مقالههای M Aminur Rahman *
توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.
۱Development of breeding and fingerling production techniques for endangered long–whiskered catfish Sperata aor in captivity
اطلاعات انتشار: IRANIAN JOURNAL OF FISHERIES SCIENCES، چهاردهم،شماره۱، Jan ۲۰۱۵، سال ۰
تعداد صفحات: ۱۴
An experiment was undertaken to develop a suitable seed production technique for Sperata aor in captivity. Naturally produced fry of aor was reared at different densities in nine nursery ponds 0.012 ha in size with an average depth of 0.8 m each. Three stocking densities tested, each of which was triplicated. Fry of aor stocked at 100,000\ha was designated as treatment–1 (T1), 150,000\ha as treatment–2 (T2) and 200,000\ha as treatment–3 (T3). All stocked fry were from the same age group with mean length and weight of 1.78 ± 0.28 cm and 0.24 ± 0.05 g, respectively. Fry in all the treatments were fed with SABINCO nursery feed (32.06% crude protein) for the first 14 days and starter–I (31.53% crude protein) for days 15 to 56. Physico–chemical parameters and plankton population of pond water were within the optimal level being better in T1 than those in T2 and T3. Growth in terms of final weight and length, weight and length gain, specific growth rate, daily growth rate, and survival of fingerlings were significantly higher in T1 followed by T2 and T3. Food conversion rate was significantly lower in T1 than in T2 and T3. Significantly higher number of fingerlings was produced in T3 than those in T2 and T1. Despite this, consistently higher net benefits were achieved from T1 than from T2 and T3. This is the first time report that stocking of 100,000 fry\ha appears to be the most suitable density for rearing of aor fingerlings in nursery ponds.
اطلاعات انتشار: IRANIAN JOURNAL OF FISHERIES SCIENCES، چهاردهم،شماره۲، Apr ۲۰۱۵، سال ۰
تعداد صفحات: ۱۶
Diadema setosum (Leske, 1778), is one of the common echinoids widely distributed in the Indo–West Pacific Ocean, where it occurs from the Red Sea, Persian Gulf and the east coast of Africa to Japan, Australia and Malaysia. To investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of D. setosum in a controlled laboratory condition at the Institute of Bioscience, Universiti Putra Malaysia, during July–September, 2012. Matured gametes were obtained from the adult individuals and the eggs fertilized at limited sperm concentration (10–5 dilution). The obtained embryos were then reared at 24–25oC. First cleavage (2–cell), 4–cell, 8–cell, 16–cell, 32–cell and multi–cell (Morulla) stages were attained at 01.20, 02.14, 02.44, 03.09, 03.32 and 03.54 h after fertilization, respectively. Blastulae with a mean length of 111.47±1.88 µm (mean±SD) hatched 08.45 h after sperm entry. Gastrula formed 16.36 h post–fertilization and the archenteron extended constantly, while the ectodermal red–pigmented cells migrated synchronously to the apical plate. The pluteus larva started to feed unicellular algae (Chaetoceros calcitrans) in 2 d, grew continuously, and finally attained metamorphic competence within 35 d after fertilization. Induction of metamorphosis took approximately 1 h 30 min from attachment on the substratum to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well–developed pedicellaria, the whole event usually took place within 1 d post–settlement. The newly formed juvenile (473.16 ± 6.96 µm, n=30) with a complete adult structure then grew on coralline algae to 3–month old juvenile, which represents the “sea urchin seed” for stocking in grow–out culture. This study represents the first successful investigation on embryonic, larval and early juvenile development of D. setosum. The findings would greatly be helpful towards the development of breeding and seed production techniques for aquaculture of sea urchins.
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