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1. Fine-scale habitat selection of green sturgeon (Acipenser medirostris) within three spawning locations in the Sacramento River, California

Author

Wyman, M.T., Thomas, M.J., McDonald, R.R., Hearn, A.R., Battleson, R.D., Chapman, E.D., Kinzel, P., Minear, J.T., Mora, E.A., Nelson, J.M., Pagel, M.D., and Klimley, A.P.

Subjects
Sacramento River -- Natural history, Sturgeons -- Environmental aspects, Habitat selection -- Observations, Earth sciences
Abstract

Vast sections of the Sacramento River have been listed as critical habitat by the National Marine Fisheries Service for green sturgeon spawning (Acipenser medirostris), yet spawning is known to occur at only a few specific locations. This study reveals the range of physical habitat variables selected by adult green sturgeon during their spawning period. We integrated fine-scale fish positions, physical habitat characteristics, discharge, bathymetry, and simulated velocity and depth using a twodimensional hydraulic model (FaSTMECH). The objective was to create habitat suitability curves for depth, velocity, and substrate type within three known spawning locations over two years. An overall cumulative habitat suitability score was calculated that averaged the depth, velocity, and substrate scores over all fish, sites, and years. A weighted usable area index was calculated throughout the sampling periods for each of the three sites. Cumulative results indicate that the microhabitat characteristics most preferred by green sturgeon in these three spawning locations were velocities between 1.0 and 1.1 m/s, depths of 8-9 m, and gravel and sand substrate. This study provides guidance for those who may in the future want to increase spawning habitat for green sturgeon within the Sacramento River. De grands tronqons du fleuve Sacramento figurent sur la liste des habitats essentiels du National Marine Fisheries Service des Etats-Unis pour la reproduction de l'esturgeon vert (Acipenser medirostris), bien que la reproduction de ce poisson n'ait ete signalee que dans quelques endroits. La presente etude revele l'eventail de caracteristiques physiques de l'habitat selectionnees par les esturgeons verts adultes durant la periode de reproduction. Nous avons integre de l'information a echelle fine sur l'emplacement des poissons, les caracteristiques physiques de l'habitat, le debit, la bathymetrie et la vitesse et la profondeur simulees en utilisant un modele hydraulique bidimensionnel (FaSTMECH). L'objectif consistait a etablir des courbes d'adequation des habitats en fonction de la profondeur, de la vitesse et du type de substrat dans trois sites de reproduction connus sur une periode de deux ans. Une note cumulative globale d'adequation de l'habitat a ete calculee qui represente une moyenne des notes pour la profondeur, la vitesse et le substrat pour tous les poissons, sites et annees. Un index d'aire utilisable ponderee a ete calcule pour toutes les periodes d'echantillonnage pour chacun des trois sites. Les resultats cumulatifs indiquent que les caracteristiques des microhabitats privilegiees par les esturgeons verts dans ces trois sites de reproduction sont des vitesses de l'ecoulement de 1,0-1,1 m/s, des profondeurs de 8-9 m et des substrats de gravier et de sable. L'etude fournit de l'information utile aux efforts futurs visant a accroitre l'habitat de reproduction des esturgeons verts dans le fleuve Sacramento. [Traduit par la Redaction], Introduction Sturgeon species that inhabit lakes, estuaries, and oceans make upstream migrations in rivers to spawn within the headwaters of rivers. The geomorphology and physical properties of the spawning sites [...]

Published
2018
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2. Reply to: Shark mortality cannot be assessed by fishery overlap alone

Author

Queiroz, N., Humphries, N.E., Couto, A., Vedor, M., da Costa, I., Sequeira, A.M.M., Mucientes, G., Santos, A.M., Abascal, F.J., Abercrombie, D.L., Abrantes, K., Acuña-Marrero, D., Afonso, A.S., Afonso, P., Anders, D., Araujo, G., Arauz, R., Bach, P., Barnett, A., Bernal, D., Berumen, M.L., Lion, S.B., Bezerra, N.P.A., Blaison, A.V., Block, B.A., Bond, M.E., Bonfil, R., Bradford, R.W., Braun, C.D., Brooks, E.J., Brooks, A., Brown, J., Bruce, B.D., Byrne, M.E., Campana, S.E., Carlisle, A.B., Chapman, D.D., Chapple, T.K., Chisholm, J., Clarke, C.R., Clua, E.G., Cochran, J.E.M., Crochelet, E.C., Dagorn, L., Daly, R., Cortés, D.D., Doyle, T.K., Drew, M., Duffy, C.A.J., Erikson, T., Espinoza, E., Ferreira, L.C., Ferretti, F., Filmalter, J.D., Fischer, G.C., Fitzpatrick, R., Fontes, J., Forget, F., Fowler, M., Francis, M.P., Gallagher, A.J., Gennari, E., Goldsworthy, S.D., Gollock, M.J., Green, J.R., Gustafson, J.A., Guttridge, T.L., Guzman, H.M., Hammerschlag, N., Harman, L., Hazin, F.H.V., Heard, M., Hearn, A.R., Holdsworth, J.C., Holmes, B.J., Howey, L.A., Hoyos, M., Hueter, R.E., Hussey, N.E., Huveneers, C., Irion, D.T., Jacoby, D.M.P., Jewell, O.J.D., Johnson, R., Jordan, L.K.B., Joyce, W., Keating Daly, C.A., Ketchum, J.T., Klimley, A.P., Kock, A.A., Koen, P., Ladino, F., Lana, F.O., Lea, J.S.E., Llewellyn, F., Lyon, W.S., MacDonnell, A., Macena, B.C.L., Marshall, H., McAllister, J.D., Meÿer, M.A., Morris, J.J., Nelson, E.R., Papastamatiou, Y.P., Peñaherrera-Palma, C., Pierce, S.J., Poisson, F., Quintero, L.M., Richardson, A.J., Rogers, P.J., Rohner, C.A., Rowat, D.R.L., Samoilys, M., Semmens, J.M., Sheaves, M., Shillinger, G., Shivji, M., Singh, S., Skomal, G.B., Smale, M.J., Snyders, L.B., Soler, G., Soria, M., Stehfest, K.M., Thorrold, S.R., Tolotti, M.T., Towner, A., Travassos, P., Tyminski, J.P., Vandeperre, F., Vaudo, J.J., Watanabe, Y.Y., Weber, S.B., Wetherbee, B.M., White, T.D., Williams, S., Zárate, P.M., Harcourt, R., Hays, G.C., Meekan, M.G., Thums, M., Irigoien, X., Eguíluz, V.M., Duarte, C.M., Sousa, L.L., Simpson, S.J., Southall, E.J., Sims, D.W., Queiroz, N., Humphries, N.E., Couto, A., Vedor, M., da Costa, I., Sequeira, A.M.M., Mucientes, G., Santos, A.M., Abascal, F.J., Abercrombie, D.L., Abrantes, K., Acuña-Marrero, D., Afonso, A.S., Afonso, P., Anders, D., Araujo, G., Arauz, R., Bach, P., Barnett, A., Bernal, D., Berumen, M.L., Lion, S.B., Bezerra, N.P.A., Blaison, A.V., Block, B.A., Bond, M.E., Bonfil, R., Bradford, R.W., Braun, C.D., Brooks, E.J., Brooks, A., Brown, J., Bruce, B.D., Byrne, M.E., Campana, S.E., Carlisle, A.B., Chapman, D.D., Chapple, T.K., Chisholm, J., Clarke, C.R., Clua, E.G., Cochran, J.E.M., Crochelet, E.C., Dagorn, L., Daly, R., Cortés, D.D., Doyle, T.K., Drew, M., Duffy, C.A.J., Erikson, T., Espinoza, E., Ferreira, L.C., Ferretti, F., Filmalter, J.D., Fischer, G.C., Fitzpatrick, R., Fontes, J., Forget, F., Fowler, M., Francis, M.P., Gallagher, A.J., Gennari, E., Goldsworthy, S.D., Gollock, M.J., Green, J.R., Gustafson, J.A., Guttridge, T.L., Guzman, H.M., Hammerschlag, N., Harman, L., Hazin, F.H.V., Heard, M., Hearn, A.R., Holdsworth, J.C., Holmes, B.J., Howey, L.A., Hoyos, M., Hueter, R.E., Hussey, N.E., Huveneers, C., Irion, D.T., Jacoby, D.M.P., Jewell, O.J.D., Johnson, R., Jordan, L.K.B., Joyce, W., Keating Daly, C.A., Ketchum, J.T., Klimley, A.P., Kock, A.A., Koen, P., Ladino, F., Lana, F.O., Lea, J.S.E., Llewellyn, F., Lyon, W.S., MacDonnell, A., Macena, B.C.L., Marshall, H., McAllister, J.D., Meÿer, M.A., Morris, J.J., Nelson, E.R., Papastamatiou, Y.P., Peñaherrera-Palma, C., Pierce, S.J., Poisson, F., Quintero, L.M., Richardson, A.J., Rogers, P.J., Rohner, C.A., Rowat, D.R.L., Samoilys, M., Semmens, J.M., Sheaves, M., Shillinger, G., Shivji, M., Singh, S., Skomal, G.B., Smale, M.J., Snyders, L.B., Soler, G., Soria, M., Stehfest, K.M., Thorrold, S.R., Tolotti, M.T., Towner, A., Travassos, P., Tyminski, J.P., Vandeperre, F., Vaudo, J.J., Watanabe, Y.Y., Weber, S.B., Wetherbee, B.M., White, T.D., Williams, S., Zárate, P.M., Harcourt, R., Hays, G.C., Meekan, M.G., Thums, M., Irigoien, X., Eguíluz, V.M., Duarte, C.M., Sousa, L.L., Simpson, S.J., Southall, E.J., and Sims, D.W.

Published
2021

3. Reply to: Caution over the use of ecological big data for conservation

Author

Queiroz, N., Humphries, N.E., Couto, A., Vedor, M., da Costa, I., Sequeira, A.M.M., Mucientes, G., Santos, A.M., Abascal, F.J., Abercrombie, D.L., Abrantes, K., Acuña-Marrero, D., Afonso, A.S., Afonso, P., Anders, D., Araujo, G., Arauz, R., Bach, P., Barnett, A., Bernal, D., Berumen, M.L., Lion, S.B., Bezerra, N.P.A., Blaison, A.V., Block, B.A., Bond, M.E., Bonfil, R., Braun, C.D., Brooks, E.J., Brooks, A., Brown, J., Byrne, M.E., Campana, S.E., Carlisle, A.B., Chapman, D.D., Chapple, T.K., Chisholm, J., Clarke, C.R., Clua, E.G., Cochran, J.E.M., Crochelet, E.C., Dagorn, L., Daly, R., Cortés, D.D., Doyle, T.K., Drew, M., Duffy, C.A.J., Erikson, T., Espinoza, E., Ferreira, L.C., Ferretti, F., Filmalter, J.D., Fischer, G.C., Fitzpatrick, R., Fontes, J., Forget, F., Fowler, M., Francis, M.P., Gallagher, A.J., Gennari, E., Goldsworthy, S.D., Gollock, M.J., Green, J.R., Gustafson, J.A., Guttridge, T.L., Guzman, H.M., Hammerschlag, N., Harman, L., Hazin, F. H.V., Heard, M., Hearn, A.R., Holdsworth, J.C., Holmes, B.J., Howey, L.A., Hoyos, M., Hueter, R.E., Hussey, N.E., Huveneers, C., Irion, D.T., Jacoby, D.M.P., Jewell, O.J.D., Johnson, R., Jordan, L.K.B., Joyce, W., Keating Daly, C.A., Ketchum, J.T., Klimley, A.P., Kock, A.A., Koen, P., Ladino, F., Lana, F.O., Lea, J.S.E., Llewellyn, F., Lyon, W.S., MacDonnell, A., Macena, B.C.L., Marshall, H., McAllister, J.D., Meÿer, M.A., Morris, J.J., Nelson, E.R., Papastamatiou, Y.P., Peñaherrera-Palma, C., Pierce, S.J., Poisson, F., Quintero, L.M., Richardson, A.J., Rogers, P.J., Rohner, C.A., Rowat, D.R.L., Samoilys, M., Semmens, J.M., Sheaves, M., Shillinger, G., Shivji, M., Singh, S., Skomal, G.B., Smale, M.J., Snyders, L.B., Soler, G., Soria, M., Stehfest, K.M., Thorrold, S.R., Tolotti, M.T., Towner, A., Travassos, P., Tyminski, J.P., Vandeperre, F., Vaudo, J.J., Watanabe, Y.Y., Weber, S.B., Wetherbee, B.M., White, T.D., Williams, S., Zárate, P.M., Harcourt, R., Hays, G.C., Meekan, M.G., Thums, M., Irigoien, X., Eguiluz, V.M., Duarte, C.M., Sousa, L.L., Simpson, S.J., Southall, E.J., Sims, D.W., Queiroz, N., Humphries, N.E., Couto, A., Vedor, M., da Costa, I., Sequeira, A.M.M., Mucientes, G., Santos, A.M., Abascal, F.J., Abercrombie, D.L., Abrantes, K., Acuña-Marrero, D., Afonso, A.S., Afonso, P., Anders, D., Araujo, G., Arauz, R., Bach, P., Barnett, A., Bernal, D., Berumen, M.L., Lion, S.B., Bezerra, N.P.A., Blaison, A.V., Block, B.A., Bond, M.E., Bonfil, R., Braun, C.D., Brooks, E.J., Brooks, A., Brown, J., Byrne, M.E., Campana, S.E., Carlisle, A.B., Chapman, D.D., Chapple, T.K., Chisholm, J., Clarke, C.R., Clua, E.G., Cochran, J.E.M., Crochelet, E.C., Dagorn, L., Daly, R., Cortés, D.D., Doyle, T.K., Drew, M., Duffy, C.A.J., Erikson, T., Espinoza, E., Ferreira, L.C., Ferretti, F., Filmalter, J.D., Fischer, G.C., Fitzpatrick, R., Fontes, J., Forget, F., Fowler, M., Francis, M.P., Gallagher, A.J., Gennari, E., Goldsworthy, S.D., Gollock, M.J., Green, J.R., Gustafson, J.A., Guttridge, T.L., Guzman, H.M., Hammerschlag, N., Harman, L., Hazin, F. H.V., Heard, M., Hearn, A.R., Holdsworth, J.C., Holmes, B.J., Howey, L.A., Hoyos, M., Hueter, R.E., Hussey, N.E., Huveneers, C., Irion, D.T., Jacoby, D.M.P., Jewell, O.J.D., Johnson, R., Jordan, L.K.B., Joyce, W., Keating Daly, C.A., Ketchum, J.T., Klimley, A.P., Kock, A.A., Koen, P., Ladino, F., Lana, F.O., Lea, J.S.E., Llewellyn, F., Lyon, W.S., MacDonnell, A., Macena, B.C.L., Marshall, H., McAllister, J.D., Meÿer, M.A., Morris, J.J., Nelson, E.R., Papastamatiou, Y.P., Peñaherrera-Palma, C., Pierce, S.J., Poisson, F., Quintero, L.M., Richardson, A.J., Rogers, P.J., Rohner, C.A., Rowat, D.R.L., Samoilys, M., Semmens, J.M., Sheaves, M., Shillinger, G., Shivji, M., Singh, S., Skomal, G.B., Smale, M.J., Snyders, L.B., Soler, G., Soria, M., Stehfest, K.M., Thorrold, S.R., Tolotti, M.T., Towner, A., Travassos, P., Tyminski, J.P., Vandeperre, F., Vaudo, J.J., Watanabe, Y.Y., Weber, S.B., Wetherbee, B.M., White, T.D., Williams, S., Zárate, P.M., Harcourt, R., Hays, G.C., Meekan, M.G., Thums, M., Irigoien, X., Eguiluz, V.M., Duarte, C.M., Sousa, L.L., Simpson, S.J., Southall, E.J., and Sims, D.W.

Abstract

Our global analysis1 estimated the overlap and fishing exposure risk (FEI) using the space use of satellite-tracked sharks and longline fishing effort monitored by the automatic identification system (AIS)...

Published
2021

4. Global spatial risk assessment of sharks under the footprint of fisheries

Author

Queiroz, N., Humphries, N.E., Couto, A., Vedor, M., da Costa, I., Sequeira, A.M.M., Mucientes, G., Santos, A.M., Abascal, F.J., Abercrombie, D.L., Abrantes, K., Acuña-Marrero, D., Afonso, A.S., Afonso, P., Anders, D., Araujo, G., Arauz, R., Bach, P., Barnett, A., Bernal, D., Berumen, M.L., Bessudo Lion, S., Bezerra, N.P.A., Blaison, A.V., Block, B.A., Bond, M.E., Bonfil, R., Bradford, R.W., Braun, C.D., Brooks, E.J., Brooks, A., Brown, J., Bruce, B.D., Byrne, M.E., Campana, S.E., Carlisle, A.B., Chapman, D.D., Chapple, T.K., Chisholm, J., Clarke, C.R., Clua, E.G., Cochran, J.E.M., Crochelet, E.C., Dagorn, L., Daly, R., Cortés, D.D., Doyle, T.K., Drew, M., Duffy, C.A.J., Erikson, T., Espinoza, E., Ferreira, L.C., Ferretti, F., Filmalter, J.D., Fischer, G.C., Fitzpatrick, R., Fontes, J., Forget, F., Fowler, M., Francis, M.P., Gallagher, A.J., Gennari, E., Goldsworthy, S.D., Gollock, M.J., Green, J.R., Gustafson, J.A., Guttridge, T.L., Guzman, H.M., Hammerschlag, N., Harman, L., Hazin, F.H.V., Heard, M., Hearn, A.R., Holdsworth, J.C., Holmes, B.J., Howey, L.A., Hoyos, M., Hueter, R.E., Hussey, N.E., Huveneers, C., Irion, D.T., Jacoby, D.M.P., Jewell, O.J.D., Johnson, R., Jordan, L.K.B., Jorgensen, S.J., Joyce, W., Keating Daly, C.A., Ketchum, J.T., Klimley, A.P., Kock, A.A., Koen, P., Ladino, F., Lana, F.O., Lea, J.S.E., Llewellyn, F., Lyon, W.S., MacDonnell, A., Macena, B.C.L., Marshall, H., McAllister, J.D., McAuley, R., Meÿer, M.A., Morris, J.J., Nelson, E.R., Papastamatiou, Y.P., Patterson, T.A., Peñaherrera-Palma, C., Pepperell, J.G., Pierce, S.J., Poisson, F., Quintero, L.M., Richardson, A.J., Rogers, P.J., Rohner, C.A., Rowat, D.R.L., Samoilys, M., Semmens, J.M., Sheaves, M., Shillinger, G., Shivji, M., Singh, S., Skomal, G.B., Smale, M.J., Snyders, L.B., Soler, G., Soria, M., Stehfest, K.M., Stevens, J.D., Thorrold, S.R., Tolotti, M.T., Towner, A., Travassos, P., Tyminski, J.P., Vandeperre, F., Vaudo, J.J., Watanabe, Y.Y., Weber, S.B., Wetherbee, B.M., White, T.D., Williams, S., Zárate, P.M., Harcourt, R., Hays, G.C., Meekan, M.G., Thums, M., Irigoien, X., Eguíluz, V.M., Duarte, C.M., Sousa, L.L., Simpson, S.J., Southall, E.J., Sims, D.W., Queiroz, N., Humphries, N.E., Couto, A., Vedor, M., da Costa, I., Sequeira, A.M.M., Mucientes, G., Santos, A.M., Abascal, F.J., Abercrombie, D.L., Abrantes, K., Acuña-Marrero, D., Afonso, A.S., Afonso, P., Anders, D., Araujo, G., Arauz, R., Bach, P., Barnett, A., Bernal, D., Berumen, M.L., Bessudo Lion, S., Bezerra, N.P.A., Blaison, A.V., Block, B.A., Bond, M.E., Bonfil, R., Bradford, R.W., Braun, C.D., Brooks, E.J., Brooks, A., Brown, J., Bruce, B.D., Byrne, M.E., Campana, S.E., Carlisle, A.B., Chapman, D.D., Chapple, T.K., Chisholm, J., Clarke, C.R., Clua, E.G., Cochran, J.E.M., Crochelet, E.C., Dagorn, L., Daly, R., Cortés, D.D., Doyle, T.K., Drew, M., Duffy, C.A.J., Erikson, T., Espinoza, E., Ferreira, L.C., Ferretti, F., Filmalter, J.D., Fischer, G.C., Fitzpatrick, R., Fontes, J., Forget, F., Fowler, M., Francis, M.P., Gallagher, A.J., Gennari, E., Goldsworthy, S.D., Gollock, M.J., Green, J.R., Gustafson, J.A., Guttridge, T.L., Guzman, H.M., Hammerschlag, N., Harman, L., Hazin, F.H.V., Heard, M., Hearn, A.R., Holdsworth, J.C., Holmes, B.J., Howey, L.A., Hoyos, M., Hueter, R.E., Hussey, N.E., Huveneers, C., Irion, D.T., Jacoby, D.M.P., Jewell, O.J.D., Johnson, R., Jordan, L.K.B., Jorgensen, S.J., Joyce, W., Keating Daly, C.A., Ketchum, J.T., Klimley, A.P., Kock, A.A., Koen, P., Ladino, F., Lana, F.O., Lea, J.S.E., Llewellyn, F., Lyon, W.S., MacDonnell, A., Macena, B.C.L., Marshall, H., McAllister, J.D., McAuley, R., Meÿer, M.A., Morris, J.J., Nelson, E.R., Papastamatiou, Y.P., Patterson, T.A., Peñaherrera-Palma, C., Pepperell, J.G., Pierce, S.J., Poisson, F., Quintero, L.M., Richardson, A.J., Rogers, P.J., Rohner, C.A., Rowat, D.R.L., Samoilys, M., Semmens, J.M., Sheaves, M., Shillinger, G., Shivji, M., Singh, S., Skomal, G.B., Smale, M.J., Snyders, L.B., Soler, G., Soria, M., Stehfest, K.M., Stevens, J.D., Thorrold, S.R., Tolotti, M.T., Towner, A., Travassos, P., Tyminski, J.P., Vandeperre, F., Vaudo, J.J., Watanabe, Y.Y., Weber, S.B., Wetherbee, B.M., White, T.D., Williams, S., Zárate, P.M., Harcourt, R., Hays, G.C., Meekan, M.G., Thums, M., Irigoien, X., Eguíluz, V.M., Duarte, C.M., Sousa, L.L., Simpson, S.J., Southall, E.J., and Sims, D.W.

Abstract

Brucellosis is a highly contagious zoonosis affecting humans and a wide range of domesticated and wild animal species. An important element for effective disease containment is to improve knowledge, attitudes and practices (KAP) of afflicted communities. This study aimed to assess the KAP related to brucellosis at the human–animal interface in an endemic area of Egypt and to identify the risk factors for human infection. A matched case–control study was conducted at the central fever hospitals located in six governorates in northern Egypt. Face‐to‐face interviews with cases and controls were conducted using a structured questionnaire. In total, 40.7% of the participants owned farm animals in their households. The overall mean practice score regarding animal husbandry, processing and consumption of milk and dairy products were significantly lower among cases compared with controls (−12.7 ± 18.1 vs. 0.68 ± 14.2, respectively; p < .001). Perceived barriers for notification of animal infection/abortion were predominate among cases and positively correlated with participants’ education. The predictors of having brucellosis infection were consumption of unpasteurized milk or raw dairy products and practicing animal husbandry. Applying protective measures against infection significantly reduced its risk. A model predicting risk factors for brucellosis among those who own animal showed that frequent abortions per animal increased the chance for brucellosis infection among human cases by 50‐fold (95% CI: 8.8–276.9), whereas the use of protective measures in animal care reduced the odds (OR = 0.11 [95% CI: 0.03–0.45]). In conclusion, consumption of unprocessed dairy products was equally important as contact with infected/aborted animals as major risk factors for Brucella spp. infection among humans in Egypt. There is poor knowledge, negative attitudes and risky behaviours among villagers which can perpetuate the risk of brucellosis transmission at the human–animal interface.

Published
2019

5. Highly directional swimming by scalloped hammerhead sharks, Sphyrna lewini, and subsurface irradiance, temperature, bathymetry, and geomagnetic field

Author

Klimley, A.P.

Subjects
Sharks -- Behavior, Biological sciences
Abstract

Navigation techniques adopted by scalloped hammerhead sharks, Sphyrna lewini, in oceanic surroundings, are analyzed using behavioral and environmental measurements, bathymetric and magnetic surveys and swimming statistics. Vertical diving activity of hammerheads are contrasted with their spectral irradiance pattern, while the commuting of sharks to and from a seamount is contrasted with the topographic characteristics observed in bathymetry and geomagnetic field. Hypothetic geomagnetic topotaxis propels hammerheads toward the Espiritu Santo Seamount.

Published
1993

6. School fidelity and homing synchronicity of yellowfin tuna, Thunnus albacares

Author

Klimley, A.P. and Holloway, C.F.

Subjects
Yellowfin tuna -- Research, Ichthyological research -- Analysis, Fishes -- Migration, Biological sciences
Abstract

A study was conducted to analyze the level of fidelity of acoustically-tagged yellowfin tuna to a school and to test whether that school repeatedly visited the same location. Coded ultrasonic beacons were utilized to tag the yellowfin tuna between Mar and Dec 1994. Results indicated that tuna support migratory pathways with way points that are visited with temporal regularity.

Published
1999

9. Visual pigments and photoreceptors in two species of shark, Triakis semifasciata and Mustelus henlei

Author

Sillman, A.J., Letsinger, G.A., Patel, S., Loew, E.R., and Klimley, A.P.

Abstract

The retinal photoreceptors of brown smoothhound sharks (Mustelus henlei) and leopard sharks (Triakis semifasciata) were studied by spectrophotometric analysis of visual pigment extracts, microspectrophotometric examination of single cells, and scanning electron microscopy. Juvenile and adult brown smoothhounds have one, identical visual pigment in their rod photoreceptors. The visual pigment is based on the vitamin A1 chromophore and has a peak absorbance (λmax) (at 496 ± 2 nm. Juvenile and adult leopard sharks also have a single, vitamin A1 based visual pigment, this one with λmax at 502 ± 1 nm. No evidence was found for a shift from a vitamin A2 based visual pigment in the juveniles to a vitamin A1 based pigment in the adults, as is known to occur in the lemon shark, Negaprion brevirostris (Cohen et al. [1990] Vision Res., 30:1949–1953). The retinas of brown smoothhounds and leopard sharks contain both rods and cones, with the rods dominating. The rod outer segments of the brown smoothhound are much longer than are those of the leopard shark. The greater length of brown smoothhound rod outer segments and the shorter wavelength λmax of the brown smoothhound's rod pigment support the idea that brown smoothhounds are either more nocturnal than leopard sharks or are active at greater depths. Cones are very rare in both species with only three identified with the scanning electron microscope and none with the microspectrophotometer. The apparent paucity of cones most likely relates to the bottom dwelling lifestyle of these sharks, although the possibility remains that their retinas contain small, specialized regions of high cone density, which were simply missed. © 1996 Wiley‐Liss, Inc.

Published
1996
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