Mortality and Exploitation Rates of Challawa Gorge Dam Fishes, Kano State, Nigeria

Ahmad, Ibrahim M.; Id, Yola; N, Suleiman

doi:10.4172/2332-2608.1000262

Cited by 2 publications

(4 citation statements)

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“…The optimum fishing mortality rate (F opt ) and exploitation level (E) were estimated as 0.4M (Pauly, 1984) and F/Z (Gulland, 1969) respectively. Exploitation rates (E max, E 0.1 and E 0.5 ) were computed following Ahmad et al (2018). The impact of exploitation on yield was done based on the interrelationship between exploitation rate (E max ) and critical length ratio (Lc 50 /L∞).…”

Section: Mortality Parametersmentioning

confidence: 99%

Estimates of Population parameters for Sardinella maderensis (Lowe, 1838) in the coastal waters of Ghana

Amponsah¹,

Ofori-Danson²,

Nunoo³

et al. 2019

Greener J Agr Sci

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This study examined some population parameters of Sardinella maderensis landed along the eastern coast of Ghana, based on length-frequency data from June, 2014 to January 2015. Overall, 1401 samples of S. maderensis were measured for standard length and resultant data analysed with FiSAT II. The asymptotic length (L ∞) and growth rate (K) were 23.63 cm SL and 0.61 yr-1 respectively. The theoretical age at birth (t 0) and growth performance index (ϕ) were-0.284 yr-1 and 2.532 respectively. The recruitment pattern was continuous with two recruitment pulses. Total mortality rate (Z), natural mortality rate (M) and fishing mortality rate (F) were 2.96 yr-1 , 1.30 yr-1 and 1.63 yr-1 correspondingly. Fishing mortality rate surpassed the optimum fishing rate which showed that the assessed fish species is under high fishing pressure. The estimated exploitation rate (E curr) was 0.55, implying that the stock is over-exploitation. VPA outcome revealed higher harvesting rate on individuals with length between 10-11 cm. The spawning biomass which was below the 30% of unexploited biomass indicated future recruitment failure of the stock. As a result, urgent management interventions such as the application of biological reference points and mesh size regulations are urgently recommended for sustainable exploitation of Sardinella maderensis.

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Section: Mortality Parametersmentioning

confidence: 99%

Estimates of Population parameters for Sardinella maderensis (Lowe, 1838) in the coastal waters of Ghana

Amponsah¹,

Ofori-Danson²,

Nunoo³

et al. 2019

Greener J Agr Sci

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show abstract

“…The low value of E in the two species in this finding suggests that levels of exploitation may be increased in order to reduce waste of stock through natural mortality; however, caution must be taken to avoid what can be called a skewed exploitation situation (Chukwu & Deekae, 2010). Ahmad et al (2018) reported lower values of Z (1.31), M (1.0), F (0.31), and E (0.24) for B. nurse from the Challawa Gorge dam, Kano. Higher values of the fore mentioned parameters were observed for B. nurse by Kwarfo-…”

Section: Discussionmentioning

confidence: 87%

“…The L c value recorded in this study falls within the range of the total length 7.30 to 23.00 cm for B. nurse and 11.50-27.00 cm for B. macrolepidotus. A lower value of L c (7.58) was recorded for B. nurse by Ahmad et al (2018). Uneke and Nwani (2013) found the L c for B. nurse in Cross River to be 8.83 while Kwarfo-Apegyah (2008) found the L c for B. nurse in Bontanga Reservoir (Northern Region of Ghana) to be 10.94.…”

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confidence: 98%

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ESTIMATION OF GROWTH, MORTALITY, AND EXPLOITATION STATUS OF NURSE TETRA (Brycinus nurse) AND TRUE BIG SCALE TETRA (Brycinus macrolepidotus) (FAMILY: ALESTIDAE) FROM THE NEW CALABAR RIVER, NIGERIA

Olopade

Dienye

Nworgu

2020

Indonesian Fisheries Research Journal

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This study aimed to determine the growth patterns, mortality, and exploitation status of two species of Alestidae in the New Calabar River, Nigeria. For this purpose, fish samples were collected monthly from three landing sites from the local fishermen using gill nets (mesh sizes: 15-25mm), beach seine (mesh sizes: 2.3-10mm), and cast nets (mesh sizes: 15 -25mm). The length-weight relationship revealed exponent “b” value for Brycinus nurse was 3.54 and 3.21 for Brycinus macrolepidotus while the condition factors were 1.08 and 1.02 for Brycinus nurse and Brycinus macrolepidotus respectively. The growth parameters of Brycinus nurse asymptotic length (L) and growth coefficient (K) were 24.46 cm and 0.52 yr-1, respectively, while those for Brycinus macrolepidotus L was 28.88 cm and K was 0.22 yr-1. The reproductive load (L50/L) ratio was found to be 0.59 and 0.61 for B. nurse and B. macrolepidotus, respectively. Exploitation rate (E) for B. nurse was 0.26 and 0.11 for B. macrolepidotus while length-at-first capture (Lc) was 14.49 cm for B. nurse and 17.64 cm for B. macrolepidotus. The natural mortality was greater than the fishing mortality for both species and Logistic regression of the probability of capture routine values recorded for B. nurse were higher than that of B. macrolepidotus. Maximum exploitation rate (Emax) was less than 0.5 for both B. nurse (0.41) and B. macrolepidotus (0.42). These values were close to the maximum allowable limit; therefore, the species may be unsustainable when fishery intensifies in the future. To ensure sustainable exploitation of the two Alestid species in the area, fishing effort should be regulated.

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Mortality and Exploitation Rates of Challawa Gorge Dam Fishes, Kano State, Nigeria

Cited by 2 publications

References 0 publications

Estimates of Population parameters for Sardinella maderensis (Lowe, 1838) in the coastal waters of Ghana

Estimates of Population parameters for Sardinella maderensis (Lowe, 1838) in the coastal waters of Ghana

ESTIMATION OF GROWTH, MORTALITY, AND EXPLOITATION STATUS OF NURSE TETRA (Brycinus nurse) AND TRUE BIG SCALE TETRA (Brycinus macrolepidotus) (FAMILY: ALESTIDAE) FROM THE NEW CALABAR RIVER, NIGERIA

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