What contribution does marine food make to mankind?

A long time ago, humans began to eat marine food. The ancient Egyptians used to fish in the Nile and Mediterranean and tried to raise fish in ponds, because fish was their best source of protein. The ancient Greeks also widely used fish and shellfish, including those in seawater and fresh water. They make them into delicious canned food and dried salted fish.

Although humans began to eat marine food very early in history, there is hardly any information about the world seafood catch as far back as hundreds of years ago. Why is this happening? That's because people haven't fully understood the nutritional components of marine food and its importance to human health, so that marine food has not been taken seriously for many years.

With the development of society, people find that marine food contains protein, carbohydrates, lipids, vitamins and minerals, which are essential nutrients for human growth, development, health and longevity. Now, most people have realized that marine food is an excellent source of human nutrition.

Algae occupies a special and important position in marine biological resources. The algae that people often eat are: Nostoc commune, Nostoc flagelliforme, Nostoc commune and Spirulina; Green algae, Carex and Ulva among green algae; Porphyra and agar in red algae; Kelp and Undaria pinnatifida in brown algae. Seaweed is mostly sweet, cold and salty, and it is a popular product.

Seaweed food is rich in nutrition, as follows:

Protein: Different kinds of algae have different protein contents. Generally, the content of green algae and red algae is higher than that of brown algae. The protein content of green algae is between 10%-26% (dry weight), and the content of red algae is relatively high. The protein content of some red algae can reach 47%, far exceeding the protein content of soybean. The protein content of seaweed will change with the seasons. Usually, the protein content is higher in late winter and early spring, and the protein content is lower in summer.

Sugar: marine algae plants have high sugar content, mostly sticky sugar. These sugars are not easy to digest. As a heat source, their nutritional value is not high, but they have the function of regulating the stomach.

Vitamins: Algae are rich in various vitamins, among which the content of β -carotene is the highest, especially laver, which can reach 1 1000 international units per100g of dry product.

Ash: Algae plants are generally rich in ash, for example, the calcium content in Nostoc flagelliforme can reach 2.5%, while kelp is1.3%; The potassium content in laver is 65438 0.6%, and that in kelp is 65438 0.5%. The iodine content in seaweed is high, such as kelp 0.2% ~ 0.5% and Undaria pinnatifida 0.02% ~ 0. 1%. Iodine plays a great role in preventing goiter.

Apart from algae, animal resources are the most important and vivid marine life, including1.5 ~ 40,000 species of fish, more than 20,000 species of crustaceans such as prawns, and more than 80,000 species of mollusks such as shells, whales, sea cucumbers, seals, walruses and seabirds, which constitute a vibrant marine world. In mariculture, fish is the main body of aquatic products and occupies the most important position.

At present, more than 90% of the aquatic products caught from the ocean in the world are fish, and the rest are cetaceans, crustaceans and mollusks. There are many kinds of fish, including 1, 500 kinds of edible fish. Fish is full of treasures, with high nutritional value and delicious taste. Regular consumption can strengthen the brain and improve intelligence.

When it comes to aquatic products, you can't help but mention fish, shrimp and crabs, which can be described as delicious food on the table. Among them, a krill growing in Antarctica contains 80% water, 12% protein, 3% fat and 3% ash, and its protein content is 20 times that of beef, so it is known as "popular food of 2 1 century".

There are many kinds of shellfish, which live in various sea areas and are easy to find, so people have been fishing for a long time, among which abalone, mussels, scallops, clams, oysters and squid are of economic value. They are delicious and nutritious, and are deeply loved by people.

in-shore fisheries

We know that there are many food chains in the marine world. In the ocean, with algae, shellfish will appear. With shellfish, small fish and even big fish will appear ... Most fishing grounds in the world are offshore. This is because algae need sunlight and compounds such as silicon and phosphorus to grow, and only the ocean near land has such conditions. Deep-sea water below 1000 meters is rich in silicon, phosphorus and other elements, but they cannot float to the warm surface. Therefore, only a few small sea areas, under the action of natural forces, the deep seawater automatically rises to the surface, thus making these sea areas full of algae and dense fish, becoming rich fishing grounds.

Generally speaking, there are many fishing grounds in temperate waters. This is because the seasonal changes in temperate waters are significant, and the surface seawater and bottom seawater exchange in winter, and the flooded seawater is rich in nutrients, which is conducive to plankton reproduction. In addition, the confluence of cold and warm air currents and the flooding of cold sea water are rich in bait, and a rare fishing ground can also be formed here.

Broadly speaking, there are five major fishing grounds in the world, namely:

1. North Pacific Fishing Ground: a vast area including Hokkaido Fishing Ground, Zhoushan Fishing Ground in China, Hokkaido Fishing Ground and many fishing grounds on the west coast of North America;

2. Southeast Pacific fishing grounds: a vast area including Peruvian fishing grounds;

3. Northwest Atlantic fishing grounds: a vast area including Newfoundland fishing grounds;

4. North-East Atlantic Fishing Ground: a vast area including North Sea Fishing Ground;

5. Southeast Atlantic fishing grounds: a vast area including the coastal fishing grounds in southwest Africa.

Most fishing grounds in the world are in waters with a water depth of several hundred meters, and 80% of the area belongs to the shallow sea on the continental shelf. So, how can we make the seawater in the depths of the ocean rise to the surface, thus forming favorable conditions for fishing grounds? Oceanographers have found a breakthrough. They use the principle of updraft to artificially pump deep seawater to the surface in those areas with strong sunshine, then cultivate algae there, feed shellfish with algae, and feed processed shellfish to lobsters. Surprisingly, this series of experiments was a complete success.

Experts believe that marine food banks have great potential. At present, the annual output per hectare of land crops with the highest yield is only 0.7 1 ton in protein. However, scientific experiments show that the maximum output of mariculture in the same area can reach 27.8 tons, of which 16.7 tons still has great commercial competitiveness.

Of course, from scientific experiments to actual production, we often encounter some unimaginable difficulties. Most importantly, pumping water from the deep sea below 1000 meters requires considerable electricity. How did such a huge amount of electricity come into being? Obviously, it is still difficult to meet this demand under the current conditions.

However, scientists finally got the hang of it: they intend to use the temperature difference between surface water (heat source) and deep water (cold source) in tropical and subtropical oceans to generate electricity. This is the so-called seawater temperature difference power generation. In other words, the designed marine fishery will be combined with the seawater temperature difference power station to achieve the expected effect.

According to experts, there are as many as 6,250 trillion cubic meters of warm water available for power generation due to the strong light in tropical and subtropical waters. If people use 1% warm water to generate electricity every time, and then pump the same amount of deep seawater to cool down, and use this electricity to breed in fishing grounds, they can get 750 million tons of various seafood every year. It is equivalent to four times the total amount of fish and meat consumed by human beings in the mid-1970s. It is not difficult to see from these figures that it is not impossible for the ocean to become the granary of mankind in the future.

No country in the world has such a great capacity, and the marine industry can share this task, while the traditional fishery has reached or exceeded its regenerative capacity, so people have to turn to the research on the development technology of marine living resources, and huge marine living resources are waiting for human beings to explore and develop.

ocean energy resources

The vast ocean is not only rich in mineral resources and food resources, but also has inexhaustible marine energy in the true sense. It is not only different from the seabed energy resources such as coal, oil and natural gas stored on the seabed, but also different from the chemical energy resources such as uranium, magnesium, lithium and heavy water dissolved in water. It has its own unique way and form, and its charm is endless.

The meaning and characteristics of ocean energy

Ocean energy is a renewable energy in the ocean. The ocean receives, stores and releases energy through various physical processes. These energies exist in the ocean in the form of tides, waves, temperature differences, salinity gradients and ocean currents. Its various advantages attract all parties to actively study.

Ocean energy has four remarkable characteristics, namely:

1. Ocean energy accounts for a large part of the whole ocean water body, while the energy per unit volume, unit area and unit length is relatively small. This means that if you want to get great energy, you must get it from a lot of seawater.

2. Ocean energy is renewable. It doesn't need to burn coal or oil, but comes from the solar radiation energy and the gravity between celestial bodies. As long as the sun, the moon and other celestial bodies are with the earth, this energy will not be exhausted.

3. Ocean energy can be divided into stable energy and unstable energy. The stable energy sources are temperature difference energy, salinity difference energy and ocean current energy. There are two kinds of unstable energy, one is regularly changing and the other is irregularly changing. There are unstable but regularly changing tidal energy and tidal current energy. In reality, people can make daily and hourly tidal and tidal forecasts according to the changing laws of tides and tidal currents, and predict the size and intensity of future tidal currents. Tidal power stations and tidal power stations can adjust the power generation operation according to the forecast table. Wave energy is an unstable and irregular energy.

4. Ocean energy is a new type of clean energy, which does not need to consume fuel, produce waste, waste liquid and waste gas, and does not need transportation. The development of marine energy will not produce new pollution, and the impact on the environment is less than that of the traditional energy development industry, and the advantages outweigh the disadvantages. It can be said to be the "blue power" with the most green environmental protection concept.