Fish species identification is traditionally based on external morphological features. Yet, in many cases fishes and especially their diverse developmental stages are difficult to identify by ...morphological characters. DNA-based identification methods offer an analytically powerful addition or even an alternative. This work intends to provide an updated and extensive overview on the PCR-methods for fish species identification. Among the ten main methods developed, three PCR-RFLP, PCR-FINS and PCR-specific primers have been the most used. Two other emerging methods, namely real-time PCR and microarray technology, offer new potential for quantification of DNA and simultaneous detection of numerous species, respectively. Almost 500 species have been targeted in the past decade, among which the most studied belong to gadoids, scombroids, and salmonids. The mitochondrial cytochrome b gene was by far the most targeted DNA markers. The most common applications belonged to the forensic, taxonomic, and ecological fields. At last, some key problems, such as the degradation of DNA, the reliability of sequences, and the use of scientific names, likely to be encountered during the development of molecular identification methods are described. In conclusion, the tremendous advances in molecular biology in the past 10 years has rendered possible the study of DNA from virtually any substrates, offering new perspectives for the development of various applications, which will likely continue to increase in the future.
The agricultural world today is dominated by a few domesticated mammal species, that is, animals modified from their wild ancestors through selective breeding in captivity for traits beneficial to ...human usages. As a result, a clear dichotomy exists between wild (from hunting) and domesticated mammals (produced in farms) used for human consumption. Similar to agriculture, aquaculture is often viewed as the only solution that can provide more fish products given that harvesting wild stocks have reached an upper limit. Aquaculture is considerably younger than agriculture relying on natural sources to farm numerous species. To better describe the diverse strategies for fish production, we propose a new classification comprising five levels of ‘domestication’ with 1 being the least to 5 being the most domesticated. Our classification places 70% of the 250 farmed finfish species recorded in the 2009 FAO database into levels 1, 2 and 3 representing a transitory form of fish production dependent on the availability of the wild resource. In contrast, only a few species, or more accurately populations, can be considered truly domesticated, similar to cattle or sheep. Based on this classification, two scenarios for the future of aquaculture are discussed: either the industry focuses on few truly domesticated species, similar to the path taken by agriculture, but avoiding its negative impacts or aquaculture proceeds with inter‐specific diversification by focusing primarily on the domestication of native species.
Domestication, which is by definition a long ongoing process, was one of the most significant cultural and evolutionary transitions of human history, as well as a fundamental change in the evolution ...of the biosphere. Nevertheless, despite a vivid interest from numerous scholars, both the terms "domestication" and "domestic animal" remain confusing, and several animal groups are still poorly studied. This book contains contributions from diverse researchers and includes seven chapters, three on land animals and four on aquatic animals. The goal of this book is to stimulate fruitful exchanges to help better define the concepts of domestication and domesticated animals, and on a more applied view, help develop a more sustainable production, with animals more efficient and resilient to global change.
Domestication is a long and endless process during which animals become, generations after generations, more adapted to both captive conditions and humans. Compared to land animals, domestication of ...fish species has started recently. This implies that most farmed marine fish species have only changed slightly from their wild counterparts, and production is based partly or completely on wild inputs. In the past decades, global marine fish production has increased tremendously, particularly since the 1990s, to reach more than 2.2 million tons in 2013. Among the 100 marine fish species listed in the FAO’s database in 2013, 35 are no longer produced, and only six have a production higher than 100,000 tons. The top ten farmed marine species accounted for nearly 90% of global production. The future growth and sustainability of mariculture will depend partly on our ability to domesticate (i.e., control the life cycle in captivity) of both currently farmed and new species.
Even though an accurate description of early life stages is available for some teleostean species in form of embryonic and post-embryonic developmental tables, there is poor overlap between ...species-specific staging vocabularies beyond the taxonomic family level. What is called "embryonic period", "larval period", "metamorphosis", or "juvenile" is anatomically different across teleostean families. This problem, already pointed out 50 years ago, challenges the consistency of developmental biology, embryology, systematics, and hampers an efficient aquaculture diversification. We propose a general solution by producing a proof-of-concept hierarchical analysis of ontogenetic time using a set of four freshwater species displaying strongly divergent reproductive traits. With a parsimony analysis of a matrix where "operational taxonomic units" are species at a given ontogenetic time segment and characters are organs or structures which are coded present or absent at this time, we show that the hierarchies obtained have both very high consistency and retention index, indicating that the ontogenetic time is correctly grasped through a hierarchical graph. This allows to formally detect developmental heterochronies and might provide a baseline to name early life stages for any set of species. The present method performs a phylogenetic segmentation of ontogenetic time, which can be correctly seen as depicting ontophylogenesis.
A host of abiotic factors modify fish social behavior. However, few studies have characterized the effects of temperature on behavior. In this study, brown trout Salmo trutta fry were reared at 5 ...dif- ferent temperatures （4℃, 6℃, 8℃, 10℃, and 12℃）. In order to characterize group structure, 3 be- havioral parameters were investigated： group social structure （based on inter-individual distances）, inter-individual relationships （based on physical contacts）, and individual activity. These behavioral parameters were studied at the emergence stage, which corresponds to a switch from a social gre- garious life in the gravel to a solitary one in the water column. Data analysis showed that the inter- individual distances increased with increasing temperature, particularly the nearest neighbor distance. The mean number of physical contacts between fry increased at both low and high tem- peratures. At high temperatures, most fry moved apart from each other after a physical contact. Swimming activity decreased at both the lower and upper temperatures （18% of activity at 4℃, 38% at 8℃, and 12% at 12℃）. This study showed that temperature modifies brown trout fry activity, inter-individual relationships, and social behavior, which all affect group cohesion before emer- gence and can influence their survival and dispersal.
Temperature is the main abiotic factor that influences the life cycle of poikilotherms. The present study investigated the thermal tolerance and phenotypic plasticity of several parameters ...(development time, morphometric measures, bioenergetics) for both embryos and fry of a cold stenothermal fish species, brown trout (Salmo trutta L.) in order to allow for a holistic evaluation of the potential effects of temperature. Five temperatures (4°C, 6°C, 8°C, 10°C, and 12°C) were tested, and the effects of temperature were analyzed at three stages: hatching, emergence, and first food intake. A mean of 5,440 (S.E. ± 573) eggs, coming from seven females and seven males (seven families) captured close to Linkebeek (Belgium), were used for each temperature. Maximum survival of well-formed fry at first food intake and better use of energy budget were found at 6°C and 8°C, temperatures at which the possible contribution to the next generation should therefore be greatest. At 12°C, the experimental population fell dramatically (0.9% survival rate for well-formed fry at first food intake), and fry had almost no yolk sac at first food intake. The present results on survival at 12°C are in accordance with predictions of a sharp decrease in brown trout numbers in France over the coming decades according to climate change projections (1°C to 5°C temperature rise by 2100 for France). At 10°C, there was also a lower survival rate (55.4% at first food intake). At 4°C, the survival rate was high (76.4% at first food intake), but the deformity rate was much higher (22% at first food intake) than at 6°C, 8°C, and 10°C. The energetic budget showed that at the two extreme temperatures (4°C and 12°C) there was less energy left in the yolk sac at first food intake, suggesting a limited ability to survive starvation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To study the influence of temperature (4, 6, and 12 °C) on the development of brown trout (Salmo trutta) from hatching to the end of metamorphosis, an analysis of allometric growth patterns was ...conducted to identify two different groups of individuals, namely developmental phases at total lengths (TL) ranging from 2.72 cm at 4 °C to 2.22 cm at 12 °C. Then, a multitrait approach considering different variables like the survival rate, development time, morphometric characteristics, energetic value, and skeletal mineralization was conducted on these two groups. Results indicated that the first growth phase was slower at 4 °C, whereas the second was also slower at this temperature, even though swimming behavior was already present. However, at 12 °C, fry showed a delay in their development (i.e., lower levels of skeletal mineralization and energetic content) during the first growth phase, but they compensated during the second growth phase, reaching the same size in TL when compared with the other temperatures (4 and 6 °C); fry at 12 C° showed low energy reserves. Our study demonstrated that the use of an allometric analysis to identify different developmental stages coupled with a multitrait approach was more efficient than a classical distinction between biological stages (hatching, emergence, first food intake, and exogenous feeding), and this procedure is of interest when evaluating the impact of rearing conditions on early development in fish.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Temperate fish species are annual spawners and mainly rely on annually cycling cues (temperature and photoperiod) to synchronise the three main phases of their reproductive cycle, that is, induction ...(initiation of oogenesis), vitellogenesis and the final stages (including maturation, ovulation and oviposition). This review synthesises how these three phases are controlled by specific temperature and photoperiod variations. The direction of the changes (i.e. decrease or increase) is the most important factor, although the amplitude, rates and timing of variations should also be considered to improve/optimise the quality of reproduction in aquaculture. In addition, we tentatively classified temperate fish species sharing similar temperature and/or photoperiod variation requirements for reproduction into three general functional groups. The first group (salmonids) is induced by increasing photoperiod. Vitellogenesis and the final stages are synchronised by decreasing photoperiod. The second group (percids, moronids and gadids) is induced by decreasing both temperature and photoperiod. A chilling period allows vitellogenesis. Increasing temperatures synchronise the final stages. The third group (cyprinids) is induced by decreasing either photoperiod or temperature. Vitellogenesis is faster at warm temperatures. The final stages require an increase in either photoperiod or temperature. This classification may help future research on the control of reproduction in newly cultured fish species.
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