According to the public relations office of Iranian Fisheries Science Research Institute of the country, in the scientific note of Dr. Seyyed Ahmad Reza Hashemi, it is stated:
“Stocks conservation is a universally emphasized principle and a key criterion in the sustainability of exploitation of all aquatic resources. The effort of all fisheries managers is focused on access to adequate and reliable food supply from natural resources and meeting the needs of human societies, taking into account the permissible and correct utilization of them. The global catch in 2018 was about 96 million tons, 87% of which was in marine waters (84 million tons) and 13% in inland waters (12 million tons). The fishing fleet in 2018 was about 4.6 million vessels and is remained at about the same level in 2015. Asia has the largest fishing fleet with 3.5 million vessels (75% of the world's fishing fleet). The total production of fisheries aquatics in Iran through fishing and exploitation of the southern waters of the country, has reached more than 700 thousand tons in 2019 from about 239 thousand tons in 1997, and Sistan and Baluchestan province has the highest amount of fishing and the largest annual increase in fishing.
There are 15 genera and 52 species of tuna in the order of Perciform and the family Scrambridae, and there are 8 species of tuna. All members of the tuna family are marine and pelagic and live in the middle of the water in the upper layer (from the surface to a depth of 300 meters) and sometimes make important food or reproductive migrations. Tuna is one of the most economically important fish for most countries and is the most valuable economic fish in industrial fishing in the world's waters and is widely distributed in temperate and tropical seas, especially in Pacific, Atlantic and Indian Oceans, but it is also found in Mediterranean and Black Sea and elsewhere. Seven species of tuna are of high global commercial importance, including Thunnus alalunga, Thunnus obesus, Katsuwonus pelamis, Tunnus albacares and three species of Thunnus thynnus. Thunnus maccoyii and Thunnus orientalis. The species Tunnus albacares, Katsuwonus pelamis, and Thunnus obesus usually account for more than 80% of the global tuna catch, which varies across different oceans. The most part of this economic species catches is from Pacific Ocean (more than 70% of the total world catch in 2017) and the Indian Ocean (about 20% of the total world catch in 2017). Tuna fishing around the world, is mainly done in Asia specially Indonesia as one of the main producers and other important countries in this field and other important countries in Asia include Iran, Vietnam, Japan and the Philippines. Spain and France in Europe, and Ecuador and the United States in America are important countries in tuna fishing.
Changes in fishing in southern waters of the country
The amount of fishing in southern waters of the country has increased from 238 thousand tons in 1997 to 731 thousand tons in 2018. As can be seen in Figure 1, the proportion of benthic catches, the level of large losses and the level of small losses of the total catch in 1997 were 60%, 33% and 5%, respectively (the remaining percentage was allocated to other species) and in 2018, these ratios have changed to 36%, 46% and 13%, respectively (the remaining percentage has been allocated to other species). In fact, by comparing the expressed ratios, it can be said that the ratio of benthic species has decreased and the ratio of loss level has increased, and the ratio of surface to benthic catch in 1997 was about 0.62 and in 2018 this ratio increased to 1.63 (more than 2.5 times). The highest ratio of surface to benthic catch was about 2.15 in 2006 and after that it has a decreasing trend and in recent years this ratio is changing slightly. These changes are also related to the characteristics of aquatic species and the region, and on the other hand, planning has been considered to increase production relying on catching loss levels (Figure 2).
The amount of tuna fishing (tuna, quasi-tuna and needlefish) in southern waters of the country has increased more than 290 thousand tons in 1398 (more than 40% of the total catch of water in the south of the country) from about 61 thousand tons in 1997 (78% of large-scale catch and 25% of the total catch of southern waters). With this amount of tuna catch, Iran has about 3-4% of the world's tuna catch (7/6 million tons in 2017) and about 20-25% of the Indian Ocean catch (about 1 million tons in 2017) And the highest amount of tuna catches in 2019 was Tunnus albacares (58 thousand tons), long tail tuna (49 thousand tons) and Katsuwonus pelamis (39 thousand tons), respectively. The amount of tuna catches in south of the country in 2019 was more than 290 thousand tons and more than 10 thousand billion tomans (more than 470 million dollars) is the initial turnover (sale of raw materials).
Sistan and Baluchestan Province:
Sistan and Baluchestan province has a greater share in the development of tuna exploitation due to its proximity to Oman Sea coast and access to Indian Ocean. In this province, the volume of tuna and other aquatics fishing is the result of fishing activities of about 2700 traditional fishing boats (about 1000 dinghies and more than 1700 boats are allowed) and about 25 thousand fishermen in the region who are directly engaged in the fishing industry. Tuna fishing in Sistan and Baluchestan province has a very important role in the economy of the fishing community in the region and even in the country, and more than 60% of the country's tuna fishing is provided by fishing activities in this province, so that it is the main hub of tuna fishing in the country. In this region, 5 species of tuna are caught, of which tuna Tunnus albacares as oceanic species and common long tail tuna species, yolk and tuna as coastal species (Figure 1). Tuna fishing tools in the southern waters of the country show that catch nets are still the dominant fishing tool (more than 90% of the total tuna catch) in the region and Purse Sein and Long Line fishing tools have a small share in the amount of depleted fishing.
Sistan and Baluchestan province has the highest catch of large losses (more than 65%) and tuna (more than 60%) in the southern waters of the country in 2018 and it is estimated that more than half of tuna fishing in this province is related to international waters (waters above 12 nautical miles) and Bandar Konarak is the most important port for tuna fishing in the province and Iran. About 170 thousand tons of tuna was caught in 2019 in Sistan and Baluchestan province and considering 40 thousand Tomans per kilogram, more than 6.5 thousand billion Tomans (more than 270 million dollars) initial turnover (sale of raw) of these species in the coasts of the province is estimated every year.
Tuna fishing information according to the world fishing tools:
Tuna fishery data (three groups of tuna, quasi-tuna and spearfish) according to the world fishing tools in 2020 show that Purse Seine fishing, which was done in two ways of with or without herd, owns more than 60% of the Tuna catch of the world which is the largest share of fishing gear used, and Tunnus albacares catch in some areas such as the East of Pacific Ocean uses up to 90% of tuna fishing gear and Katsuwonus pelamis catch in the center and west of Pacific Ocean uses up to 80% of it. The longline fishing method is another tuna fishing tool, accounting for about 10% of the global tuna catch, some of which are up to ten nautical miles long with several thousand hooks. In the method of catching Thunnus obesus in the east of Pacific Ocean more than 30% and fishing for Thunnus alalunga fish in the south of Pacific Ocean more than 90% of the long hook is used. Pole and Line fishing method is another method of tuna fishing with about 8% of global tuna fishing, more than 30% of Thunnus alalunga fishing in Pacific Ocean and about 20% of Katsuwonus pelamis fishing in Indian Ocean. (Figure 3).
Gillnet fishing accounting for about 4% of global tuna catches, about 20% of Tunnus albacares and more than 20% of Katsuwonus pelamis in Indian Ocean, does not account for the high rate of tuna fishing in the world. In Iran, more than 85-90% of tuna fishing has been done with gillnets, which due to implicit fishing and high waste fishing, other alternative methods such as long hook string should be used, which has less implicit and waste fishing.  Hook fishing, which includes traction hook and hand hook, has the lowest share of tuna fishing. The rest of the fishing methods are in the next categories and they are indicated by the symbol (OTH) (Figure 4).
- For catching tuna in the southern waters of the country, the gillnet has been used more than the global average long line and pole and line have been used less than the global average and to expand long line fishing (long hook string), pole and line (string and cane) and reduce gillnet fishing is needed.
- There is a capacity to expand the fishing fleet to catch Tunnus albacares (long line target catch) and Katsuwonus pelamis (target and pole and line catch) in the region, but due to the uncontrolled catch of Tunnus albacares in the province, Iran and Indian Ocean, this expansion of fishing capacity should be accompanied by caution and the elimination of traditional tuna vessels gillnets.
- Longline and pole and line fishing operations should be based on the sight of tuna herds to increase the chances of successful hooking.”
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