Essential Fish Habitat Research Papers (original) (raw)

Anchovy and round sardinella are two important small pelagic species in the Mediterranean that spawn during the summer period. This is a first attempt to model and predict the two species' potential spawning habitats in this area. Generalized additive models (GAMs) were constructed based on satellite environmental variables and presence/absence egg data, available from ichthyoplankton surveys conducted in the North Aegean Sea during early summer . These models were subsequently used to predict the probability of anchovy and round sardinella spawning in the Greek Seas as well as the entire Mediterranean and Black Sea during the same month of the year. The interaction of bottom depth and chlorophyll explained most of the deviance in the presence/absence GAMs of both species, indicating spawning over continental shelf areas with increased surface chlorophyll values. Round sardinella spawned closer to coast than anchovy. Predicted potential spawning areas for anchovy and round sardinella in unsampled areas of the Greek Seas and the entire Mediterranean and Black Sea were in good agreement with existing information on the distribution and extent of the spawning grounds, especially for anchovy. Modeling the species' reproductive activity in relation to easily accessible environmental information and applying the models in a predictive way could be an initial, low-cost step to designate potential spawning fish habitats.

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- Earth Sciences, Remote Sensing, Spatial Analysis, Statistical Modelling
- by Dean Grubbs
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- Gulf of Mexico, Essential Fish Habitat

A reduction in population abundance, brought on by an unprecedented 6 years of low recruitment, has reduced shell input through natural mortality on Delaware Bay oyster beds. Quantitative stock surveys provide an estimate of surficial shell over the same time period, permitting the reconstruction of the time history of shell since 1998 and estimation of the rates of shell addition and loss. Shell loss rates were unexpectedly high. In most cases, half of the shell added to an oyster bed in Delaware Bay in a given year is lost over a subsequent period of 2e10 years. Unexpectedly, the shortest half-lives, typically two to three years, are at intermediate salinities. Half-lives increase upbay into lower salinity and downbay into higher salinity to about 10 years. Minimal shell doubling times were calculated under the assumption of no shell loss, a maximum accretion rate. Minimal doubling times vary from somewhat less than a decade to more than a score of years. Doubling times of decadal scale emphasize that shell has the potential to accumulate rapidly on human time scales. The rarity of definitive documentation of shell accumulation, in terms of reef vertical accretion or lateral expansion, can only be explained if most shell produced yearly does not long remain recognizably intact. Doubling times are not rapid on the scale of oyster generation time, however. Management of essential fish habitat in the estuarine realm must include management of the shell budget and management of commercial shell-producing species must include the provision of animals as carbonate producers for habitat maintenance. Shell, at least in estuarine habitats, may have low preservational potential, even in areas that, when preserved, will appear to be shellbeds. The biases in the fossil record may not be minimized in shell-rich environments of preservation because shelliness does not imply good preservability.

- by John Kraeuter
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- Earth Sciences, Taphonomy, Biological Sciences, Fossil record

This synthesis brings together published and unpublished data in an evaluation of restoration of former salt hay farms to functioning salt marshes. We compared nine years of field measurements between three restored marshes (Dennis, Commercial, and Maurice River Townships) and a reference marsh (Moores Beach) in the mesohaline portion of Delaware Bay. In the process, we compared channel morphology, geomorphology, vegetation, sediment organic matter, fish assemblages, blue crabs, horseshoe crabs, benthic infauna, and diamondback terrapins. For fishes we compared structural (distribution, abundance) and functional (feeding, growth, survival, reproduction, production) aspects to evaluate the restored marshes in an Essential Fish Habitat context. Marsh vegetation and drainage density responded gradually and positively with restored marshes approximating the state of the reference marsh within the nine-year study period. The fauna responded more quickly and dramatically with most measures equal or greater in the restored marshes within the first one or two years after restoration. Differences in response time between the vegetation and the fauna imply that the faunal response was more dependent on access to the shallow intertidal marsh surface and intertidal and subtidal creeks than on characteristics of the vegetated marsh. The fishes in created subtidal creeks in restored marshes responded immediately and maintained fish assemblages similar to the reference marsh over the study period. The intertidal creek fish assemblages tended to become more like the reference marsh in the last years of the comparison. Overall, these results document the success of the restoration and how marshes function for both resident and transient fauna, especially fishes.

- by David Nemerson
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- Zoology, Fisheries Sciences, Blue Crab, Salt marsh
- by Bryan Legare
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- Shark, Acoustic telemetry, Shark Nursery Area, Essential Fish Habitat

Shark nursery areas are widely regarded as
essential habitats for the growth and survival of young individuals.
The effective management and protection of shark
nursery habitat are contingent upon a clear understanding
of how individual species utilize such habitat both spatially
and temporally. Although shark nurseries have been identified
in the Caribbean, this information is generally lacking.
From 2006 to 2012, we used passive acoustic telemetry to
monitor the presence, movements, and habitat use of 65
juvenile blacktip sharks (Carcharhinus limbatus) and 42
juvenile lemon sharks (Negaprion brevirostris) within Fish
Bay and Coral Bay, two shark nurseries in St. John, United
States Virgin Islands. Both species were present in each bay
during all months of the year, but abundance peaked during
the summer (June–September). Although telemetry dataindicated that blacktip and lemon sharks moved throughout
each embayment, each species exhibited strong site fidelity
to core areas across all years of the study. Habitat partitioning
was observed in both nurseries as blacktip sharks
generally occurred in areas characterized by water depths
of 1.5–6 m with seagrass and sand/mud substrate, while
lemon sharks remained in close proximity to or within shallow
(<1 m), mangrove-fringed seagrass habitat. Blacktip
sharks were also observed to exhibit greater activity space
during the nighttime hours (1900–0659 h) within Coral
Bay. The results of this study indicate that Fish Bay and
Coral Bay are nursery areas that warrant designation as
essential fish habitat and exemplify the need for additional
focused management measures.

- by Bryan Legare
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- Marine Biology, Sharks, Habitat, Acoustic telemetry
- by Alex Wertheimer
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- Essential Fish Habitat

The relationships between fish assemblages, their associated habitat, and degree of protection from fishing were evaluated over a broad spatial scale throughout the main Hawaiian islands. Most fish assemblage characteristics showed positive responses to protection whether it was physical (e.g. habitat complexity), biological (e.g. coral cover growth forms), or human-induced (e.g. marine reserves). Fish biomass was lowest in areas of direct wave exposure and highest in areas partially sheltered from swells. Higher values for fish species richness, number of individuals, biomass, and diversity were observed in locations with higher substrate complexity. Areas completely protected from fishing had distinct fish assemblages with higher standing stock and diversity than areas where fishing was permitted or areas that were partially protected from fishing. Locations influenced by customary stewardship harbored fish biomass that was equal to or greater than that of no-take protected areas. Marine protected areas in the main Hawaiian islands with high habitat complexity, moderate wave disturbance, a high percentage of branching and/or lobate coral coupled with legal protection from fishing pressure had higher values for most fish assemblage characteristics.

- by Paul Jokiel and +3
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- Earth Sciences, Coral Reefs, Biological Sciences, Environmental Sciences

This study reports the distribution, abundance and habitat use of juvenile goliath grouper Epinephelus itajara along fringing red mangrove Rhizophora mangle shorelines of the Florida Keys, USA. The species has been protected from fishing in US waters since 1992, after reaching commercial extinction, yet juvenile habitat use remains poorly studied. The aim of this study was to evaluate the importance of underwater mangrove habitat structure and complexity in determining distribution of juvenile goliath grouper in the Florida Keys. Visual underwater surveys were used to record juvenile presence, abundance and size. Habitat characteristics as continuous variables (depth, canopy, overhang and prop root width) and nominal variables (bottom type, sun exposure, shoreline shape and shoreline type) were also recorded. Juveniles aggregated in sites with high structural complexity, soft sediment and eroded shorelines. Well-developed fringing red mangrove shorelines were the preferred juvenile goliath grouper habitat.

- by Sarah Frias-Torres
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- Endangered Species, Biological Sciences, Environmental Sciences, Habitat Use

We review the variety of existing modelling approaches applied to species habitat mapping and we discuss issues arising from the availability and nature of sampled biological data and corresponding ecological and environmental habitat descriptors, as well as the different spatial analysis approaches that are selected according to specific hypotheses. We focus on marine species habitat mapping, presenting an overview of work on modelling fish habitat carried out through a European Communities Policy-Support Action, EnviEFH 'Environmental Approach to Essential Fish Habitat (EFH) Designation' (2005)(2006)(2007)(2008). The selection of the appropriate habitat model is dataset-specific and the resulting EFH maps are often similar in spite of using different models. Derived EFH maps are based on either environmental ranges (used as minimum and maximum environmental habitat descriptors) or probability of occurrence values. We apply model outputs to regions larger than sampled areas making use of the capacity of satellite data to cover wide areas.

- by Guillaume Bernard
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- Earth Sciences, Remote Sensing, Spatial Analysis, Modeling

In order to properly determine the efficacy of marine protected areas (MPAs), a seascape perspective that integrates ecosystem elements at the appropriate ecological scale is necessary. Over the past four decades, Hawaii has developed a system of 11 Marine Life Conservation Districts (MLCDs) to conserve and replenish marine resources around the state. Initially established to provide opportunities for public interaction with the marine environment, these MLCDs vary in size, habitat quality, and management regimes, providing an excellent opportunity to test hypotheses concerning MPA design and function using multiple discrete sampling units. Digital benthic habitat maps for all MLCDs and adjacent habitats were used to evaluate the efficacy of existing MLCDs using a spatially explicit stratified random sampling design. Analysis of benthic cover validated the a priori classification of habitat types and provided justification for using these habitat strata to conduct stratified random sampling and analyses of fish habitat utilization patterns. Results showed that a number of fish assemblage characteristics (e.g., species richness, biomass, diversity) vary among habitat types, but were significantly higher in MLCDs compared with adjacent fished areas across all habitat types. Overall fish biomass was 2.6 times greater in the MLCDs compared to open areas. In addition, apex predators and other species were more abundant and larger in the MLCDs, illustrating the effectiveness of these closures in conserving fish populations within their boundaries. Habitat type, protected area size, and level of protection from fishing were all important determinates of MLCD effectiveness with respect to their associated fish assemblages. Although size of these protected areas was positively correlated with a number of fish assemblage characteristics, all appear too small to have any measurable influence on the adjacent fished areas. These protected areas were not designed for biodiversity conservation or fisheries enhancement yet still provide varying degrees of protection for fish populations within their boundaries. Implementing this type of biogeographic process, using remote sensing technology and sampling across the range of habitats present within the seascape, provides a robust evaluation of existing MPAs and can help to define ecologically relevant boundaries for future MPA design in a range of locations.

- by Alan Friedlander
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- Remote Sensing, Spatial Ecology, Ecology, Biological Sciences

R ecent reports have raised serious concerns about the rapid declines of historically productive marine fishery resources and the degradation of essential fish habitats. This global crisis has spurred development of innovative management strategies to rebuild depleted fisheries and marine ecosystems. One highly touted strategy involves the design and creation of marine reserves (areas off limits to extractive uses) to rebuild fisheries and conserve marine biodiversity. In this paper, we propose an integrated sequence of methodologies that provides an objective, quantitative framework for the design of marine reserves in spatially heterogeneous coastal ocean environments. The marine reserve designs proposed here satisfy the multiple, often-conflicting criteria of disparate resource user groups. This research is the first attempt to explicitly explore the trade-off between the conservation goals of fishery management and coral reef protection and the consumptive interests of commercial and recreational fishing fleets. The spatial distribution and size abundance of reef fish stocks throughout the Florida Keys coral reef ecosystem were estimated from a database consisting of more than 18,000 visual samples taken from 1979 to 2002. These distributions of multispecies abundance and biomass, in conjunction with a geographic database of coral reef habitats, are used to demonstrate an integer goal programming methodology for the design of networks of marine reserves, called plans. Once multiple plans are proposed, a simulation model is used to assess the effects of reserve size and shape on select Florida Keys reef fish populations under dynamic spatial and temporal conditions.

- by Jerald Ault
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- Geography, Computer Science, Management Science, Marine biodiversity

Biological, oceanographic and geomorphologic data of the Azores were integrated into a Geographical Information System (GIS) in order to determine occurrence and spatial behavior of commercially-exploited coastal fishes in relation to benthic habitats. Essential fish habitats (EFHs) are identified and the information is incorporated into decision making tools to design a network of coastal Marine Protected Areas (MPAs) at an island scale. The Azores are the most isolated archipelago in the North-Atlantic, characterized by complex geologic settings, a variety of marine habitats, diversity of marine life, scarcity of shallow waters and its remoteness. As a result the islands are of great nature conservation and marine biological interest. In the study area of Faial and Pico, two islands of the central group, different zones for environmental protection according to national/regional, Natura 2000 and OSPAR regulations were designated during the last two decades. Recently the Faial-Pico Channel was declared as Nature Park. MPAs gain importance as fisheries management tool and for the conservation of biodiversity. Ideally, core populations of the target species are protected in the boundaries of a MPA and it serves as refuge. Still, practical effort to design and manage marine reserves based on a multi-species approach is scarce. In order to support and refine the existing zoning schemes and to define new coastal MPAs different datasets are brought together in this study: 1) geomorphologic data, including depth, bottom type, slope and distance to e.g. nearest rock. The information is extracted from habitat maps derived by seafloor mapping with multibeam; 2) oceanographic data, based on average literature data for chlorophyll a, sea surface temperature, currents and swell; and 3) biological data: predicted fish abundances based on visual census from over ten years and patterns of spatial behavior obtained by passive and active acoustic underwater telemetry for important coastal commercial species. All information is visualized as layers in ArcGIS and for the first time GIS modelling of all available data combined in one approach is done. The aim is to develop comprehensive and clear maps that illustrate species distribution related to (a)biotic factors and are comprehendible for the public and policy makers. Areas fundamental for the long-term survival of fishes (i.e. spawning grounds) and thus for sustainable fishery are identified (EFH). First results are presented. In the next step decision making tools (software like MARXAN) will be applied to consider animal behaviour, environmental data and the needs of different stakeholders in one approach for the design of a MPA network in the Azores. Furthermore, the possibility of using advanced Autonomous Underwater Vehicle (AUV) technology to enhance acoustic telemetry and the study of marine animals is investigated: for a prolonged time certain electronic tags of animals are able to register and store data like (animal/water) temperature, depth and any biological information measurable via suitable, integrated sensors. Special equipped AUVs are a potential tool to download those data; so far only feasible if the tag can be retrieved. First tests for target tracking and exclusion of interference between AUV and telemetry equipment are promising (GREX project). Making this technology available in the future would give a unique opportunity to gain important information about spatial behavior of marine animals even when they are out of our range. Understanding the behavior and spatial use of endangered species will help us finding the best solution for their protection. I.

- by Ricardo Santos
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- Environmental Science, Decision Making, Marine Protected Areas, Marine Engineering

Subtidal accumulations of oyster shell have been largely overlooked as essential habitat for estuarine nekton. In southeastern U.S. estuaries, where oyster reef development is mostly confined to the intertidal zone, eastern oyster (Crassostrea virginica) shell covered bottoms are often the only significant source of hard subtidal structure. We characterized and quantified nekton use of submerged shell rubble bottoms, and compared it to use of intertidal reefs and other subtidal bottoms in the North Inlet estuary, South Carolina. Replicate trays (0.8 m 2 ) filled with shell rubble were deployed in shallow salt marsh creeks, and were retrieved after soak times of 1 to 25 days from May 1998 to March 2000. Thirty six species of fishes, representing 21 families, were identified from the 455 tray collections. Water temperature, salinity, soak time and the presence of a shell substrate all affected the catch of fishes in the trays. Catches during the warmer months were two to five times greater than those during the winter. Fishes were present in 98% of the trays with an overall average of 5.7 fish m Ϫ2 . The assemblage was numerically dominated by small resident species including naked

- by Dennis Allen
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- Earth Sciences, Biological Sciences, Environmental Sciences, Estuaries

Extensive and unregulated harvest of marine ornamental fishes can lead to localized depletion of target species and habitat degradation from inappropriate collecting techniques. One potential solution to these problems is the creation of marine reserves where fishing is prohibited. Marine reserves have been shown to increase fish abundance and protect ecosystems from habitat destruction associated with fishing. If protective areas

- by Alan Friedlander
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- Habitat complexity, Protected Area, Marine Protected Area, Marine Reserve

Spawning condition was determined for 28 species of reef fish represent- ing 11 families (Balistidae, Berycidae, Carangidae, Centrolophidae, Haemuli- dae, Lutjanidae, Malacanthidae, Polyprionidae, Scorpaenidae, Serranidae, Sparidae) collected off the Carolinas, Georgia and east coast of Florida (including the Keys) in depths from 1 - 686 m. The presence of migratory- nucleus oocytes, hydrated oocytes and/or postovulatory follicles was used to

- by David Wyanski
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- Seasonality, South Carolina, Reproductive behavior, Marine Protected Area

We conducted hydroacoustic, gill-net, and push trawl surveys to quantify changes in habitatspecific fish size and biomass in shallow (,2-m) estuarine waters of Barataria Bay, Louisiana, in order to evaluate essential fish habitat. Surveys were conducted monthly between June 2003 and May 2004 among regions located along a north-south salinity gradient. The fish length distributions derived from the gill-net and push trawl catches showed moderate concordance with the measured target strength distributions, indicating that our integrated approach more effectively characterized the fish community than using only a single gear type would have. Acoustic estimates showed that biomass was highest during fall (mean 6 SE; 2.30 6 0.27 g/m 3 ) and next highest in spring (1.49 6 0.20 g/m 3 ), with relatively low biomass during summer (0.70 6 0.14 g/m 3 ) and winter (0.86 6 0.14 g/m 3 ); pelagic fish biomass from nets was low during winter (53.9 6 14.9 grams per unit effort [gpue]) but relatively high in fall (846.1 6 207.2 gpue), spring (774.3 6 175.5 gpue), and summer (620.3 6 140.7 gpue). Oyster habitat supported a greater biomass of pelagic fish (acoustic survey: 1.54 6 0.15 g/m 3 ; gill-net survey: 467.3 6 81.0 gpue) than soft-bottom habitat (acoustic: 0.94 6 0.11 g/m 3 ; gill-net: 315.2 6 54.8 gpue). Among regions, the greatest biomass of pelagic fish was observed at polyhaline stations (acoustic: 1.78 6 0.19 g/m 3 ; gill-net: 654.3 6 136.5 gpue), followed by mesohaline (acoustic: 1.18 6 0.15 g/m 3 ; gill-net: 378.5 6 79.1 gpue) and oligohaline stations (acoustic: 0.82 6 0.12 g/m 3 ; gill-net: 228.3 6 50.2 gpue). Gill-net biomass was linearly related to the acoustic biomass estimates of small pelagic fish. The complementary, multigear approach proved to be useful in evaluating habitat use and may be particularly helpful in identifying and monitoring ecosystem reference points to evaluate change and in standardizing ecosystem-based assessment approaches.

- by Kevin Boswell and +1
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- Engineering, Seasonality, Small Pelagic Fish, Habitat Use

There has been much interest recently in the use of marine reserves to conserve fish stocks, particularly those species such as groupers, which are long-lived and slow growing and in many cases aggregate to spawn. Marine reserves may benefit fish stocks in several ways, including protection of spawning stock biomass and the maintenance of undisturbed fish habitat. Studies on the habitat preferences of Turks & Caicos grouper indicate that grouper occupy a wide range of habitats. Coney (Epinephelus fulvus) and adult Nassau grouper (E. striatus) were most abundant on high-relief shelfedge bank reefs. Studies of the effects of protection on grouper in the Bahamas, Barbados, Belize, Cuba, the Dominican Republic, and the Florida Keys have shown increased density and biomass of groupers in protected areas. However, recent research in the Turks & Caicos Islands shows no effect of marine reserves on grouper abundance or distribution. Moreover, fishing pressure on grouper in the Turks & Caicos Islands may be insufficient to cause differences in density or biomass between fished and protected areas. Several species of grouper, such as Nassau grouper and gag (Mycteroperca microlepis) undertake seasonal spawning migrations of up to several hundred km. During these migrations, grouper may leave the boundaries of marine reserves and may be subject to fishing mortality. More information is needed on the habitat preferences and migratory habits of groupers in order to design more effective reserves.

- by Mark Tupper
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- Fisheries, Coral Reef Fishes, Essential Fish Habitat

The habitat needs of nearshore juvenile rockfish Sebastes spp. have rarely been studied but are an essential component of habitat identification for management. We investigated the relationships between habitat type, species composition, and growth of juvenile rockfish after settlement into nearshore reefs and estuaries in central Oregon. We identify and prioritize essential fish habitat (EFH) for blue rockfish S. mystinus and black rockfish S. melanops caught by minnow traps and by scuba divers with hand nets. Species were confirmed through genetic analysis. Our nearshore samples were dominated by blue rockfish, while estuary samples contained almost exclusively black rockfish. Settlement patterns suggest that black rockfish had a strong preference for anthropogenic habitat (docks, pilings, jetties) within the Yaquina Bay estuary. Growth was not significantly different among habitats or sampling years for either black rockfish or blue rockfish. We identify estuaries as EFH for black rockfish juveniles along the central Oregon coast and confirm nearshore reef areas as EFH for blue rockfish juveniles. Small sample sizes of juvenile yellowtail rockfish S. flavidus and widow rockfish S. entomelas suggest that estuaries are also important for these species.

- by Selina Heppell
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- Engineering, Species Composition, Oregon, Genetic Analysis

We review the variety of existing modelling approaches applied to species habitat mapping and we discuss issues arising from the availability and nature of sampled biological data and corresponding ecological and environmental habitat descriptors, as well as the different spatial analysis approaches that are selected according to specific hypotheses. We focus on marine species habitat mapping, presenting an overview of work on modelling fish habitat carried out through a European Communities Policy-Support Action, EnviEFH 'Environmental Approach to Essential Fish Habitat (EFH) Designation' (2005-2008). The selection of the appropriate habitat model is dataset-specific and the resulting EFH maps are often similar in spite of using different models. Derived EFH maps are based on either environmental ranges (used as minimum and maximum environmental habitat descriptors) or probability of occurrence values. We apply model outputs to regions larger than sampled areas making use of the capacity of satellite data to cover wide areas.

- by L. Direach
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- Earth Sciences, Environmental Science, Remote Sensing, Fisheries

Many coastal and offshore fish species are highly dependent on specific habitat types for population maintenance. In the Baltic Sea, shallow productive habitats in the coastal zone such as wetlands, vegetated flads/lagoons and sheltered bays as well as more exposed rocky and sandy areas are utilized by fish across many life history stages including spawning, juvenile development, feeding and migration. Although there is general consensus about the critical importance of these essential fish habitats (EFH) for fish production along the coast, direct quantitative evidence for their specific roles in population growth and maintenance is still scarce. Nevertheless, for some coastal species, indirect evidence exists, and in many cases, sufficient data are also available to carry out further quantitative analyses. As coastal EFH in the Baltic Sea are often found in areas that are highly utilized and valued by humans, they are subjected to many different pressures. While cumulative pressures, such as eutrophication, coastal construction and development, climate change, invasive species and fisheries, impact fish in coastal areas, the conservation coverage for EFH in these areas remains poor. This is mainly due to the fact that historically, fisheries management and nature conservation are not integrated neither in research nor in management in Baltic Sea countries. Setting joint objectives for fisheries management and nature conservation would hence be pivotal for improved protection of EFH in the Baltic Sea. To properly inform management, improvements in the development of monitoring strategies and mapping methodology for EFH are also needed. Stronger international cooperation between Baltic Sea states will facilitate improved management outcomes across ecologically arbitrary boundaries. This is especially important for successful implementation of international agreements and legislative directives such as the Baltic Sea Action Plan, the Marine Strategy Framework Directive, the Habitats Directive, and the Maritime Spatial Planning Directive, but also for improving the communication of information related to coastal EFH among researchers, stakeholders, managers and decision makers. In this paper, efforts are made to characterize coastal EFH in the Baltic Sea, their importance and the threats/pressures they face, as well as their current conservation status, while highlighting knowledge gaps and outlining perspectives for future work in an ecosystem-based management framework.

- by Laura Briekmane
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- Coastal Zone Management, Habitats, Baltic Sea, Essential Fish Habitat

We coupled multibeam sonar data with submersible and remotely operated vehicle (ROV) observations to classify and describe bottomfish essential fish habitat (EFH) on four banks in the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve (NWHICRER). From �001 to �00�, a total of �� Pisces IV and V dives along with �� RCV-150 ROV dives were conducted on Raita Bank, W.

- by Christopher Kelley
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- Remotely Operated Vehicle, Coral Reef, Hawaiian Islands, Deep water

Mobile consumers have potential to cause a cascading of habitat degradation beyond the region that is directly stressed, by concentrating in refuges where they intensify biological interactions and can deplete prey resources. We tested this hypothesis on structurally complex, species-rich biogenic reefs created by the eastern oyster, Crassostrea virginica, in the Neuse River estuary, North Carolina, USA. We (1) sampled fishes and invertebrates on natural and restored reefs and on sand bottom to compare fish utilization of these different habitats and to characterize the trophic relations among large reef-associated fishes and benthic invertebrates, and (2) tested whether bottom-water hypoxia and fishery-caused degradation of reef habitat combine to induce mass emigration of fish that then modify community composition in refuges across an estuarine seascape. Experimentally restored oyster reefs of two heights (1 m tall ''degraded'' or 2 m tall ''natural'' reefs) were constructed at 3 and 6 m depths. We sampled hydrographic conditions within the estuary over the summer to monitor onset and duration of bottom-water hypoxia/anoxia, a disturbance resulting from density stratification and anthropogenic eutrophication. Reduction of reef height caused by oyster dredging exposed the reefs located in deep water to hypoxia/anoxia for Ͼ2 wk, killing reef-associated invertebrate prey and forcing mobile fishes into refuge habitats. Refugee fishes accumulated at high densities on reefs in oxygenated shallow water, where they depleted epibenthic crustacean prey populations. Thus, physical disturbances can impact remote, undisturbed refuge habitats through the movement and abnormal concentration of refugee organisms that have subsequent strong trophic impacts. These results have implications for the design of Marine Protected Areas (MPAs), showing that reserves placed in proximity to disturbed areas may be impacted indirectly but may serve a critical refuge function on a scale that matches the mobility of consumers.

- by James Jeb Byers
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- Ecosystem management, Stratification, Biological Sciences, Environmental Sciences
- by Dana Bethea
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- Gulf of Mexico, Essential Fish Habitat

An ecological niche modelling (ENM) approach was used to predict the potential feeding and spawning habitats of small (5–25 kg, only feeding) and large (>25 kg) Atlantic bluefin tuna (ABFT), Thunnus thynnus, in the Mediterranean Sea, the North Atlantic and the Gulf of Mexico. The ENM was built bridging knowledge on ecological traits of ABFT (e.g. temperature tolerance, mobility, feeding and spawning strategy) with patterns of selected environmental variables (chlorophyll-a fronts and concentration, sea surface current and temperature, sea surface height anomaly) that were identified using an extensive set of precisely geo-located presence data. The results highlight a wider temperature tolerance for larger fish allowing them to feed in the northern – high chlorophyll levels – latitudes up to the Norwegian Sea in the eastern Atlantic and to the Gulf of Saint Lawrence in the western basin. Permanent suitable feeding habitat for small ABFT was predicted to be mostly located in temperate latitudes in the North Atlantic and in the Mediterranean Sea, as well as in subtropical waters off northwest Africa, while summer potential habitat in the Gulf of Mexico was found to be unsuitable for both small and large ABFTs. Potential spawning grounds were found to occur in the Gulf of Mexico from March–April in the southeast to April–May in the north, while favourable conditions evolve in the Mediterranean Sea from mid-May in the eastern to mid-July in the western basin. Other secondary potential spawning grounds not supported by observations were predicted in the Azores area and off Morocco to Senegal during July and August when extrapolating the model settings from the Gulf of Mexico into the North Atlantic. The presence of large ABFT off Florida and the Bahamas in spring was not explained by the model as is, however the environmental variables other than the sea surface height anomaly appeared to be favourable for spawning in part of this area. Defining key spatial and temporal habitats should further help in building spatially-explicit stock assessment models, thus improving the spatial management of bluefin tuna fisheries.

- by Jean-Noel Druon and +9
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- Marine Habitat Mapping, Essential Fish Habitat, Chlorophyll a fronts

We used growth rates (estimated from otolith microstructure), morphometric (Fulton's K condition index) and lipid (triacylglycerols:sterols ratio, TAG:ST) condition indices measured on 0-group juveniles of common sole, to compare the habitat quality of 7 nursery grounds with differing levels of anthropogenic pressure. Along the French coast of the Southern Bight of the North Sea and the Eastern English Channel, we compared 2 sites located in intensively developed and industrialised harbour areas (Dunkerque and Calais), 1 site in a medium and less industrialised harbour (Boulogne), 1 site near a large and polluted estuary (Seine) and 3 other sites located near small estuaries less subject to human pressure (Canche, Authie and Somme). Indicators of human disturbance as well as hydrological and biotic data were used to establish between-site differences in environmental quality. Our results indicate consistent differences in the growth and condition indices of 0group sole among the 7 sites. Sole had the slowest growth (mean G = 0.54 mm d -1 ) and lowest condition indices (mean K = 1.07; TAG:ST = 0.32) at Dunkerque and Calais and the fastest growth (mean G = 0.70 mm d -1 ) and highest condition indices (mean K = 1.19; TAG:ST = 2.18) at the Authie, Canche and Somme estuaries. The indices measured in this study correlated well with anthropogenic disturbance and may provide a useful tool to assess habitat quality. Sites with highest sediment chemical contaminants had the lowest habitat quality and, through growth and lipid-storage limitation, could dramatically lower over-winter survival of the juveniles living in these nursery grounds.

- by Rachid Amara
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- Zoology, Ecology, Essential Fish Habitat

- by ANGEL GONZALEZ
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- Earth Sciences, Water quality, Life history, Biological Sciences

Habitat restoration encompasses a broad range of activities, emphasizing very different issues, goals, and approaches depending on the operational definition of 'restoration'. This is particularly true for many shellfish (molluscan) dominated systems (e.g. oyster reefs, mussel beds, vermetid gastropod reefs). In contrast to other well-studied biogenic habitats, such as seagrasses, mangroves, or salt marshes, bivalves are directly consumed as a resource. Hence resource extraction has direct consequences for habitat health. Restoration objectives have typically included reduction of public health risks through improved water quality to increase harvest. Restoration or enhancement of populations of commercially exploited shellfish depressed by overharvesting and/or reduced environmental quality remains the principal motivation behind most shellfish 'restoration' efforts. Direct and indirect ecosystem services (e.g. filtering capacity, benthic-pelagic coupling, nutrient dynamics, sediment stabilization, provision of habitat, etc.) derived from oyster habitat have been largely ignored or underestimated. Only recently, the restoration of lost ecological function associated with shellfish communities has been included in our discussions and related research examining habitat development and function through a scientific approach. The former area has been reviewed extensively and will not be our focus here. In this review, we examine some of the restoration efforts made in the name of fisheries enhancement, address their effectiveness, and discuss some of the issues associated with realizing the broader goal of ecological restoration. We note the importance of linking success criteria to specific goals and make the case for a greater need in clarifying the ecological functions of shellfish and shellfish habitats. We recognize the limitations of existing datasets and summarize ongoing attempts to address oyster habitat restoration throughout the broad geographic distribution of the American oyster, Crassostrea 6irginica (Gmelin). In many ways this topic parallels the ongoing debate over 'attraction versus production' associated with artificial reef management. We consider how local conditions (e.g. tidal range, bottom topography, turbidity, salinity) and resulting habitat traits affect restoration strategies. We also discuss the underappreciated value of shellfish populations from those areas

- by Loren Coen
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- Engineering, Ecological Engineering, Earth Sciences, Fisheries Management

The deep-water rose shrimp, Parapenaeus longirostris (Lucas 1846, Decapoda: Penaeidae) is one of the main target species of the demersal fishery in the Moroccan Atlantic region. However, in the last decade, there is a severe decline of shrimp fisheries in the area without the existence of any management plan. The purpose of this article is to investigate the relationships between the spawning of the deep-water rose shrimp and environmental factors in order to provide basic information for any future management measure. The spatial distribution of mature females is investigated through statistical techniques on data collected in the Moroccan Atlantic Ocean from bottom trawl surveys during 1981-2004. The geographic distribution of mature females is jointly analyzed in association to the spatial distribution of salinity and temperature at the depth of species catch. The study reveals a strong relationship between locations of spawning females and high salinity. Most spawning occurrences are observed in high salinity 'islands ' (35.6-36.5 psu) or in the boundaries of higher-lower salinity patterns in the specific range of 36.2-36.4 psu in shallower (75-200 m) and deeper zones (250-500 m). Spawning occurs mostly in the shallower zone from spring to summer while during winter, it occurs in both depth zones. Temperature seems to be important on catch levels of the species.

- by Isidora Katara
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- Earth Sciences, Crustacea, Ecology, Hydrobiology
- by Matthew Ajemian
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- Gulf of Mexico, Essential Fish Habitat

The spring and summer distribution of adults and larval fish stages of Sparids and Scorpaenids was studied in two sites in the western Mediterranean. Fish adults and larvae of those two taxa were identified and sorted according to their life stages in order to study their distribution and develop suitable habitat maps. Study areas were located on French coastal waters, the “Côte Bleue” Marine Park (CBMP) has an east-west orientation with substratum dominated by Posidonia beds and the Marine Reserve of Cerbe’re-Banyuls (MRCB) runs north-south and is dominated by rocky substrates. Generalised Additive Models (GAM) combined with Geographic Information System (GIS), were used to model the suitable habitats for fish larvae and adults. During spring months, waters exhibit low Sea Surface Temperatures (SST), low Photosynthetically Active Radiation (PAR), high values of Sea Surface Chlorophyll-a concentration (Chl-a), and mostly negative values of Sea Level Anomaly (SLA) indicating anticyclonic eddies. During summer months, waters have higher values of SST, lower values of Chl-a and positive values of SLA indicating cyclonic eddies. The results revealed different environmental responses in the distribution of fish adults and larvae in the CBMP and MRCB. Suitable habitats for adult were mainly dependent on the substrate types (Posidonia meadows and sand) and they were found close to the coast, whereas fish larvae were dependent on environmental cues (Chl-a, SLA, SST) with a sparse spatial distribution.

- by Gwenael Cadiou
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- Earth Sciences, Remote Sensing, Spatial Analysis, Modeling

The status of declining marine fisheries through the wider Caribbean region has been thoroughly documented. However, there is a lack of quantitative data to determine if there is any cause and effect relationship between declining fish populations and declining ecological conditions of essential fish habitats. We have quantitatively documented the ecological conditions of essential fish habitats and fish communities through an anthropogenic environmental stress gradient in seven northeastern Puerto Rican coral reef communities. Study sites differ in fishing pressure and in water quality, factors which create an anthropogenic environmental stress gradient as we move off degraded coasts. Line intercept transects were used to assess coral reef epibenthic communities. Stationary visual censuses were used to assess fish communities. There were significant differences in the structure of coral reef epibenthic and fish communities as we moved offshore, which suggests that anthropogenic environmental stress and fishing pressure gradients can change the structure of coral reef epibenthic and fish communities. Degradation is stronger at inshore habitats, which showed lower coral species richness, percentage of living coral cover and species diversity. These habitats are also characterized by having higher algal cover, and low abundance and diversity of reef fishes. Offshore, less degraded habitats are characterized by higher coral species richness, percentage of living coral cover and species diversity. These habitats are also characterized by having lower algal cover, and high abundance and diversity of reef fishes. There were also severe overfishing effects at some of the less disturbed offshore sites, which masked the expected results for a healthy reef. Reef fish abundance and biomass was significantly lower at overfished sites. Given the alarming conditions of depleted fish stocks, even within the boundaries of Natural Reserves, we recommend the establishment of a network of small Marine Fishery Reserves (=no take zones) at Cayo Diablo, Palominitos Island, Cayo Icacos and at the western coast of Culebra Island to help restore depleted fish stocks. There is a relationship between the ecological conditions of essential fish habitats and reef fish communities. The status of essential fish habitats could affect the status of fish communities. But under the absence of significant environmental degradation, the status of fish communities could also affect the status of essential fish habitats (i.e., coral reefs). These aspects should be taken in consideration in the design of coral reef fishery management measures, including the establishment of marine fishery

- by Alberto Sabat
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- Water quality, Coral Reef, Fishery Management, Species Diversity

- by Andy Smerdon
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- Earth Sciences, Sea surface temperature, Biological Sciences, Environmental Sciences

In the Atlantic, economic losses have been reported from shark, swordfish and tuna longline fisheries due to depredation by cetaceans. We examined interactions of odontocete cetaceans with commercial longliners operating in waters off Brazil and the Azores archipelago during 2006–2007, analyzing relationships between catches, depredation on hooked fish, cetacean sightings, acoustic records of cetacean presence and environmental variables. Data were provided by skippers of six vessels and by on-board observers for two vessels. The percentage of longline sets depredated by cetaceans was low (ranging from 1% to 9% of total sets per ship) but the proportion of fish damaged was high (up to 100%) when depredation occurred. Catches were related to the phase of the moon, cloud cover, sea surface temperature and water depth whereas cetacean sightings were primarily related to catches. In particular there was a positive association between Delphinus delphis sightings and catches of swordfish, and between Stenella frontalis sightings and mako catches. Acoustic detection was low when depredation by false killer whales occurred although high rates of clicks were detected when delphinids were sighted and false killer whales were by-caught. This may indicate that false killer whales are not echolocating when feeding on fish hooked on a longline.

- by Gema Hernandez-Milian and +3
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- Earth Sciences, Sea surface temperature, Biological Sciences, Environmental Sciences

The conservation of deep-sea corals is of growing interest in the United States. A range of issues including biodiversity protection, conservation of seafloor habitats, and the role of deep-sea corals as essential fish habitat places greater significance on understanding the distributions of these corals and fishing activities. At the same time overfishing of some groundfish populations highlights the need for

- by Lance Morgan and +1
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- United States, Ecological Footprint, Fishery Management, Ecosystem based management

- by Ricardo Santos
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- Environmental Science, Decision Making, Marine Protected Areas, Marine Engineering

- by Isidora Katara
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- Earth Sciences, Remote Sensing, Spatial Analysis, Modeling
- by Cecil Jennings
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- Zoology, Water quality, Ecology, Discriminant Analysis

Growth and feeding rates were measured in juvenile summer flounder Paralichthys dentatus and winter flounder Pseudopleuronectes americanus exposed to sub-lethal hypoxia (low dissolved oxygen, DO) over a range of temperatures, to determine its potential effects on nursery habitat quality for these 2 estuary-dependent flatfishes. Growth rates of both species were generally reduced as DO decreased, particularly at DO levels of 50 to 70% air saturation, and as temperature increased. Summer flounder were more tolerant of low DO than were winter flounder at both 20 and 25°C. At these temperatures, summer flounder growth was reduced by ~25% (compared to growth at normoxia [7.0 mg O 2 l -1 ]) at 3.5 mg O 2 l -1 and by 50 to 60% at 2.0 mg O 2 l -1 . In contrast, growth of winter flounder at 20°C was reduced by ~50% at both 3.5 and 5.0 mg O 2 l -1 , and growth was zero at 2.0 mg O 2 l -1 . At 25°C, winter flounder grew poorly in all DO treatments and lost weight at 2.0 mg O 2 l -1 . Summer flounder were also tested at 30°C. Growth was significantly reduced even at 5.0 mg O 2 l -1 , and was reduced by ~90% at 2.0 mg O 2 l -1 . A significant relationship between feeding rate and growth suggested reduced consumption to be a major cause of growth limitation under hypoxia. There was no evidence of growth acclimation for either species after 7 to 14 d exposure to hypoxia. The effect of hypoxia on growth of summer flounder was reduced at lower salinity (15 vs. 25 ‰) and was unaffected by the presence of a sand substrate. Similarity between modeled growth under hypoxic conditions, based on our laboratory results, and observed growth of summer flounder in a hypoxic estuarine tributary suggests growth limitation in the wild. These laboratory and field results demonstrate that even moderate hypoxia can adversely affect growth rates, and thus the quality of estuarine nursery habitats for juvenile flatfishes.

- by Timothy Targett
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- Zoology, Ecology, Habitat Quality, Growth rate

Cephalopods are highly sensitive to environmental conditions and changes at a range of spatial and temporal scales. Relationships documented between cephalopod stock dynamics and environmental conditions are of two main types: those concerning the geographic distribution of abundance, for which the mechanism is often unknown, and those relating to biological processes such as egg survival, growth, recruitment and migration, where mechanisms are sometimes known and in a very few cases demonstrated by experimental evidence. Cephalopods seem to respond to environmental variation both 'actively' (e.g. migrating to areas with more favoured environmental conditions for feeding or spawning) and 'passively' (growth and survival vary according to conditions experienced, passive migration with prevailing currents). Environmental effects on early life stages can affect life history characteristics (growth and maturation rates) as well as distribution and

- by Jose Bellido and +2
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- Earth Sciences, Water quality, Life history, Biological Sciences

- by Angel Revolledo Guerra
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- Earth Sciences, Water quality, Life history, Biological Sciences

SUMMARY: Indicators of growth and condition were used to compare the habitat quality of nurseries of juvenile sole (Solea solea L.) in the Bay of Biscay, based on one survey in 2000. The four biological indicators are poorly correlated with each other, suggesting that no single measure may give an adequate description of fish health and of its habitat's quality.

- by Olivier Pape and +2
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- Genetics, Earth Sciences, Scientometrics, Life history

- by Isidora Katara and +2
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- Earth Sciences, Water quality, Life history, Biological Sciences

Estuaries serve as nursery grounds for many marine fish species. However increasing human activities within estuaries and surrounding areas lead to significant habitat loss for the juveniles and decrease the quality of the remaining habitats. This study is based on the data of 470 beam trawls from surveys that were conducted in 13 French estuaries for the purpose of the European Water Framework Directive. It aimed at testing the effects of anthropogenic disturbances on the nursery function of estuaries. With a multispecific approach based on ecological guilds, two fish metrics, abundance and species richness of Marine Juvenile migrant fishes, were used as proxies for the estuarine nursery function. Indices of heavy metal and organic contaminations were used to estimate anthropogenic disturbances impacting these estuaries. Fish metrics were described with statistical models that took into account: (a) sampling protocol, (b) estuarine features and (c) contamination. The results of these models showed that the fish metrics highly depend on the sampling protocol, and especially type of gear, depth and salinity, which highlights the necessity of considering such metrics at the sampling (trawl haul) scale. Densities and species richness of Marine Juvenile fishes appeared to be strongly and negatively correlated to contamination indices. These results are consistent with the hypothesis that human disturbances impact the nursery function of estuaries. Finally, the densities of Marine Juvenile migrant species appeared as a potential robust and useful fish indicator for the assessment of the ecological status of estuaries within the Water Framework Directive.

- by A Courrat and +2
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- Earth Sciences, Biological Sciences, Environmental Sciences, Anthropogenic Disturbance

- by Gema Hernandez-Milian and +3
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- Earth Sciences, Sea surface temperature, Biological Sciences, Environmental Sciences

Shallow coastal waters act as nurseries for various fish species and have been recognized as essential fish habitat. We studied heavy metal concentrations in four fish species (plaice, dab, flounder and cod) as an indicator of large-scale habitat quality. The study took place along the French coasts between the Eastern English Channel and the Southern Bight of the North Sea.

- by Rachid Amara
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- Skeletal muscle biology, Multidisciplinary, England, Quality Control

The fisheries benefits of marine reserves are hard to achieve for highly vagile fish species. An alternative is to protect essential habitats, such as spawning grounds, especially if these are stable over time. We studied the movements and habitat use patterns of white trevally Pseudocaranx dentex (Carangidae), a commercially important species, to assist in the design of marine reserves. Diel, seasonal and inter-annual movements of trevally were studied using active acoustic tracking, passive acoustic monitoring and standard tag-release in the Faial Channel, Azores Islands. White trevally were captured at inshore and offshore reefs. Inshore trevally moved daily alongshore, using large activity spaces, while the short-term movements of offshore trevally were restricted to the reef summits. During the summer spawning season, both groups displayed frequent migrations of up to several kilometres, but inshore fish remained inshore, whereas offshore reef fish expanded their range to include visits to inshore sites. This behaviour eventually resulted in low long-term residence within the study area, especially that of inshore fish. During the spawning season, one inshore site was visited by most of the fish. However, instead of gathering in large aggregations at a single location, it appears that the trevally adopted a multiple-site visiting behaviour, which may increase mating opportunities through mixing between inshore and offshore fish that are otherwise segregated for most of the year. Protection of spawning biomass and sites for this species seems potentially feasible, but this would require protecting a suite of sites per island. Furthermore, because fish would not be fully protected under this scenario, we argue that such spatial management measures need to be accompanied by conventional fishing-effort control measures applied to all local populations.

- by Jorge Fontes
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- Life history, Ecosystem management, Recruitment, Abundance

Natural Resource management is evolving toward ensuring sustainable ecosystems rather than sustainable yields. Understanding how a species interacts with its environment is fundamental for sound ecosystem management. If we are progressing toward an ecosystem management approach, then we must first understand how a species interacts with its environment and how the environment affects a species population dynamics. Ladyfish (Elops saurus) are a valuable commercial and recreational species; however, limited information is available describing the importance of their habitat. To date, only a few studies have noted the environmental conditions during ladyfish field-collections, and only one study has investigated ladyfish nursery habitats in any detail. Given the economic importance of ladyfish in Florida (USA), the objective of this investigation was to define, for the first time, juvenile ladyfish relative abundance in association to environmental conditions and habitat use at multiple Florida estuaries. In addition, this investigation re-examined some of the scientific findings and conclusions of previous ladyfish studies; incorporated additional data sets; and evaluated available ladyfish data at a finer scale of phenomena. Overall, juvenile ladyfish were collected in waters with wide-ranging environmental conditions having a sandy bottom, but preferred specific locations with particular dissolved oxygen, pH, water temperature, and salinity levels according to their size.

- by Juan C . Levesque, Ph.D.
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- Fisheries, Life history, Fisheries Management, Ecosystem management

We review the variety of existing modelling approaches applied to species habitat mapping and we discuss issues arising from the availability and nature of sampled biological data and corresponding ecological and environmental habitat descriptors, as well as the different spatial analysis approaches that are selected according to specific hypotheses. We focus on marine species habitat mapping, presenting an overview of work on modelling fish habitat carried out through a European Communities Policy-Support Action, EnviEFH 'Environmental Approach to Essential Fish Habitat (EFH) Designation' (2005-2008). The selection of the appropriate habitat model is dataset-specific and the resulting EFH maps are often similar in spite of using different models. Derived EFH maps are based on either environmental ranges (used as minimum and maximum environmental habitat descriptors) or probability of occurrence values. We apply model outputs to regions larger than sampled areas making use of the capacity of satellite data to cover wide areas.

- by Marina Santurtun
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- Earth Sciences, Environmental Science, Remote Sensing, Spatial Analysis