Essay on Techniques for Conservation of Fish Genetical Resources

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Among all vertebrate taxa, fishes have the highest diversity in species. Fishes have huge diversity in shape, size, and biology in their aquatic environment. According to the NATIONAL BUREAU OF FISH GENETIC RESOURCES, 32,042 finfish species were recorded globally and India is home to 9.2% of this global finfish diversity . According to NBFGR India accounts for 5070 Mollusca species, 2934 crustaceans species, and 765 echinoderms species.

Fishes are considered as cheapest and high protein source food source worldwide. Fishes are very important from commercial and economic viewpoints. India holds the second rank in fish production in the world and China ranks first. The fisheries sector issue work to 14 million individuals and the fisheries sector alone offers a GDP of around 1%. Major of these fishes come from the wild and the main reason for this is low training or domestication. The fisheries sector is so important and is getting exploited day by day due to rising population and demands and may become a problem for future use.

Due to regular anthropogenic actions like overfishing, pollution load, the introduction of exotic species, dam construction which alters the path of water including fishes, unendurable fishing, and global climatic variations our whole aquatic biodiversity is at a stage of serious threat. These threats may lead to biodiversity loss. Biodiversity loss is of serious concern. It is well known that in an ecosystem there is the interdependency of species on other species. Extinction of one species may affect directly or indirectly to other species. We are now at a stage of taking the preservation process for endangered species as a serious concern.

For the conservation of fish genetic resources, we are a step back despite having such a high economic value. In the fisheries sector, there is a scarcity of resources and scientific management practices. Therefore, the significance of conservation in the fisheries sector is considered seriously by fishery scientists. As per International Union for Conservation of Nature and Natural Resources, 1,275 species of fish are threatened around the world. In Asia out of 6,106 threatened species, 688 species are finfish. According to the current scenario conservation of fish, and resources are quite important. It is important to maintain species diversity for long-term maintenance and for future use also. The government of India and the Ministry of Environments, Forest, and climate change have enlisted many marine finfish and shellfish such as Pristis microdon, Rhincodon typus, Glyphius glypius, Sea horses, Gaint Grouper and some other threatened species under Wildlife Protection Act,1972. According to NBFGR (2010), there were 120 threatened freshwater fishes and 36 marine fishes.

Techniques for Conservation

There are two main ways to the conservation of resources that is In-situ conservation- conservation in their natural environment and Ex-situ conservation-conservation outside of their natural environment.

1. In-Situ Conservation

It is a way of protecting genetic resources in their own natural environment. It leads to the protection of the whole habitat. It includes Wildlife Sanctuaries, National parks, Conservation reserves, Community reserves, etc. The main benefits of In-situ conservation are that it proceeds with co-evolution where in the wild species may keep on co-advancement with different forms, giving vital resistance to breeders which lost in ex-situ protection. It is also low-cost protection than ex-situ protection.

According to the Ministry of Forest, Environment and Government of India (As of 2019) there is a total of 903 protected areas in India which include 101 National Parks, 553 Wildlife Sanctuaries, 86 Conservation Reserves, and 163 Community reserves. Out of these 903 protected areas, there are only 25 Marine protected areas which are very less as compared to terrestrial areas. These 25 marine protected areas include 4 National parks, 20 sanctuaries, and 1 community reserve.

These 4 important National Parks are

Gulf of Kachchh- It was founded in 1980 and is located in Gujarat. Major life supported here is corals, pearl, oysters, lobsters, octopus, seahorse, etc.
Gulf of Mannar- It was set up in 1983 and is located in Tamil Nadu. Major life forms supported here are Dugong Turtles, Dolphins Balanoglossus, etc.
Mahatma Gandhi Marine National Park, Wandoor- It was set up in 1983 and is located in Andaman. Major life forms are corals and turtles.
Rani Jhansi Marine National parks- It was founded in 1996. Mangrove forests are mainly supported here.

There are 3 chief Marine Sanctuaries

Gahirmatha Sanctuary – It was set up in 1998 and is located in Odisha. It is famous for Olive ridley sea turtles. It is a nesting beach for these turtles.
Malvan Marine Sanctuary – It was set up in 1987 in Maharashtra. Fishes inhabiting this area are Mystus seenghala.Tor putitora , Labeo dero etc.
Gulf of Kachchh Sanctuary – It was set up in 1980 and is located in Gujarat. It is famous for flamingos and Wild ass.

An International settlement for the protection and viable use of wetlands has signed on 2 February 1971 at Ramsar, Iran known as Ramsar Convection. Wetlands are considered as most productive habitat. Wetlands are home to many plant and animal species. In India 37 sites are comes under Ramsar convection sites are Chilka Lake (Orissa), Wular Lake (J&K), Rudrasagar Lake (Tripura), Sambhar Lake (Rajasthan), Sunderban Wetlands(West Bengal), Deepor Beel (Assam), Ashtamudi Wetland (Kerela),Beas Conservation Reserve (Punjab), East Kolkata Wetlands (West Bengal), Bhitarkanika Mangrooves (Odisha), Chandertal Wetland ( Himachal Pradesh), Bhoj Wetland (Madhya Pradesh ), Kanjli Lake (Punjab), Hokera Wetland ( J&K), Harike Wetland(Punjab), Roopar Lake (Punjab), Kolleru Lake (Andhra Pradesh), Loktak Lake (Manipur), Nalsarovar Bird Sanctuary (Gujarat), Pong Dam Lake (Himachal Pradesh), Renuka Wetland (Himachal Pradesh), Nandur Madhameshwar (Maharashtra), Parvati Agra Bird Sanctuary(Uttar Pradesh ), Sarsai Nawar Jheel (Uttar Pradesh), Upper Ganga River (Brijghat to Narora Stretch )(UP), Nangal Wildlife Sanctuary (Punjab), Keshopur Community Reserve(Punjab), Keolado Ghana NP (Rajasthan), Nawabganj Bird Sanctuary(UP), Vembanad Kol Wetland (Kerela), Point Calimere Wildlife Sanctuary(Tamil Nadu), Samaspur Bird Sanctuary (UP), Sasthamkotta Lake(Kerela), Sandi Bird Sanctuary(UP), Surinsar –Mansar Lakes(J&K), Saman Bird Sanctuary(UP), Tsomoriri Lake(J&K).

Some Streams and rivers located nearby temples or divine places are protected due to spiritual value. Human Actions are strictly prohibited here. These areas are known as sacred areas. Examples of some sacred areas are Haridwar, Rishikesh, and Sri Sardamath – located in Sringeri and situated at the bank of Tunga river where mahseer such as Tor khudree, Tor musullah, and barbs such as Hypselobarbus jerdoni, Hypselobarbus dobsoni, Hypselobarbus kolus are present and protected. Kulathupuzha Temple in Kerela presents on the bank of the Kallada river where fishes such as Tor khudree, and Tor malabaricus were present.

Improvement of stock through a captive breeding program

It is a breeding program in which juveniles are taken away from their natural environment and kept in the lab or any safe confinement until they attain sexual maturity to breed in that lab or safe confinement to make a healthy population after that offspring are reared for sometimes and then get released back to their natural environment. It was first started by Norway and US in 1980. Anadromous species like Sturgeon, Herring, cod, Stripped bass, and haddock were ranched through this breeding program. These methods require knowledge of the breeding season of species and give chance to study the life pattern, adaptability, and survival of that species. Information on genes and genetic constituents is required in this breeding program so that before releasing the species back to their natural environment alleles of species in the lab and in wild should be matched. For successful ranching alleles of artificially bred species and species in wild should be the same. NBFGR, Lucknow has to begin ranching of golden mahseer in the Sharda and Ladhiya rivers and ranching of Labeo dussumieri and Horabagrus brachysoma in Kerela which result in a good increment after 2 years in their landing center like Labeo dussumeiri from 0.68% to 3.9% and Horabagrus brachysoma from 1.8% to 11%.

The idea of State Fish

The ICAR- NBFGR gives a conception of the protection of fish biodiversity by adopting a state fish by each state. This includes the incorporation of key shareholders in the protection proposal in which 16 states of our country have selected their state fish.

Live Gene Bank

It is set up for the preservation of the germplasm of threatened species with the help of captive breeding. NBFGR has set up a live gene bank at Lucknow holding 12 working pond with high protection which include the collection of threatened fish species. It includes the study of genetic constituents and genes of that species which can become an important tool for in-situ and ex-situ protection methods.

2. Ex-Situ Conservation

It is a way of conservation of endangered species that are protected from their natural environment in an artificial environment. Technique involved in ex-situ protection is Zoological Garden, Botanical Garden, Cryopreservation of gametes and embryos of fishes, Tissue banks, etc. Cryopreservation is one of the most important methods of ex-situ preservation. Ex-situ is more expensive to process than in-situ conservation because the techniques involved in it are costly.

Cryopreservation of gametes and embryos of fish

Cryopreservation is a low temperature (below freezing point) preservation of cells or organelle, tissues, etc without losing its feasibility. Chemicals used for cooling in cryopreservation is mainly liquid nitrogen (-196 degree Celsius). In this preservation, all reactions in the cell remain suspended because at very low-temperature water in the cell gets converted into crystals. It leads to the long-term preservation of cells. In Aquaculture cryopreservation of fish gametes and embryos are very significant . Cryopreservation leads to the preservation of fish eggs and sperm for a long time without losing their capacity for fertilization. In India, NBFGR is the essential association to convey cryopreservation. It is species-specific preservation.

Fish sperm cryopreservation

It is a low-temperature preservation of fish sperm for a long duration without losing its capacity for fertilization. Such preservation of sperm of fishes is created through test normalization of different parameters after the captive breeding program. Due to the drawing out of the breeding season and the low training of the majority of fish species particularly marine species cryopreservation has become congestion. In many cases experiments, studies and various research programs depend on the breeding time of fish and this breeding time is short. Due to these limitations, it is very important to preserve the gametes of fish. These gametes are available when natural milt is not present which is helpful in artificial breeding and producing seeds. As we know marine areas are very vast so the preservation of marine fish is very important.

Process of cryopreservation of sperm- This process mainly follows five steps

Collection of sperm: Milts are collected in spawning season. Inducers like hormones are used to increase the volume the milt and it is collected in tubes or syringes. It is mainly done by two ways as milt can be collected by pressing the abdomen of fish or by removing the testis of fish and collecting the sperm. Collection by removing testis is done for that fishes which not allow to release sperm by pressing the abdomen of fishes like Clarius batrachus.
Quality assessment of milt: This is an important method where efficiency of sperm is evaluated before preservation like motility of sperm, sperm count, volume of sperm to volume of milt and activeness of sperm.
Use of extenders: It is a solution of salts or some organic compounds used to dilute the milt and making the sperm work easy. It is use to maintain feasibility of cells and osmotic balance of cell. It keeps sperm alive in dormant condition and increases the storage time of sperms.
Cryoprotectant addition: It is used prevent damage and death of tissues or cells during the process of freezing. Some examples of commonly used cryoprotectant are glycerol and dimethyl sulfoxide.
Preservation of spermatozoa: It can be non cryogenic and cryogenic. Non cryogenic includes storage for short duration and at 4 degree Celsius. Cryogenic preservation includes preservation for a long time at (-196 degree Celsius ) using liquid nitrogen.

Cryopreservation has been successful for 200 fish species such as Cyprinus carpio, Catla catla, Clarius batrachus, Labeo rohita, Labeo dero, Labeo dussumieri, Labeo dyocheilus, Salmo truta fario, Oncorhyncus mykiss, Schizothorax richardsoni, Tenualosa ilisha, Tor putitora, Tor tor khudree, Ompok malabaricus, Labeo calbasu, Barbodes carnaticus, Heteropneustes fossilis, Garra surendranathanii, Horabagrus nigricollaris, Etroplus suratenesis, Osteochilichthys longidorsalis, Puntius sarana, Horabagrus brachysoma, Pangasius pangasius and Puntius chalakkudiensis. Sperms under cryopreservation have been used for the production of rohu seed when natural milt is not present and it has shown a positive impact.

Cryopreservation of egg and embryo

Cryopreservation of gametes of fishes is still facing many difficulties in the case of egg and embryo preservation. It has not succeeded in the world so far due to tough Zona radiata, a high amount of yolk, and the big size of the embryo and egg. The tough layer of zona radiata does not allow cryoprotectant to pierce and does not allow deep cooling. After cooling high amount of yolk become hard and break the cell. These are the limitations in the cryopreservation of eggs and embryos.

Tissue Bank

It is a process of collecting and storing tissues of long duration to recover genetic details. This tissue bank is also used for education, research, and transplantation processes. It is not a species-specific preservation.

Conclusion

The conservation of fish genetic diversity as a term looks straightforward forward but its enforcement is not an easy job. In the fisheries sector, there is a scarcity of resources and management practices. Methods used in the conservation process are not developed in the case of fishes there are very less marine protected areas in comparison to terrestrial areas despite the diversity of fishes declining very fast. Preservation processes like cryopreservation, tissue bank, and live gene bank are less developed for fishes. The main reasons for such decline are continuous human actions are as fishing without any mesh size regulation, aquatic pollution, the introduction of exotic species, illegal fishing, habitat alteration, construction of dams, etc. In a developing country like India where the fisheries sector gives job to 14 million individual conservation of fish resources are very significant for future plans. Extinction of any species leads to the permanent loss of genes of that species and regaining those genes is impossible. In a developing country like India implementation of the law are more difficult than making a law so there is a need for strict in-laws. Species diversity is important to maintain a stable ecosystem and for future use also. It is important to create awareness about the importance of conservation and to decrease regular anthropogenic actions for the conduction of responsible fisheries. According to Food and Agriculture Organization, it is essential to maintain and conserve genetic resources for the present and future fulfillment of human use.

References

Dr W.S. Lakra, Dr P. Das, Dr U.K. Sarkar, 2019. Fish Genetic Resources and their Conservation. Handbook of Fisheries and Aquaculture. New Delhi. Indian Council of Agricultural Research.
A D DIWAN et al. “Cryopreservation of fish gametes and embryos”, Indian Journal of Animal Sciences 80 (4) (Suppl. 1.): 109-124, April 2010.
ENVIS Centre on Wildlife & Protected Areas, Hosted by Wildlife Institute Of India, Dehradun.
FAO/UNEP, Conservation of the Genetic Resources of Fish: Problems and recommendations. Report of the Expert Consultation on the genetic resources of fish. Rome, 9-13 June 1980.

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