WO2021004026A1 - Method for estimating body length and weight of prawn on the basis of diameter of eyeball thereof - Google Patents

Abstract

A method for estimating the body length and the weight of a prawn on the basis of the diameter of an eyeball thereof, in which an image of an eyeball of a prawn is acquired, data of the diameter of the eyeball of the prawn is accurately obtained by means of software analysis, and data of the body length and the weight of the prawn can be accurately determined according to a fitting model of the diameter of an eyeball and a body length and a fitting model of the diameter of an eyeball and a weight. The coefficient of correlation between the diameter of an eyeball and the weight of a prawn, which is measured by means of the present method, is equivalent to the coefficient of correlation between a body length and a weight, and the eyeball of a prawn can autofluoresce in a weak light condition, facilitating image recognition by a computer, achieving automated monitoring.

Description

A method for estimating body length and weight of prawns based on eyeball diameter Technical field

The invention belongs to a method for estimating biomorphological indicators in the field of marine biological technology and a method for pattern recognition in the field of information technology, and specifically relates to a method for estimating body length and weight of the eyeball diameter of Litopenaeus vannamei cultivated in circulating water.

Background technique

Litopeneaus vannamei, also known as Penaeus vannamei, is native to the Pacific coast waters from northern Peru to Sanola, Mexico. It is a warm-water economic shrimp species. In the process of recirculating aquaculture, it is necessary to ensure sufficient feeding amount of bait, but also to avoid the deterioration of aquaculture water quality caused by feeding too much bait. Therefore, it is necessary to accurately calculate the biomass in the breeding system and perform precise feeding to save feed costs and reduce the water treatment load of the breeding system. In order to construct an automatic identification technology of shrimp biomass in aquaculture ponds, the first thing to be solved is to find an index that is convenient for computer identification to estimate the weight of shrimp, and then combine the number of shrimp to estimate the biomass.

In the related research of prawn morphological character models, many scholars at home and abroad have used multiple regression methods to analyze various morphological indicators of prawns (such as body length, carapace length, breast width, breast height, number of spurs on the forehead, and spurs under the forehead. The relationship between weight and tail length, etc.) and body weight ^[1-6] . The results of the study show that there is a strong correlation between body length and body weight of Litopenaeus vannamei. However, to estimate body weight based on body length, it is necessary to measure the length from the base of the eyestalk to the end of the caudal stalk. In actual measurement, the body of the prawn always shows a certain curve, which often results in large errors in the measurement results and is not conducive to automatic computer recognition. Therefore, inventing a new method for estimating shrimp weight is of great significance for accurately estimating the cultivation biomass and facilitating automatic computer identification.

List of references:

[1] Huang Zhong, Lin Heizhu, etc. The relationship between body length and body weight of 5 families of Penaeus monodon[J]. Guangdong Agricultural Sciences, 2011, 38(04): 116-119.

[2] He Tong. Multivariate statistical analysis and genetic parameter estimation of growth traits of Litopenaeus vannamei [D]. Northwest Sci-tech University of Agriculture and Forestry, 2010.

[3] Gopalakrishnan A, Rajkumar M, Rahman M, et al. Length--weight relationship and condition factor of wild, grow-out and'loose-shell affected' giant tiger shrimp, Penaeus monodon (Fabricius, 1798)[J] .Journal of Applied Ichthyology,2014,30(1):251-253.

[4]Daud S K, Ang K J. Selection of broodstock of tiger prawn, Penaeus monodon Fabricius, on the basis of morphometric traits [J]. Pertanika Journal of Tropical Agricultural Science, 1995, 18: 15-20.

[5]Primavera J H, Parado-Estepa F D, Lebata J L. Morphometric relationship of length and weight of giant tiger prawn Penaeus monodon according to life stage, sex and source[J]. Aquaculture, 1998, 164(1-4) ): 67-75.

[6]Abohweyere P O,Williams A B.Length-weight relationship and condition factor of Macrobrachium macrobrachion in the Lagos-Lekki Lagoon system,Nigeria[J].Research,Journal of BiologicalSciences,2008,Journal(11) .

Summary of the invention

In order to solve the problems of large measurement errors when measuring prawn body length data and the difficulty of obtaining body length data through machine vision recognition in a weak light environment, the present invention provides a method for estimating body length and weight by using the diameter of the eyeball of a prawn.

The purpose of the present invention is achieved through the following technical solutions:

A method for estimating body length and weight of prawns by using the diameter of the eyeballs of prawns. By using the measured eyeball diameter data of prawns and the known fitting relationship between the diameter of the eyeballs and the body length and weight, the data of the body length and weight of prawns can be accurately obtained.

The data of shrimp eyeball diameter can be obtained by direct measurement or by computer image recognition.

The prawn eyeball is nearly elliptical, and the diameter of the prawn eyeball is the length of the long axis of the elliptical prawn eyeball, that is, the length between the two points at the furthest distance between the prawn eyeball edge is taken as the prawn eyeball diameter.

The fitting relationship between eyeball diameter (d) and body length (L) and weight (W) is obtained after fitting the measured data of at least 10 prawns of the same species, L=f ₁ (d), W=f ₂ (d) , Where f ₁ and f _{2 are} obtained by data fitting.

Eyeball diameter d (unit: mm), body length L (unit: mm), weight W (unit: g);

The fitting relationship between the eyeball diameter of Litopenaeus vannamei and the body length and weight is known: the expression of the relationship between the eyeball diameter d and the body length L of the prawn is: L=15.978d–2.31

The relationship between eyeball diameter d and weight W:

d<2mm, W＝0.0326d ^3.7363 ;

2mm≤d<3.9mm, W＝0.0401d ^3.1040 ;

3.9mm≤d<5.8mm, W＝0.0421d ^3.0311 ;

5.8mm<d, W＝0.1030d ^2.6226 .

Eyeball diameter d (unit: mm), body length L (unit: mm), weight W (unit: g);

It is known that the fitting relationship between the eyeball diameter and body length and weight of Penaeus chinensis is: L=4.9741d+94.985; W=5.4174d ^0.8627 , and the applicable range of the formula: 5.5<d<7.5.

It is known that the fitting relationship between the eyeball diameter and the body length and weight of the eagle claw shrimp is: L = 18.12d-21.175; W = 0.0151d ^3.5573 , and the formula adaptation range: 4.0<d<6.5.

The fitting relationship between eyeball diameter and body length and weight of mantis shrimp is known: L=21.703d-15.703; W=0.0549d ^3.3611 , and the formula adaptation range: 5.0<d<7.0.

The advantages and positive effects of the present invention are:

1. The diameter of the prawn eyeball can be accurately measured with small measurement error.

2. The eyeballs of prawns can auto-fluoresce under low light conditions, which is convenient for computer image recognition and automatic monitoring.

3. The correlation coefficient between eyeball diameter and body weight and the correlation coefficient between body length and body weight are equivalent.

Description of the drawings

Figure 1 is a schematic diagram of selecting prawn eyeballs;

Figure 2. Principles for selecting the long axis of the prawn eyeball.

Figure 3. The relationship between eyeball diameter and body length of Litopenaeus vannamei.

Figure 4. Eyeball diameter-weight relationship of Litopenaeus vannamei (d<2mm)

Figure 5. Eyeball diameter-weight relationship of Litopenaeus vannamei (2mm<d<3.9mm)

Figure 6. Eyeball diameter-weight relationship of Litopenaeus vannamei (3.9mm<d<5.8mm)

Figure 7. Eyeball diameter-weight relationship of Litopenaeus vannamei (d>5.8mm)

Figure 8. The relationship between eyeball diameter and body length of Penaeus chinensis.

Figure 9. Eyeball diameter-weight relationship of Penaeus chinensis.

Figure 10. The relationship between eyeball diameter and body length of eagle claw shrimp.

Figure 11. The relationship between eyeball diameter and body weight of eagle claw shrimp.

Figure 12. The relationship between eyeball diameter and body length of mantis shrimp.

Figure 13. The relationship between eyeball diameter and body weight of mantis shrimp.

Detailed ways

1. Obtaining the fitting relationship between eyeball diameter and body length and weight of Litopenaeus vannamei

In different growth stages of prawns, a total of 300 prawn samples were collected. The body length of the prawns was measured with a vernier caliper. The measurement accuracy was 0.02mm. The range of the body length of Litopenaeus vannamei was 19.12mm-161.3mm; the weight was measured with an analytical balance and the measurement accuracy was The weight range of Litopenaeus vannamei is 0.084g-53.034g.

Take pictures to obtain images of prawn eyeballs, and use computer software to measure the diameter of prawn eyeballs. As shown in Figure 1, when shooting, place the prawns under the dissecting mirror, straighten the body of the prawns to avoid bending, and shoot with the back of the prawns from a bird's-eye view. At the same time, place a measuring ruler during the shooting;

Use dimmizer4.2 image analysis software to measure the eyeball parameters of Litopenaeus vannamei; as shown in Figure 2, the eyeball of the prawn is approximately elliptical, and the long axis of the ellipse is selected as the diameter of the eyeball. The data range of eyeball diameter is 1.33mm-12.1mm. The eyeball diameter, body length and weight data of Litopenaeus vannamei are shown in Table 1.

Table 1. Eyeball diameter, body length and weight data of Litopenaeus vannamei.

Using the measured prawn eyeball diameter d (14.21mm<d<70.93mm) and body length data L (19.12mm<L<161.3mm), as shown in Figure 3, the prawn eyeball diameter d (unit ：Mm) and the prawn body length L (unit: mm):

L = 15.978d-2.31, R ² = 0.9793

According to the growth characteristics of Litopenaeus vannamei, the segmented fitting method is used in the fitting process, and the body length data of Litopenaeus vannamei is used as the segmentation basis. As shown in Figure 4-7, the fitted body length L is 0- The relationship between the corresponding eyeball diameter d (unit: mm) and weight W (unit: g) when 30mm, 30-60mm, 60-90mm and greater than 90mm are:

d<2mm, W＝0.0326d ^3.7363 , R ² ＝0.9288;

2mm≤d<3.9mm, W＝0.0401d ^3.1040 , R ² ＝0.9629;

3.9mm≤d<5.8mm, W＝0.0421d ^3.0311 , R ² ＝0.9216;

5.8mm<d, W＝0.1030d ^2.6226 , R ² ＝0.9457.

The same method as above was used to measure 30 fresh eagle claw shrimp, Chinese prawns, and mantis shrimp. As shown in Table 3, the eyeball diameter range of eagle claw shrimp was 4.14mm-6.55mm and the body length range was 55.31. mm-96.41mm, the weight range is 2.66g-9.95g; the measured eyeball diameter range of Penaeus chinensis is 5.5mm-7.52mm, the body length range is 123.23mm-133mm, and the weight range is 24.32g-30.62g; the measured mouth shrimp The eyeball diameter of the cricket ranges from 5.02mm to 6.82mm, the body length ranges from 88.9mm to 129.72mm, and the weight ranges from 10.88g to 34.33g. As shown in Figure 8-13, the partial fitting relationship between eyeball diameter d (unit: mm), body length L (unit: mm), and weight W (unit: g) is as follows:

Penaeus chinensis: L = 4.9741d+94.985, R ² = 0.8424; W = 5.4174d ^0.8627 , R ² = 0.8822, the applicable range of the formula: 5.5<d<7.5.

Eagle claw shrimp: L = 18.12d-21.175, R ² = 0.9324; W = 0.0151d ^3.5573 , R ² = 0.881, the applicable range of the formula: 4.0<d<6.5.

Mantis shrimp: L = 21.703d-15.703, R ² = 0.8628; W = 0.0549d ^3.3611 , R ² = 0.877, the applicable range of the formula: 5.0<d<7.0.

Table 2. Morphological data of Penaeus chinensis, eagle claw shrimp and mantis shrimp

2. Sampling and measuring eyeball diameter to obtain body length and weight

Every 5 days, 50 samples of Penaeus vannamei cultured in circulating water were taken, and samples were taken 6 times, totaling 300 Penaeus vannamei. Place the prawn with its back upright on the dissecting mirror stage, place a ruler next to the prawn as a reference object and take an image.

The dissecting mirror is equipped with a multifunctional control unit, integrated with a 3.5-inch LCD display, and stores prawn images with a resolution of 2048x1536.

The prawn image is read in real time by the computer, and the pixels on the unit length of the scale on the image are measured to obtain the pixel length r (pixel/mm) contained in the unit length on the scale.

As shown in Figure 2, the image segmentation method is used to intercept the image near the prawn’s eyeball, the contour of the prawn’s eyeball is obtained through the canny operator, the coordinates of all pixels on the contour are extracted, and the longest Euclidean distance between the coordinates is calculated to obtain the pixel length L. L×r is calculated to obtain the long axis length d (unit: mm) of the shrimp eyeball.

Taking d as the diameter of the prawn’s eyeballs, the prawn’s eyeball-body length relationship and the eyeball-weight relationship model are brought into the prawn’s body length and weight data.

3. Underwater image acquisition to obtain body length and weight

Fix the infrared camera vertically at a distance of 30cm from the bottom of the breeding pond to take underwater images, set the coordinate system in the plane that the CCD lens can shoot, and focus the camera on the plane where the coordinate system is located.

The image is transmitted back to the host computer through wireless transmission, the image is stored in the hard disk, the file address is stored in the database, and the shooting time is used as the main key, which is convenient for querying and saving the data of prawn eyeball, body length and weight.

Read the image in real time, take the bright spot formed by the reflection of the shrimp eyeball as the feature point, use the edge detection algorithm in OpenCV to obtain the eyeball number Q, and extract the contour and segment the image near the shrimp eyeball. The number of prawns in the coordinate system can be calculated by Q/2, rounded up.

Furthermore, the binary contour of the shrimp eyeball is extracted by means of image corrosion and image expansion, and the coordinates of the pixel points on each binary image are obtained. The traversal method calculates the Euclidean distance between any two points on the contour, and records the most The long Euclidean distance is stored in the database.

A total of 233 groups of Penaeus vannamei eyeball data were extracted from the database, and the prawn eyeball-body length and eyeball-weight models were used to calculate the body length and weight of the prawns, and the calculated body length and weight data were stored in the database. The corresponding data is as follows table 3.

Table 3 Eyeball diameter, body length and weight data of Litopenaeus vannamei

Using this method to identify shrimp eyeballs can avoid underwater image noise and achieve the purpose of accurate weight calculation. When cultivating Litopenaeus vannamei in circulating water, the accurate total biomass of culture can be calculated by the host computer, and then the feeding amount can be adjusted and the total amount of culture can be estimated.

Claims (8)

1. A method for estimating body length and weight by using the diameter of the eyeballs of prawns, characterized in that:

   Using the measured prawn eyeball diameter data and the known fitting relationship between eyeball diameter and body length and weight, the prawn body length and weight data can be accurately obtained.
2. The method according to claim 1, wherein the data of the diameter of the eyeball of the shrimp can be obtained by direct measurement or by computer image recognition.
3. The method according to claim 1 or 2, wherein the eyeball of the prawn is nearly elliptical, and the diameter of the eyeball of the prawn is the length of the long axis of the eyeball of the ellipse, that is, the distance between the two points of the eyeball of the prawn at the farthest distance The length is used as the diameter of the prawn’s eyeball.
4. The method according to claim 1, wherein the fitting relationship between eyeball diameter (d) and body length (L) and weight (W) is obtained after fitting the measured data of at least 10 prawns of the same species, L= f1(d), W=f2(d), where f1 and f2 are obtained by data fitting.
5. The method according to claim 1, 2, 3 or 4, characterized in that:

   Eyeball diameter d (unit: mm), body length L (unit: mm), weight W (unit: g);

   The fitting relationship between the eyeball diameter of Litopenaeus vannamei and the body length and weight is known: the expression of the relationship between the eyeball diameter d and the body length L of the prawn is: L=15.978d–2.31

   The relationship between eyeball diameter d and weight W:

   d<2mm, W=0.0326d3.7363;

   2mm≤d<3.9mm, W=0.0401d3.1040;

   3.9mm≤d<5.8mm, W=0.0421d3.0311;

   5.8mm≤d, W=0.1030d2.6226.
6. The method according to claim 1, 2, 3 or 4, characterized in that:

   Eyeball diameter d (unit: mm), body length L (unit: mm), weight W (unit: g);

   It is known that the fitting relationship between the eyeball diameter and body length and weight of Penaeus chinensis is: L=4.9741d+94.985; W=5.4174d0.8627, the applicable range of the formula: 5.5<d<7.5.
7. The method according to claim 1, 2, 3 or 4, characterized in that:

   Eyeball diameter d (unit: mm), body length L (unit: mm), weight W (unit: g);

   It is known that the fitting relationship between the eyeball diameter and the body length and weight of the eagle claw shrimp is: L = 18.12d-21.175; W = 0.0151d 3.5573, the formula adaptation range: 4.0<d<6.5.
8. The method according to claim 1, 2, 3 or 4, characterized in that:

   Eyeball diameter d (unit: mm), body length L (unit: mm), weight W (unit: g);

   The fitting relationship between eyeball diameter and body length and weight of mantis shrimp is known: L = 21.703d-15.703; W = 0.0549d3.3611, the formula adaptation range: 5.0<d<7.0.

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