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Mitchell A. Roffer - One of the best experts on this subject based on the ideXlab platform.
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Linkages between environmental conditions and recreational King Mackerel (Scomberomorus cavalla) catch off west-central Florida
Fisheries Oceanography, 2009Co-Authors: Carrie C. Wall, Frank E. Muller-karger, Mitchell A. RofferAbstract:Catch statistics for the King Mackerel (Scomberomorus cavalla) recreational fishery off west-central Florida were derived from angler interviews conducted during 19 seasonal tournaments held in April‐May and October‐November of 2004 and 2005. Fishing location, number of fish per line per hour (catch per unit effort), and presence of baitfish from the tournament data were examined in the context of bathymetric gradients and other benthic features (e.g., wrecks or artificial reefs), and the location and persistence of oceanic fronts mapped using satellite imagery of sea surface temperature (AVHRR) and ocean color (MODIS and SeaWiFS). Generalized linear models were applied to identify the relationship between King Mackerel catch rates and environmental data. The distance of fishing activity to the nearest front varied substantially, particularly when winds and front position were variable. However, baitfish presence with proximity to water clarity fronts (as defined by waterleaving radiance at 443 nm) significantly influenced successful King Mackerel catch. Positive catch rates were significantly influenced by chlorophyll values and period (season and year). Additionally, intermediate water clarity (in the range 0.7‐1.0 mW cm )2 lm )1 sr )1 ) led to higher catch rates. Decreased water quality, primarily associated with a large Karenia brevis red tide, led to a lower number of catch and lower catch rates (122 King Mackerel, 0.13 catch per unit effort) in fall 2005, compared to spring 2004 (179, 0.14), fall 2004 (360, 0.17) and spring 2005 (296, 0.21), despite a consistent seasonal effort.
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Satellite remote sensing of surface oceanic fronts in coastal waters off west–central Florida
Remote Sensing of Environment, 2008Co-Authors: Carrie C. Wall, Frank E. Muller-karger, Mitchell A. Roffer, Wensheng Yao, Mark E. LutherAbstract:Abstract Two algorithms designed to detect deepwater oceanic features and arbitrary edge profiles were tuned to automatically delineate fronts in coastal waters off west–central Florida using satellite-derived sea surface temperature (SST), chlorophyll-a concentration (Chl), normalized water-leaving radiance (nLw), and fluorescence line height (FLH) images during select periods in the spring and fall of 2004 and 2005. The dates correspond to recreational King Mackerel, Scomberomorus cavalla, tournaments. A histogram-based algorithm was useful to detect coastal surface SST, nLw, and FLH fronts, specifically. A gradient-based algorithm, with a smaller kernel box of 3 × 3 pixels, best identified nearshore (
Carrie C. Wall - One of the best experts on this subject based on the ideXlab platform.
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Linkages between environmental conditions and recreational King Mackerel (Scomberomorus cavalla) catch off west-central Florida
Fisheries Oceanography, 2009Co-Authors: Carrie C. Wall, Frank E. Muller-karger, Mitchell A. RofferAbstract:Catch statistics for the King Mackerel (Scomberomorus cavalla) recreational fishery off west-central Florida were derived from angler interviews conducted during 19 seasonal tournaments held in April‐May and October‐November of 2004 and 2005. Fishing location, number of fish per line per hour (catch per unit effort), and presence of baitfish from the tournament data were examined in the context of bathymetric gradients and other benthic features (e.g., wrecks or artificial reefs), and the location and persistence of oceanic fronts mapped using satellite imagery of sea surface temperature (AVHRR) and ocean color (MODIS and SeaWiFS). Generalized linear models were applied to identify the relationship between King Mackerel catch rates and environmental data. The distance of fishing activity to the nearest front varied substantially, particularly when winds and front position were variable. However, baitfish presence with proximity to water clarity fronts (as defined by waterleaving radiance at 443 nm) significantly influenced successful King Mackerel catch. Positive catch rates were significantly influenced by chlorophyll values and period (season and year). Additionally, intermediate water clarity (in the range 0.7‐1.0 mW cm )2 lm )1 sr )1 ) led to higher catch rates. Decreased water quality, primarily associated with a large Karenia brevis red tide, led to a lower number of catch and lower catch rates (122 King Mackerel, 0.13 catch per unit effort) in fall 2005, compared to spring 2004 (179, 0.14), fall 2004 (360, 0.17) and spring 2005 (296, 0.21), despite a consistent seasonal effort.
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Satellite remote sensing of surface oceanic fronts in coastal waters off west–central Florida
Remote Sensing of Environment, 2008Co-Authors: Carrie C. Wall, Frank E. Muller-karger, Mitchell A. Roffer, Wensheng Yao, Mark E. LutherAbstract:Abstract Two algorithms designed to detect deepwater oceanic features and arbitrary edge profiles were tuned to automatically delineate fronts in coastal waters off west–central Florida using satellite-derived sea surface temperature (SST), chlorophyll-a concentration (Chl), normalized water-leaving radiance (nLw), and fluorescence line height (FLH) images during select periods in the spring and fall of 2004 and 2005. The dates correspond to recreational King Mackerel, Scomberomorus cavalla, tournaments. A histogram-based algorithm was useful to detect coastal surface SST, nLw, and FLH fronts, specifically. A gradient-based algorithm, with a smaller kernel box of 3 × 3 pixels, best identified nearshore (
John R. Gold - One of the best experts on this subject based on the ideXlab platform.
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Population structure of King Mackerel (Scomberomorus cavalla) around peninsular Florida, as revealed by microsatellite DNA*
2002Co-Authors: John R. Gold, Elena Pak, Doug A. DevriesAbstract:A total of 1006 King mack erel (Scomberomorus cavalla) repre senting 20 discrete samples collected be tween 1996 and 1998 along the east (Atlantic) and west (Gulf) coasts of Flor ida and the Florida Keys were assayed for allelic variation at seven nuclear encoded microsatellites. No significant deviations from Hardy-Weinberg equi librium expectations were found for six of the microsatellites, and genotypes at all microsatellites were independent. Allele distributions at each microsatel lite were independent of sex and age of individuals. Homogeneity tests of spa tial distributions of alleles at the micro satellites revealed two weakly divergent “genetic” subpopulations or stocks of King Mackerel in Florida waters—one along the Atlantic coast and one along the Gulf coast. Homogeneity tests of allele distributions when samples were pooled along seasonal (temporal) boundaries, consistent with the tem poral boundaries used currently for stock assessment and allocation of the King Mackerel resource, were nonsig nificant. The degree of genetic diver gence between the two “genetic” stocks was small: on average, only 0.19% of the total genetic variance across all samples assayed occurred between the two regions. Cluster analysis, assign ment tests, and spatial autocorrelation analysis did not generate patterns that were consistent with either geographic or spatial-temporal boundaries. King Mackerel sampled from the Florida Keys could not be assigned unequivo cally to either “genetic” stock. The gen etic data were not consistent with cur rent spatial-temporal boundaries em ployed in stock assessment and allo cation of the King Mackerel resource. The genetic differences between King Mackerel in the Atlantic versus those in the Gulf most likely stem from reduced gene flow (migration) between the Atlantic and Gulf in relation to gene flow (migration) along the Atlantic and Gulf coasts of peninsular Florida. This difference is consistent with findings for other marine fishes where data indi cate that the southern Florida penin sula serves (or has served) as a biogeo graphic boundary. Manuscript accepted 4 March 2002. Fish. Bull. 100:491–509 (2002). Population structure of King Mackerel (Scomberomorus cavalla) around peninsular Florida, as revealed by microsatellite DNA*
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Microsatellite variation suggests substantial gene flow between King Mackerel (Scomberomorus cavalla) in the western Atlantic Ocean and Gulf of Mexico
Fisheries Research, 2002Co-Authors: Richard E. Broughton, Leah B Stewart, John R. GoldAbstract:Abstract We developed microsatellite loci for King Mackerel (Scomberomorus cavalla) and used them to investigate population structure and gene flow between samples from regional localities in the western Atlantic Ocean (Atlantic) and Gulf of Mexico (Gulf). Based on mark-recapture and spatial–temporal sampling, King Mackerel in US waters have been perceived as organized into two or more “migratory units” that tend to move in the spring from southern wintering areas off south Florida and the Yucatan peninsula to more northern spawning areas along the southeastern US coast and the northern Gulf. We surveyed allelic variation at five microsatellite loci between samples of King Mackerel from eight geographic localities in the Atlantic and Gulf. Tests of homogeneity in allele distribution indicated that two samples from the northern Gulf (Port Aransas, TX, and Gulfport, MS) differed significantly from the remaining samples. However, no significant genetic differences were found between samples representing geographic extremes, and no significant geographic patterns of genetic divergence were found when samples were combined into regional groupings reflecting current hypotheses of population structure. There also was no evidence of an isolation-by-distance effect. We hypothesize that the regional migratory groupings in King Mackerel do not restrict gene flow to the extent that significant genetic population structure may arise.
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Mitochondrial DNA variation in King Mackerel (Scomberomorus cavalla) from the western Atlantic Ocean and Gulf of Mexico
Marine Biology, 1997Co-Authors: John R. Gold, Á. Ý. Kristmundsdóttir, Linda R. RichardsonAbstract:King Mackerel (Scomberomorus cavalla Cuvier) collected in 1992 and 1993 from 13 localities along the Atlantic coast of the southeastern USA and in the northern Gulf of Mexico were surveyed for variation in mitochondrial (mt)DNA and a nuclear-encoded dipeptidase locus (PEPA-2). Both polymorphic and fixed mtDNA restriction sites were identified and mapped using conventional and polymerase chain-reaction (PCR)-based methods. Heterogeneity in mtDNA haplotype frequencies was found only in comparisons of pooled haplotypes from Atlantic localities versus pooled haplotypes from Gulf localities. This finding indicates weak genetic divergence between King Mackerel from the Atlantic and those from the Gulf. Frequencies of two PEPA-2 alleles essentially paralleled previous findings: one allele (PEPA-2a) was common among samples from western Gulf localities, whereas the other allele (PEPA-2b) was common among samples from Atlantic and eastern Gulf localities. There was considerable variation in PEPA-2 allele frequencies within broadly-defined regions. Variation in mtDNA haplotypes and PEPA-2 genotypes was independent, as was variation in mtDNA haplotypes with sex or age of individuals. Variation in PEPA-2 genotypes was not independent of sex or age of individuals. The latter result suggests that frequencies of PEPA-2 alleles in samples of King Mackerel may stem, in part, from sex and age distributions of individuals within samples, and indicates that caution should be exercised in using allelic variation at PEPA-2 as a measure of population (stock) structure in King Mackerel. The discordance in spatial patterning of mtDNA haplotypes versus PEPA-2 alleles across the Gulf (i.e. homogeneity in mtDNA haplotype frequencies versus heterogeneity in PEPA-2 allele frequencies) may be due to either female excess at several localities, sex-biased migration, or both. Observed patterns of genetic variation also are consistent with the hypothesis that King Mackerel in the western Atlantic may have been subdivided during Pleistocene glaciation, and that the current distribution of PEPA-2 alleles may be a historical artefact.
John C Whitehead - One of the best experts on this subject based on the ideXlab platform.
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2006. A Comparison of Contingent Valuation Method and Random Utility Model Estimates of the Value of Avoiding Reductions in King Mackerel Bag Limits
2014Co-Authors: John C WhiteheadAbstract:This paper estimates the value of King Mackerel bag limit changes with both stated and revealed preference methods. The 1997 Marine Recreational Fishery Statistical Survey allows estimation of the value of avoiding bag limit reductions with the random utility model and the contingent valuation method. Using the contingent valuation method, the willingness to pay to avoid a one fish reduction in the bag limit is $2.45 per year. Using the random utility model, the willingness to pay to avoid a one fish reduction in the bag limit for a two-month time period is $10.83. Considering several methodological issues, the difference in willingness to pay between the stated and revealed preference methods is in the expected direction.
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www.business.appstate.edu/economics Valuing Bag Limits in the North Carolina Charter Boat Fishery with Combined Revealed and Stated Preference Data*
2011Co-Authors: John C Whitehead, Christopher F. Dumas, Craig E. Landry, Jim Herstine, Craig E. L, Associate Professor, Jim Herstine ProfessorAbstract:1 Abstract: We use telephone survey data on charter boat anglers to estimate demand models to value snapper-grouper and King Mackerel bag limits in the North Carolina forhire fishery. The telephone survey presents respondents with hypothetical situations about higher charter fees and lower snapper-grouper and King Mackerel bag limits and asks about the number of trips they would take in each situation. Stated preference trip responses are used in a jointly estimated revealed and stated preference demand model. We find that reduction in the snapper-grouper bag limit from 15 fish to 7 fish would reduce the annual aggregate value of charter boat fishing by 29 % due to quality effects. The reduction in the snapper-grouper bag limit would reduce the number of charter boa
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Valuing Bag Limits in the North Carolina Charter Boat Fishery with Combined Revealed and Stated Preference Data
Marine Resource Economics, 2011Co-Authors: John C Whitehead, Christopher F. Dumas, Craig E. Landry, Jim HerstineAbstract:We use telephone survey data on charter boat anglers to estimate demand models to value snapper-grouper and King Mackerel bag limits in the North Carolina for-hire fishery. The telephone survey presents respondents with hypothetical situations about higher charter fees and lower snapper-grouper and King Mackerel bag limits and asks about the number of trips they would take in each situation. Stated preference trip responses are used in a jointly estimated revealed and stated preference demand model. We find that reduction in the snapper-grouper bag limit from 15 fish to 7 fish would reduce the annual aggregate value of charter boat fishing by 29% due to quality effects. The reduction in the snapper-grouper bag limit would reduce the number of charter boat fishing trips by 25% and aggregate economic value an additional 25% million. Key Words: recreation demand, revealed preference, stated preference, charter fishing
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a comparison of contingent valuation method and random utility model estimates of the value of avoiding reductions in King Mackerel bag limits
Applied Economics, 2006Co-Authors: John C WhiteheadAbstract:This paper estimates the value of King Mackerel bag limit changes with both stated and revealed preference methods. The 1997 Marine Recreational Fishery Statistical Survey allows estimation of the value of avoiding bag limit reductions with the random utility model and the contingent valuation method. Using the contingent valuation method, the willingness to pay to avoid a one fish reduction in the bag limit is $2.45 per year. Using the random utility model, the willingness to pay to avoid a one fish reduction in the bag limit is $2.24 per trip and $7.71 for a two-month time period. Considering several methodological issues, the difference in willingness to pay between the stated and revealed preference methods is in the expected direction.
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contingent valuation and random utility model estimates of the recreational value of King Mackerel
2005Co-Authors: John C WhiteheadAbstract:This paper estimates the value of King Mackerel bag limit changes with both stated and revealed preference methods. The 1997 Marine Recreational Fishery Statistical Survey allows estimation of the value of avoiding bag limit reductions with the random utility model and the contingent valuation method. Using the contingent valuation method, the willingness to pay to avoid a one fish reduction in the bag limit is $2.45 per year. Using the random utility model, the willingness to pay to avoid a one fish reduction in the bag limit for a two-month time period is $10.83. Considering several methodological issues, the difference in willingness to pay between the stated and revealed preference methods is in the expected direction.
Dewi D. A. - One of the best experts on this subject based on the ideXlab platform.
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Analisa Perbedaan Umpan Dan Waktu Pengoperasian Pancing Ulur Terhadap Hasil Tangkapan Ikan Tenggiri (Scomberomorus Commerson) Di Perairan Prigi Kabupaten Trenggalek, Jawa Timur
Diponegoro University, 2015Co-Authors: Susanto M., Pramonowibowo P., Dewi D. A.Abstract:Nelayan perairan Prigi umumnya mengoperasikan pancing ulur. Salah satu ikan hasil tangkapan yang memiliki nilai ekonomis tinggi adalah ikan tenggiri (Scomberomorus commerson). Tujuan penelitian ini adalah untuk mengetahui adanya perbedaan hasil tangkapan ikan Tenggiri (Scomberomorus commerson) berdasarkan perbedaan umpan dan waktu penangkapan alat tangkap pancing ulur. Metode eksperimental pada penelitian ini menggunakan 2 variabel yaitu perbedaan umpan dan waktu penangkapan. Umpan yang digunakan pada penelitian ini adalah umpan alami danumpan buatan, serta perbedaan waktu penangkapan yaitu waktu penangkapan siang hari dan waktu penangkapan malam hari. waktu penangkapan siang hari memberikan jumlah tangkapan ikan Tenggiri (Scomberomorus commerson) lebih banyak menggunakan umpan alami. Dengan demikian penggunaan umpan alami dan buatan memiliki hasil tangkapan ikan Tenggiri (Scomberomorus commerson) yang berbeda. Kesimpulan dari penelitian ini adalah pancing ulur dengan menggunakan umpan alami memberikan hasil tangkapan ikan Tenggiri (Scomberomorus commerson) lebih banyak daripada pancing ulur menggunakan umpan buatan. Pancing ulur dengan waktu penangkapan malam hari memberikan hasil tangkapan Ikan Tenggiri (Scomberomorus commerson) lebih banyak dari pada waktu penangkapan siang hari. Fishers objectives in prigi are commonly using hand line. One kind of fish with high economic value is King Mackerel. The purpose of this research to know the difference of King Mackerel catches. With hand line use differentce bait and fishing time. Experimental method use 2 variables, were squid bait and fishing time. The baits used in this research were natural bait and artificial bait,elastic bait squid with fosfor, and the difference of fishing time, were the day light time and night. The result artificial bait was showed difference bait in the day light. So that natural bait and artificial bait using on hand line give different catches. The conclusion of this research that hand line fishing natural bait catch King Mackerel more than artificial bait. While the night fishing time catch King Mackerel more than the day fishing time
