What are the Effects of Climate Change on Fisheries Sector

Fisheries sector plays an important role to meet up the nutritional requirement, create employment opportunity, earn foreign currency that means overall economic development of Bangladesh. Bangladesh possesses third position in the world for collecting fish from internal water bodies and possesses fifth position for culturing fish. There is about 4.7 million hectare area of internal open and closed water body including river, canal-beel, haor, pond, lake, tidal area etc. in this country. Moreover, there is wide sea area of 1 lakh 66 thousand square kilometer. Presently, fish production from these water bodies is not sufficient as compared with its area. More production can be possible from them. Presently (2010-2011), fish production in this country is about 30.60 metric ton and target production is 34.78 metric ton up to the year of 2012-2013. Although, fish production in this country has gradually been increased for last few years, and it is increased due to fish culture. But, natural fish production in internal open water bodies like river, canal, beel, haor, tidal land has been decreased drastically. Biodiversity of fishes is also decreased there and this happened due to climate change. Climate change causes increase of environmental temperature, increase of the surface height of the sea, increase of salinity, absence or shortage of rainfall. Severity and number of cyclone and tidal wave is increased. For this reason, fish culture, natural breeding of fish and their movement is hampered. The effect of climate change on fisheries sector is described below:

a) Effects on Fish Culture and Fry Production

1. In our country, farmers release fries in the seasonal pond if it is merged by rain water in April-May. Climate change decreases rainfall or causes late rainfall. That�s why fries releasing becomes late. Besides, pond is also dried out quickly after the fries are released lately. As a result, culturing period is reducing and small fishes are to be marketed before reaching their maturity. In this way, farmers are lossing.
2. Fish breeding and fry production in hatchery are inhibited due to the increase of temperature and low rainfall which are caused by climate change. In hatchery, fish does not give response for artificial breeding due to not getting favorable environment for breeding and high temperature. They do not release eggs even they bear in their belly. Eggs are being absorbed in the body. If fish release eggs, these are not fertilized or very less amount is fertilized. Thus, climate change is hampering the fry production in the hatchery.
3. Fishes are easily affecting with the diseases due to high temperature in shallow pond and the rate of mortality is increasing. As a result, production is becoming less and farmers� income is decreasing.
4. Water is getting less in culture pond due to low rainfall. As a result, farmers are spending much money for supplying water in the pond or farm.
5. Severity and number of flood, cyclone, and tidal wave is increasing due to climate change. That�s why; difficulty of farmers is increasing with the increase of amount of loss in fisheries sector. Fishes are going out of the pond.
6. Culture ponds in coastal area may be merged due to the increase of the height of the level of sea surface.

b) Effects on Fish Production in Internal Open Water Body

1. Less water is found in river due to low rainfall and as a result, it is easily possible to harvest fish in low water. Thus, small-big and matured fishes are being caught. As a result, biodiversity and permanent production of fish are hampering.
2. Sea surface height is increasing due to the increase of temperature and that�s why, salinity is entering towards the main land. In this way, natural breeding and living ground of fresh water for fish are decreasing in coastal area. At the same time, production is also decreasing.
3. In beel, baor, tidal area of our country, month of April-May is the breeding period of native type small fish. In the recent years, water body is not to be merged by water till the month of July due to absence or low rainfall during rainy season. That�s why, fish breeding is being hampered greatly. As a result, this affects whole fish production and nutrition and livelihood of those people who are involved with harvesting fish.
4. In our country, naturally rui types of fish release eggs only in Halda river, They release eggs during heavy rainfall after extreme heat in the month of Boishakh. Then fishermen collect fertilized egg from the river and produce fries by hatching the eggs. Due to increase of temperature caused by climate change, egg maturity of brood fish comes earlier. On the other hand, starting time of rainfall is gradually going backward. Thus, dissimilarity is observed between the physiological condition of fish and the time of rainfall. As a result, possibility of getting eggs is decreasing.

c) Effects on Marine Fish

1. Carbon dioxide is increasing day by day in the air and that�s why temperature of air and sea level are increasing. So, movement of wind and nature of rainfall are changing. Hence, fish movement in the ocean and their production are affected. Thus, fish quantity may be increased in one part of ocean. Besides, the place which is popular for safe living for fish may be fishless.
2. Global warming and climatic change cause the movement of fishes from tropical area to temperate area. Many fishes have already changed their migration route, breeding place and living space. As a result, the places of ocean where fishermen have been fishing based on their knowledge and experience since long past, if changes occurs to these places, they will fall in trouble.
3. Coral reef is the suitable living place for marine fishes where various types of fish live in and is used as breeding place. Coral is being destroyed due to increasing temperature in water, variation of waves, increasing acidity in ocean, pollution, changes of waves speed etc.