A survey of cured fish establishments in 5 countries of South East Asia, revealed that cured fish is a nutritionally and economically important commodity in the region and that insect infestation, in particular blowfly infestation during processing and dermestid beetle infestation during storage, are major causes of losses in cured fish. Many processors have responded by illegally applying household and agricultural insecticides to their fish. Field investigations in Indonesia and Thailand, identified Chrysomya megacephala (Fab.) as the most widespread cause of infestation during processing. Lucilia caprina (Wied.) was also a common cause of infestation. Dermestes maculatus (Degeer), D. carnivorus (Fab.), D. ater (Degeer) and Piophila casei (L.), were the most common causes of infestation during storage. These species were able to tolerate the relatively high salt concentrations of the processed fish. Field infestation reduction trials, demonstrated that salting the fish for an extended period failed to provide protection against insect infestation. Guarding the salting tank with a closely fitting lid, prevented blowfly infestation during salting. Flyscreens were found to reduce blowfly infestation during drying, but the design used, presented practical difficulties and was not acceptable to the processor. The pyrethroid insecticide Fastac (alphacypermethrin), prevented blowfly infestation during processing at concentrations as low as 0.00.3% and had a marked repellent effect against blowflies at a concentration of 0.001%. Fastac, applied at a concentration of 0.006%, protected fish against dermestid beetle infestation and damage. Fastac residues in fish treated with a 0.006% dip decreased to less than 2 rag/kg after drying and 1 week's storage. The pyrethroid insecticide deltamethrin, prevented insect infestation during processing and storage, when applied as a 0.003% dip before drying. The FAO/WHO approved insecticide piriraiphos-methyl, reduced blowfly infestation and prevented damage during processing and reduced dermestid beetle infestation during storage, when applied as a 0.03% dip before drying. This treatment resulted in residues, after processing, that were within the FAO/WHO maximum residue limit of 10 mg/kg.Spray applications of pirimiphos-methyl, at dosages of 5-20 mg/kg and deltaraethrin, at dosages of 1-3 mg/kg, were effective in reducing dermestid beetle infestation of smoked fish during storage. Laboratory investigations demonstrated that C. megacephala produced similar numbers of male and female offspring and that there was no difference between the mortalities of the 2 sexes. Female flies greatly outnumbered male flies at the processing site. Mean lifespans of C. megacephala cage populations ranged from 47-54 days and the maximum survival time ranged from 80-98 days. C. megacephala eggs matured within 3 weeks of adult emergence and the mean egg count for the adult female flies was 221.The presence of C. megacephala eggs on fish, stimulated oviposition by C. megacephala and freshly laid eggs were found to have a higher stimulatory effect than eggs which had been previously boiled. Fish being salted exerted a marked, differential attractive effect on gravid, female flies. When presented with fish of a range of salt concentrations, C. megacephala preferentially oviposited on the fish with the lowest salt concentration. In the absence of choice, C. megacephala readily oviposited on fish with relatively high salt contents of 30-40% (dwb). A feeding medium salt content of 33.8% was necessary to significantly reduce larval growth rate and salt contents in excess of 39.5% were necessary to obtain high larval mortalities. Salt contents of up to 39.5% had no effect on pupal mortality.

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The ICES International Bottom Trawl Survey (IBTS) quarter 3 (Q3) data, Dutch Beam Trawl Survey (BTS) Q3 data, and ICES stock assessment data were analysed to model the catchability of each 1-cm size class of demersal fish caught in the Q3 IBTS. Estimates of catchability were generally low, suggesting that raw trawl survey density data seriously underestimated actual densities.

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The ability of a novel fish oil emulsion antigen-delivery system administered orally and by immersion, to stimulate antibody responses in the dab, was measured in a further experiment. On this occasion, oral intubation of HGG (25 mg) in saline induced no detectable responses. Immersion in a bath containing HGG in lipid emulsion induced a transient ASC response in the blood only. Anal intubation of HGG (25 mg) in saline induced a slight ASC response in the gut and blood. Oral intubation of HGG (25 mg) in lipid emulsion induced ASC responses in the gut and transiently in the gill but no response (above background) in the head kidney. None of the above methods of immunisation induced serum antibody titres. Intraperitoneal injection of HGG (1 mg) in saline induced high numbers of ASC in the head, kidney, gut and gill as well as serum antibody. The ASC response in the head kidney was detected from week 5 to 10, peaking at week 5. The response in the gill was from week 3 to 10, peaking at week 6, and the response in the gut was from week 5 to 10, peaking at week 8. The results indicate that systemic stimulation induced ASC responses in both systemic and mucosal compartments. The orally protected HGG in lipid emulsion was more effective than oral HGG in saline and anal HGG in saline in inducing ASC responses in the gut and the gill without including serum antibody, suggesting that oral immunisation can induce a common mucosal response independently of the head kidney. Leucocytes were isolated from the perfused gill of rainbow trout (<I>Oncorhynchus mykiss</I>) and fractioned on a 40-70% Percoll gradient into two subpopulations, top and bottom cell fractions. On stimulation with calcium ionophore, the isolated gill cells, following nylon wool filtration, were shown to be capable of producing chemoattractants for head kidney leucocytes at a dilution of 1:8. Only the bottom cell fraction exhibited migration toward a 2% dilution of trout serum while dilutions of 0.25% and 0.5% rainbow trout serum were not chemoattractive for either head kidney or gill leucocyte populations. The highest migration index was achieved after 1.5 h and the optimal cell number for migration was 4.65x10⁷ cells/ml. Respiratory burst activity was undetectable with isolated gill cells. Mitogenic responses of isolated and fractionated gill cells to LPS and PHA suggested the presence of few B-cells and a preponderance of T-cells.

Convincing molecular evidence for the existence of both cytokines and their receptors in teleost fish is presented. TGF-β is present in <I>O. mykiss</I> encoding a 112 amino acid mature peptide. An integrin binding site (RGD) and a characteristic tetrabasic cleavage site (RKKR) are present, as is the TGF-β superfamily motif. The mature peptide has 9 conserved cysteine residues (8 of which occur in pairs) as well as two additional conserved TGF-β superfamily residues (Pro₃₆ and Gly₄₆). TGF-β exhibits a wide range tissue distribution including head-kidney macrophages, PBL, brain, gill and spleen tissue, and is encoded by a 2.5Kb mRNA. The trout TGF-β gene is spread over 7 exons, with an additional intron in exon 7 when compared to mammalian and avian models. Isolation of a partial sequence also reveals the presence of TGF-β in a cyprinid species. Phylogenetic analysis suggests trout TGF-β to cluster with mammalian TGF-β1 isoforms, and the avian (TGF-β4) and amphibian (TGF-β5) homologs. Neither TNF-α or TNF receptors were detected in <I>O. mykiss</I> at either the cellular or molecular level. The use of degenerate primers in PCR lead to the isolation of a partial sequence for <I>O. mykiss</I> MHC class I. A full length CXC-R gene of 1.6Kb isolated from <I>O. mykiss</I> displays approximately 65% identity to mammalian CXC-R4 receptors, exhibits the seven-transmembrane domain structure of the G-protein coupled receptors and a tissue-specific distribution. Characteristic superfamily motifs and a putative glycosylation site are present in the sequence. Along with the major features of the adaptive immune response such as the major histocompatibility complex (MHC), T-cell receptor (TCR) and immunoglobulin (Ig), cytokines are now shown to be present at the level of teleost fish.

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