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

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Fig. 8. The presence and absence of acoustically tagged fish at the Main channel FSA between January 2010 and May2011. Black bars indicate detection of tagged E. fuscoguttatus and grey bars indicate detection of tagged E. polyphekadion.Site fidelity and spawning frequencyNone of the fish tagged at Site A were detected at Site B during the course of the study. Fidelity toSite A was high with 91.7 and 89.5 % of tagged E. fuscoguttatus and E. polyphekadion, respectively,detected in the next spawning season, approximately one year after being tagged. Most E.fuscoguttatus that came back to the spawning site one year after tagging (spawning season 2) weredetected on two spawning months, with smaller numbers being detected in only one or three ofthe spawning months of the second season (Fig. 8). The only E. fuscoguttatus that was detected on3 consecutive spawning months in the second season was a male and the largest fish tagged, with atotal length of 93 cm. Of the two E. fuscoguttatus that were detected in only one spawning month,one was a female and the other was of unidentified sex. Epinephelus polyphekadion were detectedin only two months of the second monitored spawning season, with 13 of the 16 fish that cameback being detected in both spawning months (Fig. 8). Out of the three E. polyphekadion that weredetected on only one spawning month in the second season, one was a male, one a female andone was of unidentified sex. Our results suggest that the number of aggregations attended withina spawning season is not affected by sex and that most individuals of both species participate inaggregations over two consecutive months. No fish tagged at Site A were detected at Site B. The82
three mature E. polyphekadion that were tagged inside the lagoon in the vicinity Site B in November2010 were not detected at the two monitored FSA sites by May 2010, suggesting that there couldbe other spawning sites in addition to the two already known.DiscussionDetectionBoth E. fuscoguttatus and E. polyphekadion were detected less frequently at night than during theday. Reductions in night time detection of acoustic tags during range testing have been reported bysome authors (e.g. Afonso et al. 2012) but not others (e.g. Welsh et al. 2012). We believe that themost plausible explanation for the observed diel pattern in detections is reduced signal detectioncaused by increased background noise at night in coral reef environments (Bijoux, J. unpubl data).Both E. fuscoguttatus and E. polyphekadion are known to be active at night (Johannes et al. 1999;Hamilton et al. 2005) but the level of activity between night and day has never been quantified. Ifdistinct diel activity does occur, fewer night time detections could be attributed to signal blockingat times when individuals are resting within the reef structure (Zeller 1997; Pastor et al. 2009; Alóset al. 2011). During the day, both species are highly active, with the male E. polyphekadion beingoften involved in cheek to cheek posturing (Rhodes and Sadovy 2002b) and male E. fuscoguttatuschasing each other (Robinson et al. 2008b), thus increasing the probability of daytime detections.Alternatively, tagged fish may have moved from the FSA site during feeding forays at night andthereby reduced detections. Nocturnal active tracking of tagged fish would help elucidate theactivity patterns.Lunar and hourly timing of arrivals and departuresSex-specific patterns of movement in the two species at Site A agree with observations made atother locations (Johannes et al. 1999; Rhodes and Sadovy 2002b; Rhodes et al. 2012). Earlierarrival of males has been documented for both study species (Rhodes and Sadovy 2002b; Robinsonet al. 2008b; Rhodes et al. 2012) and numerous other serranids (Johannes 1989; Johannes et al.1999; Nemeth et al. 2007), suggesting that this is a common trait among aggregating groupers. Ithas been suggested that the earlier arrivals of males at aggregations is for the purpose of establishingterritories (Robinson et al. 2008b) and securing favourable spawning areas with increased probabilityof attracting females. Male arrival at spawning sites at least one month prior to reproduction hasbeen reported for squaretail coral grouper, Plectropomus areolatus (Rhodes and Tupper 2008).Departures from the spawning site were more abrupt than arrivals and occurred just after the newmoon, with all tagged E. fuscoguttatus and E. polyphekadion having left aggregations within fiveand three days after the new moon, respectively. In Pohnpei, E. polyphekadion have been foundto spawn one to two days prior to the full moon and to disperse from the site within 48 – 72 h(Rhodes and Sadovy 2002b), while E. fuscoguttatus have been found to spawn around the fullmoon and to disperse within 4 days (Rhodes et al. 2012). In both our study species departuresmostly occurred at night, which contrasts with observations of Plectropomus leopardus from theGreat Barrier Reef, Australia that departed the FSA during the day (Zeller 1998).Residency at the FSAThe study accurately calculated aggregation site residence and absence times. The early arrivalof males leads to longer residency time at the aggregation site than females, a pattern that hasbeen documented for both species at other locations (Rhodes and Sadovy 2002b; Rhodes et al.2012) and for other spawning aggregation forming serranids (Zeller 1998). Interestingly, maleresidency time was greater during the first spawning month of the season, and while this hasbeen documented elsewhere in E. fuscoguttatus (Rhodes et al. 2012), an explanation has notbeen proposed. More research is needed to understand the biological mechanism of these longerresidency times in the first month. Longer residency and shorter absence time at the spawning siteby males also indicates that they are aggregated for longer and are therefore more vulnerable to83
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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.
Page 40 and 41: The estimate of size at maturity in
Page 42 and 43: This study was designed to verify S
Page 44 and 45: were selected. Fish selected for ta
Page 46 and 47: The number of traps increased on th
Page 48 and 49: Of the 9 tagged fish detected by re
Page 50 and 51: Fig. 7. Diel patterns ofdetection f
Page 52 and 53: Spawning aggregation site fidelity
Page 54 and 55: Chapter 6: Shoemaker spinefoot rabb
Page 56 and 57: anterior of the anus and below the
Page 58 and 59: A high percentage (80.8%) of depart
Page 60 and 61: arrivals and departures at these tw
Page 62 and 63: are typically applied for reef fish
Page 64 and 65: (a)(b)(c)Chapter 3, Figure 3. Spati
Page 66 and 67: (1)(2)(3)(4)(5)(6)Chapter 7, Table
Page 68 and 69: Chapter 12, Fig. 1 Fraction of fema
Page 70 and 71: Plates 8. Selected photographs from
Page 72 and 73: 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 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 124 and 125: of protecting the normal residence
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
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Grüss A, Kaplan DM, Hart DR (2011b
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Kaunda-Arara B, Rose GA (2004a) Eff
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Newcomer RT, Taylor DH, Guttman SI
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Sancho G, Petersen CW, Lobel PS (20
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Appendix 1. QuestionnaireMASMA SPAW
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8. Spawning aggregation knowledgeUs
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Example items KSh Furthest site Clo
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Appendix II. Experimental testing o
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Clove oil concentrationAt a concent
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Appendix III. Application of acoust
Page 161 and 162:
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