Reproductive biology and body condition of exploited populations of Emperor Angelfish, Pomacanthus imperator (Bloch, 1787) along the Kenyan Coast

A substantial proportion (in terms of value and quantity) of the Pomacanthus imperator catch on the Kenyan coast are traded, and the species is also harvested as food in the artisanal fishery. However information on their reproductive biology is scanty. The overall sex ratio differed significantly from 1:1 according to chi-square test (p<0.05). Sizes at maturity (L50) were estimated to be 25cm and 28cm TL for females and males respectively. Fecundity was estimated to be in the range of 17,790-266,472 with a Mean ±SE of 79,353±11,747, and was linearly related to total length and ovary weight. March-April was the main period of reproductive activity based on gonad somatic indices and monthly proportion of mature individuals. The LWR indicated isometric growth both in males and females of P. imperator, as the allometric coefficient b values were not significantly different from the expected isometric value of 3 (Student’s t-test; p=0.12). Relative condition factor did not vary significantly between the months sampled. The reproductive parameters obtained from this study provide some baseline information for management of this species which has proven to be highly vulnerable to depletion due to overfishing.

Conditions and from factor of the five threatened fishes from the Jamuna (Brahmaputra River Distributary) River, Northern Bangladesah

The small indigenous species namely Ailiichthys punctata (Day 1871), Botia lohachata (Chaudhuri 1912), Chanda nama (Hamilton 1822), Laubuca laubuca (Hamilton 1822) and Mystus cavasius (Hamilton 1822) comprise an important component of riverine fisheries of Bangladesh. But the natural populations are decreasing fast due to high fishing pressure as well as environmental degradation. Therefore, data and information is needed to avert the alarming decline and initiate conservation measures for these important fishes of the Jamuna River. This study describes the condition- (Fulton’s and Relative weight) and form-factor (a3.0) of the five threatened fishes from the Jamuna River, a distributary of the Brahmaputra River in northern Bangladesh. A total of 919 specimens from five species in five families used for this study were caught by traditional fishing gear during March 2010 through February 2011. For each individual, the total (TL), fork (FL) and standard (SL) length were measured by digital slide calipers while individual body weight (BW) was measured using a digital balance. The Fulton’s condition factor (KF) showed significant variations (p0.05) indicating a balanced habitat with food availability relative to the presence of predators. The calculated minimum and maximum form factor (a3.0) was 0.0062 for A. punctata and 0.0158 for B. lohachata, respectively. To the best of our knowledge, this study presents the first reference on KF, WR and a3.0 factors for these threatened species in Bangladesh. The results would be useful for sustainable management and conservation of the limited stocks in the Brahmaputra River ecosyste