Tag: Aquaculture

Introduction

Fish was one of the easily accessible foods that humans in the past often consumed. All around the world, several fish species are consumed as food. It is a significant food that is rich in many nutrients. Different fish, whether freshwater or marine, are used by humans as food. Fish and other sea creatures that are eaten for food are more commonly referred to as seafood.

Fish as food

• Nearly half of the fish consumed today was raised through fish farming, which is practized globally.
• In aquaculture, fish such as tuna, salmon, halibut, cod, and trout are regularly farmed.
• Aquafarms can be constructed as mesh cages submerged in water in addition to concrete enclosures on land.
• Fish farms, however, have the potential to damage the ecology by introducing diseases, pollutants, and invasive species.
• In the coastal parts of India, fish is a common diet.
• Up until 1961, the annual increase in fish consumption worldwide was roughly 3.2% and it has exceeded both the size of the population and the demand for meat of terrestrial animals .
• In addition to increased production, the expansion in consumption has also been influenced by a number of other factors such as-less waste, better use, improved distribution systems, and rising consumer demand.

Fish production

• Fish production, which is known as mariculture or aquaculture where a number of fish are raised and expanded for commercial purposes. Fish can be produced using a number of techniques:
• Fishing capturing: As the name implies, fish in this are collected from many water bodies such as ponds, lakes, rivers etc.
• Fish breeding: It is the practise of raising particular fish species in confined water bodies with great care to achieve optimal yield. This is often referred to as pisciculture or fish farming. It is divided into two further categories:
  • Inland fishery– Fishing in fresh waterbodies such rivers, ponds, lakes, etc. is referred to as inland fishery. The production in this is average. Examples of fishes grown are Rohu, Catla,  carp, etc.
  • Marine fishery– The majority of marine fisheries include fishing in sea and ocean water. Offshore and deep-water fisheries are the two main categories of marine fishery. Fishes grown here are Pomfret, sardines, hilsa,etc.
• Additionally, there are three different approaches to fish farming: extensive, semi-intensive, and intensive.
  • Extensive fish farming– In extensive fish farming, fish productivity is based on the natural productivity of water, it requires large ponds with minimal care.
  • Semi-intensive farming– This method  uses fertilisers to boost the natural productivity of fishes. It has relatively small ponds with a higher fish density.
  • Intensive farming- An extremely well-maintained and well- controlled method of raising fish, in small ponds and tanks, is known as intensive farming.

Making of Regional Cultures

People eat what is easily accessible to them in a particular place. For instance, rice and fish are the two main staple foods of Bengal, which has hot and arid climate. Numerous instances may be found in the literature, sculptures, and artwork of the Bengali people that demonstrate how important fishing has always been to their culture.  For instance, the walls of temples and viharas sometimes have ceramic plaques showing scenes of fish being prepared and transported to markets in baskets. Since fish is a common cuisine in Bengal, Brahmins were allowed to eat some varieties of fish even if their religion forbids doing so. This was found in  a text from the thirteenth century called the Brihaddharma Purana. All of these demonstrate how the regional culture of Bengal developed, due to fish and how eating fish did not become a matter of debate there.

Summary

The consumption of fish as a staple food became common practice since it was easily available. People started using different techniques to capture and breed fish. In general, there are two types of fisheries-  inland fisheries where fish are caught from fresh water, and marine fisheries salt where fish are caught from seas and oceans. A number of variables, including decreased waste and rising consumer demand, contributed to the increase in fishing productivity.

Frequently Asked Questions

1. Why is fish considered a healthy food?
Ans: One of the world’s healthiest foods is fish because it has important nutrients like protein and vitamin D in abundance. Also, omega-3 fatty acids, which are vital for your body and brain, are also found in fish.

2. Which fish has high protein content?
Ans: Fresh tuna contains the greatest protein per gram. It is the most commercially  available and provides the greatest protein per weight (30.7g in a 100-gram serving).

3. Is fish more nutritious than meat?
Ans: Red meats (beef, hog, and lamb) often contain higher cholesterol and saturated (bad) fat than chicken, fish, and plant-based proteins like beans. Saturated fat and cholesterol can increase blood cholesterol levels and aggravate heart disease. Hence as compared to red meat, chicken and fish have less saturated fat and are more healthier.

Introduction

A dam is a physical structure that slows or restricts the flow of subsurface or surface water. Dams build reservoirs that serve multiple purposes, including flood control, irrigation, human consumption, industrial use, aquaculture, and navigability. Although they are more frequently erected on rivers, dams can be constructed anywhere. They may also be built on streams and estuaries.

What is a Dam?

A dam is a sizable, barrier-like structure that is erected across a body of flowing water. Water is held back and stored for later use because of construction. A reservoir is a term used to describe the vast amount of water storage created on the upstream side of a river when it is prevented from flowing by a barrier. Floodgates on dams can be opened or closed to allow only a small flow for human use.

During floods, gates also enable the release of extra water from the reservoir side. A surplus of water collects on the reservoir side of a river when it floods. To let surplus water out, the floodgates are slowly opened. Dams are primarily built for this reason.

For more help, you can Refer to lesson 16 – Water in Science Class 7. Checkout the video Lesson for a better understanding

Uses of Dams

• Irrigation: In recent years, irrigation for crops has primarily been provided by dams. Rainfall in tropical nations like India is only experienced for a portion of the year. However, agriculture is a year-round industry that uses water for growth, depending on the stage of growth. While others, like rice and sugarcane, require excessive amounts of water. Agriculture was made possible by irrigation, even in remote areas with low subterranean water levels.
• Electricity: The floodgates are opened, allowing the reservoir’s water which is already under high pressure to pass through the turbine that powers the generator. A turbine transforms the kinetic energy of water into mechanical energy, which is then transformed into electrical energy by a generator.
• Reservoirs are a great place for recreation. Many reservoirs provide the local people with camping, boating, and fishing facilities.

Advantages of Dams

• Hydroelectric power, which is produced by dams, is independent of all fossil fuels. As a result, hydroelectricity is a source of energy that is constantly replenishing and can be used. With a growing population comes a rising need for energy. One of the safest methods to address the energy situation is using hydroelectric electricity.
• A reservoir maintains a sizable water reserve that is mostly used to store fresh water that can be used later in times of water scarcity.
• You can irrigate with the reservoir water. Crop plants can be effectively watered across long distances. Food is produced on the irrigated farmlands. Demands for drinking water are alarmingly rising along with population growth.
• Floods are prevented by dams, which redirect water flow. Numerous lives are saved every time water is slowly released from reservoirs through floodgates, and property damage is also avoided. 
• A reservoir is a gathering place for many aquatic animals, including fish and turtles. When dams are built, a river that is already flowing becomes a lake. It becomes a lake environment when freshwater fish and turtle species seize the opportunity to multiply.

Disadvantages of Dams

• To create a sturdy basement and reservoir, large layers of dirt must be dug out during the dam’s construction. The earth’s topography is harmed by this. Because of this, earthquakes happen more frequently. However, effective engineering, design, and planning can stop such destruction. 
• Dams are substantial, concrete buildings. They are not built economically. 
• Dam construction necessitates a vast area. It is necessary to move the local farmers and residents to the area. Their social and economic lives are affected, and there are long-term repercussions.
• In addition to displacing people, the natural habitat is also greatly disturbed. Concerns about the flora impacted by dam construction are mostly focused on deforestation and the loss of agriculturally productive land. 
• Natural wildlife that lives in the dam region is also out of control and occasionally even poses a threat to its population. To maintain their populations, breeding grounds and nesting locations are crucial. When other factors perturb these areas, their population changes. 
• Bird species are disturbed, in addition to terrestrial and aquatic species. 
• Fish living in freshwaters are the primary food source for migratory birds that nest on riverbanks. 
• Migratory birds lose their feed and are prevented from reproducing as they do throughout the year due to the drastic shift in aquatic life caused by dam building.
• The groundwater table in the surrounding areas is decreased as a result of deepening the riverbed to create reservoirs. This has a significant negative influence on nearby, naturally occurring vegetation.

Summary

A dam is a physical obstruction that slows or restricts the flow of subsurface or surface water. Floodgates on dams can be opened or closed to allow only a small flow for human use. In recent years, irrigation for crops has primarily been provided by dams.  A reservoir maintains a sizable water reserve that is mostly used to store fresh water that can be used later in times of water scarcity. Dams are substantial, concrete buildings. They are not built economically.

Frequently Asked Questions 

1. Do Dams Last Forever?
Ans. A dam may be built in around ten years, and its lifespan is about one hundred years. Certain mechanical components, including motors and gates, need to be changed after a dam has been in place for 50 years. However, operational dams will undergo routine inspections. When necessary, all repairs and maintenance will be carried out right away.

2. Can we Rely Solely on Hydroelectricity to Provide our Electricity?
Ans. A renewable energy source is a hydroelectricity. Since the dam-related operation does not disrupt the water cycle, the claim that water will not run out is valid. The problem is that rivers and streams are the only sources of flowing water that dams may use. Hydroelectric power cannot be the only source of sustainably produced energy.

3. What Connection does a Dam have to Greenhouse Gases?
Ans. Large expanses of vegetation are flooded when a dam is built, submerging numerous trees. Low oxygen levels can be found near the bottom of stagnant waters in reservoirs. The reservoir’s lower layers, which are abundant in biomass, effectively release methane into the atmosphere as it breaks down.

4. What Advantages do Dams Offer to Farmers?
Ans. Large amounts of water are stored in reservoirs where they can be irrigated for use in agriculture. Croplands can also be effectively irrigated in semiarid areas far from the riverbed. Rainfall is not necessary for farmers to be able to cultivate.