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

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Hepatosomatic index121086420BarramundiBull sharkMulletQueenfishFigure 1.1. Boxplot (showing the means, quartiles and ranges) of hepatosomatic index for the laboratoryassessedfish species.To avoid any apparent biases due to the varying combinations of fish caught at each location and trip, ‘fishtype’ was included as a main effect in all models, and the ‘location by trip’ tables were extracted using the‘full’ option. This effectively estimates missing (fish) values for those location/trip combinations wheneach fish type was not caught, and correctly adjusts each mean to the overall expectation.The deliberate laboratory sampling of both diseased and unaffected fish (the target was for five of each,for each location/trip combination) introduced further complexity into the analyses. In the field, each fishwas defined as ‘not diseased’ if its skin condition, lesions category and eye condition were all zero, and‘diseased’ otherwise. For the variables measured in the laboratory, any unweighted analyses for locationsand times would only reflect the proportions of diseased fish that were submitted to the laboratory, ratherthan the overall population (as best measured by all the fish obtained in the field). To correctly adjust forthis stratification, weighting factors were calculated as:Proportion (diseased or not diseased) in the whole sampleProportion (diseased or not diseased) in the laboratory subsampleThese weighting factors were determined at the location by trip by fish species level, and then used tocorrectly weight each of the respective observations (diseased or not) in the analyses.Fish size (length or weight) was trialed as an overall covariate, but showed inconsistent trends. Problemswere encountered due to the greatly varying size ranges of the species – there was evidence that this termwas merely fitting to the overall differences in size between the fish types. Adjusting all results back to acommon mean size also made little sense, given the large difference between the average lengths for bullsharks vs. the others. Hence size was omitted from all of the cross‐species analyses, leaving size effects tobe captured in with the ‘fish type’ factor. Length was included as a covariate in the separate barramundi103
analyses, but this was not done for mullet, as (within this group of fish) lengths were confounded with theactual species of mullet.‘Time since death’ was trialed as a covariate for those laboratory ratings for which there was a reasonablehypothesis that they would increase after death. This was tested at the individual species level, and for theinstances where this relationship was not significant, time since death was then dropped for the finalmodel.In addition to conducting the primary weighted analyses of location by trip by fish species (along withtheir interactions), second analyses were conducted for each variable including ‘disease status’ in themodel. This allowed the direct testing and reporting of the impact of disease status on each variable.The analyses of each of the variates (in turn) are followed by a multivariate summarisation. This adopts aprincipal components representation of all the data, taking the first two orthogonal dimensions, to obtainan overview as to which locations and times are most similar.2. RESULTS TRAWL AND NET DATA (SPECIES NOT SUBMITTED TO THE LABORATORY)2.1 PrawnsOf the 574 prawns observed, there were only five with shell erosions – three from the Harbour and twofrom the Fitzroy River, with none from the Bundaberg samples. There was no statistical difference in thepercentages of prawns with erosions, with mean values (± s.e.) of 1.8% (± 1.0%) for Gladstone Harbour,1.0% (± 0.7%) for the Fitzroy River, and 0.0% (n/a) for Bundaberg.2.2 FishAll of the grinner (179), herring (345) and threadfin (545) were field‐classified as ‘not diseased’, having arating of zero for skin condition, lesion grade and eye condition. The grinners and herring also had noparasites. For threadfin, there were two found with parasites, one from Bundaberg (a reference site) andone from Gladstone Harbour. Similarly, all 71 Queenfish had ratings of zero for the skin and eye ratings,with two fish having lesions – one each from Bundaberg and the Calliope River. There were 36 queenfishwith externally‐observed parasites, with 28 from the reference sites and 8 from the Gladstone region.3. TRAWL AND NET DATA (SPECIES WHICH WERE SUBMITTED TO THE LABORATORY)Table 3.1 shows the distributions of the fish numbers that were submitted to the laboratory. In many ofthe location / trip combinations, these were the whole sample.Table 3.1. Distribution of numbers submitted to the laborato ry.Barra. Bull shark Mullet QueenfishTrip 1 Trip 2 Trip 1 Trip 2 Trip 1 Trip 2 Trip 1 Trip 2Fitzroy R 10 10 7 0 10 11 1 10Bundaberg 10 7 1 0 10 10 10 10Hamilton Pt 10 10 1 0 0 0 0 0Calliope R 10 10 3 0 7 10 0 0Spoil Grounds 0 0 0 0 0 0 5 0Upp. Boyne R 10 6 0 0 10 10 0 0Low Boyne R 10 10 0 0 10 10 0 1Rodds Bay 7 2 0 0 10 10 0 0Lake Awoonga 5 0 0 0 0 00 0Excluding net damage, there were only three fish with a recordable eye condition – one barramundi in theCalliope River, one barramundi at Bundaberg, and one sea mullet in the Fitzroy River. Notably, the lattertwo were from the reference sites. Due to this low incidence level, eye condition was not analysed.Similarly, for general condition, only one fish was classified as ‘emaciated’ – a barramundi from HamiltonPoint. All others were rated as ‘normal’.104
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Department of Agriculture, Fisherie
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ContentsTable of tables 1Table of f
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Mullet (Mugilidae) 80Banana prawn (
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Figure 7. Barramundi caught in the
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Figure 38. Sharks caught in the Cal
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Phase 1 (August 2011-February 2012)
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The results in this study support t
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ecognised expertise and research pu
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Mr Mitchell reported high catches u
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Figure 2. Sampling sites within the
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Phase 2: Expanded Gladstone Fish He
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Mud crab (Scylla serrata): Mud crab
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For mud crabs, hepatopancreas, gill
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Table 2. The number of fish, crusta
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Significant findings and discussion
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Commercial barramundi catch and cat
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Figure 6. Eye condition observed in
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Conditions observed in barramundi s
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Figure 12. A barramundi caught in t
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provided another environmental stre
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was somewhat reduced because post-m
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4,000Commercial effort (days fished
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Size structure of mud crabs observe
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Figure 21. Examples of shell abnorm
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Of the 58 crabs observed to have sh
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HistopathologyLipid storage vacuola
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Commercial fishing effort for mulle
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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
Page 101 and 102: Lesion photos Description GradeThis
Page 103 and 104: L4continuedoperculumgrazing;cuts or
Page 105 and 106: Appendix A-3: Fish health assessmen
Page 107: Appendix B - Statistical report: Gl
Page 111 and 112: was a significant (P < 0.05) locati
Page 113 and 114: Percentage with fin condition > 015
Page 115 and 116: Table 3.6b. Effects of locations an
Page 117 and 118: Table 3.7d. Spleen categories - cou
Page 119 and 120: 32Bundy2Bundy1UpBoyne1UpBoyne2LwBoy
Page 121 and 122: Table 3.9c. Regional group means an
Page 123 and 124: Table 4.2c. Effects of locations an
Page 125 and 126: 4.5 Summarising by regionsThe means
Page 127 and 128: Ta ble 5.2a. Effects of locations a
Page 129 and 130: 5.5 Summarising by regionsThe means
Page 131 and 132: 6.3 ResultsThere was no significant
Page 133 and 134: Table 6.5 lists the mean values whe
Page 135 and 136: Standardized residualsStandardized
Page 137 and 138: Table 2.3f. Muscle lesions.Lake Fit
Page 139 and 140: Table 4. 1f. Muscle lesions.Fitzroy
Page 141 and 142: Table 5.6. Regiona l m eans for the
Page 143 and 144: Contaminants in Tissue ofFish and C
Page 145 and 146: Contaminants in Tissue of Fish and
Page 151 and 152: Department of Science, Information
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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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