Gladstone Fish Health Investigation 2011 - 2012 - Western Basin ...

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Laboratory testing Phase 1The mud crabs examined showed evidence of erosive shell disease. Signs of this diseaseare consistent with bacterial infection by Vibrio spp., which are naturally occurring in marinewaters. Photobacterium (Vibrio) damaselae was isolated in one mud crab sample. Thesebacteria are opportunistic and proliferate on damaged shell to cause erosion due to theirchitinolytic enzymes.Observational findings Phase 2Mud crab sampling during Phase 2 was conducted in April/May 2012 and was repeated inJune/July 2012. The results from these sampling events are recorded below, along with asummary for Phase 2.April/May 2012: A total of 853 crabs were observed during sampling from seven sites withinthe study area (385 in the reference sites and 468 within Gladstone). The prevalence of shellabnormalities ranged from 2.1% in the Rodds Bay area to 8.1% within the Port DevelopmentArea and averaged 4% in the reference sites and 4.4% in the combined Gladstone sites.June/July 2012: A total of 746 crabs were observed during sampling in June/July 2012 fromseven sites within the study area (491 in Gladstone and 255 in the reference sites). Theprevalence of all shell abnormalities ranged from 1.4% in the Fitzroy River area to 4.7%within the Narrows, and averaged 1.96% in the reference sites and 3.26% in Gladstone.Phase 2 summary: In total, 1599 crabs were observed during Phase 2 sampling from sevensites within the study area (640 in the reference sites and 959 within Gladstone). Of these,58 crabs (3.6%) were observed to have shell abnormalities.The prevalence of shell abnormalities as shown in Figure 23 ranged from 2.4% in the RoddsBay and Bundaberg Reference sites to 6.2% within the Port Development Area, andaveraged 3.2% in the reference sites and 3.9% in Gladstone. Grade 5 lesions (most severeshell damage – perforated partially or fully > 20 mm in diameter) were found throughout thestudy area, including both reference sites (Fitzroy River and Bundaberg).Percentage of mud crabs showing signs of shell abnormalities at each site Phase 2.NormalAffectedPercentage100%90%80%70%60%50%40%30%20%10%0%Fitzroy River(n = 387)Narrows(n = 147)PortDevelopmentArea(n = 161)Hamilton Point(n = 192)Calliope River(n = 94)Rodds Bay(n = 365)Bundaberg(n = 253)LocationFigure 23. The combined percentage of mud crabs with shell abnormalities observed at all sites duringthe Gladstone Fish Health Monitoring Program, Phase 2. Note, (n) refers to the total number of crabsexamined at each site.43
Of the 58 crabs observed to have shell abnormalities in the field, 9 (15.5%) had lesionslocated on areas of the shell other than the dorsal carapace (legs, claws, abdomen andthorax).Lesion grade ratings recorded by Fisheries Queensland field staff and those recorded byBiosecurity Queensland from June/July sampling showed a significant (P < 0.001) degree ofassociation, with the counts listed in Table 5. There was agreement between field andlaboratory assessments in 79.71% of these cases. Interestingly, the field assessment washigher than the laboratory assessment in 14.49% of these cases, whereas the reverse onlyoccurred in 5.8% of the crabs. These results provide confidence for the field assessmentsmade by Fisheries Queensland staff when recording the presence and severity of lesions inthe field for both Phase 1 and Phase 2 of the program.Table 5. Highest lesion grade for each crab as assessed by Fisheries Queensland in the field andBiosecurity Queensland in the laboratory. The grey numbers indicate agreement between the twoassessments.LaboratoryAssessmentLesion Grade(0 – 5)Field AssessmentLesion Grade (0 – 5)0 1 2 3 4 50 47 0 2 4 1 01 2 1 2 0 0 02 0 1 2 0 0 13 0 0 0 1 0 04 0 0 1 0 1 15 0 0 0 0 0 3Considering the prevalence of rust spot shell disease documented by Andersen and Norton(2001), the potential bias by Fisheries Queensland staff to overestimate the prevalence ofshell lesions during field observations, and that observations of shell lesions were notrestricted to the dorsal carapace during this program, these results of 3.9% shell lesionssuggest that the prevalence of rust spot shell disease has decreased from levels of 10.2%previously recorded by Andersen and Norton (2001).It was assumed that the number of crabs with shell lesions that were reported in Phase 1were not under reported, as the above statistical analysis of Phase 2 for mud crabs did notidentify under reporting, and the staff and field methods were the same between Phases 1and 2. The combined results of Phase 1 and 2 do not indicate changes in the frequencies ofoccurrence over the sampling period or sampling location in the Harbour. The level of shelllesions observed during Phase 1 and 2 was significantly lower than the 37.8% reported formud crabs from Gladstone by Landos (2012), and lower than Andersen and Norton (2001).Andersen and Norton (2001) found the highest average percentage in Gladstone of 18.3% in1998/99, which reduced to 10.2% in 2001.Laboratory findings Phase 2NecropsyThere was no significant difference (P = 0.68) between the hepato-somatic index ofapparently normal and abnormal crabs (0.057 ± 0.002 vs. 0.054 ± 0.002). Hepato-somaticindex (HSI) is defined as the ratio of liver weight to body weight. HSI is generally used as anindication of energy stores, and these results would suggest that the presence of shelllesions is not having a significant effect on feeding.44
Page 1 and 2: Department of Agriculture, Fisherie
Page 3 and 4: ContentsTable of tables 1Table of f
Page 5 and 6: Mullet (Mugilidae) 80Banana prawn (
Page 7 and 8: Figure 7. Barramundi caught in the
Page 9 and 10: Figure 38. Sharks caught in the Cal
Page 11 and 12: Phase 1 (August 2011-February 2012)
Page 13 and 14: The results in this study support t
Page 15 and 16: ecognised expertise and research pu
Page 17 and 18: Mr Mitchell reported high catches u
Page 19 and 20: Figure 2. Sampling sites within the
Page 21 and 22: Phase 2: Expanded Gladstone Fish He
Page 23 and 24: Mud crab (Scylla serrata): Mud crab
Page 25 and 26: For mud crabs, hepatopancreas, gill
Page 27 and 28: Table 2. The number of fish, crusta
Page 29 and 30: Significant findings and discussion
Page 31 and 32: Commercial barramundi catch and cat
Page 33 and 34: Figure 6. Eye condition observed in
Page 35 and 36: Conditions observed in barramundi s
Page 37 and 38: Figure 12. A barramundi caught in t
Page 39 and 40: provided another environmental stre
Page 41 and 42: was somewhat reduced because post-m
Page 43 and 44: 4,000Commercial effort (days fished
Page 45 and 46: Size structure of mud crabs observe
Page 47: Figure 21. Examples of shell abnorm
Page 51 and 52: HistopathologyLipid storage vacuola
Page 53 and 54: Commercial fishing effort for mulle
Page 55 and 56: Figure 28. (a) Mullet caught in Rod
Page 57 and 58: June/July: Mullet samples were coll
Page 59 and 60: Sharks and raysThe monitoring progr
Page 61 and 62: Observational findings Phase 1Phase
Page 63 and 64: Encysted larval parasites were foun
Page 65 and 66: in particular bull sharks, have bee
Page 67 and 68: Commercial banana prawn catch for t
Page 69 and 70: Observational findings Phase 2April
Page 71 and 72: Laboratory testing Phase 1Seven riv
Page 73 and 74: four displayed signs of redness. Th
Page 75 and 76: Conditions observed in pelagic fish
Page 77 and 78: FinfishObservational findingsDuring
Page 79 and 80: ConclusionsIn 2011, a wide range of
Page 81 and 82: Mud crabsFisheries Queensland did n
Page 83 and 84: Owens, L. 1983. Bopyrid isopod Epip
Page 85 and 86: Candidate speciesThe monitoring pro
Page 87 and 88: Table 1: Candidate species for each
Page 89 and 90: Sample processingSample processing
Page 91 and 92: Herring/grinner/Australian threadfi
Page 93 and 94: For example: the third specimen, re
Page 95 and 96: oooGonad - present/absentHepatopanc
Page 97 and 98: Cloudy eye,swollen,redness orhemorr
Page 99 and 100:
Red pin pointmarks - nogeneral redn
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Lesion photos Description GradeThis
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L4continuedoperculumgrazing;cuts or
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Appendix A-3: Fish health assessmen
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Appendix B - Statistical report: Gl
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analyses, but this was not done for
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was a significant (P < 0.05) locati
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Percentage with fin condition > 015
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Table 3.6b. Effects of locations an
Page 117 and 118:
Table 3.7d. Spleen categories - cou
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32Bundy2Bundy1UpBoyne1UpBoyne2LwBoy
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Table 3.9c. Regional group means an
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Table 4.2c. Effects of locations an
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4.5 Summarising by regionsThe means
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Ta ble 5.2a. Effects of locations a
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5.5 Summarising by regionsThe means
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6.3 ResultsThere was no significant
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Table 6.5 lists the mean values whe
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Standardized residualsStandardized
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Table 2.3f. Muscle lesions.Lake Fit
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Table 4. 1f. Muscle lesions.Fitzroy
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Table 5.6. Regiona l m eans for the
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Contaminants in Tissue ofFish and C
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Contaminants in Tissue of Fish and
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Department of Science, Information
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Appendix E - Time line BarraBy John
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friends. Rapidly rising flood water
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To make note - condition loss was e
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May/June- FinsMy initial observatio
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Thes e escapee were now also in awo
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Figure N. Barramundi showing net ma
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September- Deaths and SicknessFigur
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There is numerous distinguishing fe
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Department of Agriculture, Fisherie
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Gladstone Fish Health Investigation 2011 - 2012 - Western Basin ...

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