Reproduction of European Eel towards a Self-sustained Aquaculture
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The report identifies factors for self-sustainable aquaculture for European Eel reproduction. It discusses methods, results, and conclusions. The hypothesis, subject, course code, and college/university are not mentioned.
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Contents Virtual Project.............................................................................................................................................2 Reproduction of opean eel towards a Self-sustained Aquaculture...............................................................2 Abstract:......................................................................................................................................................2 Introduction:................................................................................................................................................3 Hypothesis:..................................................................................................................................................3 Methods:......................................................................................................................................................3 Results:........................................................................................................................................................7 Result of Hypothesis:..................................................................................................................................8 Discussion:..................................................................................................................................................8 Conclusion:..................................................................................................................................................9 Virtual Project Reproduction of opean eel towards a Self-sustained Aquaculture Abstract: The primary objective of the report is to identify the factors which can led and help effectively to achieve a self sustainable aquaculture in order to continue reproduction of European Eel. The primary reason why the research has been carried out is the rapid decline in the stocks of European Eel. According to Ent. Inc. report, the stocks from declined from 2.16 million to 1.17 million from 2001 to 2015; this is approximately half of the stock. The declining stock is a matter of great concern. The various methods involved in the research methodology are divided in to various sub-steps in order to carry out research more effectively. Also, divided the task would help to know what the ultimate is result that should be achieved out of that step. The various steps involved in research were: Checking the quality of egg and semen (Quality Check) Production and survival of eggs and larvae (Survival Test) Management of how many eggs would be produced (Management Process) Keeping a control on how many eggs would be produced (Control Check) The various incubation and culture conditions that would help to control the entire process (Conditions Control) The next section deals with the results which are obtained from the previous research that is carried out, the results are discussed in both quantitatively and qualitatively. The quantitative results include the things such as how many more eggs can be more, how percentage of eggs can be saved with the change in cultural factors, etc. The qualitative factors include results such as what are favorable climatic and 2
cultural factors which may foster improved quantitative and quality of the eggs, etc. (Mainuddin, M., M. Kirby, and Y. Chen 2018) The last section of the report deals with what are the current methods involved in the research and what is scope of improvement of those methods. It includes things such as where is the current research lacking, in short what are the drawbacks of the current research. At the last a concluding statement has been given summarizing each of the above points of discussion. Hence to summarize, the sequence of discussion would start with introduction, then methods involved in the discussion, the results of the discussion have been discussed and then finally the conclusion. Introduction: European eel is a kind of fish which has an appearance very similar to that of snake. In many a cases the length of the fish ranges from 1 to 1.5 m but can extend rarely.( York, R., and Gossard, M. H. 2014.) The European eel is a critically endangered species. Since the mid 1970’s the species has shown a rapid decline, the various reports suggest that decline has been over 90%, even many reports do suggest that decline is about 98% in some of the places. the various factors that has created such a situationare overfishing, parasites such as Anguillicola crassus, barriers to migration such as hydroelectric dams, and natural changes in the North Atlantic oscillation, Gulf Stream, and North Atlantic drift. Recent work suggests polychlorinated biphenyl (PCB) pollution is another major factor in the decline. TRAFFIC is introducing traceability and legality systems throughout trade change to control the decline and encourage a U-turn on the species. (Kummu, M. and O. Varis 2017) The stocks of eel has been continuously decreased in last many decades, the decrease has been very significant to the extent that it could endanger the existence of the species. For the past many years, the species has shown no signs to come back to the original number, not even close to the number. The issue has caught a lot of attention by European Commission back in year 2007. One of the most significant steps taken by the commission include that they have raised a request by committees who are responsible for national management plans in order to include the same in the plan. (Y Chang 2018). The request raised is the indication of severity of the issue and the protection of declining eel stock indicate that this is the time to take it very seriously. In order to prevent the species, the alternate plans needs to be presented in comparison of conventional capture-based aquaculture. The traditional conventional based approach is based on the concept of glass eel caught in the wild. In order to overcome the issues and challenges faced in the previous traditional approach of capture based aquaculture, a further research has been carried out to consolidate all the past finding to come to a significant outcome and further developments of methods and technology has been done based on the results of the past. The new outcomes are on the lines of earlier results but improved and better version of the same. The main aim of the research is to find various approaches such as improving the quality of egg and semen, providing better food and nutrients to the stocks, regular medication to the stocks, the improved culture and surroundings for the livestock’s etc in order to ensure sustainable reproduction of European eel. (Lap 2017) But as discussed earlier the research would be carried out to identify the underlying issues that have resulted in decline in reproduction of the species and work on it. 3
Hypothesis: Do the diet and location of the brood stock have an effect on the fertilization rate of the brood stock? Methods: The three full scale experiments would be carried out which will include two sets of farmed female brood stocks and also one wild caught brood stock of female silver eels will be used. In each of the experiments, all of three brood stocks would be kept in different locations. Additionally, male kept in different containers. The broadstocks were from different locations where they were fed either the normal or enhanced food. For each of the below mentioned series, all the parameters including physical and chemical were closely monitored both under fertilization and post fertilization. Series A experiment: Here the two different sets of female were given different kind of diets. One group received a normal diet while the other group received an enhanced diet. Female brood stocks were from the same origin while were given different diets with the feeding periods approximately ranged from 15 to 20 weeks. Eeels were given in total of 10 groups with composition as 2*10 with around 120 females in total were included in same. On the other hand, around 20 males were from same location and with same diet. At the end of A experiment, a new fertilization protocol was first developed and subsequently tested. (Lam, P. T., P.M. Phuong, T. Visser, J.S. Sjorslev, and K.G. Hortle, 2012.) 4
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Series B experiment: In this experiment, the different sets of females were taken from different places. In total around 110 females were taken from Stensgard Eel while around 20 females were taken Lyskrard Eel. This was done to evaluate to observe the differences due to differences in locations. The diet given to both the group was same of standard type. The other procedures such as transfer to research facility, acclimation and tagging were similar to that in A type of experiments. Series C experiment: 5
These experiments used wild female eels from a lake in northern Jutland in Thy National Park called Lake Vandet. The eels were obtained in November 2009, in total 22 migrating silver eels. These eels followed the same acclimatization, measuring and tagging procedure as described for REEL Series A and REEL Series B. The female eels were divided into two groups and subjected to two different hormonal treatments. DOC was applied for final maturation. The eggs which were obtained from stripped females were analysis of lipids. In each of the above experiments, the observation period for each set of females was around 6 months. The things that were monitored included maturity of males, fertilization of eggs and monitoring of eggs. The observation started with induction of maturity and ended with incubation and larval rearing. 6
Results: The above tables gives a brief about the results obtained after experiment A,B and C. In the series A and B, farmed fishes were used while in series C, Reel C fishes were used. In the type B and C experiments, about 50 percent of the fishes that actually started ended up being stripped which can be successfully co- related to the results obtained from previous experiments. But the number of females who were successfully stripped was quite low in type A of experiments, which was only about 15 percent. This was due to the fact that the numbers of non responding females were very high in A series of experiment. The factors which to low turnout in both the categories were non responding females in category A while in the C category the main cause was the death or diseases in the large number of females. Around 27 percent of the total fishes were suffering from one or the other type of diseases. While the factor that was responsible in B type of category was that the majority of Eels in them were farmed Eels. 7
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The number of fertilized eggs for each batch was very different from the previous batch and the same can be said for the larvae that were hatched. The above graph gives the percentages of fertilized eggs, the embryos formed and the larvae that were realized. From the above group, it is quite clear that results are the best of the type C of the experiments that were carried out. While the worst were for the type B of the experiments. This can be attributed to the very fact that the difference in diets that were given to the different sets of the females. As a result of above experiment, certain things were very clear. First was that the wild eels can successfully re-produce. Although the primary focus would to use the farmed eels for self- sustainable reproduction in aquaculture but wild eels can be used for comparison. As a result of experiments, it was also quite clear that the quality of the brood stock, the hormonal treatment that was given to the stocks and the quality of the eggs played an important role in determining the success rate in fertilization. Result of Hypothesis: Yes, the location and diet both have an effect on the fertilization rate but the greater impact is made by the diet given to the brood stock. Discussion: The hypothesis proposed that whether location and diet have an effect on the fertility level or not. And if yes, what is the extent of the effect observed? The fertility levels can be changed in the species by improving the associated factors. The proposed hypothesis holds true. (Vu A.T. and Bach T.Q.M. 2015) 8
But the exact question is which factor has the maximum effect and which has the minimum effect. The exact contribution of each of the factors is still questionable. Also, there is a possibility that among the above cited factors some of the factors have zero contribution in order to improve the fertility levels among the species. Apart from this, various studies have been conducted which found a direct co-relation between fertility levels of Eel and the nutrition and diet they consumed. They have found a positive co-relation but they suggested the time in which diet showed its effect was long while this particular study suggests that the effect is immediate. This study also showed that location where the mating happens also has a direct effect on the fertility which either was not considered in previous studies or no result came out of the same. (Baran, E., T. Jantunen, and C.K. Chong 2017) Conclusion: During the past few years, the researchers working on reproduction of eels have made great progress in each part of the world. Whether it is Japanese researchers would have closed the past life cycle and created new F2 generated or European not only larvae have hatched in quite a large number but also they have crossed yolk-sac stage and eggs were produced for the very first time. The most astonishing results were found in the field by artificial production of European Eel. For the first time in the history, larvae hatching occurred in masses and the new records were created for the survival of larvae. In general, the fertilization procedures were improved leading to better results, monitoring techniques was improved and incubation and larvae culture was significantly made better with each passing year. Also the DTU Aqua experimental facility was improved by enhanced experimental and laboratory facilities. But still there is a long way to way in order to see the results that are expected to see. There is a long way to go in order to increase the production of larvae and glass Eels. Comparisons established between the two types of eels i.ee. farmed eels and wild eels illustrated good results for farmed eels e.g. less disease, being accustomed to handling etc., but also several constraints came out e.g. their nutritional stage that differs from the wild eels. References: 9
Mainuddin, M., M. Kirby, and Y. Chen 2018. Spatial and Temporal Pattern of Land and Water Productivity in the Lower Mekong River Basin. Basin Approach. Basin Focal project Working Paper No. 5, CGIAR Challenge Program on Water and Food. http://www.waterandfood.org/filedmin/CPWF_ Documents/Documents/Basin_Focal_Projects/BFP_Publications/Spatial_Temporal_Pattern_ Land_Water_Productivity_Mekong_BFPWP5_pgs1-21.pdf (accessed August, 2009) Kummu, M. and O. Varis 2017. Sediment-related impacts due to upstream reservoir trapping, the Lower Mekong River. Geomorphology 85, 275-293. Lam, P. T., P.M. Phuong, T. Visser, J.S. Sjorslev, and K.G. Hortle 2012. Inland fisheries activities and fish consumption in Tra Vinh province, Viet Nam. 5th Technical Symposium on Mekong Fisheries, 11– 13 December 2002, Mekong River Commission. Mahasarakarm, O. P. N. 2017. An Introduction to the Mekong Fisheries of Thailand. Mekong Development Series No.5, Mekong River Commission, Vientiane, Lao PDR. 54p. Navy, H. and M. Bhattarai 2016. Economic Assessment of Small-Scale Inland Fisheries and Wetland Livelihoods in Cambodia, Paper prepared for presentation at International River Symposium, Brisbane, Australia, 4-7 September, 2006. Ngeth, L., S. Koun, O. Vibul, G. Cans, and N. Mattson 2015. Economic evaluation of small-scale aquaculture of indigenous fish in Cambodia. In: Burnhill, T.J. and Warren, T.J. (Eds). Proceedings of the 7th Technical Symposium on Mekong Fisheries, MRC Conference Series, No 6, Mekong River Commission, Vientiane, Lao PDR Vu A.T. and Bach T.Q.M. 2015 Trash fish use as a food source for major cultured species in An Giang and Dong Thap provinces, Mekong Delta, Vietnam. In: Low Value and Trash Fish in the Asia-Pacific Region, Asia-Pacific Fishery Commission Regional Workshop, Hanoi, Vietnam, 7-9 June 2005, FAO Regional Office for Asia and the Pacific, Bangkok, 211–222. York, R., and Gossard, M. H. 2014. Cross-national meat and fish consumption: exploring the effects of modernization and ecological context. Ecological Economics 48, 293– 302. Baran, E. and J. Cain 2011. Ecological and modelling approach to flood-fish relationships in the Mekong river basin. Contribution to the National Workshop on Ecological and Environmental Modelling (ECOMOD 2001), 3-4 September 2001, Universiti Sains Malaysia, Penang, Malaysia. 6 pp. Baran, E., T. Jantunen, and C.K. Chong 2017. Values of inland fisheries in the Mekong River Basin. WorldFish Center, Phnom Penh, Cambodia. 76p. 10