WIOMSA-CORDIO spawning book Full Doc 10 oct 13.pdf

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of protecting the normal residence areas (i.e. juvenile and non-spawning adult habitats). All theseresults are summarized in Table 2.1. Fisheries effects of spawning aggregation-based NTRsTable 1 Description of the no-take reserve (NTR) scenarios simulated in the studyNTR Scenario Description#1 Some spawning sites are closed to fishing; the effort that was in reserves before they were closeddisappears at the time of NTR creation; fish are not faithful to spawning sites#2 Some spawning sites are closed to fishing; the effort that was in reserves before they were closeddisappears at the time of NTR creation; fish are faithful to spawning sites#3 Some spawning sites are closed to fishing; the effort that was in reserves before they were closedis fully redistributed to spawning sites remaining open to fishing at the time of NTR creation;fish are not faithful to spawning sites#4 Some spawning sites are closed to fishing; the effort that was in reserves before they were closedis fully redistributed to spawning sites remaining open to fishing at the time of NTR creation;fish are faithful to spawning sites#5 All spawning sites are closed to fishing; the effort that was in reserves before they were closeddisappears on NTR creation#6 All spawning sites are closed to fishing; the effort that was in reserves before they were closed isfully redistributed to non-spawning sites at the time of NTR creation#7 Some normal residence areas are closed to fishing; the effort that was in reserves before theywere closed disappears on NTR creation#8 Some normal residence areas are closed to fishing; the effort that was in reserves before theywere closed is fully redistributed to non-protected normal residence areas remaining open tofishing on NTR creationTable 2 Summary of the main effects of NTRs on female spawning stock biomass-per-recruit (SSBR), sex ratio andyield-per-recruit (YPR) for Epinephelus fuscoguttatus and Siganus sutor for different scenarios of spawning site fidelityand the fate of effort formerly in NTRs. Colour scheme: light grey = positive effects; white = no effects; dark grey =negative effects.116
• Patterns of YPR in presence of NTRs were qualitatively similar for grouper and rabbitfish.• For all scenarios examined, encompassing both the protection of a fraction or allspawning aggregations, there are no benefits for YPR and even negative effects undermost scenarios.• Only if effort is much higher than is currently applied in the trap fishery for rabbitfish,equating to an overexploited stock, can pre-reserve levels of YPR be maintained byprotecting a fraction of spawning aggregations.• For the grouper population, YPR decreases with the fraction of spawning areas protectedand, the higher the value of effort, the more YPR decreases with the fraction of spawningsites in reserves.• The greatest declinesin YPR occur when all spawning aggregations are protected, sinceglobal fishing mortality is considerably reduced in this situation, both when effortdisappears and when effort is redistributed.• The negative effects on YPR are more pronounced for grouper than rabbitfish, sincecatchability increases to a larger extent with grouper aggregation formation.2. Conservation effects of protecting a fraction of spawning aggregations using NTRs• Patterns of female SSBR in the presence of NTRs were qualitatively similar for grouperand rabbitfish.• Unsurprisingly, the greatest conservation benefits (i.e. increases in SSBR and decreasesin sex ratio) were obtained when effort previously expended on spawning aggregationssimply disappeared when the NTRs were established. Interestingly, female SSBR and sexratio were relatively unchanged between the site fidelity and non-site fidelity scenarioswhen effort disappears.• However, at higher levels of annual effort than those observed in the fisheries, SSBR andsex ratio would benefit more from the site fidelity than the non-site fidelity situation, asthe fraction of protected spawning sites increases.• By contrast, site fidelity has important consequences for conservation benefits if effortat spawning sites is redistributed when NTRs are created. As we assumed that effortwould be redistributed to the remaining unprotected spawning sites if only a fraction areprotected using NTRs, SSBR is invariant with the fraction of spawning sites in reservesin the non-site fidelity scenario, as fish would suffer mortality when they attended nonprotectedspawning aggregations.• Conversely, if fish are faithful to spawning sites, conservation benefits are attained oneffort redistribution, but at lower levels than when effort disappears.• However, the effects of effort redistribution on sex ratio for the protogynous grouperpopulation were negative. At high effort levels and with a relatively large fraction ofspawning sites protected by NTRs, sex ratio at fished spawning sites would be moreheavily female-biased than if the same level of effort was applied in the fishery withoutany NTRs.3. Conservation effects of protecting all spawning aggregations using NTRs• If all spawning aggregations are protected by NTRs, conservation benefits occur anddo not differ much if effort disappears or is redistributed. This is because, under thisassumption, all effort would be directed towards non-spawning periods and areas wherecatchability is much lower. Therefore, even the addition of redistributed effort on nonspawningfish does not affect SSBR to a large degree.• There are greater conservation benefits for groupers than rabbitfish, since in the former,aggregation formation is associated with much larger increases in relative catchability.• The benefits for male groupers are also higher than those for females – as males spendlonger times aggregating, total closure of spawning sites increases SSB for males to alarger extent than for females.117
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The designation of geographical ent
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Chapter 1: IntroductionJan Robinson
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limited, subsistence levels of expl
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NTRs for spawning aggregations usin
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al. 2003). Verification may include
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a fraction of spawning sites are pr
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Chapter 3: Targeted fishing of the
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verifying spawning aggregations, we
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ecorded from inshore close to the c
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(a)(b)Fig. 3. Spatial patterns ofca
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pooled sizes of the three spawning
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found S. sutor contributed up to 44
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2011b). However, observations of fi
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MethodsTo identify seasonal and lun
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n=199Females GSI (mean ± SE)2.521.
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The estimate of size at maturity in
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This study was designed to verify S
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were selected. Fish selected for ta
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The number of traps increased on th
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Of the 9 tagged fish detected by re
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Fig. 7. Diel patterns ofdetection f
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Spawning aggregation site fidelity
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Chapter 6: Shoemaker spinefoot rabb
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anterior of the anus and below the
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A high percentage (80.8%) of depart
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arrivals and departures at these tw
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are typically applied for reef fish
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(a)(b)(c)Chapter 3, Figure 3. Spati
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(1)(2)(3)(4)(5)(6)Chapter 7, Table
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Chapter 12, Fig. 1 Fraction of fema
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Plates 8. Selected photographs from
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MethodsStudy sitesThe study area wa
Page 74 and 75: which shelved gently ( ca. 25 o ) t
Page 76 and 77: Fig. 4. Lunar periodicity in number
Page 78 and 79: Behaviour and appearanceDescription
Page 80 and 81: eported aggregations forming betwee
Page 82 and 83: The sizes of E. fuscoguttatus aggre
Page 84 and 85: Materials and methodsStudy area and
Page 86 and 87: TL. All fish tagged were considered
Page 88 and 89: Lunar timing of arrivals and depart
Page 90 and 91: Fig. 8. The presence and absence of
Page 92 and 93: aggregation fishing. This critical
Page 94 and 95: Chapter 9: Persistence of grouper (
Page 96 and 97: ResultsBetween 2003 and 2006, the c
Page 98 and 99: Fig. 2. Mean (± standard error, SE
Page 100 and 101: A few species (e.g. Epinephelus gut
Page 102 and 103: (a)(b)Fig. 1. Map of (a) study site
Page 104 and 105: Fig. 2. Number of E. lanceolatus ob
Page 106 and 107: was having any impact on the popula
Page 108 and 109: A spawning aggregation is said to o
Page 110 and 111: Chapter 11: Evaluation of an indica
Page 112 and 113: Table 1 Aggregation fisheries asses
Page 114 and 115: the lists of Jennings et al. (1999)
Page 116 and 117: with the more vulnerable labrids an
Page 118 and 119: The remaining serranid populations
Page 120 and 121: Spawning aggregation behaviour is c
Page 122 and 123: tiger grouper, Mycteroperca tigris:
Page 126 and 127: • Since grouper males are afforde
Page 128 and 129: Fig. 2 Yield-per-recruit normalized
Page 130 and 131: The approaches identified above are
Page 132 and 133: during full moon periods. Siganus s
Page 134 and 135: model, many parameter estimates are
Page 136 and 137: ReferencesAbunge C (2011) Managing
Page 138 and 139: Cox DR (1972) Regression models and
Page 140 and 141: Grüss A, Kaplan DM, Hart DR (2011b
Page 142 and 143: Kaunda-Arara B, Rose GA (2004a) Eff
Page 144: Newcomer RT, Taylor DH, Guttman SI
Page 147 and 148: Sancho G, Petersen CW, Lobel PS (20
Page 149 and 150: Appendix 1. QuestionnaireMASMA SPAW
Page 151 and 152: 8. Spawning aggregation knowledgeUs
Page 153 and 154: Example items KSh Furthest site Clo
Page 155 and 156: Appendix II. Experimental testing o
Page 157 and 158: Clove oil concentrationAt a concent
Page 159 and 160: Appendix III. Application of acoust
Page 161 and 162: 153
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