Reproductive biology and implications for management of the orange‐spotted grouper Epinephelus coioides in the southern Arabian Gulf

Abstract

The reproductive biology of Epinephelus coioides was determined from the examination of 1455 individuals collected between July 2005 and June 2007 in the southern Arabian Gulf. Histological preparations of gonads indicated that males were either derived from a juvenile phase or the transition of postspawning females, confirming a diandric protogynous sexual pattern. The spawning season was well defined, occurring once a year during April and early May. Peaks in spawning occurred after the full and new moons and was completed within a single lunar cycle. The presence of mature males over the entire size and age range and the absence of inactive mature females during the spawning season suggested that the population was not constrained by sperm limitation. While specimens undergoing sexual transition were only observed in size and age ranges of 335-685 mm total length (L(T)) and 5-6 years, patterns in the proportion of males in size and age classes suggested that sex change occurred at a relatively constant rate after female maturation up to the maximum size (1002 mm L(T)) and age (11 years). Relationships between reproductive output and capacity with size and age indicated that conventional regulations that equate the mean size at first capture to sexual maturation are unsuitable for the management of E. coioides. The maximum age, small size and young age at sexual maturation (L(min)= 320 mm L(T), 2 years, for females and 242 mm L(T), 1 year, for males) conflict with the general pattern for large epinepheline groupers and may be a direct result of the intensive demersal fishery in the southern Arabian Gulf.

Spawning seasons of Rasbora tawarensis (Pisces: Cyprinidae) in Lake Laut Tawar, Aceh Province, Indonesia

“…However, the reported sex ratios may have be biased due to selectivity of fishing gear, therefore independent data from other fishing gears would be required to validate whether the samples obtained from existing gears were representative of the population [7]. Furthermore, the seasonal variation in the sex ratio observed was probably because once fertilization of eggs was completed, male possibly emigrates from spawning area towards feeding ground located in the shallow areas [32].…”

“…Studies on reproductive behaviour of fish are important and a basic requirement for improvement and effective fishery resources management and conservation [3-7], determination of basic life-history information and for assessing the impacts of environmental variability on the dynamics of fish populations [8]. Life history parameters such as spawning frequency and sex ratio may vary between populations of a species and temporally within population [9].…”

An Evaluation of the Management Effectiveness of a Stock Re-Building Strategy for a Multi-Species Demersal Trap Fishery in Abu Dhabi, United Arab Emirates

“…The large differences between estimates of the sizes at first capture with those which would give the highest yields, emphasizes the need to revise existing gear regulations for the trap fishery. This is of critical importance to a stock rebuilding strategy, particularly given the detrimental impact that the depletion of the older age classes can have on reproductive capacity and output, as has been demonstrated for E. coioides [14]. However, because of the differences among species, it is not possible to have a gear regulation that would select all species at the optimum sizes and ages at first capture.…”

“…The annual instantaneous rate of fishing mortality (F) was calculated for each species and year by subtracting the natural mortality rate (M), estimated as 0.13 and 0.20 for D. Pictum and L. nebulosus respectively [3] and 0.19 for E. coioides [7], from the total mortality rate (Z) derived from age based catch curves. Juvenile retention (J) was calculated as the proportion of fish in landings that were below the mean size at first sexual maturity of fe-males given as 31.8 cm L F and 27.6 cm L F for D. Pictum and L. nebulosus respectively [3] and 42.6 cm L T for E. coioides [14].…”

Reproductive biology of Heteropneustes fossilis in a wetland ecosystem (Gajner Beel, Bangladesh) in relation to eco-climatic factors: Suggesting a sustainable policy for aquaculture, management and conservation

“…Fruitful fisheries management largely depends on exact assessment of biological parameters, such as reproduction, growth and assessment of stock ( Tracey et al, 2007 ). Understanding of reproductive biology of fish species is vital and a prerequisite for conservation and relevant management approaches ( Brewer et al, 2008 , Grandcourt et al, 2009 , Muchlisin et al, 2010 ). Besides, conscientious evaluations of reproductive behavior unearth dynamic causes that may influence survival in addition to recruitment of different fish species ( Khatun et al, 2019 ).…”