Fishing impacts and the degradation or loss of habitat structure

The wider effects of fishing on marine ecosystems have become the focus of growing concern among scientists, fisheries managers and the fishing industry. The present review examines the role of habitat structure and habitat heterogeneity in marine ecosystems, and the effects of fishing (i.e. trawling and dredging) on these two components of habitat complexity. Three examples from New Zealand and Australia are considered, where available evidence suggests that fishing has been associated with the degradation or loss of habitat structure through the removal of large epibenthic organisms, with concomitant effects on fish species which occupy these habitats. With ever-increasing demands on fish-stocks and the need for sustainable use of fisheries resources, new approaches to fisheries management are needed. Fisheries management needs to address the sustainability of fish-stocks while minimizing the direct and indirect impacts of fishing on other components of the ecosystem. Two long-term management tools for mitigating degradation or loss of habitat structure while maintaining healthy sustainable fisheries which are increasingly considered by fisheries scientists and managers are: (1) protective habitat management, which involves the designation of protected marine and coastal areas which are afforded some level of protection from fishing; and (2) habitat restoration, whereby important habitat and ecological functions are restored following the loss of habitat and/or resources. Nevertheless, the protection of marine and coastal areas, and habitat restoration should not be seen as solutions replacing conventional management approaches, but need to be components of an integrated programme of coastal zone and fisheries management. A number of recent international fisheries agreements have specifically identified the need to provide for habitat protection and restoration to ensure long-term sustainability of fisheries. The protection and restoration of habitat are also common components of fisheries management programs under national fisheries law and policy.     

Left-side displacement of the abomasum in dairy cows at pasture

The presentation of approximately 40 dairy cows affected with left-side displacement of the abomasum (LDA) per annum in a cattle practice in East Gippsland, Victoria provided an opportunity to conduct a survey and case-control study of the disease in a grazing environment. The study, involving 37 dairy cows at pasture, revealed significant differences from the pattern of the disease occurring in the northern hemisphere where cows in older age groups, of larger frame size, higher production and fed high grain rations are at increased risk. Affected cows were diagnosed over a 10-month period and represented approximately 0.06% of the dairy cow population. Most cases were diagnosed in the early lactation period. Evidence for a genetic predisposition was suggested by the discovery that one sire generated a disproportionately large number (9) of the cows with LDA. Although affected cows were average producers in their herds, being a member of a high-producing herd was a significant risk factor.     

Prostate vascular flow: The effect of the ejaculation on the power doppler ultrasonographic examination

Power Doppler sonography (PD) can accurately depict tissue perfusion, recognize slow flows, and is relatively angle independent. The monitoring of local blood flow by Doppler ultrasonography is helpful in differentiating prostatic physio‐pathological conditions, but the recognizing of physiological variables that could affect it is crucial to apply this technique in clinical practice. This study aimed to evaluate if ejaculation affects blood flow to the prostate and to state how long this effect lasts. Serial PD examinations of prostate were performed in 18 dogs (1–5 years, 6–40 kg) immediately before (T0) and after (T1) the ejaculation, and repeated 6 (T2), 18 (T3) and 24 (T4) hours later. For each examination, two representative PD images were chosen and ranked by two independent observers according to the following scoring system: 0 = mild subcapsular (S) vascularization without clear evidence of parenchymal (P) vascularization; 1 = moderate P and S vascularization; 2 = severe S and moderate P vascularization; 3 = severe P and moderate S vascularization; 4 = severe P and S vascularization. Interobserver agreement was assessed using Kappa of Cohen. Ranked data, grouped according to time, were compared by ANOVA and Tukey HSD test (p < .05). Variations in the vascular flow pattern at different times were observed for all dogs. The statistical analysis evidenced a significant difference for T0 vs T1 and vs T2 and vs T3 (p < .01), with no significant difference for T0 vs T4 (p > .05). Interobserver agreement was very good (Kappa of Cohen = 0.86). This study demonstrated a definite increase in vascular flow to the prostate after ejaculation. The present results suggest a minimum of 24 hr sexual rest before the PD examination of the gland. This result should be taken into account whenever Doppler sonography is used to evaluate potential hyperaemia in dogs suspected of having prostate abnormalities.     

Vaccination and challenge studies with psittacine beak and feather disease virus

SUMMARY: Psittacine beak and feather disease virus (PBFDV) was administered to adult galahs ( Eolophusroselcapillus ) by mouth or by intramuscular injection. Concentration of PBFDV antibodies in serum and excretion of PBFDV were monitored by haemagglutlnation inhibition (HI) and haemagglutination (HA) respectively. After oral administration, 17 of 18 galahs remained clinically normal and a small rise in antibody titre was detected in 3 of 18 birds. After intramuscular administration, antibody was detected in all birds. PBFDV was not detected in the feather dander of birds in either group. One bird developed diarrhoea and high faecal HA titres within 4 days of oral administration and then died. Adult and nestling cockatoos were vaccinated with an experimental inactivated double-oil emulsion vaccine. PBFDV antibody responses are comparable to those induced by a primary-oil emulsion vaccination regimen using Freund's adjuvants. Both vaccines protected nestlings. Three sibling wild-caught sulphur-crested cockatoos were vaccinated but died of PBFD before experimental challenge despite antibody responses in all birds. Unvaccinated control chicks developed acute PBFD within 4 weeks of challenge, probably from PBFDV-induced hepatitis since high concentrations of PBFDV were detected in their livers.     

Laboratory diagnosis of psittacine beak and feather disease by haemagglutination and haemagglutination inhibition

SUMMARY Simple and sensitive haemagglutination and haemagglutination Inhibition assays were developed for psittacine beak and feather disease (PBFD) virus and serum antibody, respectively. The assays were used in the examination of samples from 73 birds clinically affected with PBFD. High antigen titres (log₂ 9 to log₂ 12) were detected In feathers, faeces and cloacal contents of PBFD-affected birds. Antigen was not detected In either faecal or feather samples from 20 normal galahs (Eolophus roselcapillus) and 9 normal sulphur crested cockatoos (Cacatua galerita). After kaolin treatment and haemadsorption of serum, haemagglutination inhibition (HI) antibody titres could not be detected in serum from 42 PBFD-affected birds, whereas serum HI titres from 64 normal psittacine birds ranged from less than log₂ 1 to log₂ 8. Serum and yolk HI antibody responses of 6 PBFD virus-inoculated layer hens were measured. Pre-inoculation chicken sera contained high concentrations of non-specific haemagglutination inhibitors (not detected in chloroform-extracted yolk), which were removed by kaolin treatment and haemadsorption.     

Molecular detection of norovirus in sheep and pigs in New Zealand farms

Human norovirus (NoV) is reportedly the major cause of non-bacterial gastroenteritis outbreaks worldwide and is commonly associated with water- and food-borne transmission via the faecal-oral route. Aside from humans, norovirus has been detected in pigs, cattle and mice. The close relatedness of some human and animal noroviruses has raised concerns about potential zoonotic transmission. Our laboratory recently reported the development of a multiplex real-time RT-PCR for the detection and genotyping of norovirus of genogroups I-III. Here we report a study of 56 faecal specimens from pigs and sheep that were collected and screened for noroviruses using this assay. Norovirus was found in 2/23 (9%) of porcine specimens (all were genogroup II) and in 8/33 (24%) of ovine specimens (all were genogroup III). Samples tested positive for norovirus were verified by conventional RT-PCR with different primer sets. Genomes of representative porcine and ovine norovirus strains underwent partial sequence analysis (343 and 2045 bases, respectively). This is the first report describing norovirus in sheep.     

Phosphorus supplements and fluorosis in cattle—a northern Australian experience

SUMMARY Chronic fluoride toxicosis caused lameness, dental lesions and illthrift in an extensive beef cattle herd in northern Australia. Up to 15% of the herd was lame and the disease forced the culling of large numbers of cows. The source of fluoride was fertiliser-grade monoammonium and diammonlum phosphate fed as part of a mineral supplement. Large quantities of mineral supplement were provided to the cattle because lameness was attributed to phosphorus deficiency, which is endemic in the area. Most lameness developed in the late dry season in the post-lactation phase. Severe lameness was caused by fractured pedal bones.