Basic Parameters of Single Trawl Fishing Gear

In the VBVB of Quang Nam province, fishermen use two types of trawl nets, which are single trawl nets and three-layer trawl nets. Single trawl nets have been used for a long time and have become a traditional occupation of the locality. Three-layer trawl nets (called three-screen trawl nets by fishermen) were introduced to Quang Nam about 15 years ago (2005). They are effective in catching fish but also have harmful effects on aquatic resources and marine ecosystems.

The structure of the 3-layer trawl net consists of 3 overlapping mesh panels, including 1 panel in the middle (called the inner panel) and 2 panels on both sides (called the outer panels). The inner panel usually has a smaller mesh size than the 2 outer panels. The upper edges of the 3 mesh panels are assembled onto the buoy grid, while the lower edges of the 3 panels are joined together onto the lead grid.

Nets are rectangular nets, depending on the target fished, each type of net uses a different specification and color. The net thread material is PA, d= 0.35mm, white, frog-foot knotted; the mesh size 2a of the 2 outer nets is 50mm.

The rope system includes buoy rope and tape rope. Float rope type PE, Φ = 8mm.

The lead wire helps to shape the net in water and during the working process, the lead wire always tends to stretch the net downwards. The lead wire is made of PA material, model number 210D/24, diameter d = 0.85mm and is threaded into the net cover. Each assembled net cover is about 7 kg of lead.

The 3-layer trawl buoy has dimensions of 130 * 30 * 20 (mm); the distance between two buoys is 16 ÷ 18 meshes; each net has 80 small buoys evenly distributed on the buoy's girder. The basic parameters of the trawl net used for exploitation in VBNC are shown in Figure 3.1 and Table 3.9.

80 PVC (130x30x20)mm 2 x 42.30m PE Φ 8 U1 = 0.75

Figure 3.1: Drawing of the trawl net development

Table 3.9: Basic parameters of trawl net

Required Information

Single trawl

3 layer trawl net

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	Inner plate	Outer plate
Mesh panel material	PA fee	PA fee	PA fee
Mesh size	10  15	15 ÷ 30	20 ÷ 35
Horizontal reduction factor U1	0.8	0.75	0.75
Horizontal reduction factor U1	0.58	0.58	0.58
Shortened length of 1 mesh (m)	40	50	50
Height of 1 net panel (m)	10	10	10
Number of nets per ship	50	60	60

3.1.2.2. Fishing gear

Source: survey data

Hook is also a type of fishing gear with a very simple structure, easy to manufacture, low investment cost, so it appeared very early in the folk. Hook is also a passive fishing gear but has high selectivity, is an environmentally friendly profession, does not damage the living environment of aquatic species. In the VBVB of Quang Nam province, hook is the fishing gear that accounts for the second largest proportion after trawling. Fishing gear usually has 2 types: pole fishing (hand fishing) and longline fishing. Hand fishing has a simple structure while longline fishing has a complex structure. The results of the survey of the current situation and the basic parameters of fishing gear are presented in Table 3.10.

Table 3.10: Basic parameters of longline fishing gear

TT

Name	Material	Quantity	Specifications
1	Main line	PA Mono	7,500	Ø1.80mm
2	The above sentence tag	PA Mono	1.500x28	Ø0.90mm
3	Tag below	PA Mono	1,500x2	Ø0.90mm
4	Lifebuoy	PE	1.500x11	Ф5mm
5	Artificial bait	PVC	1500	L = 140mm
6	Beads create a link button	PVC	1,500x2	Ф5mm
7	Sentence rotation lock	Stainless steel	1,500x2	L = 30mm
8	Clamp (with swivel lock)	Stainless steel	1,500	L = 35mm
9	float	PVC	1,500	L400, Ф100
10	Lead	Pb	1,500x7	20g
11	Flag buoy	PVC	30	L400, Ф100
12	Big flag (yellow head)	Bamboo, fabric	2	2.5m

3.1.2.3. Purse fishing gear

Source: survey data

Purse nets are fishing gear used to catch pelagic fish, an active fishing method with complex structure and high technical requirements. On the other hand, pelagic fish reserves in Quang Nam province are not large, only 16.23% of the total reserves. Therefore, the proportion of purse seine fishing in Quang Nam province is not high, only 3.17% of the total number of vessels. Mainly the

There are vessels over 20CV operating in purse seine fishing here, but there are no vessels under 20CV. The results of the survey of the basic structural parameters of purse seine fishing are presented in Table 3.11.

Table 3.11: Basic parameters of the purse seine

Name

Materials, specifications	2a (mm)	Quantity
Meat mesh	Close	PA210D/9	23	25
	Pine	PA210D/15	15  20 mm	10
	Wing	PAP210D/9	25	50
Net	float	PA210D/21	25	1
	Lead	PE700D/18	40	1
	Chao Bien	PE700D/18	40	2
Rope	Float ring	PPɸ14 car	d =14	2
	Lead	PPɸ10,PPɸ12	d =10÷12	2
	withdrawal	PP ɸ36 braided	d =36	1
Lifebuoy		Flexible foam	200x60x40	2000
Lead		Lead (Pb)	60x30 ɸ11	1700
Ring		Cu D190xɸ25	d=25÷35	70

Source: survey data

From Table 3.11, it can be seen that the purse seine here has a mesh structure in the upper part that does not satisfy the regulations in Appendix II, Circular 19/2018/TT-BNNPTNT [4]. Thus, it can be said that the purse seine fishing industry is generally environmentally friendly, but with 2a in the middle part, the product is smaller than the regulations, so there is a possibility of catching juvenile fish, young fish, and immature fish.

3.1.2.4. Trawl fishing gear

Trawling is a fishing gear that operates on the principle of filtering water to get fish. Trawling is a type of fishing gear that harms resources and their habitat. Therefore, the State has issued a document banning trawling in the VBVB nationwide since 2006 [2, 7, 11]. Due to many different reasons, fishermen still defy the law and bring trawling boats here to operate. In the VBVB of Quang Nam province, there are two types of trawling nets operating illegally day and night: pair trawling nets and single trawling nets. The results of the actual investigation of the basic parameters of single trawling nets and pair trawling nets operating in the VBVB of Quang Nam province are presented in Table 3.12 and Table 3.13.

Table 3.12: Basic parameters of single trawl fishing gear

TT

Name	Materials, structures	Specifications	Quantity
1	Mesh Wing	PE700D/21	2a= 60÷80 (mm)	2
2	Mesh body	PE700D/15	2a=25÷40 (mm)	6

Name	Materials, structures	Specifications	Quantity
3	missed	PE700D/25	2a=15÷20 (mm)	1
4	Lead	PP	 20÷30 (mm)	1
5	Float ring	PP	 15÷30 (mm)	1
6	Cable pull	Fe	 18÷22 (mm)	2
7	Lifebuoy	PVC	 200÷250 (mm)	20
8	Lead	Pb, chain	 10÷12 (mm)	1 wire
9	Mesh board	Steel covered with wood,	1.5mx0.5m	2

TT

Source: survey data

Table 3.13: Basic parameters of pair trawl fishing gear

TT

Name	Materials, structures	Specifications	Quantity
1	Mesh Wing	PE700D/21	2a = 60÷80 (mm)	2
2	Mesh body	PE700D/15	2a = 25÷40 (mm)	6
3	missed	PE700D/25	2a = 15÷20 (mm)	1
4	Lead	PP	 25÷40 (mm)	1
5	Float ring	PP	 20÷40 (mm)	1
6	Lifebuoy	PVC	 200÷250 (mm)	20
7	Lead	Pb, chain	 10÷12 (mm)	1 wire
8	Red wire	Jute sheathed cable	 80; 100 m	2
9	Cable pull	Fe	 20÷25 (mm)	2

Source: survey data

From Table 3.12 and Table 3.13, it can be seen that the trawl here has a mesh size in the fish holding part smaller than the regulation [2, 7]. On the other hand, both types of trawls have a lead structure and especially the single trawl is equipped with a net board which is the part that scrapes the seabed during the working process. This is an important factor that harms the resources and habitat of aquatic species.

3.1.2.5. Fishing gear for cage and trap fishing

Cage traps are one of the traditional occupations of fishermen in Quang Nam province, including crab traps, squid traps, crab traps, etc. Cage traps are considered an environmentally friendly fishing profession because they are fixed fishing gear that people drop to the bottom of the sea, and seafood species crawl into them and are then retained. In recent years, in Quang Nam province, cage trap fishing gear from China (commonly known as wire traps) has been imported. Currently, wire traps, also known as octagonal cages, Chinese stacking traps, are fishing gear prohibited from exploitation according to Circular 19/2018 of the Ministry of Agriculture and Rural Development [4]. The structure of the wire trap fishing gear is as follows:

Figure 3.2: Structure of the fishing gear

- Average length: 10m

- Width: 300  350 mm

- Height: 200  250 mm

- Mesh size 2a in the fish holding part: 10  15 mm

- Mesh size 2a of the net jacket (fish guide): 15  20 mm

- Rectangular cuttings, size: 14 * 80 mm

Each fishing household equips its boat with 100 to 150 fishing lines (if pulling manually); or 300 to 400 fishing lines (if using a fishing machine). The basic parameters of the fishing lines are described in Figure 3.2 and Table 3.14.

Table 3.14: Technical parameters of wire rope

TT

Specifications	Unit	Biggest	Medium	Smallest
1	Length	m	12	10	8
2	Height	m	0.3	0.25	0.2
3	Width	m	0.35	0.3	0.25
4	2a of the mesh bag	mm	20	15	10
5	Length of the cutting	mm	10	9	8
6	Width of the trap	mm	300	250	200
7	2a of hom lu	mm	20	15	10
8	2a in the bag	mm	15	10	8

Source: survey data

3.1.3. Current status of labor on KTTS fishing vessels in VBVB, Quang Nam province

3.1.3.1. Age structure and education level of workers

To clearly see the current situation of labor working on fishing vessels in Quang Nam province, the researcher conducted direct interviews with crew members of 366 vessels. The total number of respondents was 1956, distributed by occupation as shown in Table 3.15. The survey results by education level and age are presented in Table 3.16.

Table 3.15: Distribution of the number of surveyed workers by mining occupation in 2019

TT

Profession	Number of respondents	Rate (%)
1	trawl	360	18.40
2	Sentence	240	12.27
3	Seine	300	15.34
4	Seine net	360	18.40
5	Trap cage	396	20.25
6	Other professions	300	15.34
Total		1,956	100

Source: survey data

Table 3.16: Education level and working age of KTTS

TT

Age	Level of education				Total
	Illiterate	Elementary	Secondary School	High School	(People)	(%)
1	< 20	8	130	175	0	313	16.00
2	20 ÷ 39	21	485	431	61	998	51.02
3	40 ÷ 59	41	238	177	33	489	25.00
4	≥ 60	35	74	42	5	156	7.98
Total		(People)	105	927	825	99	1,956	100
		(%)	5.37	47.39	42.18	5.06	100

Source: survey data

Chart 3.4: Distribution of people by age of workers

Chart 3.5: Distribution of people by education level

From table 3.16, chart 3.4, it is easy to see that the age group with the best health, suitable for the marine fishing profession, is 20÷39 years old, accounting for 51.02%. Although this age group has good health, they do not have much experience. Next is the age group from 40 to 59, accounting for 25.00% of the total number of people surveyed. At this age group, the advantage is that workers have a lot of experience but their health begins to decline. At the remaining age group, under 20 years old, they have good health but lack experience at sea (accounting for 16.00%), on the contrary, those aged 60 and over have a lot of experience but poor health, accounting for only 7.98%.

From table 3.15, chart 3.5 shows that the majority of crew members on fishing vessels operating in VBVB, Quang Nam province have low education, primary school level accounts for 47.39%, even 5.37% of the total number of respondents are illiterate. The number of crew members with secondary school education accounts for a relatively high proportion (42.18%), after the primary school group. The remaining number with high school education accounts for only 5.06% of the total number of crew members surveyed. This situation is quite high compared to the education level of crew members operating in VBVB fishing vessels nationwide [10, 42]. However, compared to the requirements for applying science, technology and State laws to fisheries, there are still many difficulties and shortcomings.

3.1.3.2. Professional qualifications and experience of workers

Partly due to low education level, on the other hand, fishermen have long abandoned books, so their main occupation is to study while doing, learning practically according to family tradition, passed down from father to son by hand-holding. The level of skills and expertise mainly depends on experience at sea through the number of years working on ships. The more you work

The longer a person has been at sea, the more experience he has and the higher his skill level. The certificates that the captain, chief engineer, mate, crew member, and mechanic have are to assess the level of law enforcement of the ship owner. The results of the survey on the professional qualifications and experience of workers are shown in Table 3.17.

Table 3.17: Age and experience of crew members

TT

Age in career (years)	Number (people)	Rate (%)	Rating level
1	< 5	246	12.60	New to the profession, no experience
2	5 ÷ 10	641	32.80	Moderate experience
3	10 ÷ 20	716	36.60	Highly experienced
4	≥ 20	353	18.00	Very experienced
Total		1956	100

From table 3.17 shows:

Source: survey data

- The survey was conducted on a total of 1,956 crew members, according to the following groups: under 5 years, 5 ÷ 10 years, 10 ÷ 20 years, ≥ 20 years. The group of crew members with 10 ÷ 20 years of experience accounted for the highest proportion (36.6%) compared to the remaining groups. The group of crew members with 5 ÷ 10 years of experience ranked second with 32.80%. The remaining group with low experience (under 5 years) accounted for only 12.6% and the group of experienced crew members accounted for 18% of the total number of respondents.

Table 3.18: Professional qualifications of crew members

Ship length

Type of training	Captain's Certificate	Chief Engineer Certificate	Sailor's Certificate	Mechanic Certificate
<6m	Number of respondents	271	271	271	271
	Number of people with certificates	170	117	0	0
6÷<12m	Number of respondents	95	95	95	95
	Number of people with certificates	95	95	65	0

Source: survey data

According to Circular No. 22/2018/TT-BNN [5], ships under 6m in length are not required to have a captain, chief engineer, sailor, or mechanic certificate; for ships from 6÷12m in length, only the captain and 1 sailor are required to have a certificate. The results of the investigation of 366 fishing vessels operating in the VBVB of Quang Nam province, of which 271 vessels were under 6m in length, 95 vessels were from 6÷12m in length, the specific results are presented in Table 3.18. From Table 3.18, it can be seen that: