Now showing items 1-5 of 5

    • Article

      Growth and production of deformed and nondeformed hatchery-bred milkfish (Chanos chanos) in brackishwater ponds 

      NS Sumagaysay, GV Hilomen-Garcia & LMB Garcia - The Israeli Journal of Aquaculture-Bamidgeh, 1999 - Society of Israeli Aquaculture and Marine Biotechnology
      This study evaluated the growth and survival of morphologically deformed and nondeformed hatchery-bred milkfish in brackishwater ponds. It compared the size-frequency distribution of the nondeformed fish with the deformed ones, and determined the effects of different types of deformity on growth. The deformities include the absence of an upper jaw, a folded operculum with gills exposed, a cleft branchiostegal membrane, scoliosis, etc. The results were compared with production of wild stock. Hatchery-bred and wild milkfish fry were grown separately in nursery ponds (500 m2/pond) at 10 individuals/m2. After a month, the juveniles (average weight hatchery-bred 6.0 g; wild 9.5 g) were transferred to seven rearing ponds of 1000 m2 each (stocking density 3000/ha). Three ponds were stocked with selected, nondeformed hatchery-bred fish (unmixed stock), three ponds with a combination of deformed and nondeformed hatchery-bred fish (1:2 ratio; mixed stock), and one pond with wild fish. The final weight, specific growth rate and survival of the nondeformed fish (mixed and unmixed stock) after four months of culture were significantly higher (p<0.05) than those of the deformed fish. Production, however, did not significantly differ between the unmixed nondeformed (433 kg/ha) and the mixed deformed and nondeformed (377 kg/ha) fish. Survival of the deformed stock (56%) was significantly lower (p<0.05) than that of the nondeformed stock (86-88%). Approximately 92% of the deformed stock and 17-20% of the nondeformed were below 150 g. Severe deformities such as the absence of an upper jaw and exposure of all or most of the gills hindered fish growth, while widening of the operculum or branchiostegal membrane, scoliosis, or absence of the anal fin had less effect on growth. To lower the incidence of deformities in grow-out ponds, milkfish fry should be reared to the early juvenile stage in nursery ponds for at least a month. The harsh natural conditions in the nursery ponds (e.g., presence of predators, abrupt changes in salinity, temperature and dissolved oxygen) and stress during transfer to rearing ponds may eliminate most of the weak fish and those with severe deformities.
    • Article

      Morphological abnormalities in hatchery-bred milkfish (Chanos chanos Forsskal) fry and juveniles 

      GV Hilomen-Garcia - Aquaculture, 1997 - Elsevier
      Morphological abnormality has been observed in hatchery-bred milkfish juveniles. To characterize and quantify the occurrence of these anomalies, hatchery-bred milkfish juveniles from commercial nursery ponds were sampled, and the development of abnormalities in tank-reared fry and juveniles was monitored. Small specimens were cleared and stained using a KOH-alizarin technique for osteological examination. The occurrence of gross abnormalities in hatchery-bred milkfish juveniles reared in commercial ponds was highly variable (3–26%). These abnormalities were predominantly a cleft on the branchiostegal membrane (CBM) and a deformed operculum (DOp), which was mostly folded. CBM was commonly associated with a deformity or the partial to total absence of its supporting branchiostegal rays (DABr). DOp and DABr, but not CBM, were first detected during the early juvenile stage. Reference samples of wild fry did not develop similar proportions of abnormalities when reared in tanks, indicating that these abnormalities are predetermined or induced before the fry stage. Slow growth and development were observed in fish with opercular and branchiostegal abnormalities. A high mortality rate (70%) of abnormal fish was also observed after handling and transfer of stock. These results demonstrate that morphological abnormalities such as CBM and DOp do not only affect the appearance of milkfish but also interfere with its growth and survival.
    • Article

      Phenotypic differences between hatchery-reared and wild mud crabs, Scylla Serrata, and the effects of conditioning 

      L Parkes, ET Quinitio & L Le Vay - Aquaculture International, 2011 - Springer Verlag
      Hatchery-reared animals for stock enhancement should be competent to survive and grow at rates equivalent to those of wild conspecifics. However, morphological differences are often observed, and pre-conditioning steps may be required to improve the fitness of hatchery-reared juveniles prior to release. In the present study, hatchery-reared Scylla serrata juveniles were reared either individually (HR-solitary) or groups in tanks (HR-communal), the latter group being exposed to intraspecific competition and foraging for food. After 21 days, both groups were compared to similar size wild-caught juveniles in terms of morphometric measurements of carapace spination, abnormalities and carapace colouration. There were some limited significant differences between HR-communal crabs and HR-solitary crabs in terms of length of 8th and 9th lateral spines and in body-weight-carapace width ratio, but both treatments differed from wild crabs, which were heavier and had longer carapace spines for thei
    • Article

      Runt-deformity syndrome in cultured giant tiger prawn Penaeus monodon 

      JH Primavera & ET Quinitio - Journal of Crustacean Biology, 2000 - Crustacean Society
      A total of 24 morphological abnormalities associated with the Runt-Deformity Syndrome (RDS) is reported for the first time in 17- to 18-mo old F3 generation Penaeus monodon (>40 mm CL) belonging to three breeding families. Although diagnosed as positive for the infectious hypodermal and hematopoietic necrosis virus (IHHNV), the shrimp appeared normal at 9 to 10 mo when they were procured from a commercial facility in Antique, central Philippines, in September 1996. The abnormalities affected either specific shrimp organs and appendages (e.g., rostrum, antennae, uropods) or the whole body (e.g., shell color and hardness). A two-way analysis of variance was used to evaluate differences in the morphometric characters rostral length (RL), carapace length (CL), abdominal length (AL), body length (BL), total length (TL), carapace width (CW), 1st abdominal segment width (AS1W), and body weight (BW) and the morphometric ratios RL:CL, CL:AL, and CW:AS1W by sex and stock (3 families and wild controls). Female P. monodon had significantly larger CL, AL, BL, TL, CW, and BW than males, regardless of stock. Wild females had longer BL and TL than cultured ones, whereas wild male shrimp had shorter CL, CW, and BW than cultured male P. monodon. Cultured shrimp had significantly higher CL:AL and CW:AS1W ratios and lower RL:CL ratio compared to wild P. monodon. The shorter and narrower abdomen relative to the carapace gave the shrimp a “runted” or dwarf appearance characteristic of RDS earlier described in Litopenaeus vannamei with IHHNV. Confirmed by parallel studies, IHHNV infection of the cultured P. monodon may account for their cuticular deformities, slower growth, and smaller sizes. The appearance of deformities in older (and bigger) P. monodon suggests that RDS expression is dependent on age and size. Examination for external abnormalities and evaluation of the three morphometric ratios may complement existing screening protocols for diseases and growth rates in shrimp breeding programs. Cultured giant tiger prawn also had lower sperm count, greater proportion of dead and abnormal sperm, and lower incidence of mating (absence of sperm in thelyca) compared to wild P. monodon.
    • Article

      Some histological observations on the opaque eyes of milkfish Chanos chanos Forskal 

      CT Tamse, F Piedad-Pascual & MC de la Cruz - Fisheries Research Journal of the Philippines, 1983 - Fisheries Research Society of the Philippines
      In a study on energy-protein requirements of milkfish fingerlings using semi-purified diets, several gross observations were made on individual milk-fish such as fin and tail rot, yellowish coloration of the abdomen, opacity and swollen adipose membrane of the eyes. The latter abnormality occurred four to five weeks after feeding semi-purified diets. Milkfish eyes with the abnormality were processed for histological analysis. Opacity of the cornea and lens and degeneration of the eye tissues, thickening of the corneal epthelium and oedema of the stromal layers were seen. Necrosis of the iris, slight thickening of the lens capsule, detachment and destruction of the retinal layers were also observed.