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

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MethodsTo identify seasonal and lunar spawning periodicity and size at sexual maturity for S. sutor, artisanalfishery catches were sampled during 11 of 13 months between March 2009 and March 2010,inclusive (catches were not sampled in May and December 2009), at a coastal landing site inMsambweni, southern Kenya. Sampling was stratified based on reported reproductive (November-March) and non-reproductive periods (Ntiba and Jaccarini 1988), with 5 days sampled eachmonth during the spawning season and 3 days sampled each month for the remainder of theyear. Sampling trips focused on new moon periods, but included other lunar phases during onecycle from November to December 2010 in order to estimate lunar periodicity in spawning.Females were preferentially sampled as ovarian development is more reliable for detailing spawningperiodicity than testicular development (West 1990).Fish were sampled for total length (TL, to the nearest mm; from snout to tip of longest lobe ofcaudal fin) and wet weight (nearest 0.1 g), and gonads were removed and weighed (nearest 0.01 g).To determine lunar periodicity in spawning, a sub-set of samples collected over one complete lunarcycle was evaluated microscopically and gonad maturity stage assessed using a developmental scaleranging from immature to spent (Table 1). To document lunar periodicity and confirm seasonalperiodicity, gonadosomatic index (GSI) for females was estimated using the following formula:GSI = weight of ovary (g) / (weight of fish (g) - weight of ovary (g)) x 100.For histological preparations, sampled gonads were preserved in a 10% formalin solution, bufferedwith acetic acid and calcium chloride (FAACC). Microscopic staging was based on standardtechniques (Ntiba and Jaccarini 1990; West 1990; Samoilys and Roelofs 2000). An automatictissue processor (Leica TP 1020, Wetzlar, Germany) was used to process haematoxylin/eosinstainedtissue samples which were then sectioned at 5-7 µm. Reading of slides was done by twoobservers using Table 1 criteria.The size at sexual maturity (L m50) was defined as the size at which 50% of females were reproductivelyactive during the main spawning periods. This parameter was estimated by fitting a logistic curve,using the least square method, to the proportion of macroscopically mature individuals by size class(see Kolding and Skaalevik 2010). This method, termed effective maturity, recognises that, despitematurity, not all females are reproductively active in the spawning season (Pears et al. 2006) andalso minimises errors in assigning immature fish as inactive females (Samoilys and Roelofs 2000).Gonads that were undetermined in terms of maturity stage were excluded from this assessment.28
Table 1. Macro-and microscopic criteria of female gonadal development (modified from de Souza 1988; Ntiba andJaccarini 1990; Samoilys and Roelofs 2000; West 1990).Development stageMicroscopic oocytestageMicroscopic: othercriteriaMacro-stage descriptionMacrostagenoImmature, IMPre-vitellogenicoocytes:Oogonia, chromatinnucleus, early perinucleolusstains darkly,late perinucleolusstains faintly, oocytesirregularly shapedwith no defined cellmembraneNo sign of priorspawning: Thingonad wall, compact,lamellae wellpacked, no cytoplasmicvacuolesGonads thin and threadlike,running longitudinally alongdorsal wall of the body cavity,sex indeterminateIResting, REPre-vitellogenicoocytes(as above):Residual atreticoocytes present, cytoplasmicvacuolesThick wall, lamellaenot compact, oftenvacuolated, fewrounded oocytesbrown bodiesOvaries are cylindrical andpinkish tapering graduallytoward posterior end, and occupyhalf the body cavityIIMature, RIVitellogenic oocytes:Yolk vesicle, early andlate yolk globule, migratorynucleus stageMay have atreticoocytes, may havepost- ovulatory follicles(POFs) fromprevious spawningOvaries are opaque andyellowish with some large oocytesclearly visible; Ovariesfully swollen with oocytesclearly visible, heavy networkof blood vessels appears onthe surface of ovary wallIIIIVRunning ripe, RRHydrated oocyte, yolkgranules in the cytoplasm,defined striatedcell membraneFinal stage of oocytedevelopment leadingto egg release.Ovulation results inruptured or emptyPOFsOvaries are very soft andswollen: translucent and fullof water; slight pressure onabdomen produces eggs atthe vent, yellowish in colourdue to large yellow oocytes,blood vessels coalesce to formlarge ones on the external ofovary wallVSpent, SPAtretic vitellogenicoocytes, pre-vitellogenicoocytes, densenetwork of bloodvesselsLamellae disruptedand remnant latestageoocytes andprominent musclebundles presentOvaries are small, flaccid,wrinkled and very red withloose follicular tissueVIResultsA total of 376 samples were collected over 12 months, including 85 that were collected over fourlunar phases in November and December 2010. Excluded from the analysis were 177 individualsthat were either immature or of undetermined sex. The highest GSI was observed in Novemberwhile the lowest values occurred in April, August and September, based on the Mar 2009-Mar2010 new moon dataset (Fig. 2a). Monthly GSI showed two distinct peaks, one in June and Julyand one in November and January, suggesting two distinct peak spawning periods within the year.These peaks, particularly the latter one, corresponded with high numbers of running ripe and spentovaries in the samples (Figure 2b).29
Page 4: The designation of geographical ent
Page 9: Chapter 1: IntroductionJan Robinson
Page 12 and 13: limited, subsistence levels of expl
Page 14: NTRs for spawning aggregations usin
Page 17 and 18: al. 2003). Verification may include
Page 19 and 20: a fraction of spawning sites are pr
Page 21 and 22: Chapter 3: Targeted fishing of the
Page 23 and 24: verifying spawning aggregations, we
Page 25 and 26: ecorded from inshore close to the c
Page 27 and 28: (a)(b)Fig. 3. Spatial patterns ofca
Page 30 and 31: pooled sizes of the three spawning
Page 32 and 33: found S. sutor contributed up to 44
Page 34 and 35: 2011b). However, observations of fi
Page 38 and 39: 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
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TL. All fish tagged were considered
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Lunar timing of arrivals and depart
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Fig. 8. The presence and absence of
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aggregation fishing. This critical
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Chapter 9: Persistence of grouper (
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ResultsBetween 2003 and 2006, the c
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Fig. 2. Mean (± standard error, SE
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A few species (e.g. Epinephelus gut
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(a)(b)Fig. 1. Map of (a) study site
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Fig. 2. Number of E. lanceolatus ob
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was having any impact on the popula
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A spawning aggregation is said to o
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Chapter 11: Evaluation of an indica
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Table 1 Aggregation fisheries asses
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the lists of Jennings et al. (1999)
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with the more vulnerable labrids an
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The remaining serranid populations
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Spawning aggregation behaviour is c
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tiger grouper, Mycteroperca tigris:
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of protecting the normal residence
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• Since grouper males are afforde
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Fig. 2 Yield-per-recruit normalized
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The approaches identified above are
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during full moon periods. Siganus s
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model, many parameter estimates are
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ReferencesAbunge C (2011) Managing
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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
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