Two methods for estimating bycatch-to-shrimp ratios were tested using Monte Carlo simulations. The Ratio Averager first calculates the ratio of bycatch to shrimp for each element of the sample and then averages all the entire sample. This method overestimated the ratio with a maximum bias as high as 4.5 times. In contrast, the Ratio Estimator or Ratio Estimation as termed in some literature first averages the sample catch rate of bycatch and shrimp and then calculates the ratio of the two averages. The Ratio Estimator performed quite well under all scenarios evaluated in this study, with a bias range from –1.7% to 2.8%. The reliability of the Ratio Estimator was also higher than the Ratio Averager, particularly when both bycatch and shrimp had high variability. Two sets of fishery survey data were used to demonstrate the difference in ratio estimates between the two methods.

Although there are numerous published accounts of studies utilizing heart rate (fH) transmitters in fish, few of these studies provide sufficient detail to aid other researchers in deploying these devices. Here, we detail the attachment, validation, and preliminary deployment of a commercially available ultrasonic fH transmitter. We used largemouth bass, Micropterus salmoides, for this study because they principally modulate cardiac output using fH, making them logical candidates for this technology. Using an external harness that balanced the battery on one side of the dorsum, and the transmitter on the other, we attached the device to 13 fish. Electrodes were positioned ventral-laterally to the pericardial cavity. Doppler flow probes were used to validate that the transmitter was detecting and emitting a signal when triggered by the depolarization of the ventricle (QRS wave), as indicated by peaks in blood flow. We then deployed the fH transmitters for periods of up to 32 days, generating one of the most complete series of fH data available. We present preliminary data illustrating the information available from fH transmitters at different temporal resolutions (real time vs. hourly means), including relationship of fH to temperature, behavioral correlates of fH, and diel patterns of fH.

17α-ethynylestradiol sex-reversed males of Oreochromis aureus (pseudofemales, ΔF, genotype ZZ) are used in aquaculture to produce a male monosex population by crossing with ZZ homogametic normal males. When placed with males (M) and females (F) in the same spawning tank, the spawning rate of F is higher than for ΔF. In order to understand this phenomenon, comparisons were made between the behaviour of 18 F (446 ± 96 mm) and 18 ΔF (401 ± 59 mm). ΔF showed a more aggressive behaviour and were significantly more dominant than normal F in fighting pair experiments (F × ΔF) or in fighting group experiments in four different stocking densities (8, 12, 16 and 83 fish 10–3 l with F/ΔF RATIO = 1). ΔF were also more aggressive towards males than F were. The results support the idea that behavioural differences exist between F and ΔF. These differences are probably due to the effect of the sexual genotype on behaviour.

The aim of this report is the synthetic presentation of observations related to ultrastructural aspects of the lipid metabolism during the ontogenesis of trophic mechanisms in three teleost species, the sea bass, Dicentrarchus labrax, the sea bream, Sparus aurata and the pike-perch, Stizostedion lucioperca. The results have shown the respective roles of the vitelline syncytium, the intestine, the liver and the exocrine pancreas during the change from an endogenous lipid source, the yolk vesicle, to an exogenous lipid one, food. They make it possible to stress the close correlation between the development of the biliary function, that of the exocrine function of the pancreas and that of the intestinal absorption of lipids. These activities established during the endotrophic stage are slight at the beginning of trophic life and then increase at the end of the endo-exotrophic stage. Analysis of the results suggests the occurrence of four physiological phases characteristic in early lipid metabolism establishing the main heads in acquisition of the trophic autonomy according to a pattern similar to that of mammals.

Three serological techniques (indirect immunofluorescence test, flow cytometry, and indirect dot–blot immunoenzymatic assay) have been evaluated for the detection of lymphocystis viral antigens using a gilt-head seabream cell line, SAF-1, and fish leukocytes. Six lymphocystis disease virus (LCDV) isolates from gilt-head seabream, and one reference strain (ATCC VR 342), were tested. Detection of viral LCDV antigens in SAF-1 cells and fish leukocytes by indirect immunofluorescence test occurs at similar periods (5–7 d post-inoculation), and viral antigens were detected as cytoplasmic inclusions located at the periphery of inoculated cells. The percentages of cells with LCDV antigens obtained by flow cytometry were very low, ranging between 0.9% at 5 d post-inoculation and 19.7% at 10 d post-inoculation. The optimal concentration of viral stocks detected by indirect dot–blot immunoenzymatic assay was 0.5 μg ml–1, when purified viral stocks were used as antigens. Inoculated and uninoculated SAF-1 cells could not be distinguished using LCDV antiserum binding. On the basis of these results, indirect immunofluorescence and flow cytometry tests appear to be the best serological methods to detect LCDV antigens in both SAF-1 cells and fish leukocytes.

A number of cephalopod species present substantial ecological and economical importance; however, data on the physiology of stress and on regulatory processes linking stress to immune defence against pathogens remain extremely scarce in these organisms. The present study examined the influence of a 5 min air exposure, a common perturbation associated with handling in aquaculture settings and fisheries, on neuroendocrine and immune parameters in the octopus Eledone cirrhosa. Measurements of circulating concentrations of noradrenaline and dopamine, two hormones that are released in the haemolymph during stress in bivalves and gastropods, showed that the 5 min air exposure represents a real stress to octopus. Indeed, blood levels of both hormones increased by about 2–2.5-fold in stressed animals. Concomitantly, a significant decrease in the number of circulating haemocytes was observed, whereas haemocyte phagocytotic activity and superoxide anion production increased transiently between 5 and 60 min after the beginning of the stress. These results provide a first insight into the effects of stress on catecholamine levels and immune functions in cephalopods and suggest that stress and immunity may be associated in these organisms.

The sequencing of the human genome represented a watershed in the biological sciences. Post-genomic biology will be marked not only by vastly greater knowledge about the human genome and those of other species but will see an increasing application of novel and highly sophisticated technologies. Genomic strategies, together with those that look at the proteome of cells and tissues, are likely to revolutionize scientific research over the coming years. The ease with which novel and homologous genes can be isolated using the new databases and technologies, and the ability to study the expression of thousands of genes simultaneously at a global cellular level will be the major factors in this revolution. Genomic information is already being used to further our understanding of physiology and gene evolution in fish. Furthermore, the highly compact pufferfish (Takifugu rubripes) genome is being used extensively as a model to interpret those of tetrapods. Currently, studies of the fish genome are limited to gene evolution and to a much lesser extent, environmental toxicology. However, as interpretation of fish genomes gathers pace, we are likely to see the increasing involvement of other key areas such as reproduction, growth, pathology of disease, and flesh development/quality. Here, we present some of the advanced genomic technologies currently available and discuss how these might influence our knowledge of fish biology.