Gill net selectivity of yellow perch

Figures & data

Figure 1. Location of four sample sites (M, K, G, and EC) located in the Indiana waters of Lake Michigan from 2007 to 2012.

Table 1. Summary statistics of yellow perch Perca flavescens collected in the micromesh gill nets. Mesh size, minimum, maximum, median, and averages in mm.

Mesh size	N	Minimum	Maximum	Median	Average	SD
12.5	102	55	265	61	73	38.28
16.0	362	58	269	76	84	29.22
20.0	57	71	260	93	111	38.34
25.0	288	78	235	127	132	29.36

Table 2. Results of model selection with the SELECT method for micromesh gill net selectivity estimates of yellow perch Perca flavescens collected in southern Lake Michigan, 2007–2011, only for mesh sizes 12.5, 16, 20, and 25 mm. The model with the lowest deviance statistics was considered the best.

	Large mesh		Micromesh
Model	Parameters (±SE)	Model deviance	Parameters (±SE)	Model deviance
Normal fixed spread	k = 4.31 ± 0.014	1240.81	k = 4.60 ± 0.085	1011.30
	σ = 29.69 ± 0.529		σ = 27.54 ± 0.956
Normal proportional spread	k1 = 4.56 ± 0.015	1246.61	k1 = 4.29 ± 0.337	1258.08
	k2 = 0.39 ± 0.013		k2 = 8.32 ± 1.175
Gamma	k = 0.08 ± 0.003	1070.13	k = 0.43 ± 0.030	1001.80
	α = 55.97 ± 1.875		α = 11.90 ± 0.773
Log-normal	μ = 4.97 ± 0.003	1018.32	μ = 4.77 ± 0.005	834.14
	σ = 0.13 ± 0.002		σ = 0.12 ± 0.003

Figure 2. Gill net selectivity of combined sex yellow perch based on the log-normal distribution for 12.5, 16, 20, and 25 mm mesh sizes of micromesh gill nets (2007–2011) and 32, 38, 46, 51, 64, and 76 mm mesh sizes of large mesh gill nets (2010–2012) in southern Lake Michigan.

Figure 3. Deviance residual plot for the selection curves fit to combined sex yellow perch based on (A) the log-normal distribution for 12.5, 16, 20, and 25 mm mesh sizes of micromesh gill nets (2007–2011) and (B) 32, 38, 46, 51, 64, and 76 mm mesh sizes of large mesh gill nets (2010–2012) in southern Lake Michigan. Mesh sizes 12.5–46 mm were monofilament and 51–76 mm were multifilament. Circles represent residual values (open positive; closed negative), with the area of the circle proportional to the square of the residual.

Table 3. Summary statistics of yellow perch Perca flavescens collected in large mesh gill nets. Mesh size, minimum, maximum, median, and average are in mm.

Mesh size	N	Minimum	Maximum	Median	Average	SD
Females
32.0	400	123	282	150	151	17.02
38.0	459	135	305	174	180	24.58
46.0	273	92	318	197	201	23.36
51.0	312	105	347	215	218	27.47
64.0	349	191	333	263	264	23.32
76.0	201	245	349	292	294	19.48
Males
32.0	44	125	175	150	150	9.49
38.0	26	155	217	174	175	12.28
46.0	11	191	261	198	205	20.05
51.0	18	175	241	202	206	18.18
64.0	6	154	251	246	228	37.90
76.0	6	154	302	285	263	56.41

Table 4. Results of model selection with the SELECT method for experimental gill net selectivity estimates of yellow perch Perca flavescens collected in southern Lake Michigan, 2010–2012, for mesh sizes 32, 38, 46, 51, 64, and 76 mm. The model with the lowest deviance statistics was considered the best. Parameter estimates are means and standard errors (SE).

	Female		Male
Model	Parameters (±SE)	Model deviance	Parameters (±SE)	Model deviance
Normal fixed spread	k = 4.31 ± 0.014	1122.02	k = 4.34 ± 0.090	172.41
	σ = 29.48 ± 0.536		σ = 34.14 ± 3.201
Normal proportional spread	k1 = 4.55 ± 0.015	1177.18	k1 = 4.57 ± 0.067	124.63
	k2 = 0.39 ± 0.014		k2 = 0.34 ± 0.052
Gamma	k = 0.08 ± 0.002	986.74	k = 0.10 ± 0.016	138.42
	α = 56.39 ± 1.939		α = 48.05 ± 7.35
Log-normal	μ = 4.97 ± 0.003	922.91	μ = 5.00 ± 0.204	146.90
	σ = 0.13 ± 0.002		σ = 0.16 ± 0.020

Table 5. Female and male yellow perch Perca flavescens modal lengths (mm) from best fit selectivity models.

			Combined sex
Stretch mesh size (mm)	Female2010–2012	Male2010–2012	Large mesh 2010–2012	Micromesh 2007–2011
12.5				57
16				73
20				92
25				115
32	142	146	142
38	168	174	169
46	203	210	204
51	226	233	226
64	283	293	284
76	336	347	337

Figure 4. Gill net selectivity of female (A) and male (B) yellow perch based on the log-normal distribution (female) and normal with proportional spread (male) for 32, 38, 46, 51, 64, and 76 mm mesh sizes in southern Lake Michigan, 2010–2012.

Figure 5. Deviance residual plot for the selection curves fit to female (A) and male (B) yellow perch based on the log-normal distribution (female) and normal with proportional spread (male) for 32, 38, 46, 51, 64, and 76 mm mesh sizes of large mesh gill nets (2010–2012) in southern Lake Michigan. Mesh sizes 32–46 mm were monofilament and 51–76 mm were multifilament. Circles represent residual values (open positive; closed negative), with the area of the circle proportional to the square of the residual.