247 resultados para Coral reef ecology
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The offshore shelf and canyon habitats of the OCNMS are areas of high primary productivity and biodiversity that support extensive groundfish fisheries. Recent acoustic surveys conducted in these waters have indicated the presence of hard-bottom substrates believed to harbor unique deep-sea coral and sponge assemblages. Such fauna are often associated with shallow tropical waters, however an increasing number of studies around the world have recorded them in deeper, cold-water habitats in both northern and southern latitudes. These habitats are of tremendous value as sites of recruitment for commercially important fishes. Yet, ironically, studies have shown how the gear used in offshore demersal fishing, as well as other commercial operations on the seafloor, can cause severe physical disturbances to resident benthic fauna. Due to their exposed structure, slow growth and recruitment rates, and long life spans, deep-sea corals and sponges may be especially vulnerable to such disturbances, requiring very long periods to recover. Potential effects of fishing and other commercial operations in such critical habitats, and the need to define appropriate strategies for the protection of these resources, have been identified as a high-priority management issue for the sanctuary.
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The Southern Florida Shallow-water Coral Ecosystem Mapping Implementation Plan (MIP) discusses the need to produce shallow-water (~0-40 m; 0-22 fm) benthic habitat and bathymetric maps of critical areas in southern Florida and moderate-depth (~40-200 m; 22 -109 fm) bathymetric maps for all of Florida. The ~0-40 m depth regime generally represents where most hermatypic coral species are found and where most direct impacts from pollution and coastal development occur. The plan was developed with extensive input from over 90 representatives of state regulatory and management agencies, federal agencies, universities, and non-governmental organizations involved in the conservation and management of Florida’s coral ecosystems. Southern Florida’s coral ecosystems are extensive. They extend from the Dry Tortugas in the Florida Keys as far north as St Lucie Inlet on the Atlantic Ocean coast and Tarpon Springs on the Gulf of Mexico coast. Using 10 fm (18 m) depth curves on nautical charts as a guide, southern Florida has as much as 84 percent (30,801 sq km) of 36,812 sq km of potential shallow-water (<10 fm; <18 m) coral ecosystems the tropical and subtropical U.S. Moreover, southern Florida’s coral ecosystems contribute greatly to the regional economy. Coral ecosystem-related expenditures generated $4.4 billion in sales, income, and employment and created over 70,000 full-time and part-time jobs in the region during the recent 12-month periods when surveys were conducted.
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Range overlap patterns were observed in a dataset of 10,446 expert-derived marine species distribution maps, including 8,295 coastal fishes, 1,212 invertebrates (crustaceans and molluscs), 820 reef-building corals, 50 seagrasses and 69 mangroves. Distributions of tropical Indo-Pacific shore fishes revealed a concentration of species richness in the northern apex and central region of the Coral Triangle epicenter of marine biodiversity. This pattern was supported by distributions of invertebrates and habitat-forming primary producers. Habitat availability, heterogeneity and sea surface temperatures were highly correlated with species richness across spatial grains ranging from 23,000 to 5,100,000 km2 with and without correction for autocorrelation. The consistent retention of habitat variables in our predictive models supports the area of refuge hypothesis which posits reduced extinction rates in the Coral Triangle. This does not preclude support for a center of origin hypothesis that suggests increased speciation in the region may contribute to species richness. In addition, consistent retention of sea surface temperatures in models suggests that available kinetic energy may also be an important factor in shaping patterns of marine species richness. Kinetic energy may hasten rates of both extinction and speciation. The position of the Indo-Pacific Warm Pool to the east of the Coral Triangle in central Oceania and a pattern of increasing species richness from this region into the central and northern parts of the Coral Triangle suggests peripheral speciation with enhanced survival in the cooler parts of the Coral Triangle that also have highly concentrated available habitat. These results indicate that conservation of habitat availability and heterogeneity is important to reduce extinction and that changes in sea surface temperatures may influence the evolutionary potential of the region.
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Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex), usually by expulsion or xenophagy (symbiophagy) of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C) under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m−2 s−1 PAR) at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response) were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching
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The primary objective of this study was to predict the distribution of mesophotic hard corals in the Au‘au Channel in the Main Hawaiian Islands (MHI). Mesophotic hard corals are light-dependent corals adapted to the low light conditions at approximately 30 to 150 m in depth. Several physical factors potentially influence their spatial distribution, including aragonite saturation, alkalinity, pH, currents, water temperature, hard substrate availability and the availability of light at depth. Mesophotic corals and mesophotic coral ecosystems (MCEs) have increasingly been the subject of scientific study because they are being threatened by a growing number of anthropogenic stressors. They are the focus of this spatial modeling effort because the Hawaiian Islands Humpback Whale National Marine Sanctuary (HIHWNMS) is exploring the expansion of its scope—beyond the protection of the North Pacific Humpback Whale (Megaptera novaeangliae)—to include the conservation and management of these ecosystem components. The present study helps to address this need by examining the distribution of mesophotic corals in the Au‘au Channel region. This area is located between the islands of Maui, Lanai, Molokai and Kahoolawe, and includes parts of the Kealaikahiki, Alalākeiki and Kalohi Channels. It is unique, not only in terms of its geology, but also in terms of its physical oceanography and local weather patterns. Several physical conditions make it an ideal place for mesophotic hard corals, including consistently good water quality and clarity because it is flushed by tidal currents semi-diurnally; it has low amounts of rainfall and sediment run-off from the nearby land; and it is largely protected from seasonally strong wind and wave energy. Combined, these oceanographic and weather conditions create patches of comparatively warm, calm, clear waters that remain relatively stable through time. Freely available Maximum Entropy modeling software (MaxEnt 3.3.3e) was used to create four separate maps of predicted habitat suitability for: (1) all mesophotic hard corals combined, (2) Leptoseris, (3) Montipora and (4) Porites genera. MaxEnt works by analyzing the distribution of environmental variables where species are present, so it can find other areas that meet all of the same environmental constraints. Several steps (Figure 0.1) were required to produce and validate four ensemble predictive models (i.e., models with 10 replicates each). Approximately 2,000 georeferenced records containing information about mesophotic coral occurrence and 34 environmental predictors describing the seafloor’s depth, vertical structure, available light, surface temperature, currents and distance from shoreline at three spatial scales were used to train MaxEnt. Fifty percent of the 1,989 records were randomly chosen and set aside to assess each model replicate’s performance using Receiver Operating Characteristic (ROC), Area Under the Curve (AUC) values. An additional 1,646 records were also randomly chosen and set aside to independently assess the predictive accuracy of the four ensemble models. Suitability thresholds for these models (denoting where corals were predicted to be present/absent) were chosen by finding where the maximum number of correctly predicted presence and absence records intersected on each ROC curve. Permutation importance and jackknife analysis were used to quantify the contribution of each environmental variable to the four ensemble models.
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This report examines the marine biogeography of the Samoan Archipelago (~14º S latitude along the international date-line) with a focus on regional ocean climate, connectivity among islands due to larval transport, distributions of reef fish and coral communities, and the extent of existing marine protected areas. Management decisions and prior assessments in the archipelago have typically been split along the international political boundary between the islands of Samoa and those of American Samoa despite their close proximity and shared resources. A key goal in this assessment was to compile data from both jurisdictions and to conduct the characterization across the entire archipelago. The report builds upon earlier assessments by re-analyzing and interpreting many pre-existing datasets, adding more recent biogeographic data sources, and by combining earlier findings into a multidisciplinary summary of marine biogeography. The assessment is divided into 5 chapters and supporting appendices. Each chapter was written and reviewed in collaboration with subject matter specialists and local experts. In Chapter 1, a short introduction to the overall scope and approach of the report is provided. In Chapter 2, regional ocean climate is characterized using remote sensing datasets and discussed in the context of local observations. In Chapter 3, regional ocean currents and transport of coral and fish larvae are investigated among the islands of the archipelago and surrounding island nations. In Chapter 4, distinct reef fish and coral communities across the archipelago are quantified on the basis of overall biodiversity, abundance, and community structure. In Chapter 5, the existing network of MPAs in American Samoa is evaluated based on the habitats, reef fish, and coral communities that are encompassed. Appendices provide analytical details omitted from some chapters for brevity as well as supplemental datasets needed as inputs for the main chapters in the assessment. Appendices include an inventory of regional seamounts, a description of shore to shelf edge benthic maps produced for Tutuila, analytical details of reef fish and coral datasets, and supplemental information on the many marine protected areas in American Samoa.
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We review the progress made in the emerging field of coastal seascape ecology, i.e. the application of landscape ecology concepts and techniques to the coastal marine environment. Since the early 1990s, the landscape ecology approach has been applied in several coastal subtidal and intertidal biogenic habitats across a range of spatial scales. Emerging evidence indicates that animals in these seascapes respond to the structure of patches and patch mosaics in different ways and at different spatial scales, yet we still know very little about the ecological significance of these relationships and the consequences of change in seascape patterning for ecosystem functioning and overall biodiversity. Ecological interactions that occur within patches and among different types of patches (or seascapes) are likely to be critically important in maintaining primary and secondary production, trophic transfer, biodiversity, coastal protection, and supporting a wealth of ecosystem goods and services. We review faunal responses to patch and seascape structure, including effects of fragmentation on 5 focal habitats: seagrass meadows, salt marshes, coral reefs, mangrove forests, and oyster reefs. Extrapolating and generalizing spatial relationships between ecological patterns and processes across scales remains a significant challenge, and we show that there are major gaps in our understanding of these relationships. Filling these gaps will be crucial for managing and responding to an inevitably changing coastal environment. We show that critical ecological thresholds exist in the structural patterning of biogenic ecosystems that, when exceeded, cause abrupt shifts in the distribution and abundance of organisms. A better understanding of faunal–seascape relationships, including the identifications of threshold effects, is urgently needed to support the development of more effective and holistic management actions in restoration, site prioritization, and forecasting the impacts of environmental change.
Resumo:
Gray’s Reef National Marine Sanctuary (GRNMS) is located 32.4 km offshore of Sapelo Island, Georgia. The ecological importance of this area is related to the transition between tropical and temperate waters, and the existence of a topographically complex system of ledges. Due to its central location, GRNMS can be used as a focal site to study the accumulation and impacts of marine debris on the Atlantic continental shelf offshore of the Southeast United States. Previously, researchers characterized marine debris in GRNMS and reported that incidence of the debris at the limited densely colonized ledge sites was significantly greater than at sand or sparsely colonized live bottom, and is further influenced by the level of boating activity and physiographic characteristics (e.g., ledge height). Information gleaned from the initial marine debris characterization was used to devise a strategy for prioritizing cleanup and monitoring efforts. However, a significant gap in knowledge was the rate of debris accumulation. The primary objective of this study was to select, mark, and perform initial marine debris surveys at permanent monitoring sites within GRNMS to quantify long-term trends in types, abundance, impacts, and accumulation rates of debris. Ledge sites were selected to compare types, abundance, and accumulation rates of marine debris between a) areas of high and low use and b) short and tall ledges. Nine permanent monitoring sites were marked and initially surveyed in 2007/2008. Surveys were conducted within a 50 x 4 m transect for a total survey area of 200 square meters. All debris was removed and detailed information was taken on the types of debris, quantity, and associations with benthic fauna. Information on associations with benthic fauna included degree of entanglement, type of organism with which it is entangled or resting on, degree of fouling, and visible impacts such as tissue abrasions. Sites were re-surveyed approximately one year later to quantify new accumulation. During the initial survey, a total of ten debris items, totaling 16.3 kg in weight, were removed from two monitoring stations, both “tall” sites within the area of high boat use. Year-one accumulation totaled five items and approximately 7 kg in weight. Similar to the initial survey, all debris was found at sites in the area of high boat use. However, in contrast to the initial survey, two of these items were found on medium-height ledges. Removed items included fishing line, leaders, rope, plastic, and fabric. Although items were often encrusted in benthic biota or entangled on the ledge, impacts such as abrasions or other injuries were not observed. During the 2009 monitoring efforts, volunteer divers were trained to conduct the survey. Monitoring protocols were documented for GRNMS staff and included as an appendix of this report to enable long-term monitoring of sites. Additionally, national reconnaissance data (e.g. satellite, radar, aerial surveys) and other information on known fishing locations were examined for patterns of resource use and correlations with debris occurrence patterns. A previous model predicting the density of marine debris based on ledge features and boat use was refined and the results were used to generate a map of predicted debris density for all ledges.
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We have recently exchanged and integrated into a single database tag detections for conch, teleost and elasmobranch fish from four separately maintained arrays in the U.S. Virgin Islands including the NMFS queen conch array (St. John nearshore), NOAA’s Biogeography Branch array (St. John nearshore & midshelf reef); UVI shelf edge arrays (Marine Conservation District, Grammanik & other shelf edge); NOAA NMFS Apex Predator array COASTSPAN (St. John nearshore). The integrated database has over 7.5 million hits. Data is shared only with consent of partners and full acknowledgements. Thus, the summary of integrated data here uses data from NOAA and UVI arrays under a cooperative agreement. The benefits of combining and sharing data have included increasing the total area of detection resulting in an understanding of broader scale connectivity than would have been possible with a single array. Partnering has also been cost-effectiveness through sharing of field work, staff time and equipment and exchanges of knowledge and experience across the network. Use of multiple arrays has also helped in optimizing the design of arrays when additional receivers are deployed. The combined arrays have made the USVI network one of the most extensive acoustic arrays in the world with a total of 150+ receivers available, although not necessarily all deployed at all times. Currently, two UVI graduate student projects are using acoustic array data.
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Coral reefs throughout their circumtropical range are declining at an accelerating rate. Recent predictions indicate that 20% of the world’s reefs have been degraded, another 24% are under imminent risk of collapse, and if current estimates hold, by 2030, 26% of the world’s reefs will be lost (Wilkinson 2004). Recent changes to these ecosystems have included losses of apex predators, reductions of important herbivorous fishes and invertebrates, and precipitous declines in living coral cover, with many reefs now dominated by macroalgae. Causes have been described in broad sweeping terms: global climate change, over-fishing and destructive fishing, land-based sources of pollution, sedimentation, hurricanes, mass bleaching events and disease. Recognition that corals can succumb to disease was first reported in the early 1970’s. Then it was a unique observation, with relatively few isolated reports until the mid 1990’s. Today disease has spread to over 150 species of coral, reported from 65 countries throughout all of the world’s tropical oceans (WCMC Global Coral Disease Database). While disease continues to increase in frequency and distribution throughout the world, definitive causes of coral diseases have remained elusive for the most part, with reef managers not sufficiently armed to combat it.
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This report is a result of long-term fish monitoring studies supported by the National Park Service (NPS) at the Virgin Islands National Park since 1988 and is now a joint NPS and NOAA collaboration. Reef fish monitoring data collected from 1988 to 2006 within Virgin Islands National Park (VINP) and adjacent reefs around St. John, U.S. Virgin Islands (USVI) were analyzed to provide information on the status of reef fishes during the monitoring period. Monitoring projects were initiated by the National Park Service (NPS) in the 1980s to provide useful data for evaluation of resources and for development of a long-term monitoring program. Monthly monitoring was conducted at two reef sites (Yawzi Point and Cocoloba Cay) starting in November 1988 for 2.5 years to document the monthly/seasonal variability in reef fish assemblages. Hurricane Hugo (a powerful Category 4 storm) struck the USVI in September 1989 resulting in considerable damage to the reefs around St. John. Abundance of fishes was lower at both sites following the storm, however, a greater effect was observed at Yawzi Point, which experienced a more direct impact from the hurricane. The storm affected species differently, with some showing only small, short-term declines in abundance, and others, such as the numerically abundant blue chromis (Chromis cyanea), a planktivorous damselfish, exhibiting a larger and longer recovery period. This report provides: 1) an evaluation of sampling methods, sample size, and methods used during the sampling period, 2) an evaluation of the spatial and temporal variability in reef fish assemblages at selected reef sites inside and outside of VINP, and 3) an evaluation of trends over 17 years of monitoring at the four reference sites. Comparisons of methods were conducted to standardize assessments among years. Several methods were used to evaluate sample size requirements for reef fish monitoring and the results provided a statistically robust justification for sample allocation.
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Los peces constituyen uno de los atractivos principales en los arrecifes coralinos para el buceo turístico, por lo cual resulta necesario monitorear su abundancia y valores estéticos. El objetivo de esta investigación fue evaluar el estado de conservación de las asociaciones de peces arrecifales en cuatro de los principales polos turísticos del Archipiélago Sabana-Camagüey, Cuba en el año 2010. Se muestrearon 23 sitios de buceo turísticos en áreas adyacentes a las regiones de Varadero (5 sitios), cayos de Villa Clara (6 sitios), Cayo Coco (6 sitios) y Santa Lucia (6 sitios). En cada uno de ellos se realizaron seis réplicas de censos visuales de todas las especies de peces en recorridos lineales de 50 m de largo por 2 m de ancho, ocupando un área total de 600 m2. El puntaje más alto de conservación lo presentó los cayos de Villa Clara (37), siguiéndole en orden decreciente Cayo Coco (35), y con valores más bajos Varadero (24) y Santa Lucia (22). Los puntajes de las cuatro regiones fueron inferiores a los encontrados en otros arrecifes de Cuba y el Caribe. Los valores de Varadero y Santa Lucia se correspondieron con los de arrecifes de hábitats degradados y sometidos a explotación pesquera. En general, en la mayoría de las regiones predominaron peces de talla pequeña (<20 cm) pertenecientes a las familias Pomacentridae y Labridae y hubo poca abundancia de peces carnívoros y herbívoros de mediana (20-40 cm) y gran talla (>40 cm). ABSTRACT Fish are one of the main attractions on coral reefs for diving tourism; therefore, it is necessary to monitor their condition and aesthetic values. The objective of this research was to evaluate the status of reef fish assemblages in four tourist areas of Sabana-Camaguey Archipelago, Cuba in 2010. Twentythree tourist diving sites were sampled in adjacent areas to regions of Varadero (five sites), Villa Clara keys (6 sites), Coco key (6 sites) and Santa Lucia (6 sites). In each region, six replicated visual census of all fish species were conducted along belt transects of 50 m length and 2 m width, occupying a total area of 600 m2. The highest conservation score was obtained by Villa Clara keys (37), followed in decreasing order by Coco key (35), and with lower values Varadero (24) and St. Lucia (22). The scores of the four regions were lower than the values of other Cuban and Caribbean reefs. The values of Varadero and Santa Lucia corresponded to reefs with degraded habitats and subject to overfishing. In general, small fish (< 20 cm) from families Pomacentridae and Labridae, and low abundance of carnivore and herbivore fish of middle (20-40 cm) and large size (> 40 cm) predominated in most regions.
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RESUMEN Se comparó el grado de resiliencia de seis crestas arrecifales del este del golfo de Batabanó, Cuba. Tres fueron del norte del golfo de Cazones (Tramo Norte) y las restantes, del oeste de Cayo Largo (Tramo Sur). Las del primer tramo fueron las de faro Cazones, Norte de la cresta de cayo Diego Pérez y de faro Diego Pérez. Las otras tres fueron las de cayo Rico, arrecifes Los Ballenatos y arrecifes Hijos de Los Ballenatos. Se emplearon los indicadores biológicos del Protocolo AGRRA. El Tramo Norte presentó las crestas más resilientes, sobre todo la de faro Cazones. Las del Tramo Sur no exhibieron resiliencia. Fueron varios e interrelacionados, los factores aparentemente más determinantes en la resiliencia. Entre estos, cuatro se consideraron como fuerzas motrices: resguardo contra el oleaje, circulación habitual giratoria ciclónica en la ensenada de Cazones, entrada de nutrientes provenientes tanto de la ciénaga de Zapata como de aguas profundas, y abundancia del erizo herbívoro Diadema antillarum. Los demás factores, desencadenados por los anteriores y también interrelacionados, fueron, al parecer la menor afectación por oleaje y sedimentos, estabilización de fragmentos vivos de coral, índices favorables de macroalgas bentónicas, cierta retención de nutrientes y plancton, más alimentación heterotrófica de los corales, mayor auto reclutamiento de corales y del erizo Diadema; mejores condiciones para el asentamiento y viabilidad de los reclutas, y para el recapamiento de corales; mayor crecimiento y recuperación de los corales y mejores condiciones térmicas contra el blanqueamiento de corales ABSTRACT The degree of resilience of six reef crest sites was compared at the east of the Gulf of Batabano, Cuba. Three of them were located north of the Gulf of Cazones (Northern Stretch), while the remaining ones were west of Cayo Largo (Southern Stretch). Those of the Northern Stretch were “Faro Cazones”, north of the crest of cayo Diego Pérez and “Faro Diego Pérez”. The remaining sites were those of the cayo Rico, Los Ballenatos reefs, and Hijos de Los Ballenatos reefs. The AGRRA biological indicators were applied. The Northern Stretch presented the most resilient crests, mainly that of “Faro Cazones”. Those of the Southern Stretch did not reveal signs of resilience. Several interrelated factors were apparently more linked to resilience. Four of them were considered as driving forces: shelter from waves, usual cyclonic revolving water circulation in the Ensenada de Cazones, nutrient input from the Zapata swamp and deep water, and the abundance of the herbivore sea urchin Diadema antillarum. Triggered by these driving forces, the remaining factors apparently were less effect of waves and sediments, stabilization of live coral fragments, favorable benthic macro-algae indices, some retention of nutrient and plankton, increased coral heterotrophic feeding; better conditions for recruit settlement and viability, and for coral re-sheeting; faster coral growth and recuperation and better thermal conditions against coral bleaching.
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Sex-specific demography and reproductive biology of stripey bass (Lutjanus carponotatus) (also known as Spanish flag snapper, FAO) were examined at the Palm and Lizard island groups, Great Barrier Reef (GBR).Total mortality rates were similar between the sexes. Males had larger L∞ at both island groups and Lizard Island group fish had larger overall L∞. Female:male sex ratios were 1.3 and 1.1 at the Palm and Lizard island groups, respectively. The former is statistically different from 1, but is unlikely significantly different in a biological sense. Females matured on average at 2 years of age and 190 mm fork length at both locations. Female gonadal lipid body indices peaked from August through October, preceding peak gonadosomatic indices in October, November, and December that were twice as great as in any other month. However, ovarian staging revealed 50% or more ovaries were ripe from September through February, suggesting a more protracted spawning season and highlighting the different interpretations that can arise between gonad weight and gonad staging methods. Gonadosomatic index increases slightly with body size and larger fish have a longer average spawning season, which suggests that larger fish produce greater relative reproductive output. Lizard Island group females had ovaries nearly twice as large as Palm Island group females at a given body size. However, it is unclear whether this reflects spatial differences akin to those observed in growth or effects of sampling Lizard Island group fish closer to their date of spawning. These results support an existing 250 mm minimum size limit for L. carponotatus on the GBR, as well as the timing of a proposed October through December spawning closure for the fishery. The results also caution against assessing reef-fish stocks without reference to sex-, size-, and location-specific biological traits.