Life history of wahoo, Acanthocybium solandri, in the Tropical Eastern Atlantic Ocean – the importance of applying a suite of methods for fisheries assessment in data-limited situations

Richard Kindong; Feng Wu; Ousmane Sarr; Libin Dai; Siquan Tian; Xiaojie Dai

doi:10.26881/oahs-2022.1.10

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Life history of wahoo, Acanthocybium solandri, in the Tropical Eastern Atlantic Ocean – the importance of applying a suite of methods for fisheries assessment in data-limited situations

Oceanological and Hydrobiological Studies

Volume 51 (2022): Issue 1 (March 2022)

By: Richard Kindong, Feng Wu, Ousmane Sarr, Libin Dai, Siquan Tian and Xiaojie Dai

Open Access

|Mar 2022

Figures & Tables

Locations where wahoo specimens were sampled by the Chinese Longline Fishery Observer in the Eastern Atlantic Ocean between November 2010 and May 2020.

Framework process showing methods used to estimate wahoo’s life history parameters and to provide proxies for the stock status in the Tropical Eastern Atlantic.

Length frequency distribution (by sex) of wahoo in the Eastern Atlantic.

Uncertainty in growth parameters L∞ and K for wahoo in the Eastern Atlantic based on length-frequency analysis using the ELEFAN GA-Bootstrap method; N = 1000 bootstrap runs; outer contour – 95% confidence envelope; grey lines – Φ′ isopleths; marginal histograms show univariate density for both parameters.

Monthly mean (± SE) gonadosomatic index (GSI) for mature females collected from the Tropical Eastern Atlantic.

Monthly percentages of the four wahoo maturity classes. Numbers on class bars indicate the number of females in a given monthly interval.

Percentage of mature female wahoo (n = 182) caught in the Eastern Atlantic was modeled using a logistic function. Length at maturity L50 represents the mean parameter estimate for FL at 50% maturity.

Estimated values for VBGP resulting from bootstrapped ELEFAN GA analysis, estimated length (cm) at age (from 0 to 10) and Φ’ by sex, previous results from different geographical areas and age estimation methods (LFDA – length frequency distribution analysis; otolith)_ F – female; M – male; CS – combined sex_

Methods	Area	Growth parameters	Mean parameter estimate	Sex	Longevity (years)
LFDA: ELEFAN-GA-Bootstrap (this study)	Eastern Atlantic	L_∞(cm)	161.2 (CS); 166.5 (M); 164.9 (F)	CS	10
		k(year)⁻¹	0.47 (CS); 0.31 (M); 0.33 (F)
		Φ′	3.97 (CS); 3.34 (M); 3.76 (F)
		t_anchor(months)	0.64 (CS); 0.62 (M); 0.71 (F)
Sectioned Otoliths (McBride et al. 2008)	Northwest Atlantic	L_∞(cm)	170.1 (CS); 155.5 (M); 179.7 (F)	CS	9
		k(year)⁻¹	0.381 (CS); 0.44 (M); 0.32 (F)
		Φ′	CS (4.04)
		t₀(years)	–1.63 (CS); –1.64 (M); –1.91 (F)
Whole Otoliths (Zischke et al. 2013)	Coral Sea off eastern Australia	L_∞(cm)	149.9 (CS); 141.7 (M); 155.4 (F)	CS	7
		k(year)⁻¹	1.58 (CS); 2.31 (M); 1.18 (F)
		Φ′	CS (4.55)
		t₀(years)	–0.17 (CS); 0.002 (M); –0.37 (F)
Whole Otoliths (Hogarth 1976)	West Central Atlantic	L_∞(cm)	215.1 (CS)	CS	4
		k(year)⁻¹	0.152 (CS)
		Φ′	3.21 (CS)
		t₀(years)	–3.67 (CS)
Whole Otoliths (Kishore & Chin 2001)	West Central Atlantic	L_∞(cm)	153.97 (CS)	CS	10
		k(year)⁻¹	0.34 (CS)
		Φ′	3.76 (CS)
		t₀(years)	–1.54 (CS)
LFDA: MULTIFAN (Lee T.M. 2008)	waters off eastern Taiwan	L_∞(cm)	156.8 (CS)	CS	9
		k(year)⁻¹	0.245 (CS)
		Φ′	3.43 (CS)
		t₀(years)	–1.63 (CS)

Estimated values of fishing mortality obtained from the equation: fishing mortality rate (F), total mortality rate (Z), and natural mortality rate (M)_

Method used to estimate M	Natural mortality	Method used to estimate Z
	Natural mortality	LCCC		Beverton and Holt (BH)
	M	Z	F	Z	F
Gislason	0.36	0.75	0.39	0.80	0.44
ChenWatanabe	0.67		0.08		0.13
Brodziak_K	0.37		0.38		0.43
Pauly_Linf	0.65		0.10		0.15
Alverson_Carney	0.33		0.42		0.47
Then_1	0.64		0.12		0.17
Then_2	0.44		0.31		0.36
Hewitt Hoenig	0.47		0.28		0.33
Hoenig	0.45		0.30		0.35

Wahoo fishery status in the Tropical Eastern Atlantic Ocean presented by LBB (Linf, Lc50, F/M, M/K, and B/B0 and B/BMSY and their respective 95% confidence intervals; numbers in parentheses) under different M scenarios_

Scenarios	M/K^*	L_inf (CI)	M/K (CI)	F/M (CI)	L_c50 (CI)	B/B_MSY (CI)	B/B₀ (CI)	Stock status
M/K Median (Then_2)	0.94	165 (164–167)	0.89 (0.79–1.02)	0.76 (0.48–1.1)	115 (112–118)	1.4 (0.38–3.1)	0.58 (0.16–1.3)	Healthy
M/K Upper (Chen and Watanabe)	1.42	165 (164–167)	1.3 (1.17–1.44)	0.4 (0.26–0.67)	120 (116–124)	1.9 (0.53–3.8)	0.76 (0.21–1.6)	Healthy
M/K Lower (Alverson_Carney)	0.70	164 (163–165)	0.73 (0.57–0.86)	1.48 (1–2.24)	112 (109–115)	1.3 (0.35–3.3)	0.56 (0.15–1.4)	Healthy

Von Bertalanffy growth parameter (VBGP) estimates generated by various length-frequency analysis programs for the wahoo stock sampled in the Eastern Atlantic_ Parameter estimates by different methods are presented with AIC and BIC values_ NB: ELEFAN-FI and SHEPHERD (ELEFAN and Shepherd methods in FiSAT II), ELEFAN-LFDA (ELEFAN method in LFDA v 5), ELEFAN-GA, ELEFAN-SA (TropFishR package) and ELEFAN-GA-Bootstrap, ELEFAN-SA-Bootstrap (fishboot package)_

Methods	Parameter	Mean parameter estimate	AIC Score	BIC Score
ELEFAN-FI	L_∞(cm)	183.75	−10602	−10617
	k(year⁻¹)	0.69
	t₀(years)	−0.518
SHEPHERD	L_∞(cm)	175	987	965
	k(year⁻¹)	0.12
	t₀(years)	−3.22
ELEFAN-LFDA	L_∞(cm)	163.3	−10583	10598
	k(year⁻¹)	0.57
	t₀(years)	−0.652
ELEFAN-G.A.	L_∞(cm)	159.94	805	790
	k(year⁻¹)	0.49
	t_anchor(months)	0.68
ELEFAN-S.A.	L_∞(cm)	194.51	−10309	−10324
	k(year⁻¹)	0.08
	t_anchor(months)	0.54
ELEFAN-SA-Bootstrap^*	L_∞(cm)	201.56	−10648	−10663
	k(year⁻¹)	0.12
	t_anchor(months)	0.64
ELEFAN-GA-Bootstrap^*	L_∞(cm)	161.21	−11407	−11422
	k(year⁻¹)	0.47
	t_anchor(months)	0.64

Natural mortality (M) methods and equations used_ L∞, K and t0 are von Bertalanffy growth function parameters, Tmax is the maximum observed age, a and b are length–weight relationship parameters_ L50 is length at first maturation, L is the observed length, T is temperature (°C), and t is age_ In this study, the temperature was T = 18_43°C_

Acronym	Equations	M by age	References
Gislason	ln (M )=0.55−1.61 ln (L)+1.44 ln (L)+ln (K )	Yes	Gislason et al. 2010
ChenWatanabe	M=K1=e−K(t−t0) M = \frac{K}{{1 = e^{ - K_ (t - t_0 )} }} ; t = age	Yes	Chen and Watanabe 1989
Brodziak_K	M=KL50length M = K_ \frac{{L_{50} }}{{\user1{length}}}	Yes	Brodziak et al. 2011
Pauly_Linf	M=e−0.0152+0.6543ln(K)−0.279ln(L∞))+0.4634ln(T) M = e^{ - 0.0152 + 0.6543\ln (K) - 0.279ln\left( {L_\infty )} \right) + 0.4634\ln (T)}	No	Pauly, 1980
Alverson_Carney	M=3Ke(0.38TmaxK)−1 M = \frac{{3K}}{{e^{\left( {0.38\user1{Tmax}K} \right) - 1} }}	No	Alverson and Carney, 1975
Then_1	M = 4.899 ^* Tmax^0.916	No	Then et al. 2014
Then_2	M = 4.118 ^* K^0.73* L_∞^−0.33	No	Then et al. 2014
Hewitt Hoenig	M = e^{1.44−0.98ln (}^Tmax*⁾	No	Hewitt and Hoenig 2005
Hoenig	M = e^{1.46−0.101* ln (}^Tmax⁾	No	Hoenig 1983

Per-recruit results_ Current F/F0_1 and Current E references obtained for different Z and M parameters_ Stock state indication per M method; green color indicates healthy state, red indicates overfished state, and yellow indicates one of the two references indicating overfished state_

Z-M	Current F		F_0.1	Fmax	Current F/F_0.1	Current E	Stock state indication
LCCC-Gislason	F1	0.36	0.47	0.53	0.77	0.52	Overfished in terms of E
LCCC-ChenWatanabe	F2	0.67	0.49	0.59	1.37	0.11	Overfished in terms of F
LCCC-Brodziak_K	F3	0.37	0.46	0.53	0.80	0.51	Overfished in terms of E
LCCC-Pauly_Linf	F4	0.65	0.49	0.59	1.33	0.14	Overfished in terms of F
LCCC-Alverson_Carney	F5	0.33	0.47	0.53	0.70	0.56	Overfished in terms of E
LCCC-Then_1	F6	0.64	0.50	0.58	1.28	0.15	Overfished in terms of F
LCCC-Then_2	F7	0.44	0.46	0.53	0.96	0.41	Healthy
LCCC-Hewitt Hoenig	F8	0.47	0.46	0.54	1.02	0.37	Overfished in terms of F
LCCC-Hoenig	F9	0.45	0.46	0.54	0.98	0.39	Healthy
BH-Gislason	F10	0.44	0.49	0.56	0.90	0.55	Overfished in terms of E
BH-ChenWatanabe	F11	0.13	0.53	0.62	0.25	0.17	Healthy
BH-Brodziak_K	F12	0.43	0.49	0.56	0.88	0.54	Overfished in terms of E
BH-Pauly_Linf	F13	0.15	0.53	0.62	0.28	0.19	Healthy
BH-Alverson_Carney	F14	0.47	0.49	0.56	0.96	0.59	Overfished in terms of E
BH-Then_1	F15	0.17	0.54	0.62	0.31	0.21	Healthy
BH-Then_2	F16	0.36	0.49	0.57	0.73	0.45	Healthy
BH-Hewitt Hoenig	F17	0.33	0.49	0.58	0.67	0.41	Healthy
BH-Hoenig	F18	0.35	0.49	0.58	0.71	0.43	Healthy
Median-LCCC					0.98	0.40	Healthy
Mean-LCCC					1.02	0.35	Overfished in terms of F
Median-BH					0.71	0.43	Healthy
Mean-BH					0.63	0.39	Healthy

References

Authors

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Articles in this issue

DOI: https://doi.org/10.26881/oahs-2022.1.10 | Journal eISSN: 1897-3191 | Journal ISSN: 1730-413X

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Language: English

Page range: 115 - 132

Submitted on: Jul 12, 2021

Accepted on: Nov 8, 2021

Published on: Mar 31, 2022

Published by: University of Gdańsk

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

data-poor fisheries,

fisheries management,

length-frequency analysis,

Related subjects:

© 2022 Richard Kindong, Feng Wu, Ousmane Sarr, Libin Dai, Siquan Tian, Xiaojie Dai, published by University of Gdańsk
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Volume 51 (2022): Issue 1 (March 2022)

Life history of wahoo, Acanthocybium solandri, in the Tropical Eastern Atlantic Ocean – the importance of applying a suite of methods for fisheries assessment in data-limited situations

Figures & Tables

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Estimated values of fishing mortality obtained from the equation: fishing mortality rate (F), total mortality rate (Z), and natural mortality rate (M)_

Wahoo fishery status in the Tropical Eastern Atlantic Ocean presented by LBB (Linf, Lc50, F/M, M/K, and B/B0 and B/BMSY and their respective 95% confidence intervals; numbers in parentheses) under different M scenarios_

Per-recruit results_ Current F/F0_1 and Current E references obtained for different Z and M parameters_ Stock state indication per M method; green color indicates healthy state, red indicates overfished state, and yellow indicates one of the two references indicating overfished state_

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