The pernicious problem of evidence complacency, illustrated here through conservation policy and practice, results in poor practice and inefficiencies. It also increases our vulnerability to a ‘post-truth’ world dealing with ‘alternative facts’.
The continental shelves are the most biologically dynamic regions of the ocean, and they are extensive worldwide, especially in the western North Pacific. Their area has varied dramatically over the glacial/interglacial cycles of the last million years, but the effects of this variation on ocean biological and chemical processes remain poorly understood. Conversion of nitrate to N2 by denitrification in sediments accounts for half or more of the removal of biologically available nitrogen (“fixed N”) from the ocean. The emergence of continental shelves during ice ages and their flooding during interglacials have been hypothesized to drive changes in sedimentary denitrification. Denitrification leads to the occurrence of phosphorus-bearing, N-depleted surface waters, which encourages N2 fixation, the dominant N input to the ocean. An 860,000-y record of foraminifera shell-bound N isotopes from the South China Sea indicates that N2 fixation covaried with sea level. The N2 fixation changes are best explained as a response to changes in regional excess phosphorus supply due to sea level-driven variations in shallow sediment denitrification associated with the cyclic drowning and emergence of the continental shelves. This hypothesis is consistent with a glacial ocean that hosted globally lower rates of fixed N input and loss and a longer residence time for oceanic fixed N—a “sluggish” ocean N budget during ice ages. In addition, this work provides a clear sign of sea level-driven glacial/interglacial oscillations in biogeochemical fluxes at and near the ocean margins, with implications for coastal organisms and ecosystems.
Coastal marine upwelling famously supports elevated levels of pelagic biological production, but can also subsidize production in inshore habitats via pelagic-benthic coupling. Consumers inhabiting macroalgae-dominated rocky reef habitats are often considered to be members of a food web fuelled by energy derived from benthic primary production; conversely, they may also be subsidized by materials transported from pelagic habitats. Here, we used stable isotopes (δ13C, δ15N) to examine the relative contribution of pelagic and benthic materials to an ecologically and economically important benthivorous fish assemblage inhabiting subtidal macroalgae-dominated reefs along ~1,000 km of the northern Chilean coast where coastal upwelling is active. Fish were isotopically most similar to the pelagic pathway and Bayesian mixing models indicated that production of benthivorous fish was dominated (median 98%, range 69–99%) by pelagic-derived C and N. Although the mechanism by which these materials enter the benthic food web remains unknown, our results clearly highlight the importance of pelagic-benthic coupling in the region. The scale of this subsidy has substantial implications for our basic understanding of ecosystem functioning and the management of nearshore habitats in northern Chile and other upwelling zones worldwide.
Low diversity among scientists and practitioners is rampant in conservation. Currently, conservation professionals do not reflect the same diversity of perspectives and experiences of the world as the communities who bear the largest burden for implementing—or adverse consequences for failing to implement—conservation action. Acknowledging and describing the problem is important. But policies and programmes must also be put in place to correct it. Here, we highlight some measurable benefits of workforce diversity, and give an overview of some of the barriers to inclusion in marine conservation that help perpetuate low workforce diversity. Importantly, we underscore actions that both individuals and groups can take to alleviate such barriers. In particular, we describe the establishment of an online Marine Diversity Network, which conference participants proposed during a focus group meeting at the 4th International Marine Conservation Congress. The network will serve to bring together people from across the globe, from a variety of backgrounds, and from all career stages, to share knowledge, experiences and ideas, to provide and receive mentorship in marine conservation, and to forge new collaborations. Removing barriers to diverse participation requires coordinated, mindful actions by individuals and organizations. We hope that the proposed network and other actions presented in this paper find widespread support, and that they might serve both as inspiration and guide to other groups concerned with increasing diversity and inclusivity.
The connected nature of social-ecological systems has never been more apparent than in today's globalized world. The ecosystem service framework and associated ecosystem assessments aim to better inform the science–policy response to sustainability challenges. Such assessments, however, often overlook distant, diffuse and delayed impacts that are critical for global sustainability. Ecosystem-services science must better recognise the off-stage impacts on biodiversity and ecosystem services of place-based ecosystem management, which we term 'ecosystem service burdens'. These are particularly important since they are often negative, and have a potentially significant effect on ecosystem management decisions. Ecosystem-services research can better recognise these off-stage burdens through integration with other analytical approaches, such as life cycle analysis and risk-based approaches that better account for the uncertainties involved. We argue that off-stage ecosystem service burdens should be incorporated in ecosystem assessments such as those led by the Intergovernmental Platform on Biodiversity and Ecosystem Services and the Intergovernmental Panel on Climate Change. Taking better account of these off-stage burdens is essential to achieve a more comprehensive understanding of cross-scale interactions, a pre-requisite for any sustainability transition.
Studies of habitat selection by higher trophic level species are necessary for using top predator species as indicators of ecosystem functioning. However, contrary to terrestrial ecosystems, few habitat selection studies have been conducted at a fine scale for coastal marine top predator species, and fewer have coupled diet data with habitat selection modeling to highlight a link between prey selection and habitat use.
The aim of this study was to characterize spatially and oceanographically, at a fine scale, the habitats used by the European Shag Phalacrocorax aristotelis in the Special Protection Area (SPA) of Houat-Hœdic in the Mor Braz Bay during its foraging activity. Habitat selection models were built using in situ observation data of foraging shags (transect sampling) and spatially explicit environmental data to characterize marine benthic habitats. Observations were first adjusted for detectability biases and shag abundance was subsequently spatialized. The influence of habitat variables on shag abundance was tested using Generalized Linear Models (GLMs). Diet data were finally confronted to habitat selection models.
Results showed that European shags breeding in the Mor Braz Bay changed foraging habitats according to the season and to the different environmental and energetic constraints. The proportion of the main preys also varied seasonally. Rocky and coarse sand habitats were clearly preferred compared to fine or muddy sand habitats. Shags appeared to be more selective in their foraging habitats during the breeding period and the rearing of chicks, using essentially rocky areas close to the colony and consuming preferentially fish from the Labridae family and three other fish families in lower proportions. During the post-breeding period shags used a broader range of habitats and mainly consumed Gadidae. Thus, European shags seem to adjust their feeding strategy to minimize energetic costs, to avoid intra-specific competition and to maximize access to suitable habitats and preys.
Effective management and conservation of wild populations requires knowledge of their habitats, especially by mean of quantitative analyses of their spatial distributions. The Pelagos Sanctuary is a dedicated marine protected area for Mediterranean marine mammals covering an area of 90,000 km2 in the north-western Mediterranean Sea between Italy, France and the Principate of Monaco. In the south of the Sanctuary, i.e. along the Sardinian coast, a range of diverse human activities (cities, industry, fishery, tourism) exerts several current ad potential threats to cetacean populations. In addition, marine mammals are recognized by the EU Marine Strategy Framework Directive as essential components of sustainable ecosystems. Yet, knowledge on the spatial distribution and ecology of cetaceans in this area is quite scarce. Here we modeled occurrence of the three most abundant species known in the Sanctuary, i.e. the striped dolphin (Stenella coeruleoalba), the bottlenose dolphin (Tursiops truncatus) and the fin whales (Balaenoptera physalus), using sighting data from scientific surveys collected from 2012 to 2014 during summer time. Bayesian site-occupancy models were used to model their spatial distribution in relation to habitat taking into account oceanographic (sea surface temperature, primary production, photosynthetically active radiation, chlorophyll-a concentration) and topographic (depth, slope, distance of the land) variables. Cetaceans responded differently to the habitat features, with higher occurrence predicted in the more productive areas on submarine canyons. These results provide ecological information useful to enhance management plans and establish baseline for future population trend studies.
Marine protected areas (MPAs) are considered one of the main tools in both fisheries and conservation management to protect threatened species and their habitats around the globe. However, MPAs are underrepresented in marine environments compared to terrestrial environments. Within this context, we studied the Atlantic non-breeding distribution of the southern population of Balearic shearwaters (Puffinus mauretanicus) breeding in Eivissa during the 2011-2012 period based on global location sensing (GLS) devices. Our objectives were (1) to identify overall Important Atlantic Areas (IAAs) from a southern population, (2) to describe spatio-temporal patterns of oceanographic habitat use, and (3) to assess whether existing conservation areas (Natura 2000 sites and marine Important Bird Areas (IBAs)) cover the main IAAs of Balearic shearwaters. Our results highlighted that the Atlantic staging (from June to October in 2011) dynamic of the southern population was driven by individual segregation at both spatial and temporal scales. Individuals ranged in the North-East Atlantic over four main IAAs (Bay of Biscay: BoB, Western Iberian shelf: WIS, Gulf of Cadiz: GoC, West of Morocco: WoM). While most individuals spent more time on the WIS or in the GoC, a small number of birds visited IAAs at the extremes of their Atlantic distribution range (i.e., BoB and WoM). The chronology of the arrivals to the IAAs showed a latitudinal gradient with northern areas reached earlier during the Atlantic staging. The IAAs coincided with the most productive areas (higher chlorophyll a values) in the NE Atlantic between July and October. The spatial overlap between IAAs and conservation areas was higher for Natura 2000 sites than marine IBAs (areas with and without legal protection, respectively). Concerning the use of these areas, a slightly higher proportion of estimated positions fell within marine IBAs compared to designated Natura 2000 sites, with Spanish and Portuguese conservation areas being the most visited. Our results support the current design of conservation areas in Spain and Portugal regarding the protection of adult breeders of this highly mobile species.
Marine ecosystems are exposed to significant anthropogenic pressure mainly due to the exploitation of biotic and abiotic marine resources. Marine protected areas (MPAs) are important tools to achieve local and global marine conservation targets. Marine ecosystems generate goods and services vital for human well-being. Their value can be explored not only from an economic viewpoint based on market and human preferences, but also using a biophysical perspective based on the accounting of environmental costs sustained for the generation of natural capital stocks and ecosystem services flows.
In this study, the value of natural capital in the MPA “the Islands of Ventotene and S. Stefano” (Central Italy) was assessed applying a biophysical and trophodynamic environmental accounting model based on emergy accounting. The value of natural capital was estimated for the main habitats of the investigated MPA in terms of the work done by the biosphere for its generation and maintenance. Both the autotrophic and heterotrophic natural capital of the MPA was evaluated. The highest value of emergy density of 4.26∙1011 sej m−2 was shown by the habitat “Posidonia oceanica seagrass bed” when investigating the autotrophic natural capital. The sciaphilic hard bottom habitat (coralligenous) showed the highest value of emergy density of 2.76∙1012 sej m−2when investigating the heterotrophic natural capital. The high emergy cost of coralligenous confirmed the importance of this habitat that represents one of the most important hot spot of species diversity in the Mediterranean Sea. The total emergy value of natural capital of the MPA was converted to monetary units by using the emergy-to-money ratio for Italy, resulting in 8.26 M€. Finally, a GIS tool was used to show the spatial distribution of natural capital values in relation to different habitats. The outcomes of this study highlighted the usefulness of the applied biophysical and trophodynamic environmental accounting model to explore the ecological value of natural capital in marine ecosystems while supporting local managers and policy makers for the sustainable development of MPAs.
Fishery–independent surface density and abundance estimates for the swordfish were obtained through aerial surveys carried out over a large portion of the Central Mediterranean, implementing distance sampling methodologies. Both design- and model-based abundance and density showed an uneven occurrence of the species throughout the study area, with clusters of higher density occurring near converging fronts, strong thermoclines and/or underwater features. The surface abundance was estimated for the Pelagos Sanctuary for Mediterranean Marine Mammals in the summer of 2009 (n=1152; 95%CI=669.0–1981.0; %CV=27.64), the Sea of Sardinia, the Pelagos Sanctuary and the Central Tyrrhenian Sea for the summer of 2010 (n=3401; 95%CI=2067.0–5596.0; %CV=25.51), and for the Southern Tyrrhenian Sea during the winter months of 2010–2011 ( n=1228; 95%CI=578–2605; %CV=38.59). The Mediterranean swordfish stock deserves special attention in light of the heavy fishing pressures. Furthermore, the unreliability of fishery–related data has, to date, hampered our ability to effectively inform long-term conservation in the Mediterranean Region. Considering that the European countries have committed to protect the resources and all the marine-related economic and social dynamics upon which they depend, the information presented here constitute useful data towards the international legal requirements under the Marine Strategy Framework Directory, the Common Fisheries Policy, the Habitats and Species Directive and the Directive on Maritime Spatial Planning, among the others.
In conservation prioritisation, it is often implicit that representation targets for individual habitat types act as surrogates for the species that inhabit them. Yet for many commercially and ecologically important coral reef fish species, connectivity among different habitats in a seascape may be more important than any single habitat alone. Approaches to conservation prioritisation that consider seascape connectivity are thus warranted. I demonstrate an approach that can be implemented within a relatively data-poor context, using widely available conservation planning software. Based on clearly stated assumptions regarding species’ habitat usage and movement ability, this approach can be adapted to different focal species and contexts, or refined as further data become available. I first derive a seascape connectivity metric based on area-weighted proximity between juvenile and adult habitat patches, and then apply this during spatial prioritisation using the decision-support software Marxan. Using a case study from Micronesia, I present two applications: first, to inform prioritisation for a network of marine protected areas to achieve regional objectives for habitat representation; and second, to identify nursery habitat patches that are most likely to supply juveniles to adult populations on reefs within existing protected areas. Incorporating seascape connectivity in conservation prioritisation highlights areas where small marine protected areas placed on coral reefs might benefit from proximity to other habitats in the seascape, and thus be more effective. Within the context of community tenure over resources, identification of critical nursery habitats to improve the effectiveness of existing marine protected areas indicates where collaboration across community boundaries might be required. Outputs from these analyses are likely to be most useful in regions where management is highly decentralised, imposing spatial constraints on the size of individual protected areas.
The Tampa Bay region of Florida exhibits the highest concentration of ornamental aquaculture facilities in the USA. Because of the diversity of aquaculture products (~800 species and varieties) and extensive production history (began in the 1930s and 1940s), this region could be a hotspot for escaped ornamental fish. We evaluated the scope of ornamental fish invasions in this region by examining (1) escape vectors and (2) the distribution of escaped fish. We investigated potential pathways of fish escape including theft/vandalism, fish transport, bird carry-off, and through effluent discharge. Fish were sampled at the effluent discharge and continued into the surrounding environment. The dominant escape vector was through farm effluents; there was no evidence that theft/vandalism, fish transport, or bird carry-off contributed to fish escape. Most captured fish were natives, especially the ubiquitous Eastern Mosquitofish (Gambusia holbrooki). Ornamental species and varieties were also captured, especially cichlids and poeciliids such as the Green Swordtail (Xiphophorus hellerii) and Southern Platyfish (Xiphophorus maculatus). Ornamental fish were often found in the immediate vicinity of fish farms but were rarely captured in the surrounding environment. Catch per unit effort and ornamental fish diversity declined when moving away from the aquaculture facility effluent and was reduced at sites with a detention pond. The observed fish distribution might be due to relatively cold water in sub-tropical Florida, predatory fish in the environment, and additional factors related to the physical or biological habitat. Ultimately, few ornamental fishes have established in this region despite a long period of extensive culture.
Fisheries enhancement is an important strategy for maintaining and improving fisheries productivity, and addressing some of the other contemporary challenges facing marine ecosystems. Aquaculture-based enhancement includes stock enhancement, restocking, and sea ranching. Developments in aquaculture techniques, tagging, genetics, modelling and ecology have underpinned growth in this field in the 21st century, particularly in the context of marine recreational fisheries. Marine enhancement practice has now matured to the point that quantitative tools are frequently applied before any fish or shellfish are released into the natural environment, and pilot-scale enhancement scenarios and release strategies are evaluated before full implementation. Social and economic studies are also increasingly important components of this assessment. Here, several case studies from diverse geographic areas exemplify the union of aquaculture technology, quantitative modelling, social science, physiology and ecology to estimate enhancement potential, improve enhancement strategies, assess enhancement outcomes, and support adaptive management. Integrating aquaculture-based enhancement with habitat enhancement presents a remarkable opportunity for future research and development, and offers the potential to further increase the opportunities and associated socio-economic benefits that are available to a broad range of fisheries stakeholders.
Interest in restoring staghorn coral Acropora cervicornis has grown following the widespread decline of this species in recent decades. To date, thousands of nursery-reared A. cervicornis have been outplanted to restore degraded reefs, but survivorship and growth among outplanted colonies can be spatially variable. In particular, data on distribution of remnant wild populations and outplant performance in varying reef zones is lacking. To address this gap, we conducted a study to characterize existing wild populations and assess performance of nursery-reared, outplanted A. cervicornis among three reef zones of varying depth at Little Cayman Island: the shallow back reef (0–3 m), the intermediate spur-and-groove reef (8–15 m), and the deep reef terrace (>15 m). Wild populations of A. cervicorniswere present in each reef zone, and colony height and prevalence of predation by Stegastesspp. were highest in the intermediate zone. For outplanted A. cervicornis, survivorship differed among sites and was lowest for outplants in the deep zone during the 85-day observation period. Post-outplant growth and branching was lowest among outplants in the shallow zone due to high rates of colony breakage. Following the conclusion of the study, a mortality event occurred in which 90% of outplants at the shallow plots died during a period of elevated sea temperature. The information provided in this study suggests that intermediate spur-and-groove reefs are optimal for outplanting activities in Little Cayman using existing restoration methods. These data could be useful for coral restoration practitioners and government agencies in the Caribbean, particularly the Cayman Islands, which is actively expanding its coral nursery program. New strategies must be developed to improve restoration outcomes in shallow and deep zones.
Ecosystem-based fisheries management (EBFM) and ecosystem restoration are gaining momentum worldwide, including in U.S. waters of the Gulf of Mexico (GOM). Ecosystem models are valuable tools for informing EBFM and restoration activities. In this paper, we provide guidance and a roadmap for ecosystem modeling in the GOM region, with an emphasis on model development and use of model products to inform EBFM and the increasing investments in restoration. We propose eight “best practices” for ecosystem modeling efforts, including (1) identification of priority management questions, (2) scenarios as simulation experiments, (3) calibration and validation needs, (4) sensitivity and uncertainty analyses, (5) ensuring transparency, (6) improving communication between ecosystem modelers and the various stakeholders, (7) documentation of modeling efforts, and (8) maintaining the ecosystem models and codes. Fisheries management in the USA adheres to a prescriptive set of calculations. Therefore, the use of ecosystem modeling in EBFM for the GOM will likely be incremental, starting with the incorporation of environmental variables into single-species assessments, the provision of background (stage-setting) information on environmental and food web effects (e.g., the impacts of lionfish Pterois spp. invasion), and strategic advice through management strategy evaluation. Management questions related to restoration in the GOM (e.g., the impacts of freshwater and sediment diversions as part of coastal restoration, habitat preservation, and rehabilitation; and measures to mitigate nutrient loading and hypoxia) have more flexibility in how they are addressed and thus are primed for immediate use of ecosystem modeling. The questions related to restoration are appropriate for ecosystem modeling, and data collection at the restoration project level can provide critical information for modeling to then scale up to regional responses. Ecosystem modeling efforts need to be initiated and advanced now in order for the tools to be ready in the near future. Addressing resource management issues and questions will benefit greatly from the proper use of ecosystem modeling.
Fisheries stock enhancement, the release of hatchery-reared fish into wild fish populations with the aim of improving fisheries, is a common management strategy of variable success that also involves substantial tradeoffs between fisheries management objectives. We conducted an internet-based survey to assess attitudes towards fisheries stock enhancement and other management measures among marine inshore anglers in Florida. A random sample of 200,000 fishing license holders was selected from Florida’s recreational saltwater license holders. The survey received a response rate of 5.2%. The survey was designed to collect information on angler participation, fishing experience, catch preferences and motivations in addition to attitudes toward management options including fisheries stock enhancement. The concepts of recreation specialization and consumptive orientation were used to explore diversity in management perspectives and attitudes towards fish stocking. Hierarchical cluster analysis of five specialization variables was used to identify three groups of inshore anglers. Angler groups had different levels of participation, skill, fishing-related expenditures and management preferences including support for fisheries stock enhancement. Inshore anglers were generally supportive of fisheries stock enhancement, but less so than many alternative management strategies including habitat restoration and traditional bag and minimum size limits. The most specialized anglers showed significantly higher levels of support for stock enhancement and most other management measures than less specialized anglers. Regardless of specialization, anglers were largely unaware of the risks and tradeoffs inherent to stock enhancement.
Selecting target species or stocks in which releases of hatchery fish can contribute effectively to fisheries management goals is a key challenge in many fisheries enhancement programs. Here we show how fisheries modeling informed by stock assessments can be used to evaluate contributions of stocked fish to fisheries and how these contributions are influenced by life history and fishery attributes including regulatory policies and angler effort. We built an age-structured population model to quantitatively assess enhancement contributions to multiple fisheries management objectives: predicted catch, predicted harvest, abundance of catchable fish, abundance of harvestable fish and total spawning biomass. We used this model to evaluate candidate species for marine fisheries enhancement in Florida, where hatchery production capacity is scheduled to expand over the next decade yet it is unclear how fisheries managers can best use this capacity to achieve management objectives. We evaluated five candidate marine fishes in Florida: red drum Sciaenops ocellatus, spotted seatrout Cynoscion nebulosus, common snook Centropomus undecimalis, southern flounder Paralichthys lethostigma and red snapper Lutjanus campechanus. Comparative analysis shows that contribution of released fish to fisheries outcomes tend to decline with increasing time between release and capture or harvest. Enhancement of red drum, a species targeted by anglers during sub-adult life stages, is predicted to yield lower numbers of stocked fish entering the recruited population compared to alternative species but to contribute more to catch and harvest objectives. Our results demonstrate how commonly available biological information can be integrated with quantitative modeling approaches to provide useful information to managers tasked with identifying best uses of increasing enhancement capacity.
Few data exist to evaluate the performance or assess the potential impacts of hook regulations on catchability or selectivity of recreational fisheries in the northern Gulf of Mexico. The purpose of this study was to test the effects of hook type (circle vs. J hook) and hook size (1/0, 4/0, and 7/0) on catch composition, traumatic hooking, species-specific catches, and size-selectivity of red snapper, Lutjanus campechanus, and grey triggerfish, Balistes capriscus.Selectivity was estimated by conditioning size distributions from hook-specific catches against in situ size distributions observed with a remotely operated vehicle. Deep hooking (hook set in gills or beyond) was low in all hook treatments for red snapper (<10%) and grey triggerfish (<6%), but was generally higher with J hooks, especially for other fishes caught with the largest J hook (34%). Hook type did not significantly affect catches, but catches decreased significantly with increasing hook size in all groups except red snapper. Selectivity curves were dome-shaped for both focus species in all hook treatments and selection peaks were similar among treatments for red snapper. Peak selectivity was 78.1 mm larger for J hooks than circle hooks for grey triggerfish. Overall, study results indicate that the circle hook regulation may have reduced traumatic hooking mortality by up to 50%, and that catchability is similar between hook types for both red snapper and grey triggerfish when controlling for hook size. Strong dome-shaped selection estimated for nearly all selectivity curves suggest logistic size-selectivity assumptions in assessment models are likely inappropriate for recreational sectors targeting red snapper or grey triggerfish.
We used an integrated bio-economic model to explore the nature of tradeoffs between conservation of fisheries resources and their use for socioeconomic benefit, as realized through the stock enhancement of recreational fisheries. The model explicitly accounted for the dynamics of wild, stocked, and naturally recruited hatchery-type fish population components, angler responses to stocking, and alternative functional relationships that defined conservation and socioeconomic objectives. The model was set up to represent Florida’s red drum (Sciaenops ocellatus) fishery as a case study. Stock enhancement produced strong trade-offs characterized by frontiers indicating that maximizing socioeconomic objectives could only be achieved at great losses to conservation objectives when the latter were based exclusively on abundance of wild-type fish. When naturally recruited hatchery-type fish were considered equivalent to wild fish in conservation value, this tradeoff was alleviated. Frontier shapes were sensitive to alternative assumptions regarding how conservation objectives were formulated, differential harvesting of stocked and wild-type fish, and potential inherent stakeholder satisfaction from the act of stocking. These findings make more explicit the likely opportunity costs associated with recreational stock enhancement and highlight the utility of trade-off frontiers for evaluating management actions.
For more than 100 years, the Florida Keys (USA) have supported a commercial sponge fishery but there is little information about the small artisanal fishery that now exists, which is nonetheless controversial because of concerns about the ecological consequences of sponge harvest. We estimated the harvest of commercial sponges and bycatch (sublegal or non-commercial species), as well as the mortality, growth, and reproduction of commercial sponge species. In heavily fished areas, ∼33% of the legal-sized sponges, ∼3% of the sublegal sponges, and virtually none of the non-commercial species were harvested. Approximately 40% of our study area was never fished during the four month long peak in the fishing season. Self-reporting of harvest by fishers who participated in our study closely matched our fishery-independent estimates. Natural mortality of sublegal-sized sponges was ∼7% of the population/yr, with little difference among species. Discarded “roller” sponges grew at rates comparable to attached sponges and many reattached to the seafloor within 18 mos, although rates of reattachment varied among species. Growth also differed among species and sampling periods (mean = 3 cm dia/yr), and reproductive effort was positively related to sponge size in some species, but not others. Given the careful targeting of commercial sponge species and sizes by fishers and the small fraction of the sponge community that is commercially valuable, harvest is estimated to have minimal impact on the diverse assemblage of sponges in the region.