The Population Dynamics of the Mudskipper, Periophthalmus barbarus (LINNEAUS 1766) (TELEOSTEI, GOBIIDAE) and the Implication for Conservation and Management in the Mangrove Swamp of Iko River Estuary, Southeastern Nigeria | Chapter 05 | Recent Advances in Biological Research Vol. 3
The population dynamics of
Periophthalmus barbarus in the mangrove swamp of Iko River estuary, southeast
of Nigeria were obtained from a twenty four month length composition data
ranging 4.6 – 14.5 cm total length (TL) (mean 9.1841± 1.6346: n = 2,876)
corresponding to 1.16 – 50.6 g total weight (TW) (mean = 9.9626 ± 5.4796) the
growth was exponential. The asymptotic length (L∞) of the Powell-Wetheral plot
(L∞ = 15.03 cm) was seeded into FSAT II (FAO-ICLARM Stock Assessment Tools II)
software to obtain best estimates of von Bertalanfy growth parameters as L∞ =
16.22 cm TL, growth coefficient (K) = 1.2 year-1, age of fish at zero length,
to = 0.071, longevity, tmax = 2.5 years. The estimated growth performance
index, φ' = 2.449. Other FISAT II growth parameters were the amplitude of
growth oscillation, C = 0.6 and the winter point, WP = 0.6, Rn = 0.3127.
Mortality parameters were total mortality, Z = 479 year-1, natural mortality, M
= 2.39 year-1 and fishing mortality, F was 2.40 year-1. Result indicate the
fishery is optimally exploited with current exploitation rate, Ecur = 0.50 <
Emax = 0.668 > Eopt = 0.5 which suggests stock optimal exploitation,
corroborated by Z/K ration (3.184). Ecur
(0.5) means that 50% of the available stock is being fished annually. The
length-at-first capture Lc = 7.33 cm TL and Lc/L∞ was 0.45, indicating the fish
was yet to complete 55% of growth as at the time of capture at Lc, hence P. barbarus
in the ecosystem is at the optimal level of exploitation as well as the
presence of growth overexploitation. Thus to circumvent the consequences of
growth overfishing, sustainable fisheries measures such as monitoring of
fishing effort, use of selective gears and increase in mesh size should be
encouraged, implemented and enforced. The study has revealed that P. barbarus
population residing in the mangrove swamp of Iko River Estuary is experiencing
exploitation rate close to the maximum sustainable yield amidst the presence of
heavy fishing pressure. Moreover, the mudskipper fishery in this ecosystem is
currently exhibiting growth overexploitation signs which could lead to severe
implications on the population size and food security within vulnerable fishing
households in the future. Therefore, urgent management interventions in the
form of monitoring fishing efforts, return of captured juveniles back to the
water body from the non-selective fishing gear and use of selective gear with
large mesh size (to increase length at first capture) are needed to safeguard
this important fish species from possible collapse in the future.
Author Details:
Dr. Nsikak Abiaobo
Department
of Zoology, Akwa Ibom State University, Ikot Akpaden, Mkpat Enin, P.M.B. 1167,
Akwa Ibom State, Nigeria.
Dr. Mfom Tmothy Udo
Department
of Fisheries and Aquatic Environment Management, University of Uyo, P.M.B.
1017, Akwa Ibom State, Nigeria.
View Volume: https://doi.org/10.9734/bpi/rabr/v3
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