Lopholatilus Chamaeleonticeps Research Articles

Spatiotemporal patterns in the prevalence of microscopic hepatic changes in Gulf of Mexico Tilefish (Lopholatilus chamaeleonticeps) and associations with hepatic PAHs

Following the 2010 Deepwater Horizon blowout, demersal longline surveys were conducted across the Gulf of Mexico (GoM) continental shelf to evaluate polycyclic aromatic hydrocarbon (PAH) exposure, tissue accumulation, and health indices in demersal fishes. Tilefish (Lopholatilus chamaeleonticeps), a target species due to Gulf-wide distribution with documented high exposure to PAHs, were collected in the north central GoM at repeat stations 2012 to 2015, and from the northwest GoM, Bay of Campeche, and Yucatán Shelf in 2015 and 2016. Liver samples (n = 239) were analyzed for microscopic hepatic changes (MHCs) by a board-certified veterinary pathologist. Histological analyzes identified 14 MHCs. Prevalence of MHCs was generally uniform throughout the GoM, except for low prevalence on the Yucatán Shelf. Inflammatory and vacuolar changes were most prevalent, while pre-neoplasia and neoplasia were rare. Tilefish sampled annually in the north central GoM showed increases in inflammatory MHCs and glycogen-type vacuolar change over time, while lipid-type vacuolar change decreased over time. Short-term exposure to PAHs was assessed by measuring PAH metabolites in bile (n = 100) using high performance liquid chromatography with fluorescence detection. Longer-term accumulation of PAHs in tissue was assessed by analyzing liver (n = 111) for PAHs and alkylated homologs using QuEChERS extractions and gas chromatography tandem mass spectrometry. Six MHCs including glycogen-type vacuolar change, biliary fibrosis, foci of cellular alteration, parasites, hepatocellular atrophy, and necrosis were significantly associated with hepatic PAH accumulation in Tilefish from the northern central GoM; however, no MHCs were associated with biliary PAH metabolites. Combined with previous studies of PAH exposure and health indices in north central GoM Tilefish post-Deepwater Horizon, which also identified decreases in hepatic lipid storage and Fulton's condition factor that were correlated to increasing PAH exposure, these data indicate concerning temporal trends and changes in hepatic energy storage.

Detection of long chain per- and polyfluoroalkyl substances (PFAS) in the benthic Golden tilefish (Lopholatilus chamaeleonticeps) and their association with microscopic hepatic changes

Oceans are major sinks for anthropogenic pollutants, including per- and polyfluoroalkyl substances (PFAS). Although PFAS have been detected in surface waters globally, this is the first report of PFAS in a deep (170–400 m) demersal species in the Gulf of Mexico (GoM). Golden Tilefish (Lopholatilus chamaeleonticeps) plasma extracts (n = 185) were investigated for the presence of PFAS using ultra-high performance liquid chromatography-tandem mass spectrometry. A subset of liver tissues (n = 51) were also analyzed for microscopic hepatic changes (MHCs). Overall, nine of the 110 PFAS targeted were detected in Tilefish plasma at relatively high frequencies. Plasma concentrations of total PFAS (Σ9PFAS) ranged from below the detection limit to 27.9 ng g−1 w.w. Significant regional differences were observed with the highest concentrations of PFAS detected in the north central region of the GoM, where substantial industrialization and discharges from the Mississippi River occur. Compared to most wildlife and matrices analyzed globally, the PFAS profiles in Tilefish were unique as they are dominated by PFUnDA. Profile differences are hypothesized to be the result of Tilefish's distinctive lifestyle, habitat, diet, and partitioning characteristics of long-chain PFAS. Several MHCs were identified in this subset of Tilefish that could be detrimental to their health. Significant correlations between PFAS concentrations and biometric indices and MHCs were evident, however, additional research is needed to investigate the role PFAS and PFAS combined with chemical admixtures may play in inducing observed hepatic changes and other physiological effects in Tilefish. These findings give insight into the fate of PFAS at depth in aquatic ecosystems and are cause for concern regarding the health of other deep water benthic biota in GoM and other deepwater sinks for PFAS.

Environmental drivers of golden tilefish (Lopholatilus chamaeleonticeps) commercial landings and catch‐per‐unit‐effort

AbstractWe explored a range of potential low and high‐frequency environmental drivers of fishery production (landings) and catch‐per‐unit‐effort (CPUE) for northern and southern stocks of golden tilefish (Lopholatilus chamaeleonticeps), a stenothermic species that prefers a narrow band of habitat along the continental shelf and upper slope of the eastern US. Random forest regression, a machine learning technique, was used to examine the impact of numerous and sometimes correlated environmental covariates. We used important random forest covariates to inform construction of a more parsimonious generalized additive mixed model for each data type and stock. We identified several potential environmental drivers of golden tilefish fishery and stock dynamics, including low‐frequency climate indices, oceanographic currents, and high‐frequency oceanographic conditions. Both Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation indices were associated with historical golden tilefish landings for the northern stock spanning 1915–2000 at lags of 7 and 3–4 years, respectively. CPUE for both stocks (north: 1995–2017, south: 1994–2018) was associated with the AMO and oceanographic currents. In addition, northern stock CPUE was negatively related to Labrador Current flow and positively related to northerly position of the Gulf Stream. Southern stock CPUE was associated with seasonal Florida Current transport, monthly sea surface temperatures, and latitude. Oceanographic currents and water temperature primarily influenced within‐year CPUE, indicating a potential effect on adult fish or fisher behavior. In contrast, low‐frequency climate indices were associated with CPUE and landings at lags of 3–7 years, indicating their primary impact was on recruitment strength.

Regional variation in mercury bioaccumulation among NW Atlantic Golden (Lopholatilus chamaeleonticeps) and Blueline (Caulolatilus microps) Tilefish

Mercury (Hg) concentrations in fishes from the NW Atlantic Ocean pose concern due to the importance of this region to U.S. fisheries harvest. In this study, total Hg (THg) concentrations and nitrogen stable isotope (δ15N) values were quantified in muscle tissues sampled from Golden (Lopholatilus chamaeleonticeps) and Blueline (Caulolatilus microps) Tilefish collected during a fishery-independent survey conducted in the NW Atlantic to compare bioaccumulation patterns between these species. Total Hg concentrations averaged (±SD) 0.4 ± 0.4 μg/g dry weight (d.w.) for L. chamaeleonticeps and 1.1 ± 0.7 μg/g d.w. for C. microps with <2% of all sampled fish, those >70 cm fork length, exceeding the most restrictive USEPA regulatory guidelines for human consumption (THg > 0.46 μg/g w.w.), when converted to wet weight concentrations. The THg concentrations reported here for individuals from the NW Atlantic stock are comparable to those reported for similarly sized individuals collected from the SW Atlantic stock but notably lower than those reported for Gulf of Mexico L. chamaeleonticeps, indicating different Hg exposure and assimilation kinetics for fish from the NW Atlantic, and highlights the broad geographic variability of Hg bioaccumulation among Tilefish stocks. Caulolatilus microps had higher δ15N values relative to L. chamaeleonticeps and a pattern of decreasing THg concentrations was also present from south to north across the study range. It is concluded that this trophic difference and spatial pattern in Tilefish THg concentrations emphasizes the habitat and resource partitioning mechanisms described for these sympatric species that permits their coexistence in the continental shelf environment. Importantly, regional variability in THg concentrations accentuate the possible roles of fine-scale biotic and abiotic processes that can act to regulate Hg bioaccumulation among individuals and species.

Separation of realized ecological niche axes among sympatric tilefishes provides insight into potential drivers of co-occurrence in the NW Atlantic.

Golden and Blueline Tilefish (Lopholatilus chamaeleonticeps and Caulolatilus microps) are keystone taxa in northwest (NW) Atlantic continental shelf‐edge environments due to their biotic (trophic‐mediated) and abiotic (ecosystem engineering) functional roles combined with high‐value fisheries. Despite this importance, the ecological niche dynamics (i.e., those relating to trophic behavior and food‐web interactions) of these sympatric species are poorly understood, knowledge of which may be consequential for maintaining both ecosystem function and fishery sustainability. We used stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) to build realized ecological niche hypervolumes to serve as proxies for diet and production use patterns of L. chamaeleonticeps and C. microps. We hypothesized that: (a) species exhibit ontogenetic shifts in diet and use of production sources; (b) species acquire energy from spatially distinct resource pools that reflect a sedentary life‐history and differential use of the continental shelf‐edge; and (c) species exhibit differentiation in one or more measured niche axes. We found evidence for ontogenetic shifts in diet (δ15N) but not production source (δ13C) in both species, suggesting a subtle expansion of measured ecological niche axes. Spatial interpolation of stable isotope ratios showed distinct latitudinal gradients; for example, individuals were 13C enriched in northern and 15N enriched in southern regions, supporting the assertion that tilefish species acquire energy from regional resource pools. High isotopic overlap was observed among species (≥82%); however, when hypervolumes included depth and region of capture, overlap among species substantially decreased to overlap estimates of 15%–77%. This suggests that spatial segregation could alleviate potential competition for resources among tilefish species inhabiting continental shelf‐edge environments. Importantly, our results question the consensus interpretation of isotopic overlap estimates as representative of direct competition among species for shared resources or habitats, instead identifying habitat segregation as a possible mechanism for coexistence of tilefish species in the NW Atlantic.

A First Comprehensive Baseline of Hydrocarbon Pollution in Gulf of Mexico Fishes

Despite over seven decades of production and hundreds of oil spills per year, there were no comprehensive baselines for petroleum contamination in the Gulf of Mexico (GoM) prior to this study. Subsequent to the 2010 Deepwater Horizon (DWH) spill, we implemented Gulf-wide fish surveys extending over seven years (2011–2018). A total of 2,503 fishes, comprised of 91 species, were sampled from 359 locations and evaluated for biliary polycyclic aromatic hydrocarbon (PAH) concentrations. The northern GoM had significantly higher total biliary PAH concentrations than the West Florida Shelf, and coastal regions off Mexico and Cuba. The highest concentrations of biliary PAH metabolites occurred in Yellowfin Tuna (Thunnus albacares), Golden Tilefish (Lopholatilus chamaeleonticeps), and Red Drum (Sciaenops ocellatus). Conversely, biliary PAH concentrations were relatively low for most other species including economically important snappers and groupers. While oil contamination in most demersal species in the north central GoM declined in the first few years following DWH, more recent increases in exposure to PAHs in some species suggest a complex interaction between multiple input sources and possible re-suspension or bioturbation of oil-contaminated sediments. This study provides the most comprehensive baselines of PAH exposure in fishes ever conducted for a large marine ecosystem.

Spatial contrasts in hepatic and biliary PAHs in Tilefish (Lopholatilus chamaeleonticeps) throughout the Gulf of Mexico, with comparison to the Northwest Atlantic

A multinational demersal longline survey was conducted on the Gulf of Mexico continental shelf over the years 2015 and 2016 to generate a Gulf-wide baseline of polycyclic aromatic hydrocarbon (PAH) concentrations in demersal fishes. Tilefish (Lopholatilus chamaeleonticeps) were sampled in all regions of the Gulf of Mexico for biometrics, bile, and liver. Tilefish liver was also obtained from surveys in the northwest Atlantic Ocean for comparison. Liver tissues (n = 305) were analyzed for PAHs and select alkylated homologs using QuEChERS extractions and gas chromatography tandem mass spectrometry. Bile samples (n = 225) were analyzed for biliary PAH metabolites using high-performance liquid chromatography with fluorescence detection. Spatial comparisons indicate the highest levels of PAH exposure and hepatic accumulation in the north central Gulf of Mexico, with decreasing concentrations moving from the north central Gulf counterclockwise, and an increase on the Yucatán Shelf. Hepatic PAH concentrations were similar between the Gulf of Mexico and the northwest Atlantic, however, Tilefish from the northwest Atlantic had higher concentrations and more frequent detection of carcinogenic high molecular weight PAHs. Overall, results demonstrate that PAH pollution was ubiquitous within the study regions, with recent exposure and hepatic accumulation observed in Tilefish from both the Gulf of Mexico and northwest Atlantic.

Associations Between Chronic Exposure to Polycyclic Aromatic Hydrocarbons and Health Indices in Gulf of Mexico Tilefish (Lopholatilus chamaeleonticeps) Post Deepwater Horizon.

A time series of polycyclic aromatic hydrocarbon (PAH) data was collected for Gulf of Mexico demersal fishes in the years following the Deepwater Horizon oil spill (2012–2017). Tilefish (Lopholatilus chamaeleonticeps) were sampled via demersal longline at repeat stations in the northern Gulf of Mexico in 2012 to 2015 and 2017. Bile samples (n = 256) were analyzed via high‐performance liquid chromatography with fluorescence detection for PAH metabolites as a biomarker of exposure to PAHs. Liver tissues (n = 230) were analyzed for accumulation of PAHs and alkylated homologs via quick, easy, cheap, effective, rugged, and safe (QuEChERS) extractions and gas chromatography–tandem mass spectrometry quantification. Over the 6‐yr time series, exposure to petrogenic PAHs increased by an average of 178%, correlating with an average 22% decline in Fulton's condition factor. The decline in Fulton's condition factor was positively correlated with a 53% decline in percentage of liver lipid. There was no accumulation of PAHs in liver tissue over time. Together, these results suggest that increasing and chronic PAH exposure and metabolism may be taxing the energy budgets of tilefish, particularly adult females, with potentially negative impacts on fitness. Environ Toxicol Chem 2019;38:2659–2671. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Mercury bioaccumulation in Tilefish (Lopholatilus chamaeleonticeps) from offshore waters of South Carolina, USA

Mercury (Hg) concentrations in Tilefish (Lopholatilus chamaeleonticeps) have been reported to be one of the highest of all fish species, resulting in advisories that, historically, have recommended zero consumption. The current study assesses Hg bioaccumulation in Tilefish targeted by the commercial fisheries operating off the coast of South Carolina, USA. We provide results for an under-sampled region and explore how life history potentially impacts Hg uptake in Tilefish. Mercury concentration in Tilefish muscle tissue ranged from 0.10 to 0.99 ppm, with a mean of 0.23 ppm (n = 63). The majority of Tilefish samples (95%) were within the “Good Choices” range for consuming at least one serving per week, with 62% being within the range considered best for eating two meals a week”, per suggestion by the US EPA and US FDA (2017). The present study of Tilefish from the western Atlantic further substantiates the importance of monitoring Hg in commercial fish species regionally.

Factors that influence discarding in the Gulf of Mexico commercial grouper-tilefish IFQ reef fish fishery

Factors potentially affecting fish discarding were evaluated for species managed under the Gulf of Mexico grouper-tilefish individual fishing quota (GT-IFQ) program. Thirteen commercially important species are managed under the GT-IFQ program. Some of the more commonly caught species in the program include red grouper (Epinephelus morio), gag (Mycteroperca microlepis), speckled hind (Epinephelus drummondhayi), golden tilefish (Lopholatilus chamaeleonticeps), and blueline tilefish (Caulolatilus microps). It is necessary to determine why discards are occurring to develop a future discard mitigation strategy. Logistic models were constructed using data from the Southeast Fisheries Science Center’s (SEFSC) Reef Fish Observer Program (RFOP) with covariates of fish length, available allocation, gear type, calendar year quarter, and year to infer reasons for discarding. The results from RFOP models in conjunction with self-reported discard information from the SEFSC Supplemental Discard Logbook program determined that discarding due to fish length selection, not related to minimum a size limit, is occurring for golden tilefish, speckled hind, yellowedge grouper (Epinephelus flavolimbatus), and snowy grouper (Hyporthodus niveatus). Other dynamics such as multi-species quota discarding are likely responsible for discards of blueline tilefish. Based on the results of the study, potential changes to the GT-IFQ program such as additional flexibility measures were identified as potential management strategies for decreasing discards. A similar approach to inferring why discarding is occurring could be used in the other regions for more effective management promoting long-term sustainability of valuable fisheries.

DNA barcode identification of commercial fish sold in Mexican markets

The substitution of high-value fish species for those of lower value is common practice. Although numerous studies have addressed this issue, few have been conducted in Mexico. In this study, we sought to identify fresh fillets of fish, sharks, and rays using DNA barcodes. We analyzed material from "La Viga" in Mexico City, and other markets located on the Gulf and Caribbean coasts of Mexico. From 134 samples, we obtained sequences from 129, identified to 9 orders, 28 families, 38 genera, and 44 species. The most common species were Seriola dumerili, Pangasianodon hypophthalmus, Carcharhinus falciformis, Carcharhinus brevipinna, and Hypanus americanus. Pangasianodon hypophthalmus was most commonly used as a substitute for higher-value species. The substitution rate was 18% of the total. A review of the conservation status of the specimens identified against the IUNC list enabled us to establish that some species marketed in Mexico are threatened: Makaira nigricans, Lachnolaimus maximus, Hyporthodus flavolimbatus, and Isurus oxyrinchus are classified as vulnerable; Lopholatilus chamaeleonticeps and Sphyrna lewini are endangered; and the status of Hyporthodus nigritus is critical. These results will demonstrate to the Mexican authorities that DNA barcoding is a reliable tool for species identification, even when morphological identification is difficult or impossible.

Does the Lunar Cycle Affect Reef Fish Catch Rates?

AbstractThe lunar cycle was examined as a potential source of variation in CPUE for the most common commercial reef fish species captured in the Gulf of Mexico. Using fishery observer data for species captured with bottom longline and vertical line gear types, the analyses modeled CPUE with two different approaches: (1) a generalized additive model with cyclic splines to explain nonlinear variations with the 29.5‐d lunar cycle; and (2) a generalized linear model using periodic regression with the sine and cosine functions to describe cyclic variations in CPUE. A lunar effect on catch rates was detected for Red Grouper Epinephelus morio and Tilefish Lopholatilus chamaeleonticeps; however, no lunar effect was detected for Yellowedge Grouper Hyporthodus flavolimbatus, Red Snapper Lutjanus campechanus, or Vermilion Snapper Rhomboplites aurorubens based on either method. The lunar effect in the bottom longline fishery differed between species, with increased CPUE consistently predicted to occur near the new moon for Red Grouper and to take place proximal to the full moon for Tilefish. Red Grouper captured with vertical line gear had two CPUE increases predicted around the waxing and waning lunar phases. Inconsistencies in lunar effect between gear types for Red Grouper were present, possibly due to different mechanisms affecting CPUE. Results suggest that lunar cycles influence catch rates for some of the reef fish species examined and should be considered as potential environmental covariates for standardizing nominal CPUE.Received October 14, 2016; accepted February 2, 2017 Published online April 11, 2017

Limited-access Privilege Programs in the Mid-Atlantic Fisheries

The use of limited-access privilege programs (LAPP’s) in fi sheries management offers an incentive for collaborative management while also addressing economic incentives. This paper provides an overview of the development and use of limited access privilege programs by looking at a review of potential benefi ts and the arguments against them. It focuses on examining Introduction A catch share program is a generic term associated with fi shery management strategies that allocate a specifi c percentage of the fi shery catch to individuals, cooperatives, communities, or other entities. It includes more specifi c programs such as Limited Access Privilege Programs (LAPP’s). The Fishery Conservation and Management Act of 1976 (later renamed Magnuson Fishery Conservation and Management Act and then Magnuson-Stevens Fishery Conservation and Management Act) created a new national program for the conservation and management of marine fi shery resources. Fishery Management Plans (FMP’s) were to be developed by eight regional fi shery management councils and implemented by NMFS. In 2006, Magnuson-Stevens Fishery Conservation and Management Reauthorization Act (hereafter referred to as the Reauthorization Act), urged regional councils to use more LAPP’s in federal fi sheries management (NMFS, 2007). LAPP’s had also been specifi ed as a priority in the U.S. Ocean Action Plan1 and Executive Order 12866, signed by President William J. Clinton in 1993, which established the guiding principles agencies must follow when developing regulations. In 2005, under President George W. Bush, NMFS pledged to double the number of fi sheries managed under LAPP’s (from 8 to 16) by 2010. In 2010, the Obama administration solidifi ed its commitment to catch shares by issuing a Catch Share Policy (NOAA, 2010) to provide guidance and support on the design, implementation, and monitoring of catch share programs. This policy provides a foundation for facilitating the widespread consideration of catch share fi shery management plans (FMP’s) while enabling local fi shermen and communities to be part of the process. This article explains what LAPP’s are, how they work, and what benefi ts and costs can be expected from their implementation. First, a brief history of fi sheries management helps explain how LAPP’s evolved. This is followed by an explanation of the economic incentives behind LAPP’s, in the context of two fi sheries in the U.S. Mid-At1The plan, subtitled The Bush Administration’s Response to the U.S. Commission on Ocean Policy, is available online at http://www.cmts. gov/downloads/US_ocean_action_plan.pdf. lantic Region—the Atlantic surfclam/ ocean quahog, Spisula solidissima/ Arctica islandica, fi shery and the tilefi sh (also known as the golden tilefi sh), Lopholatilus chamaeleonticeps, fi shery. Limited-Access Privilege Programs Prior to 1976, U.S. marine fi sheries were managed in a completely openaccess environment, with few restrictions placed on foreign or domestic fi shermen or their activities. Competition among fi shermen under open-access conditions creates incentives for the industry to expand, over-exploit, and eventually deplete the resource (as described by the popular phrase “tragedy of the commons”), resulting in overcapacity and overfi shing (Anderson and Holliday, 2007). With the passage of the Fishery Conservation and Management Act of 1976, fi sheries management began to evolve, using various combinations of input and output controls. Input controls were put in place to restrict vessel activity in various manners, by regulating the type and/or amount of gear, or by restricting fi shing areas or fi shing times. Output controls were also established that aimed to limit the amount of catch or harvest in a fi shery, such as limits on a total allowable catch (TAC) or individual trip catch. These too had a downside. A hard TAC (a predetermined catch level that is paired with a within-season closure provision) implemented for a fi shery as a whole often leads to heightened competition to catch as much fi sh as possible before the annual limit is reached; a “derby fi shery” in which there is a “race to fi sh.” Gear restrictions and trip limits the historical context of two specifi c applications in the Mid-Atlantic—the Atlantic surfclam, Spisula solidissima, and ocean quahog, Arctica islandica, fi shery, and the tilefi sh, Lopholatilus chamaeleonticeps, fi shery. Structural components of these programs are presented along with a description of notable changes in these two fi sheries since the implementation of LAPP’s.

PAH Exposure in Gulf of Mexico Demersal Fishes, Post-Deepwater Horizon

Following the 2010 Deepwater Horizon (DWH) blowout, we surveyed offshore demersal fishes in the northern Gulf of Mexico (GoM) in 2011-2013, to assess polycyclic aromatic hydrocarbon (PAH) exposure. Biliary PAH metabolites were estimated in 271 samples of golden tilefish (Lopholatilus chamaeleonticeps), king snake eel (Ophichthus rex), and red snapper (Lutjanus campechanus), using high performance liquid chromatography with fluorescence detection. Mean concentration of naphthalene metabolites in golden tilefish (240 μg g(-1)) was significantly higher (p = 0.001) than in red snapper (61 μg g(-1)) or king snake eel (38 μg g(-1)). Biliary naphthalene metabolite concentration decreased over the study period in red snapper (58%) and king snake eel (37%), indicating likely episodic exposure, while concentrations were persistently high in golden tilefish. Naphthalene metabolite levels measured in golden tilefish are among the highest concentrations measured in fishes globally, while concentrations for red snapper and king snake eel are similar to pre-DWH levels measured in GoM species. In contrast, concentrations of benzo[a]pyrene metabolites were similar for all three species (p = 0.265, mean 220 ng g(-1)) and relatively low when compared to GoM, global data and previous oil spills. These data support previous findings that fish life history and physiology play significant roles in exposure and uptake of PAH pollution.

Sedimentary facies, geomorphic features and habitat distribution at the Hudson Canyon head from AUV multibeam data

Mapping of physical benthic habitats at the head of Hudson Canyon was performed by means of integrated analysis of acoustic data, video surveys and seafloor sampling. Acoustic mapping, performed using AUV-mounted multibeam sonar, provided ultra-high resolution bathymetric and backscatter imagery for the identification of geomorphological features and the characterization of surficial sediments. Habitat characterization in terms of seafloor texture and identification of benthic and demersal communities was accomplished by visual analysis of still photographs from underwater vehicles. Habitat classes were defined on the basis of the seafloor texture observed on photos and then compared with the geophysical data in order to associate habitats to acoustic classes and/or geomorphological features. This enabled us to infer habitat distribution on the basis of morpho-acoustic classes and extrapolate results over larger areas. Results from bottom trawling were used to determine the overall biodiversity within the identified habitats. Our analysis revealed a variety of topographic and sedimentological structures that provide a wide range of physical habitats. A variety of sandy and muddy substrates, gravel patches and mudstone outcrops host rich and varied faunal assemblages, including cold-water corals and sponge communities. Pockmark fields below 300m depth suggest that methane-based chemosynthetic carbonate deposition may contributes to creation of specific benthic habitats. Hummocky terrain has been delineated along the canyon rims and associated with extensive, long-term burrowing activity by golden tilefish (Lopholatilus chamaeleonticeps). These results show the relationships of physical features to benthic habitat variation, support the notion of the area as a biodiversity hotspot and define essential habitats for planning of sustainable regional fisheries.

Age estimation and lead-radium dating of golden tilefish, Lopholatilus chamaeleonticeps

There is a growing concern over the lack of life history information for many deepwater fisheries species, including golden tilefish, Lopholatilus chamaeleonticeps. Fundamental life history characteristics, like age and growth, are required for effective, age-structured stock assessments and management decisions. A previous effort to validate golden tilefish age estimates using bomb radiocarbon dating was inconclusive, which led to an application of lead-radium dating in the current study. Lead-radium dating uses the radioactive disequilibrium of lead-210 (210Pb) and radium-226 (226Ra) in otoliths as an independent estimate of age. Ages were also estimated using traditional age estimates by counting growth zones in thin otolith sections and lead-radium dating was used to test these estimates. Radiometric ages (corrected for time since capture) were similar to age estimates from growth zone counts for two of the female age groups and the two oldest age groups of unknown sex, which confirmed an annual growth zone deposition. However, radiometric ages did not agree with age estimates from growth zone counts for males. The difference may be attributed to geographical variations in radium levels, growth rates and growth zone formation by gender or gender transition. Male sagittal otoliths revealed inconsistent growth zone patterns in thin sections, which may have contributed to underageing. Golden tilefish longevity was confirmed to 26 years.

Life on the edge: environmental determinants of tilefish (Lopholatilus chamaeleonticeps) abundance since its virtual extinction in 1882

AbstractUnlike many temperate marine species that alter spatial or depth distributions in response to environmental change, tilefish (Lopholatilus chamaeleonticeps) has such specific habitat requirements that off the coast of New England, USA, it is restricted to the normally warm-water, upper continental shelf slope, where it excavates and occupies burrows. In 1882, tens of millions of adult tilefish died suddenly following the intrusion of lethally cold Subarctic water into the tilefish habitat. Here we show that the same climate driver implicated in the 1882 event (the North Atlantic Oscillation: NAO) has also affected commercial tilefish landings throughout most of the 20th century by altering slope water temperatures and likely the tilefish's reproductive success. We also show that this temperature–landings relationship broke down in the 1970s coincident with dramatically increased exploitation. Reconstructions of decadal to millennial scale variations in slope water temperatures explain why no mass mortality occurred following the 2010 negative NAO anomaly, despite being similar in magnitude to the NAO anomaly that preceded the 1882 event.

Two new gonad-infecting philometrids (Nematoda: Philometridae) from the yellowedge grouper Hyporthodus flavolimbatus (Serranidae) and the great northern tilefish Lopholatilus chamaeleonticeps (Malacanthidae) in the northern Gulf of Mexico

Based on light and scanning electron microscopical studies, two new gonad-infecting species of Philometra Costa, 1845 (Nematoda: Philometridae) are described from marine perciform fishes in the northern Gulf of Mexico: P. hyporthodi n. sp. from the ovary of the yellowedge grouper Hyporthodus flavolimbatus (Poey) (Serranidae) and P. lopholatili n. sp. from the ovary of the great northern tilefish Lopholatilus chamaeleonticeps Goode & Bean (Malacanthidae). Philometra hyporthodi is mainly characterised by the body length of both the males (3.62-4.07 mm) and gravid female (105 mm), the length of the spicules (135-138 μm) and the presence of dorsal transverse lamella-like structures on the distal portion of the gubernaculum. Philometra lopholatili is distinguished by the presence of a distinct dorsal protuberance consisting of two dorsolateral lamellated parts separated from each other by a smooth median field, an uninterrupted mound on the male caudal extremity, the length of the spicules (165-189 μm) and the body length of the males (2.19-2.34 mm) and gravid female (280 mm). Philometra lopholatili is the first representative of the genus and the second philometrid species reported from fishes of the family Malacanthidae.

Changes in size and age at maturity of the northern stock of Tilefish (Lopholatilus chamaeleonticeps) after a period of overfishing

The modern fishery for Tilefish (Lopholatilus chamaeleonticeps) developed during the 1970s, offshore of southern New England, in the western North Atlantic Ocean. The population quickly became over exploited, with documented declines in catch rates and changes in demographic traits. In an earlier study, median size at maturity (L50) of males declined from 62.6 to 38.6 cm fork length (FL) and median age at maturity (A50) of males declined from 7.1 to 4.6 years between 1978 and 1982. As part of a cooperative research effort to improve the data-limited Tilefish assessment, we updated maturity parameter estimates through the use of an otolith aging method and macroscopic and microscopic evaluations of gonads. The vital rates for this species have continued to change, particularly for males. By 2008, male L50 and A50 had largely rebounded, to 54.1 cm FL and 5.9 years. Changes in female reproductive schedules were less variable among years, but the smallest L50 and youngest A50 were recorded in 2008. Tilefish are dimorphic, where the largest fish are male, and male spawning success is postulated to be socially mediated. These traits may explain the initial rapid decline and the subsequent rebound in male L50 and A50 and less dramatic effects on females. Other factors that likely contribute to the dynamics of maturity parameter estimates are the relatively short period of overfishing and the amount of time since efforts to rebuild this fishery began, as measured in numbers of generations. This study also confirms the gonochoristic sexual pattern of the northern stock, and it reveals evidence of age truncation and relatively high proportions of immature Tilefish in the recent catch.

The Effects of Fishing, Climate Change, and Other Anthropogenic Disturbances on Red Grouper and Other Reef Fishes in the Gulf of Mexico

In this article, we consider the potential effects of anthropogenic disturbances on marine fish species known or suspected to be habitat engineers. The three species of interest inhabit different marine habitats at different life stages, and therefore can have significant influences across the sea floor at broad spatial scales. The primary species include the shallow-water Atlantic goliath grouper (Epinephelus itajara), which inhabits mangrove root systems as juveniles, and caves, shipwrecks, and rocky reefs as adults; red grouper (E. morio), which excavates habitat throughout its benthic life in Karst regions of the Gulf of Mexico and western Atlantic, from the coast to the shelf-edge; and tilefish (Lopholatilus chamaeleonticeps), a species that lives on the continental slope and constructs elaborate, pueblo-esque burrows. The anthropogenic disturbances of greatest interest in the Gulf of Mexico include fishing, hypoxia, red tide, oil and gas exploration, and climatic change. We suggest that to understand the broader effects of both natural and anthropogenic disturbances on biomass and productivity in these species requires that we first understand the strength of interactions between them and the other species residing within their communities (e.g., predators, prey, commensals, and mutualists).