A modified diet was formulated for Arizona inland shrimp farming and tested as a method for reducing moult-associated mortalities presumed due to trace mineral deficiencies. The experimental diet was supplemented with additional dietary magnesium, potassium, phospholipids and cholesterol to a commercial shrimp feed (Rangen 45/10, which was also used as the control diet). The modified diet was tested at Arizona Mariculture Associates (AMA), while the control diet was used at a nearby inland shrimp farm, Desert Sweet Shrimp Farm (DSSF). Both feeds were used throughout the culture season of 2001. Earthen pond-reared Litopenaeus vannamei at intermoult stages (C-D 0 ) and ranging from 7 to 30 g were sampled at intervals for determination of haemolymph osmolality (HO). Results showed that the modified diet had not only resulted in larger size shrimp at harvest, but also improved osmoregulatory capacity (OC). HO of DSSF shrimp decreased as shrimp grew bigger, whereas HO of AMA shrimp was maintained at a stable level, or showed a slightly positive linear relationship with weight. The hyper-OC of shrimp from AMA (462 mOsm kg )1 ) was greater than that from DSSF (398 mOsm kg )1 ). Shrimp at AMA fed the experimental diet presented no mass moult-associated mortalities. To further investigate the iso-osmotic point of shrimp reared in AMA, a group of six salinity gradients were designed by mixing oceanic salts into the well water to form 5, 8.5, 11.4, 14.4, 17.8, 20.7 p.p.t. medium. HO of subadult shrimp (25 g in average) were then evaluated 48 h after they had been transferred from 5 p.p.t. pond water to the medium. Shrimp HO increased with external salinity, and a plateau formed as salinity reached at 11.4 p.p.t. and higher. The iso-osmotic point of shrimp was estimated to be 695.5 mOsm kg )1 , equivalent to 26.1 p.p.t. in AMA well water. KEY WORDS

No abstract

Effective methods of traceability are urgently required for use in research as weil as in different types of aquaculture operations and to control trade in aquatic animais and praducts. In regard to the marking of fish, many different tagging methods have been described and the method to be used depends on the purpose and need for tagging. In contrast, for molluscs and crustaceans, only a few methods of marking such animais have been described, due to the practical difficulties. The authors first describe the different methods for tracing fish and fishery products, by means of external tags, such as Floy tags, Carlin tags and passive integrated transponder tags; chemical marking using inorganic substances su ch as silver nitrate or potassium nitrate, pigments, oxytetracycline, etc.; and several different types of electronic devices in which basic information such as the strain of fish, farm of origin or weight can be stored. Genetic traceability using deoxyribonucleic acid prafiling is developing quite rapidly for cultured brood stocks and wild populations. This technique may be used with very high degrees of confidence to assign to or exclude animais or products fram their claimed origin, paternity or strain, and may be used as evidence in court proceedings. The second section of this paper describes the traceability of live molluscs for restocking and for human consumption. In these applications, genetic markers have been demonstrated to be suitable. Mechanical tagging on a small scale for research purposes has also been used. Otherwise, the only means of tracing live molluscs are the movement documents and the labelling on boxes that certifies the origin of the commodity. The third section describes the methods available for tracing live and dead crustaceans. A large variety of physical tagging methods for decapod crustaceans is described, such as the injection of biological stains (fast green, Niagara sky blue, trypan red and blue) and external tags such as coloured streamer tags, wire tags and a variety of anchor tags. Furthermore, a number of different internai coding methods, such as the coded micro-wire tags and injected elastomer tags are discussed in detail. As is the case for fish, genetic molecular techniques are also applied in population studies of crustaceans; some of the molecular genetic methods are described. Prawns for human consumption are most frequently packed whole or as tails after the necessary sorting, washing and freezing and the only way of performing a traceback is thraugh documents relating to movement, invoices, health certificates and labellillg of the boxes. The minimum requirements for labelling would be the content of the packages, Le. species, quantity, identification of the manufacturer (na me and address), packing place, importer/exporter or vendor of the product, in addition to the loading bill number.

A commercially available microbicide, composed of 5‐Chloro‐2‐methyl‐4‐isothiPzolin‐3‐one and 2‐methyl‐4‐isothiazolin‐3‐one, was tested for its in vivo effectiveness in controlling pathogenicity and mortalities in the marine shrimp Penaeus stylirostris, caused by the fungus Fusurium solani. Sub‐adult shrimp (100% with Fusurium lesions) were treated with the microbicide at levels of 5.0 and 7.5 ppm (Trial 1) and with 1.0, 2.5 and 5.0 ppm (Trial 2), and each compared to a non‐treated control. In Trial 1, treatments were administered during the first 9 days of the 22 day experiment, approximately every other day as 8 h static baths. The mean levels of Fusarium lesions on Day 22 for the 0, 5.0 and 7.5 ppm treatments were 87%, 25% and 13%, respectively. Statistically both levels of treatment (5.0 and 7.5 ppm) had significantly lower levels of Fusurium lesions when compared to the controls. In Trial 2, treatments of the microbicide were administered (8 h static bath) every seventh day over the course of the 64 day experiment. The Day 64 mean Fusarium lesion levels for the 0, 1.0, 2.5 and 5.0 ppm treatments were 54%, 59%, 10% and 7%, respectively. Treatment with 2.5 and 5.0 ppm reduced the prevalence of Fusarium lesions to statistically lower levels when compared to the 0 and 1.0 ppm treatments. The microbicide had earlier been reported to be highly toxic to fish. The use of activated charcoal filters on the microbicide‐treated effluent appeared to remove any residual compound from the water. The data in the present study indicate a possible inverse relationship between the level of “BG 101” and growth rate. The data from both trials suggest that periodic treatment over a longer test period could limit or eliminate Fusurium lesions, which are known to be the potential cause of substantial mortalities, particularly in captive broodstock populations.

ABSTRACT. PvSNPV isolated from the shrimp Penaeus rtannamei was characterized after purif~cation. In negatlve staining, the rod-shaped, enveloped particles were 312 to 320 nm in length and 75 to 87 nm In diameter. The nucleocapsids, 306 to 312 nm in length and 62 to 68 nm in diameter, showed a crosshatched surface arranged in a helical pattern and a trilaminar structure capping both extremities. Purified occlusion body subunits (polyhedrin subunits) were 17 to 19 nm in diameter and, in SDS-PAGE, demonstrated 1 major polypeptide of 52 kDa. BamHI digested viral genome revealed a t least 7 different fragments. Cloning of these DNA fragments, and the resulting study of them, revealed the presence of 2 more fragments which had CO-migrated in gel electrophoresis. The cloned fragments, which represent about 40% of the estimated size of the genome, were characterized by their size and by the position of restriction sites. When the cloned fragments were labeled and used a s probes, no homology was found among the different inserts These gene probes reacted with different BP-type strains, but not with uninfected shrimp tissue The gene probes also did not react with shrimp tissues Infected with other shrimp viruses, indicating their specificity for the BP-type viruses.