area. 相似文献
17.
In the aquaculture of summer flounder (Paralichthys dentatus), the inherent variation in growth and settling behavior during metamorphosis may lead to cannibalism and necessitate increased labor due to size grading. Our goal was to use an environmental salinity change as a cue to synchronize settling behavior and produce a larger, more uniformly sized cohort of juvenile summer flounder. Early metamorphic flounder were exposed to either a 5-day fluctuating (30–20–30–20–30 ppt; “Flux”) or a single (30–20 ppt; “20 ppt”) drop in rearing salinity. A control (continuous 30 ppt) was used for comparison. Average values for a peak settlement interval (PSI; defined as the interval beginning on the day by which the first 20% had settled until the day 80% had settled) were not affected by salinity manipulation, though the 20-ppt treatment did significantly increase percent settled per day by 54 dah. Average fish size was increased by the 20-ppt treatment (19.3±0.5 mm), but not the flux treatment (17.2±0.4 mm), compared to the control (17.6±0.5 mm). Developmental stage was significantly increased in the 20-ppt treatment (3.2±0.1) in comparison to the Flux (2.9±0.1), but not the control (3.1±0.1). However, the 20-ppt treatment reduced variance in development. To confirm the positive effects of the 20-ppt treatment, a second experiment was performed. A single salinity drop (“20 ppt”), a previously successful ([Gavlik, S., Albino, M., Specker, J.L., 2002. Metamorphosis in summer flounder: Manipulation of thyoid status to synchronize settling behavior, growth, and development. Aquaculture 203 (3-4), 359-373]thyroid hormone manipulation treatment (“TH”) and a combination of the two (“TH+20 ppt”) were compared to a control (continuous 30 ppt, no thyroid manipulation). The mean PSI was significantly reduced by both TH (7±1 days) and TH+20 ppt (8±0 days) treatments, compared to the control (11±1 days). The PSI for the 20-ppt treatment (9±0 days) was not significantly different than the control. The percent flounder settled per day was significantly increased by 20 ppt salinity and significantly modified (decreased, then increased) by TH manipulation. Flounder exposed to 20-ppt salinity were both larger (20 ppt: 18.6±0.3 mm; TH+20 ppt: 18.3±0.3 mm) and more developmentally advanced (20 ppt: 3.1±0.04; TH+20 ppt: 3.2±0.03) than flounder in 30 ppt (TH: 17.8±0.3 mm/3.1±0.3; Control: 17.9±0.3 mm/3.0±0.05). Finally, 20-ppt treatment reduced variance in development, while TH treatment reduced variance in both growth and development. Percent survival was unaffected by treatment in both experiments. In summary, a decrease in rearing salinity, from 30 to 20 ppt, increased growth, settling behavior and development of metamorphosing summer flounder. A decrease in rearing salinity, in combination with a TH manipulation, should result in larger, more uniformly sized flounder cohorts. We expect this synchronization will reduce the cannibalism and labor costs associated with size grading of cultured, metamorphosing summer flounder. 相似文献
18.
The identification of North Atlantic redfish has been controversial and remains a difficult task due to overlapping of meristic and morphological characters. Here we used nine microsatellite loci to assess the level of genetic differentiation among these species and assess the resolution power of these microsatellite loci for individual assignment-based analyses. Conventional analyses as well as individual Bayesian assignment methods clearly separated the four species of North Atlantic redfish as well as the giant form of Sebastes marinus and the so-called “oceanic” and “deep-sea” types of Sebastes mentella. Locus-by-locus analyses revealed that only five microsatellite loci out of nine used could discriminate the concerned species. The advantage of the Bayesian methods relies in the individual information retrieved. It therefore gave additional information on the interrelationship among species. Indeed, we provide evidence of potential hybridization among species as well as individual misclassification based on morphological identification. We provide a powerful tool to discriminate North Atlantic redfish species, which might be useful for legal issues such as poaching, unintentional harvesting and control label. 相似文献
19.
Labor costs of guppy growers and breeders are largely those of manual sorting (by strain, quality and gender) and counting fish. In most farms, female and male fish are grown together and sold either separately or together. Sorting fish according to gender is important for marketing as well as for breeding programs, so that a device for sorting and counting fish can potentially reduce production costs and improve quality.
A project aiming to develop sorting and counting technologies for ornamental fish growers included development and testing of image-processing algorithms for sorting guppy fish (Poecilia reticulata) by gender. The algorithms are derived from shape and color differences between female and male guppies. An algorithm for the determination of landmarks on fish contours was developed and found to be accurate in accordance with human judgment, enabling extraction of specific shape and color features of the tail and the body.
The algorithms were applied to three sets of images of guppies of the “Red-Blond” strain. Gender identification accuracy was approximately 90% using shape features, approximately 96% using color features and was slightly improved when both color and shape features were used.
Some of the components used are essential for future development of a computer vision based system for sorting and grading ornamental fish by strain and quality. 相似文献
20.
Tilapias, Oreochromis aureus, were vaccinated twice with live tomites of Ichthyophthirius multifiliis in physiological saline 1 month before spawning (test group). A control group was similarly treated but with physiological saline only. Fertilized eggs were collected from the mouths of both groups and incubated until the young reached the free-swimming stage. Free-swimming fry were also collected immediately after they were expelled from the mother's mouth in other fish of the two groups. The fry were exposed to infective tomites of I. multifiliis and thereafter returned to their holding tanks. All fry obtained from the controls without mouth-brooding died after tomite exposure. However, fry with mouth-brooding before tomite exposure showed 37.3% survival. On the other hand, fry obtained from vaccinated broodstock without mouth-brooding exhibited 78.4% survival which increased to 95.3% with mouth-brooding. The protective immunity is correlated with the titres of anti-I. multifiliis antibodies in the soluble extracts of fry tissues and the mother's plasma. The results clearly indicate that protective immunity against ichthyophthiriasis “ich” in tilapia fry can not only be derived directly from the mother via eggs but also be acquired indirectly from the mouth cavity during the brooding period. The results thus suggest that proper vaccination of mothers before spawning would effectively protect fry against a protozoan disease. 相似文献