Reasons for the formation of fisheries, reasons for the formation of fisheries

The main reasons for the formation of fishing grounds are the abundance of bait and "water barriers".

Most of the reasons are the abundance of bait and "water barriers". The first is the convergence of cold and warm currents, which changes the environment of water at the confluence. Another reason is the influence of upwelling.

Peruvian fisheries are affected by the southeast trade winds, which blow from the shore to the Pacific Ocean, causing the sea water on the shore to continue to decrease, and the nutrient-rich sea water at the bottom is replenished and used as bait to collect fish.

Summary of the causes and conditions of the formation of the four major fishing grounds.

All in all, marine fishery resources are mainly concentrated in the coastal continental shelf area, that is, the part of the continental seabed that extends from the coast to a depth of about 200 meters. Plankton flourishes because of the concentration of sunlight, strong biophotosynthesis and abundant nutrients brought by rivers entering the sea. They are bait for fish and are generally abundant in temperate seas.

In terms of the impact of ocean currents on fishing grounds, there are four major fishing grounds in the world:

1. The Hokkaido Fishing Ground is formed by the confluence of the warm current of Japan and the cold current of the Kuril Islands.

2. The Newfoundland Fishery is formed by the confluence of the warm Gulf Current and the cold current of Labrador.

3. The North Sea fishery is formed by the confluence of the North Atlantic Warm Current and the East Greenland Cold Current.

4. Peruvian fisheries are formed by rising compensating currents along the Peruvian coast.

The basic conditions that should be met.

Fisheries are often confined to a certain layer of water in a given sea area, or even to a certain period of time. This limitation depends mainly on the density of the fish population and the length of its duration, as well as on the biological characteristics and ecological habits of the fish (economic marine animals) and changes in their environmental conditions. Therefore, the following conditions must be met to constitute a fishing ground.

1) There should be a large number of fish migrating through or inhabiting in clusters.

Marine fisheries production is mainly aimed at dense and stable populations of fish or economic animals that are engaged in migratory, breeding, foraging or wintering activities, especially breeding groups, which are dense and stable, and most fish stocks are clustered in the same body length group or the same age group, such as salmon trout. Therefore, in the fishing operation, if the objects that do not meet the fishing specifications (such as young or sexually immature juveniles) are coldly fished, the gains will inevitably outweigh the losses, seriously affecting the resources in the coming year, and even leading to the decline of fishery resources, and the future will be endless.

2) There should be suitable environmental conditions for fish clusters and habitats.

If, at a given time, there are external environmental conditions (both biotic and abiotic) suitable for fish and other economic animals to migrate, reproduce, forage and winter, they can cluster or inhabit together, thus creating conditions for the formation of fishing grounds. Biological conditions refer to the interspecific relationships between forage and symbiotic organisms and various other organisms. Abiotic conditions refer to ocean currents, water systems, water temperature, salinity, water depth, sediment, geomorphology, and meteorology.

Among the external environmental factors, especially the marine environmental factors, it plays an important role. The change of marine water temperature has a very close relationship with the migratory distribution and distribution of economic fish, and fish have different requirements for their surrounding environmental conditions in different life stages, so marine environmental conditions are important conditions for the formation of fishing grounds, and among the various factors of marine environment, water temperature and forage organisms are the most important factors.

In his analysis of the causes of fishing grounds in Newfoundland and Hokkaido, Japan, he said, "It is related to the convergence of cold and warm currents, which brings a variety of bait to fish. "When reviewing the knowledge of fishing grounds, it is necessary to synthesize the relevant narratives of geography in junior and senior high schools in order to make a comprehensive and systematic analysis

The conditions for the formation of fishery grounds can be summarized as follows:

How are fisheries formed?

1) The formation of fishing grounds on the continental shelf can be analyzed from three aspects:

The sea water of the continental shelf is shallow, and the solar radiation heat energy reaches the seabed, which is conducive to the reproduction and growth of fish bait (plankton);

The bottom of the continental shelf is deposited with sediment brought by the continent, which is conducive to fish spawning.

The continental shelf is contiguous to the continent, and the various organic matter brought by the rivers flowing from the continent provides nourishment for fish and plankton.

2) The convergence of cold and warm currents to form a fishing ground is mainly analyzed from two aspects:

In the sea where cold and warm currents meet, the sea water is prone to agitation, and the nutrients from the lower layer are flooded to the upper layer, which is conducive to the growth of plankton and attracts a large number of fish.

In the sea area where the cold and warm currents meet, there are often cold-water and warm-water fish that come with the cold and warm currents to stay here (the fish are not used to the nature of the oncoming currents and do not dare to move on), so the fish gather and form a large fishing ground. For example, the world-famous fishing grounds in Hokkaido, Newfoundland and Zhoushan in China have this condition.

The reason for the formation of the fishery is that there is a large amount of plankton, which provides a lot of food for the fish, attracts a large number of fish to feed, and forms the fishing ground.

Reasons for the formation of the fishing grounds: The Hokkaido fishing grounds are formed by the confluence of the warm current of Japan and the cold current of the Kuril Islands; The Newfoundland fishery is formed by the confluence of the warm Gulf Current and the cold Labrador Current; The North Sea fishery is formed by the confluence of the North Atlantic Warm Current and the East Greenland Cold Current; Peruvian fishing grounds are formed by upwelling compensating currents along the Peruvian coast. Reasons for the formation of fisheries:

The Hokkaido Fishing Ground was formed by the confluence of the Japanese Warm Current and the Kuril Cold Current'；The Newfoundland fishery is formed by the confluence of the warm Gulf Current and the cold Labrador Current; The North Sea fishery is formed by the confluence of the North Atlantic Warm Current and the East Greenland Cold Current; Peruvian fishing grounds are formed by upwelling compensating currents along the Peruvian coast.

The confluence of cold and warm currents disturbs the seawater, and the upper seawater brings nutrients to the surface of the ocean, so that plankton can flourish, and then provide abundant bait for fish, and fishery resources are abundant. In addition, the confluence of cold and warm currents can create "water barriers" that prevent fish from swimming, and for these reasons large fishing grounds can be formed.

1. Peruvian fishing grounds are formed by upwelling.

2. The North Sea fishery is formed by the confluence of the North Atlantic Warm Current and the East Greenland Current.

3. The Hokkaido fishing grounds are formed by the confluence of the warm current of Japan and the cold current of the Kuril Islands.

4. The Newfoundland fishery was formed by the confluence of the warm Gulf Current and the cold Labrador Current.

That is, only the Peruvian fishery is formed by the upwelling, and the other three are formed by the convergence of cold and warm currents!

1. Rivers input a lot of nutrients.

2. The water area is shallow, under the action of wind, waves, tides and convection, the water body is fully mixed, the bottom layer is supplemented to the upper layer, and the whole water body is well nourished.

3. Photosynthesis is sufficient, and phytoplankton multiplies in large quantities.

4. The water area is shallow, so the material circulation is fast and the primary productivity is high.

5. Due to the abundance of bait organisms, the continental shelf is generally a spawning ground, and the bay is also a fattening place for fish.

6. The water depth of the continental shelf is suitable, and the seabed is relatively flat, which is suitable for fishing gear operations.

7. At the edge of the continental shelf, due to the offshore action of the upper current, the water in the lower layer of the open sea is introduced, resulting in upwelling.

8. In the sea area near the edge of the continental shelf, coastal water systems and open sea systems generate coastal fronts.