Mini-Symposium 22: Coral reef Associated Fisheries

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Jul 21, 2003 - Are the Coral Reef Finfish Fisheries of South Florida ...... Sciences and Applied Technology, Mariano Marcos State University, Currimao 2903,.
PROCEEDINGS OF THE

Mini-Symposium 22: Coral reef Associated Fisheries

Convened and edited by:

T.R. McClanahan, N.V.C. Polunin, N.A.J. Graham, M.A. MacNeil

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Proceedings of the 11th International Coral Reef Symposium, Ft. Lauderdale, Florida, 7-11 July 2008 Session Number 22

Are the Coral Reef Finfish Fisheries of South Florida Sustainable? J.S. Ault, S.G. Smith, and J.T. Tilmant* University of Miami, Rosenstiel School of Marine and Atmospheric Science, 4600 Rickenbacker Causeway, Miami, Florida 33149 USA *National Park Service, Natural Resources Program Center, Water Resources Division, 1201 Oakridge Drive, Suite 250, Fort Collins, Colorado 80525 USA Abstract. We used population abundance and size structure data from fishery-independent (visual census) and fishery-dependent (creel surveys) monitoring programs from the Florida Keys and Biscayne National Park to estimate stock mortality rates and current reproductive potentials of the seven most commonly harvested reef fishes. Numerous indicators revealed these reef fishes are currently experiencing unsustainable rates of exploitation. Annual growth in recreational fishing effort compounds this problem. If healthy reefs are Florida’s future, exploitation of reef fish stocks must be reduced. Fishery management actions were evaluated that could possibly reduce fishing mortality and increase reproduction potential sufficiently to achieve sustainable stock conditions. Results indicated that, when using only traditional management approaches such as increased minimum harvest sizes or decreased bag limits, rather radical changes will be needed to achieve sustainable stock conditions, and any improvements may be negated by continual increases in fishing effort over relatively short time horizons. We conclude that, in addition to traditional fishery management controls, contemporary measures such as placing a portion of the population under spatial protection will likely be needed to achieve long-term sustainability of Florida’s coral reef finfish fisheries.

The Florida Keys coral reef ecosystem, including Biscayne National Park, is inhabited by more than 400 fish species and supports multibillion-dollar fishing and tourism industries. Over recent decades, reef fish populations have declined owing to a variety of human-related stressors, most notably fishing and habitat alterations (Bohnsack and Ault 1996; Ault et al. 1998, 2005a). These fishes are intensively exploited (Ault et al. 1998, 2001, 2005b) by a rapidly growing human population and recreational fishing fleet (Fig. 1). Biscayne National Park (BNP) is in the process of developing plans to guide resource management decisions for the Park over the next 1520 years that will contribute to conservation of fish species and their habitats, and sustain a tradition of quality fishing experiences for generations to come. The strategy for fisheries management is being developed cooperatively by BNP and the Florida Fish and Wildlife Conservation Commission (FWC), with input from members of government agencies, area universities, and the public. Fishery management concerns for reef fishes in south Florida are two-fold: (1) declines in the abundance of fish; and, (2) loss of quality fishing opportunities.

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Florida’s Human Population Size

Introduction

20,000,000

South Florida’s Fishing Fleets

Keywords: Florida, coral reefs, overfishing, sustainable fisheries

250,000

19,000,000+

18,000,000

(A)

16,000,000 14,000,000 12,000,000 10,000,000 8,000,000 6,000,000 4,000,000

WWII/AC Flagler’s Railroad

2,000,000 0

54,477 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2008

200,000

(B)

200,259 (4.41 X)

Commercial

Recreational

150,000 100,000 50,000

37,435 5,316

0 1960

1965

7,363 (+0.42 X)

1970

1975

1980

1985

1990

1995

2000

2005

2010

Figure 1.- Growth of south Florida: (A) human population (18402008); and, (B) fishing fleets (1964-2007).

To mitigate reef fishery declines, the South Atlantic Fishery Management Council in 1983 and the Florida Marine Fishery Commission in 1984 began establishing minimum size, season, and bag limit restrictions on a number of reef fish species. The current size and bag limit regulations for reef fishes in south Florida have been in place since the late 1990s (www.myfwc.com/marine/regulation.htm). However, the most recent assessments suggest that majority of snapper-grouper species are currently

fished at unsustainable levels (Ault et al. 2005b). To assist in the BNP management processes, in this paper we assessed the sustainability of key reef fish stocks in BNP in relation to the Florida Keys, Once exploitation levels were identified, we evaluated potential benefits of more restrictive size and/or bag limits in terms of their efficacy to achieve sustainable populations and meet regional resource management goals. Methods Data Sources.- Two principal data sources were used, fishery-independent and fishery-dependent. Fishery- independent data were visual census surveys of reef fish species abundance and size structure for the Florida Keys ecosystem, including Biscayne National Park, for the period 2000-2004 (Bohnsack et al. 1999; Ault et al. 2001, 2005b). Fishery-dependent data were creel census surveys conducted in BNP for exploited species abundance and size structure for the two time periods, 1995-1998 and 2000-2004 (Ault et al. 2007). Sustainability Analysis.The principal stock assessment indicator variable we used to quantify sustainability status was average length ( L ) of the exploited part of the population, the interval between the minimum size/age of first capture (Lc/ac) and the maximum size/age (Lλ/aλ) observed in the stock. For exploited species, L directly reflects the rate of total instantaneous mortality through alterations of the population size structure (Beverton and Holt 1957; Ehrhardt and Ault 1992; Quinn and Deriso 1999). Estimates of average length were obtained from length composition data derived from the fisheryindependent and -dependent data following the procedure described in Ault et al. (2005b, 2008). Using estimates of L , total instantaneous mortality rate Z was estimated using the method of Ehrhardt and Ault (1992) and an iterative numerical algorithm (computer program LBAR, FAO 2003). Life history parameters for maximum age, growth and maturity for the reef fish species considered are given in Ault et al. (1998, 2005b). Additionally, we evaluated the two major components of Z, namely fishing mortality rate F and natural mortality rate M. In this process, we estimated M from lifespan, and F was estimated by subtracting M from Z (Ault et al. 1998). A numerical cohort-structured model (Ault et al. 1998, 2008) was used to compute several fishery management reference points of stock status, or “sustainability benchmarks”, including yield-perrecruit (YPR), spawning potential ratio (SPR), and limit control rules. Spawning potential ratio (SPR) is a management benchmark that measures a stock’s potential to produce yields on a sustainable basis, and

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is computed as the ratio of current SSB relative to that of an unexploited stock. Benchmarks used to evaluate sustainable exploitation as a limit control rule were: Fmsy (F generating maximum sustainable yield, MSY); Bmsy (population biomass at MSY); and SPR (spawning potential ratio). We defined F = M as a proxy for Fmsy (Quinn and Deriso 1999). Bag & Size Limit Analysis.- We used the BNP creel census data to facilitate evaluation of bag limits. Catch and effort data were computed in terms of landings per angler-trip (i.e., number of fish landed and kept per person-trip). Current bag limits were evaluated in terms of percentages of trips that caught more than specific amounts of fish per person. To evaluate potential gains in population benchmarks through increases in the minimum size of first capture, we conducted a “eumetric” fishing analysis (inter alia Beverton and Holt, 1957) for each key reef fish species. This analysis identifies the optimum combination of minimum size of first capture Lc given a particular fishing mortality rate F that results in maximal yields in weight and/or numbers of fish. Results Estimates of L from BNP creel data for seven principal exploited reef fishes were consistent between the 1995-1998 and 2000-2004 time periods (Table 1). The estimates of L from the latter time period were consistent between the BNP creel and Florida Keys visual census (Fig. 2). A substantial proportion of fishes observed in the creel census were smaller than the minimum legal size (Table 1). These undersized fish were not included in the computation of L . These data, together with the known life history parameters for each of these species, were then used to calculate estimates of current fishing mortality rates, stock biomass, SPR and YPR for each of the key reef fish species. Values of the F/Fmsy ratio plotted against the B/Bmsy ratio (Fig. 3) suggest all seven species are being subjected to unsustainable rates of exploitation (F-ratio >1, B-ratio 0 fish 1.4 5.2 5.5 18.7 15.3 81.7 18.9

≥1 fish 0.4 0.9 1.7 10.1 8.6 60.4 14.1

≥2 fish 0.0 0.4 0.3 5.1 5.2 36.7 9.3

≥5 fish 0.0 0.1 0.1 0.3 1.7 9.5 3.2

≥10 fish 0.0 0.0 0.0 0.0 0.4 0.0 0.6

Table 3.- Comparison of the estimated spawning potential ratio (SPR) at the current legal minimum size with the projected SPR at the minimum size corresponding to a eumetric fishing strategy for seven reef fish species. Also given are maximum age (aλ), age at sexual maturity (am), and age at minimum capture size (ac).

Species Black grouper Red grouper Mutton snapper Gray snapper Yellowtail snapper Hogfish White grunt

aλ (y) 33 29 29 28 14 23 18

am (y) 5.2 4.3 2.0 2.0 1.3 0.8 1.6

Current min Size (mm FL) 610 508 406 254 254 305 170

ac (y) 3.4 5.4 3.7 2.3 2.4 3.3 1.5

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SPR (%) 0.8 17.7 8.4 3.1 14.1 6.7 4.9

Eumetric min Size (mm FL) 1078 648 703 545 292 569 378

ac (y) 10.0 8.8 10.0 9.5 4.3 10.5 6.5

SPR (%) 31.2 35.7 38.0 35.4 46.5 44.2 39.4

Proceedings of the 11th International Coral Reef Symposium, Ft. Lauderdale, Florida, 7-11 July 2008 Session number 22

Reproductive classification and spawning seasonality of Epinephelus striatus (Nassau grouper), E. guttatus (red hind) and Mycteroperca venenosa (yellowfin grouper) from The Bahamas N. Cushion1, M. Cook2, J. Schull3, K.M. Sullivan-Sealey1,4 1

University of Miami, Coral Gables, Fl, 33124 NOAA Fisheries Service, Panama City Laboratory, 3500 Delwood Beach Rd., Panama City, FL 32408 3 NOAA Fisheries/Southeast Fisheries Science Center, 75 Virginia Beach Drive, Miami, FL 33149 4 The College of The Bahamas, Marine Environmental Studies Institute, Nassau, Bahamas

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Abstract. Fish of the family Serranidae: subfamily Epinephelinae are some of the most heavily harvested reef fish in the Caribbean. However, large knowledge gaps exist about their reproductive biology. Understanding a species’ reproductive biology is critical for species management and provides evolutionary insight into speciesspecific reproductive strategies. Epinephelinae species possess a diversity of reproductive strategies, comprised of life-history traits which are highly variable between and amongst populations (e.g. size at sexual maturity, spawning duration, sex ratio). For this study, a reproductive histological classification system was refined for application to Bahamian fish populations of: Epinephelus striatus (Nassau grouper), E. guttatus (red hind) and Mycteroperca venenosa (yellowfin grouper). The use of a single classification system on multiple species provided a reliable framework to assess the status of reproductive life-history traits. Spawning seasonality in The Bahamas was described for populations of E. striatus, E. guttatus and M. venenosa. Spawning for E. striatus peaked November through January, while E. guttatus peaked in January and M. venenosa peak in March and April. The classification system will be used to establish consistent monitoring techniques and the results provide information for future management efforts in The Bahamas and allow for comparison to populations throughout the Caribbean. Key words: Nassau grouper, red hind, yellowfin grouper, reproductive biology, gonad histology classification Introduction The reproductive biology of a fish is defined both by the combination of the species-specific reproductive mode and reproductive traits (Winemiller and Rose 1992, Murua and Saborido-Rey 2003, Morgan 2008). The reproductive mode does not vary between populations and is defined by the combination of the sexual development pattern (e.g. gonochoristic or hermaphroditic) and the gamete production system (e.g. determinate or indeterminate). Reproductive lifehistory traits (e.g. spawning seasonality and duration, age or size of sexual maturity, and sex ratio) vary between and amongst populations (Winemiller and Rose 1992, Murua and Saborido-Rey 2003, Morgan 2008). All are critical to understand a given population because they provide insight into how different strategies influence gamete production (Winemiller and Rose 1992) and how life-history trait plasticity can greatly alter a population’s productivity or reproductive potential over time (Winemiller and Rose 1992, Morgan 2008). Histological analysis of gonads provides more accurate and specific information to quantify life-

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history traits than traditional, macroscopic gonad examinations. Balon (1975) and Winemiller and Rose (1992) established that a classification system should also allow for intra-species comparisons for ecosystem based management and evolutionary life history comparison purposes. The use of a single histological classification system on multiple species provides a means to assess the reproductive biology of species that possess different reproductive strategies with variable life-history traits, and allows for comparisons between species. Species of the family Serranidae: subfamily Epinephelinae (commonly called groupers and hinds) are heavily fished in the Caribbean. Despite their importance, large knowledge gaps exist about their reproductive biology. As with most marine fish, species-specific data is required for Epinephelinae because reproductive life-history traits are variable both within and between species (Sadovy 1996). In The Bahamas, fishery management and monitoring initiatives are focusing on securing consistent reproductive biology and landing data for commercially valuable Epinephelinae species.

Epinephelinae landings, especially Epinephelus striatus (Nassau grouper), and to a lesser, but considerable extent E. guttatus (red hind), and Mycteroperca venenosa (yellowfin grouper) constitute a major portion of fin-fish catches in The Bahamas (Cushion and Sealey 2007). To date, some reproductive life-history studies have been completed on E. striatus in The Bahamas (see Sadovy and Eklund 1999 for a review); while no formal studies on E. guttatus and M. venenosa have been conducted in The Bahamas. This paper describes the effectiveness of a histology classification system for quantifying reproductive life-history traits and identifying the reproductive maturity stage of Epinephelinae species. The goal was to affirm that the proper criteria and diagnostics were incorporated into the system, so it could be applied to multiple Epinephelinae species that possess different reproductive strategies. The system was then used to determine the spawning seasonality for E. guttatus, E. striatus, and M. venenosa harvested in the central Bahamas. The classification system will form the basis for consistent long-term monitoring initiatives in The Bahamas and provide a means to evaluate temporal and spatial differences in Epinephelinae reproductive life-history traits that influence reproductive potential. Material and Methods A fishery-dependent monitoring project commenced in January 2007 at a major commercial fish market in New Providence (the most populated island), Nassau, Bahamas to acquire Epinephelinae landings, population, and reproductive biology data (Cushion and Sealey 2007). Data was obtained via monthly monitoring corresponding with the full moon phase (the spawning period of many Epinephelinae). A standard histological classification system was incorporated into the project to evaluate, compare and monitor reproductive traits among Epinephelinae species. Monthly sampling was conducted at the market from January 2007-April 2008. Length, weight and gonad weight were measured and recorded for each fish. A section of each gonad was collected and preserved in 10% neutral buffered formalin. Gonad sections were later imbedded in paraffin, sectioned and stained using hemotoxylin and eosin following standard histological procedures (Fitzhugh et al. 1993). Gonad homogeneity tests to confirm that a subsample was representative of the entire gonad were previously performed for each species by Sadovy and Colin (1995) (E. striatus), Sadovy et al. (1994) (E. guttatus), and García-Cagide and Garcia (1996) (M. venenosa).

The reproductive biology classification system was adopted (with minor changes) from Lyon et al. (2008). Lyon et al. (2008) outlined a classification system based on previous studies including Moe (1969) and (Brown-Peterson et al. 2006). This system was adopted to classify Epinephelinae species for this study. Minor revisions were made to account for many Epinephelinae being protogynous species (thus having transitional gonads) and the common occurrence of “bisexual” gonads that contain both oogenic and spermatogenic tissue, but for which primary function as either male or female cannot be determined (Sadovy and Shapiro 1987). Female and male fish were classified using diagnostic features to determine sexual maturity, the leading gamete stage (the most advanced oocyte or spermatogenic stage present), and whether oocytes were recently released (Table 1 a and b). The presence of vitellogenic oocytes indicates spawning will occur within days or weeks. Female spawning indicators are advanced vitellogenic oocytes (lipid and yolk coalescence) that represent the initiation of spawning and fully hydrated oocytes that are indicative of actively spawning fish. Recently spawned females were detected by the presence of post-ovulatory follicles. The end of the spawning season was determined by massive cell atresia (indeterminant spawners) or the lack of vitellogenic oocytes (determinate spawners). Male sexual maturity was indicated by initiation of spermatogenesis and formation of spermatocysts. Males are classified as spawning capable when spermatozoa were evident and filling sperm ducts and lobules. Fish were classified as transitional if degenerating oogenic and proliferating spermatogenic tissue were present (Sadovy and Shapiro 1987). Fish were classified as bisexual if fairly equal amounts of oogenic and spermatogenic tissues were present, but no sexual function was determined (Sadovy and Colin 1995). All histological slides for each species were analyzed and classified by two readers. Results were used to determine reproductive class. Also, the percentage of samples in each class was determined monthly and used to estimate the spawning seasonality for each focal species. Months were designated as spawning months if over 50% of the female samples for the month were classified as active or spawning and over 50% of the male samples were classified as spawning capable. Results The histological classification scheme modified and utilized for this study provided the appropriate criteria (Table 1) for designation of 96% of gonad samples

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Sex

Table 1. A histological reproductive classification system and diagnostics for female, transitional, bisexual and male Epinephelinae. Class

Bisexual Transitional

Female

Immature, inactive

PG

Primary growth oocytes only, no evidence of prior spawning. Chromatin nucleolus stage (small cells with large nucleus), and initial perinucleolar stage (larger oocytes). Well-organized gonad. Not capable of spawning in distant future & prior spawning unclear.

Developing virgin, Developing

Cortical alveolar oocytes present. Prior spawning indicators confirm maturity (D). No spawning indicators (Dv).

Active, mature

Vitellogenic oocytes present, spawn within days or weeks.

Spawning, hydrated

Early or late hydrated oocytes or postovulatory follicles present.

Postovulatory, spent Regressed, inactive, mature. Regressed, skipped, mature.

End of spawning cycle, majority of oocytes (>50%) experiencing atresia. Post-ovulatory follicles may be present.

will

PG oocytes only, evidence of sexual maturity & recent spawn. Sexually mature but will not spawn in current season, development ended prematurely.

Sperm crypts proliferating throughout gonad. Gamete stages from primary spermatocyte through spermatid should be present. Remnant oocytes possibly undergoing atresia. Must possess evidence of degenerating oogenic and proliferating spermatogenic tissue. (Protogynous species only). Oogenic and spermatogenic tissues present, but neither is dominant or proliferating. No sexual function can be determined.

Developing virgin (only gonorchoristic species) Developing Spawning capable

Spent

Male

Diagnostics

Inactive, uncertain

Immature, inactive

Regressed, inactive, mature

CA

Includes males with spermatogonia (SGG) and no evidence of spermatogenesis (SG). Spermatogenesis begins; spermatocytes present & no prior indicators of maturity (Dv). Initiation of spermatogenesis and formation of spermatocysts (D). Fish is reproductively active and capable of spawning. All stages of spermatogenesis may be present. Spermatogenesis is ceasing. Some residual spermatozoa present Spermatogonia proliferation and regeneration of germinal epithelium common in periphery of testis. Spermatogonia dominate; no active spermatogenesis. Continuous germinal epithelium throughout.

Immature, inactive MV TL 457mm 19-Mar-08

Developing/virgin EG TL304mm 23-Oct-07

LH

VT

Active Mature ES TL654mm 10-Dec-00

ATS

Post-Ovulatory, Spent ES TL655mm 9-Jan-01

Spawning, Hydrated EG TL278mm 25-Jan-08

PG

Regressed, inactive MV TL762mm 23-Oct-07

PG/SGG PG/SGG

Transitional MV TL762mm 23-Oct-07

Bisexual (no function) ES TL635mm 24-Oct-07

Figure 1a: Epinephelinae histological reproductive classification system for females, bisexual and transitional fish. Reproductive classes, diagnostic features, size and sample collection date are highlighted for female E. striatus (ES), E. guttatus (EG) and M. venenosa (MV). Primary growth (PG), cortical alveolar (CA), vitellogenic oocytes (VT), late hydrated (LH) and atresia (ATS) are highlighted.

(n=675) into a class (Fig. 1 a and b), all species combined. The results of this study corroborate previous reproductive biology studies on the focal species. Gamete production in E. striatus is indeterminate and the species is functionally gonochoristic (Sadovy and Colin 1995). E. guttatus is a protogynous hermaphrodite with determinate gamete production (Shapiro et al. 1993); while M. venenosa is a protogynous hermaphrodite with indeterminate gamete production (García-Cagide and Garcia 1996). E. striatus samples were typically the most challenging to classify due to ~12% (26 out of 220) of all samples containing both inactive oogenic and spermatogenic tissue. The domination of oogenic or spermatigenic tissue was used to classify these fish, but 4% were classified as “bisexual” because no

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SGG

to be slightly later. Over 50% of the male and female samples collected during two sampling periods in March 2007 (one at the beginning and one at the end of the month, following the full moon schedule), and March and April 2008 (n=12, 28, 28 and 34, respectively) were in spawning condition. Additionally, 45% of the February samples were in spawning condition.

SC

Immature, inactive ES TL546mm 24-Oct-07

Developing/virgin EG TL684mm 27-Nov-07

SG SG Spawning capable MV TL889mm 31-Mar-07

Regressed, inactive, mature EG TL330mm 30-Jun-07

Figure 1b: Epinephelinae histological reproductive classification system for male fish. Reproductive classes, diagnostic features, size and sample collection date are highlighted for transitional, bisexual and male E. striatus (ES), E. guttatus (EG) and M. venenosa (MV). Spermatogonia (SGG), spermatogenesis (SG), and spermatocytes (SC) are highlighted. (Spent male not pictured.) Table 2. Spawning seasonality for Bahamian Nassau grouper (E. striatus), Red hind (E. guttatus) and Yellowfin grouper (M. venenosa). Samples collected from January 2007- April 2008 in New Providence, corresponding to the full moon cycle. Spawning months were designated as so if over 50% of the female samples were classified as “Active” or “Spawning hydrated” and over 50% of the male samples were classified as “Spawning capable” (Table 1). Spawning Years/ Months Species (Sample number in parentheses). November 2007 (21) E. striatus January and February 2008 (27 and 23) February 2007 (17) E. guttatus January and February 2008 (22 and 30) M. venenosa

March 2007* (12 and 28) March and April 2008 (28 and 34)

*Two sampling periods: one at the beginning and one at the end of the month, following the full moon schedule.

sexual function could be determined. Also, eleven E. striatus samples (5%) were classified as “inactive, uncertain”. For E. guttatus 12 out of the 200 hundred samples (6%) were classified as “inactive, uncertain”. For M. venenosa, 15 out of the 175 samples (9%) were classified as “inactive, uncertain”. For all species, the majority of samples classified “inactive, uncertain” were from the summer, non-spawning months. Spawning seasonality for the three focal species was analyzed (Table 2). Over 50% of the male and female E. striatus samples in November 2007, January and February 2008 were in spawning condition (n=21, 27 and 23, respectively) (no samples were obtained in December 2007). For E. guttatus, over 50% of the male and female samples collected in February 2007, January and February 2008 were in spawning condition (n=17, 22 and 30, respectively). M. venenosa samples revealed their spawning season

Discussion The high percentage of classification for each focal species highlights the cross-utility of the classification system. The system allows for the requisite reproductive biology information to be quantified for Epinephelinae species in the Bahamas. The confirmation E. striatus as functionally gonochoristic was supported by the overlap of males and females in all size classes. This is unlike protogynous E. guttatus and M. venenosa, in that no males were found in the relatively smaller size classes and no females were found after a certain size (unpublished data). The percentage of E. striatus that were classified as bisexual, with no sexual function being determined was not unusual. Sadovy and Colin (1995) investigated the sexual development pattern of E. striatus and found four mature bisexual individuals and 23% of all samples were immature bisexuals. The classification of 4% of E. striatus, 6% of E. guttatus and 9% of M. venenosa as inactive, uncertain was also not uncommon. These samples were primarily from summer months when fish are not spawning. Inactive and regressed fish are the main classes during this time period and both are typified by compact gonads with primary growth oocytes. Thus, without sufficient evidence of prior spawning (e.g. old hydrated oocytes) it is not possible to confirm regression. Shapiro et al. (1993) investigated sex change and reproduction in E. guttatus and could not distinguish between inactive and late, regressed females. Spawning seasonality for many Epinephelinae and other reef fish is a variable reproductive trait (within and between populations), especially for populations at different latitudes (Sadovy 1996). Spawning seasonality has previously been determined for E. striatus in the Bahamas. Colin (1992) found that the E. striatus populations off Long Island spawned during the full moon periods of December and January, possibly not during November and likely not during February. This study highlights that E. striatus spawning seasonality is slightly variable within the Bahamas. Spawning began in November 2007 and continued through February 2008. However, for E. striatus, spawning seasonality is strongly correlated with the lunar full moon as well as temperature, not the month per se (Sadovy and Eklund 1999). Colin

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(1992) found E. striatus spawning occurred at water temperatures between 25.0-25.5°C. Thus, water temperature is likely a strong contributing factor for latitudinal and annual fluctuations in spawning seasonality. This is the first documentation of spawning seasonality for E. guttatus and M. venenosa in The Bahamas. Shapiro et al. (1993) found a similar spawning seasonality for Puerto Rican E. guttatus populations. Using a gonadal size index and histology, spawning peaks were found in January and February. Meanwhile, E. guttatus spawning peaks much later in Bermuda occurring during the full moon periods from May to July (Luckhurst et al. 2004). It is noteworthy that E. guttatus spawning seasonality is not as tightly correlated to the full moon (Sadovy et al. 1994), as with E. striatus and M. venenosa. Thus the monthly, full-moon sampling regime did not likely capture all E. guttatus spawning activity in the Bahamas. Small groups of M. venenosa are often associated with aggregations of E. striatus (e.g. Whaylen et al. 2004 (Cayman Islands), Nemeth et al. 2004 (USVI)). However, January and February are not the dominant spawning times for M. venenosa. Personal communications with fishermen in this study, in conjunction with gonad sampling, confirmed full moon periods during March and April as peak spawning months of M. venenosa in The Bahamas. A large proportion of the specimens were spawning capable in February, thus indicating the spawning period may commence in February. In Cuba, GarcíaCagide and Garcia (1996) found April and May to be the strongest spawning months for M. venenosa which is consistent with later spawning at more southerly latitudes. Because reef fisheries in The Bahamas are multispecies, it is important to implement a system that can be applied to multiple species to ensure that consistent and reliable information is obtained. The fisherydependent sampling protocol with a standard reproductive classification allowed for the collection and analysis of samples year round. This combination system will provide a means for long-term monitoring of Epinephelinae species to consistently assess reproductive life-history traits and the reproductive potential of populations. Acknowledgements Funding for this project came from the University of Miami Department of Biology, The College of The Bahamas Marine and Environmental Studies Programme, Disney Wildlife Conservation Fund and Earthwatch Institute. Thanks to the fishermen and people at Montagu ramp and to Anastasia Gibson and the Department of Marine Resources staff for field assistance.

References Balon EK (1975) Reproductive guilds of fishes: a proposal and definition. J Fish Res Board Can 32: 821-864. Brown-Peterson N, Lowerre-Barbieri S, Macewicz B, SaboridoRey F, Tomkiewicz J, Wyanski,D (2008) An Improved and Simplified Terminology for Reproductive Classification in Fishes. www.usm.edu/gcrl/research/gonadal_terminology.php Colin, PL (1992) Reproduction of the Nassau grouper, E.striatus Pisces:Serranidae and relationship to environmental conditions. Environ Biol Fish 34: 357–377. Cushion ,N, Sullivan-Sealey,K (2007) Landings, effort and socioeconomics of a small scale commercial fishery in The Bahamas. Proc. 60th Gulf Carib Fish Inst Conference.p. 162166. Fitzhugh,GR, Thompson,B, Snider III,T (1993) Ovarian development, fecundity, and spawning frequency of black drum Pogonias cromis in Louisiana. Fish Bull, U.S.91:244253. García-Cagide A, Garcia, T (1996) Reproduction of M. venenosa y M. bonaci (Pisces: Serranidae) en la plataforma cubana. Revta Biol Tropical 44:2: 771-80. Luckhurst B., Hately J., Trott T. (2004) Estimation of the size of spawning aggregations of red hind (E. guttatus) using a tagrecapture method at Bermuda. Proc. 57thGCFI p.535-42. Lyon H, Duncan M, Collins A, Cook M, Fitzhugh G, Fioramonti C (2008) Chapter 9, Histological classification for gonads of gonochoristic and hermaphroditic fishes. In: LombardiCarlson L, Fioramonti C, Cook M, (eds). Procedural Manual for Age, Growth, and Reproductive Lab, 3rd ed. Panama City Laboratory Contribution 08-15: 1-18. Moe MJ (1969) Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulf of Mexico. Professional Paper Series Number Ten, Florida Dept. Nat. Resources Mar. Res. Lab., St. Petersburg. 94 pp. Morgan J (2008) Integrating Reproductive Biology into Scientific Advice for Fisheries Management. J. NW Atlantic Fish. Sci., 41: 37–51. Murua,H, Saborido-Rey,F (2003). Female Reproductive Strategies of Marine Fish Species of the North Atlantic. J. of NWAtl Fish. 33: 23-31. Nemeth R, Kadison E, Herzlieb S,Blondeau J,Whiteman E (2004) Status of yellowfin (M. venenosa) grouper spawning aggregation in the USVI. Proc. 57th GCFI. 543-558. Sadovy Y, Shapiro DY (1987) Criteria for diagnosis of hermaphroditism in fishes. Copeia 1, 136–156. Sadovy Y, Rosario A,Román A (1994) Reproduction in an aggregatinggrouper, red hind, E. guttatus. 41: 269-86. Sadovy Y, ,Colin P (1995) Sexual development and sexuality in Nassau grouper. J Fish Biology 46:961-76. Sadovy Y (1996) Reproduction of reef fishery species In:. Polunin NVC, Roberts CM (eds)Reef Fisheries, Chapman and Hall. pp.15–59. Sadovy Y,,Eklund A-M. 1999. Synopsis of biological information on Epinephelus striatus Bloch, 1972, the Nassau grouper, and E.itajara Lichtenstein, 1822 the jewfish. U.S. Department of Commerce, NOAA Technical Report NMFS 146, and FAO Fisheries. Shapiro D, Sadovy Y, McGehee M (1993) Periodicity of sex change and reproduction of the red hind, E. guttatus, a protogynous grouper. Bull Mar Sci.53(3):1150-1162. Winemiller K, Rose K (1992) Patterns of life-history Diversification in North American fishes: implications for population regulation.Can J Fish Aquat. Sci 49:2196-2218. Whaylen L, Pattengill-Semmens C, Semens B, Bush P, Boardman M (2004) Observations of a Nassau grouper, E. striatus, spawning aggregation site in Little Cayman, Cayman Islands, including multi-species spawning information. Environ Biol Fish 70:305–313.

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Proceedings of the 11th International Coral Reef Symposium, Ft. Lauderdale, Florida, 7-11 July 2008 Session number 22

Spatio-temporal patterns of juvenile and adult abundance and biomass of reef fishes in the Sulu Sea, Philippines M.R. Deocadez1, E.P. Moleño2, H.O. Arceo3, J.P. Cabansag4, J.L. Apurado5, S.S. Mamauag1, C.L. Villanoy1 and P.M. Aliño1 1) Marine Science Institute, University of the Philippines, Diliman, Quezon City 2) Mindanao State University @ Naawan, Naawan, Misamis Oriental, Philippines 3) DAI USAID Philippine Environmental Governance 2 Project, Philippines 4) University of the Philippines-Tacloban, Tacloban City, Philippines 5) San Carlos University, Cebu City, Philippines Abstract: Underwater fish visual census was undertaken to determine juvenile and adult abundance and biomass of commonly occurring reef fish taxa/species at several sites along the major marine corridors in the Sulu Sea. Presence/absence, abundance, and biomass of taxa/species in both stages showed varying patterns within and among sites. Variation in adult abundance and biomass of some species suggests decreasing similarities with increasing distance at some sites while other species showed contrasting patterns with distant sites exhibiting similarities. For juvenile abundance, patterns were similar with those of the adults. Significant correlation between juvenile and adult abundance was observed at some sites. The match and mismatch of spatial patterns of distribution of adults and juveniles of reef-associated fishes are influenced by two major factors. Local water circulation patterns at the different corridors, which potentially disperse egg and larvae within and between corridors shows changing connectivity potential of fish populations. Relatively high species diversity of juvenile and adult fish was observed in areas of high entrainment. On the other hand, disturbance and stresses such as over-fishing and habitat degradation will increase mortality in fish populations at varying stages of their life history and, therefore, reduces the connectivity potential in a range of spatial scales in the Sulu Seascape. Keywords: reef fish abundance and biomass, entrainment and habitat degradation, spatial and temporal patterns Introduction The marine corridors in the Sulu Sea have been proposed to be strategic marine priority conservation areas that help provide the resiliency in the Sulu Sea (Ong et al. 2002). These areas are found at the heart of the Coral Triangle, which has been recognized as the center of highest marine biodiversity (Carpenter and Springer 2005). Regular monitoring of adult and juvenile reef fish abundances serve as crucial proxies to reef conditions and help understand the major determinants of the population structure of coral reef fishes (Booth and Beretta, 2004). Observations of the changes in reef benthos and community structure of associated fish dovetail with other factors such as hydrography (Cowen 2002) and larval biology (Leis and McCormick 2002) to fully understand the connectivity of reef populations (Cowen et al. 2006). This study presents the dynamics of the reef fish community structure in the marine corridors of the Sulu Sea. Materials and Methods

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A total of 44 transects from five municipality sites covering the three marine corridors in the Sulu Sea were sampled (Mabini and Verde in the Verde Island Passage; Balabac in the Balabac Strait; Cagayancillo and Tubbataha reefs in the Cagayan Ridge) (Fig.1). Survey months were made during the transition periods of the Northeast monsoon (October 2006) and Southwest monsoon (April-May 2006 and 2007). Fish Visual Census (FVC) was used to determine fish assemblages and abundance of adults and juveniles (English et al. 1997). Fish were identified if possible at the species level, their numbers and sizes estimated within an area of 500m2 (adult) and 50m2 (juvenile) per transect. Multivariate analyses of spatial pattern of adult and juvenile fish correlation with forcing factors were performed using the ordination technique, non-metric Multidimensional Scaling (nMDS). In addition, Analysis of Similarities (ANOSIM) was carried out to determine significance of generated patterns (PRIMER 6 ver. 6.1.6). This approach examines factors that influence the spatial and temporal patterns

of the reef associated fish communities. From the patterns we can infer insights that will facilitate marine biodiversity conservation measures to reduce the threats on reef health and help in the design of MPA networks.

Figure 1. Map of study sites within the three major marine corridors (i.e., Verde Island Passage, Balabac Strait and Cagayan Ridge includes Tubbataha and Cagayancillo.

Results Adult abundance and biomass Presence/absence, abundance and biomass of taxa/species at adult stages showed varying patterns within and among the municipality sites in the three corridors. Non-metric MDS analysis for abundance showed clear patterns only in between-site category (Fig. 2a). For biomass, ordination analysis provided similar patterns as with abundance. Analysis of Similarity (ANOSIM) of abundance and biomass revealed that factor Site (municipality) was more important than Time (season) (Table 1) suggesting that site-specific attributes are more important forcing factors upon the fish community structure. Pair-wise comparison for differences in abundance and biomass between municipalities showed large variation between Balabac and Tubbataha (Table 2) especially for the abundances of families Apogonidae, Pomacentridae, Caesionidae Labridae, Lutjanidae, Anthiinae and Acanthuridae. There were more apogonids and labrids (Cheilininae) at Balabac than at Tubbataha but more caesionids, pomacentrids, acanthurids, and lutjanids at the latter than at the former. Between Tubbataha and Mabini/Verde sites, there were more caesionids, acanthurids, lutjanids and serranids at Tubbataha than at Mabini/Verde. Some sites showed increasing similarities with decreasing distance (e.g. adjacent sites Cagayancillo-Tubbataha versus distant sites Cagayancillo-Mabini/Verde) based on the abundances of dominant taxa such as caesionids, acanthurids, lutjanids and serranids. However, distant sites such as Balabac and

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Mabini/Verde also showed similarities based on the abundances of pomacentrids (Acanthochromis polyacanthus) and anthiinids (Pseudanthias huchtii). Following Tubbataha in reef fish biomass is Cagayancillo, Mabini, Verde and Balabac. Consistent peaks were observed for Tubbataha for the three intermonsoon seasons, while Mabini was observed to be highest in October. Palawan sites were recorded with highest biomass in the April-May transition periods. In addition, its relatively isolated location in the Sulu Sea (island mass effect; Hammer and Hairy 1981, AMERCO and Andrews 1989) affords the Cagayancillo reefs the high abundance observed. Temporal pattern in abundance did not differ (April-May 2006 and April-May 2007; R=0.107, p