埋植17α—甲基睾酮诱导点带石班鱼性转化技术

论述了埋植17α-思虑在睾酮诱导点带石斑鱼（Epinephelus malabaricus)性转化的方法,包括药物的处理,用量,手术操作等3龄的雌性点带石班鱼经过2次埋植外源激素手术转化为功能性雄鱼,139d后58％可挤出精液,301d后100％可挤出精液,功能性雄鱼用于人工繁殖,亲鱼自然产卵,1999－2000年2年内共孵出存鱼7103万尾,所得仔鱼用鱼苗培育,得到发育正常的幼鱼,认为埋植外源激素诱导点带石斑鱼完成性转化的方法简便可行,能满足规模化人工繁殖的需要。     

Reconstruction of walleye exploitation based on angler diary records and a model of predicted catches

The walleye population in Canadarago Lake, New York, was 81-95% exploited in the 1988 fishing season, the year in which a previous restriction on the length and number of legally harvestable fish was liberalized. Using diary records from a subset of fishermen, growth estimates, and an estimate of the walleye population in the following year, a method is developed to reconstruct the fish population back to the spring of 1988 and thus determine the exploitation rate. The method is based on a model of diary catches that partitions time and fish length into a set of cells and relates predicted catches and population sizes in these cells. The method's sensitivity to the partitioning scheme, the growth estimates, and the diary data is analyzed. The method could be employed in other fish exploitation analyses and demonstrates the use of inexpensive angler-collected data in fisheries management.     

基于Matlab的鱼类游泳动力学分析

鱼类游泳动力学分析研究对解决鱼道等工程应用中水力学设计方面的关键问题有着重要的意义,利用计算机技术对鱼类游泳动力学进行分析有助于研究目标鱼类的生理特性、游泳能力及其与水力环境因子的响应关系。基于MATLAB软件对我国特有鱼类鲢幼鱼进行游泳动力学分析,借助鲢幼鱼游泳时的摆尾行为,得到不同水流速度下鲢幼鱼的摆尾频率、摆尾幅度、游泳速度和加速度;对比人工计数和手动跟踪分析方法,从实际操作复杂程度和实验数据准确性的角度,分析各数据采集方法的优劣性。结果表明基于Matlab软件采用跟踪鱼的身体中线的思路能更高效的获取大量的运动参数,比如摆尾频率、摆尾幅度、游泳速度和加速度等指标。文章介绍了一种基于Matlab开发的鱼类游泳动力学分析方法,有助于为以后鱼类游泳动力学研究提供依据。     

BrdU-Hoechst-Giemsa方法的进一步改进以及青鱼和草鱼复制带核型的研究

对BrdU-Hoechst-Giemsa方法进行了一定的改进和补充;并将它应用于青鱼和草鱼的核型研究中。实验进一步阐明,BrdU-Hoechst-Giemsa方法的关键性步骤之一是要先测算实验鱼的细胞周期;BrdU、AMD、Hoechst 33258,EB和AO虽都有抑制鱼类染色体浓缩、促进染色体分带的作用,但其中以DNA碱基特异性给合物BrdU、AMD和Hoechst 33258较佳,特别用AMD和Hoechst 33258同时处理活细胞的分带效果最好。     

Irregularities of the bottom and fish aggregations on a stretch of the Irtysh

An original method for estimation of the effect of bottom irregularities on density of fish aggregations is elaborated. Calculation of the investigated relationship is based on material of surveys collected by an AsCor hydroacoustic complex and is made by means of special software. With reference to a deep-water stretch of the Irtysh channel, the quantitative parameters of the relationship between densities of fish aggregations and the index of bottom irregularity are revealed. The diagram of the relationship between bottom irregularities and density of fish aggregations, the three-dimensional model of bottom relief of the investigated water area, and echograms of fish aggregations on various stretches of the river are presented.     

Growth studies with fish—overcoming the problems of size variation

The relationship between growth rate and fish size is described by the equation log_e G _w= a —0·4 log_e W, where G_w is the specific growth rate and W is fish weight. Since the intercept (a) represents the log_e G_w of a fish unit size, the relationship presents a method allowing comparison of data from experiments involving fish of different sizes. The application of the method is demonstrated by examining the effects of environmental temperature on growth rates of cod, Gadus morhua , and it is suggested that the optimum temperature for growth of cod is 13–15° C.     

The use of fish vertebrae in scats for estimating prey size of otters and mink

A method of using fish vertebrae in scats of otters and mink in order to estimate prey size is described. Significant positive correlations between fish fork length and length of abdominal and caudal vertebrae respectively were demonstrated and described for a series of reference fish of different species. Comparison of direct length measurements of fish fed to captive mink with length estimates obtained from vertebrae recovered in then scats and derived using the appropriate regression lines determined from the reference fish revealed a close measure of agreement and indicated that the method achieves a high level of accuracy. Use of vertebrae from scats for estimating fish length is considered to have several advantages over use of scales, and the method greatly extends the range, accuracy and value of the information that can be obtained from scat analysis.     

Real-time fish detection in complex backgrounds using probabilistic background modelling

Computer vision and image processing approaches for automatic underwater fish detection are gaining attention of marine scientists as quicker and low-cost methods for estimating fish biomass and assemblage in oceans and fresh water bodies. However, the main challenge that is encountered in unconstrained underwater imagery is poor luminosity, turbidity, background confusion and foreground camouflage that make conventional approaches compromise on their performance due to missed detections or high false alarm rates. Gaussian Mixture Modelling is a powerful approach to segment foreground fish from the background objects through learning the background pixel distribution. In this paper, we present an algorithm based on Gaussian Mixture Models together with Pixel-Wise Posteriors for fish detection in complex background scenarios. We report the results of our method on the benchmark Complex Background dataset that is extracted from Fish4Knowledge repository. Our proposed method yields an F-score of 84.3%, which is the highest score reported so far on the aforementioned dataset for detecting fish in an unconstrained environment.     

The biological control of snail intermediate hosts of schistosomiasis by fish

Summary The use of molluscivorous fish for biological control of snail intermediate hosts of schistosomiasis is a regularly reappearing theme in the literature on schistosomiasis control. The effectiveness of this control method has not yet been demonstrated, and conclusive field evidence is lacking. In this article the literature on snail control by fish is critically reviewed. Special attention is paid to the cichlid fish Astatoreochromis alluaudi that has been used in well-documented field trials in Kenya and Cameroon. After some small initial success, after a longer period the fish appeared to be ineffective in snail control. Moreover, the fish reproduces at a pace too slow to be of use in large-scale biocontrol trials. Laboratory observations on foraging behaviour and anatomy of the fish give essential cues to explain the failure of the fish in snail control. An observed reduction in the fishes' pharyngeal jaw apparatus, used to crush snails shells, results in a lower profitability of snails. As predicted by a simple foraging model, the prey preference of the fish shifts towards other more profitable prey items, such as benthic and pelagic macrofauna. Although eradication of snails by fish will not be feasible in most cases, the role of natural predators of snails cannot be neglected, and may still be of importance in integrated control efforts.     

Improving Pantanal fish species recognition through taxonomic ranks in convolutional neural networks

Fish species recognition is an important task to preserve ecosystems, feed humans, and tourism. In particular, the Pantanal is a wetland region that harbors hundreds of species and is considered one of the most important ecosystems in the world. In this paper, we present a new method based on convolutional neural networks (CNNs) for Pantanal fish species recognition. A new CNN composed of three branches that classify the fish species, family and order is proposed with the aim of improving the recognition of species with similar characteristics. The branch that classifies the fish species uses information learned from the family and order, which has shown to improve the overall accuracy. Results on unrestricted image dataset showed that the proposed method provides superior results to traditional approaches. Our method obtained an accuracy of 0.873 versus 0.864 of traditional CNN in recognition of 68 fish species. In addition, our method provides fish family and order recognition, which obtained accuracies of 0.938 and 0.96, respectively. We hope that, with these promising results, an automatic tool can be developed to monitor species in an important region such as the Pantanal.     

埋植17α-甲基睾酮诱导点带石斑鱼性转化技术

论述了埋植17α-甲基睾酮诱导点带石斑鱼(Epinephelus malabaricus)性转化的方法,包括药物的处理、用量、手术操作等．3龄的雌性点带石斑鱼经过2次埋植外源激素手术转化为功能性雄鱼,139d后58％可挤出精液,301d后100％可挤出精液．功能性雄鱼用于人工繁殖,亲鱼自然产卵。1999～2000年2年内共孵出仔鱼7103万尾．所得仔鱼用于鱼苗培育,得到发育正常的幼鱼．认为埋植外源激素诱导点带石斑鱼完成性转化的方法简便可行,能满足规模化人工繁殖的需要．     

High-throughput selection of retrovirus producer cell lines leads to markedly improved efficiency of germ line-transmissible insertions in zebra fish

Vesicular stomatitis virus glycoprotein G-pseudotyped mouse retroviral vectors have been used as mutagens for a large-scale insertional mutagenesis screen in the zebra fish. To reproducibly generate high-titer virus stocks, we devised a method for rapidly selecting cell lines that can yield high-titer viruses and isolated a producer cell line that yields virus at a high titer on zebra fish embryos. Virus produced from this line, designated GT virus, is nontoxic following injection of zebra fish blastulae and efficiently infects embryonic cells that give rise to the future germ line. Using GT virus preparations we generated roughly 500,000 germ line-transmissible proviral insertions in a population of 25,000 founder fish in about 2 months. The GT virus contains a gene trap, and trap events can be detected in the offspring of almost every founder fish. We discuss potential applications of this highly efficient method for generating germ line-transmissible insertions in a vertebrate     

Evaluation of a sweep net electrofishing method for the collection of small fish and shrimp in lotic freshwater environments

A major limitation of methods for collecting small fish and shrimp is that no single method is equally effective for all species or all life history stages. We compared the efficacy of the sweep net electrofishing (SNE) method with two other commonly used sampling methods for the collection of small fish and shrimp, the standard sweep net (SW) and the point abundance electrofishing (PAE) method developed by Copp & Penaz (1988). The effectiveness of the three methods was compared under three different current speeds in an Australian lowland river. The SNE method collected an order of magnitude more shrimp and a greater size range than the other two methods, irrespective of the current speed. The SNE method captured a similar number of fish to the SW method, but significantly more individuals than the PAE method. However, the two electrofishing methods caught a greater size range of both fish and shrimp than did the SW method. The effectiveness of the SNE method appears to be due to its ability to immediately capture shocked individuals, thereby lessening the likelihood of escape. Whilst the SNE method is not quantitative, its high level of effectiveness is likely to be particularly useful in systems with low densities of fish and shrimp.     

Validation of a simple and well‐suited chemical cleaning method for fish otoliths

In marine biology, many research fields are based on use of fish otoliths. All the studies dealing with otoliths need as starting point a perfectly clean otolith. Dissection is difficult when working on small or highly jagged otoliths. A common problem is that during otolith preparation some fish tissue may remain stuck to it, even after a mechanical cleaning. Then, supplementary cleaning with chemicals is needed. Classical methods are known to possibly alter otolith's structure and/or composition. Here, we present a chemical cleaning method using only sodium hydroxide. We have validated the method on two different fish species, Oblada melanura and Dicentrarchus labrax. Observation and analyses of morphological measurements have confirmed significant suppression of residual tissues. We propose this method as a good alternative to previously published mono‐ or multichemical methods.     

Restoring depleted coral‐reef fish populations through recruitment enhancement: a proof of concept

To determine whether enhancing the survival of new recruits is a sensible target for the restorative management of depleted coral‐reef fish populations, settlement‐stage ambon damsel fish Pomacentrus amboinensis were captured, tagged and then either released immediately onto small artificial reefs or held in aquaria for 1 week prior to release. Holding conditions were varied to determine whether they affected survival of fish: half the fish were held in bare tanks (non‐enriched) and the other half in tanks containing coral and sand (enriched). Holding fish for this short period had a significantly positive effect on survivorship relative to the settlement‐stage treatment group that were released immediately. The enrichment of holding conditions made no appreciable difference on the survival of fish once released onto the reef. It did, however, have a positive effect on the survival of fish while in captivity, thus supporting the case for the provision of simple environmental enrichment in fish husbandry. Collecting and holding settlement‐stage fish for at least a week before release appear to increase the short‐term survival of released fish; whether it is an effective method for longer‐term enhancement of locally depleted coral‐reef fish populations will require further study.     

Automatically Detect and Track Multiple Fish Swimming in Shallow Water with Frequent Occlusion

Due to its universality, swarm behavior in nature attracts much attention of scientists from many fields. Fish schools are examples of biological communities that demonstrate swarm behavior. The detection and tracking of fish in a school are of important significance for the quantitative research on swarm behavior. However, different from other biological communities, there are three problems in the detection and tracking of fish school, that is, variable appearances, complex motion and frequent occlusion. To solve these problems, we propose an effective method of fish detection and tracking. In this method, first, the fish head region is positioned through extremum detection and ellipse fitting; second, The Kalman filtering and feature matching are used to track the target in complex motion; finally, according to the feature information obtained by the detection and tracking, the tracking problems caused by frequent occlusion are processed through trajectory linking. We apply this method to track swimming fish school of different densities. The experimental results show that the proposed method is both accurate and reliable.     

Induced androgenesis in fish: obtaining viable nucleocytoplasmic hybrids

A self-review of long-standing studies of induced androgenesis in fish. The data are provided on the induction of diploid androgenesis in teleost fish via blocking the first cleavage division and the development of the method of dispermic androgenesis in sturgeon fish. Androgenetic nucleocytoplasmic hybrids were obtained using the method of dispermic androgenesis and eggs of previously produced true interspecific hybrids. Specific morphological features of androgenetic hybrids were described and dispermic androgenesis was realized using cryopreserved sperm. The mechanism of sex determination in sturgeon fish is discussed with reference to possible us of androgenesis for restoration of rare and disappearing species.     

Specific detection by the polymerase chain reaction of potentially allergenic salmonid fish residues in processed foods

Salmonid fish is one of the allergenic items that are recommended to be labeled in the Japanese allergen-labeling system. This study develops a salmonid-specific polymerase chain reaction (PCR) method. A new primer pair, SKE-F/SKE-R, was designed to specifically detect the salmonid fish gene encoding mitochondrial DNA cytochrome b. Genomic DNAs extracted from 58 kinds of seafood and 11 kinds of processed food were individually subjected to PCR by using the primer pair, and a salmonid-specific fragment of 212 bp was only amplified in the salmonid samples and salmonid-containing processed foods. The detection limit of the PCR method was as low as 0.02 fg/μL of salmonid fish DNA (corresponding to 10 copies). There is no ELISA method for salmonid fish, making our PCR method the only reliable measure for detecting salmonid fish in processed foods.     

Specific Detection by the Polymerase Chain Reaction of Potentially Allergenic Salmonid Fish Residues in Processed Foods

Salmonid fish is one of the allergenic items that are recommended to be labeled in the Japanese allergen-labeling system. This study develops a salmonid-specific polymerase chain reaction (PCR) method. A new primer pair, SKE-F/SKE-R, was designed to specifically detect the salmonid fish gene encoding mitochondrial DNA cytochrome b. Genomic DNAs extracted from 58 kinds of seafood and 11 kinds of processed food were individually subjected to PCR by using the primer pair, and a salmonid-specific fragment of 212 bp was only amplified in the salmonid samples and salmonid-containing processed foods. The detection limit of the PCR method was as low as 0.02 fg/µL of salmonid fish DNA (corresponding to 10 copies). There is no ELISA method for salmonid fish, making our PCR method the only reliable measure for detecting salmonid fish in processed foods.     

Estimating Intermittent Individual Spawning Behavior via Disaggregating Group Data

In order to understand fish biology and reproduction, it is important to know the fecundity patterns of individual fish, as frequently established by recording the output of mixed-sex groups of fish in a laboratory setting. However, for understanding individual reproductive health and modeling purposes it is important to estimate individual fecundity from group fecundity. We created a multistage method that disaggregates group-level data into estimates for individual-level clutch size and spawning interval distributions. The first stage of the method develops estimates of the daily spawning probability of fish. Daily spawning probabilities are then used to calculate the log likelihood of candidate distributions of clutch size. Selecting the best candidate distribution for clutch size allows for a Monte Carlo resampling of annotations of the original data which state how many fish spawned on which day. We verify this disaggregation technique by combining data from fathead minnow pairs, and checking that the disaggregation method reproduced the original clutch sizes and spawning intervals. This method will allow scientists to estimate individual clutch size and spawning interval distributions from group spawning data without specialized or elaborate experimental designs.