Towards sustainable management of the Cunene horse mackerel (Trachurus trecae) in Guinea-Bissau waters

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Table 3

Length-based indicators (LBI) used to assess the stock status of Trachurus trecae in Guinea-Bissau.

Indicator	calculation	Reference point	Indicator ratio	Expected value	Property
L_max5%	Mean length of largest 5%	L_∞	L_max5% / L_∞	>0.8	Conservation (large individuals)
P_mega	Proportion of individuals above L_opt +10%	0.3–0.4	P_mega	>0.3	Conservation (large individuals)
L_25%	25^th percentile of length distribution	L₅₀	L_25%/L₅₀	>1	Conservation (immatures)
L_c	Length at first catch (length at 50% of mode)	L₅₀	L_c/L₅₀	>1	Conservation (immatures)
L_mean	Mean length of individuals >L_c	$L_{opt} = \frac{3}{3 + \frac{M}{k}} \times L$	L_mean/L_opt	≈1	Optimal yield
L_mean	Mean length of individuals >L_c	L_{F = M} = (0.75L_c + 0.25L_∞)	L_mean/L_{F = M}	≥1	MSY

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