Recreational fish-finders - an inexpensive alternative to scientific echo-sounders for unravelling the links between marine top predators and their prey

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dc.contributor.authorMcInnes, Alistair Men_ZA
dc.contributor.authorKhoosal, Arjunen_ZA
dc.contributor.authorMurrell, Benen_ZA
dc.contributor.authorMerkle, Dagmaren_ZA
dc.contributor.authorLacerda, Miguelen_ZA
dc.contributor.authorNyengera, Reasonen_ZA
dc.contributor.authorCoetzee, Janet Cen_ZA
dc.contributor.authorEdwards, Loyd Cen_ZA
dc.contributor.authorRyan, Peter Gen_ZA
dc.contributor.authorRademan, Johanen_ZA
dc.date.accessioned2016-01-02T05:06:19Z
dc.date.available2016-01-02T05:06:19Z
dc.date.issued2015en_ZA
dc.description.abstractStudies investigating how mobile marine predators respond to their prey are limited due to the challenging nature of the environment. While marine top predators are increasingly easy to study thanks to developments in bio-logging technology, typically there is scant information on the distribution and abundance of their prey, largely due to the specialised nature of acquiring this information. We explore the potential of using single-beam recreational fish-finders (RFF) to quantify relative forage fish abundance and draw inferences of the prey distribution at a fine spatial scale. We compared fish school characteristics as inferred from the RFF with that of a calibrated scientific split-beam echo-sounder (SES) by simultaneously operating both systems from the same vessel in Algoa Bay, South Africa. Customized open-source software was developed to extract fish school information from the echo returns of the RFF. For schools insonified by both systems, there was close correspondence between estimates of mean school depth (R 2 = 0.98) and school area (R 2 = 0.70). Estimates of relative school density (mean volume backscattering strength; S v ) measured by the RFF were negatively biased through saturation of this system given its smaller dynamic range. A correction factor applied to the RFF-derived density estimates improved the comparability between the two systems. Relative abundance estimates using all schools from both systems were congruent at scales from 0.5 km to 18 km with a strong positive linear trend in model fit estimates with increasing scale. Although absolute estimates of fish abundance cannot be derived from these systems, they are effective at describing prey school characteristics and have good potential for mapping forage fish distribution and relative abundance. Using such relatively inexpensive systems could greatly enhance our understanding of predator-prey interactions.en_ZA
dc.identifier.apacitationMcInnes, A. M., Khoosal, A., Murrell, B., Merkle, D., Lacerda, M., Nyengera, R., ... Rademan, J. (2015). Recreational fish-finders - an inexpensive alternative to scientific echo-sounders for unravelling the links between marine top predators and their prey. <i>PLoS One</i>, http://hdl.handle.net/11427/16169en_ZA
dc.identifier.chicagocitationMcInnes, Alistair M, Arjun Khoosal, Ben Murrell, Dagmar Merkle, Miguel Lacerda, Reason Nyengera, Janet C Coetzee, Loyd C Edwards, Peter G Ryan, and Johan Rademan "Recreational fish-finders - an inexpensive alternative to scientific echo-sounders for unravelling the links between marine top predators and their prey." <i>PLoS One</i> (2015) http://hdl.handle.net/11427/16169en_ZA
dc.identifier.citationMcInnes, A. M., Khoosal, A., Murrell, B., Merkle, D., Lacerda, M., Nyengera, R., ... & van der Westhuizen, J. J. (2015). Recreational fish-finders - an inexpensive alternative to scientific echo-sounders for unravelling the links between marine top predators and their prey. PloS one, 10(11). doi:10.1371/journal.pone.0140936en_ZA
dc.identifier.ris TY - Journal Article AU - McInnes, Alistair M AU - Khoosal, Arjun AU - Murrell, Ben AU - Merkle, Dagmar AU - Lacerda, Miguel AU - Nyengera, Reason AU - Coetzee, Janet C AU - Edwards, Loyd C AU - Ryan, Peter G AU - Rademan, Johan AB - Studies investigating how mobile marine predators respond to their prey are limited due to the challenging nature of the environment. While marine top predators are increasingly easy to study thanks to developments in bio-logging technology, typically there is scant information on the distribution and abundance of their prey, largely due to the specialised nature of acquiring this information. We explore the potential of using single-beam recreational fish-finders (RFF) to quantify relative forage fish abundance and draw inferences of the prey distribution at a fine spatial scale. We compared fish school characteristics as inferred from the RFF with that of a calibrated scientific split-beam echo-sounder (SES) by simultaneously operating both systems from the same vessel in Algoa Bay, South Africa. Customized open-source software was developed to extract fish school information from the echo returns of the RFF. For schools insonified by both systems, there was close correspondence between estimates of mean school depth (R 2 = 0.98) and school area (R 2 = 0.70). Estimates of relative school density (mean volume backscattering strength; S v ) measured by the RFF were negatively biased through saturation of this system given its smaller dynamic range. A correction factor applied to the RFF-derived density estimates improved the comparability between the two systems. Relative abundance estimates using all schools from both systems were congruent at scales from 0.5 km to 18 km with a strong positive linear trend in model fit estimates with increasing scale. Although absolute estimates of fish abundance cannot be derived from these systems, they are effective at describing prey school characteristics and have good potential for mapping forage fish distribution and relative abundance. Using such relatively inexpensive systems could greatly enhance our understanding of predator-prey interactions. DA - 2015 DB - OpenUCT DO - 10.1371/journal.pone.0140936 DP - University of Cape Town J1 - PLoS One LK - https://open.uct.ac.za PB - University of Cape Town PY - 2015 T1 - Recreational fish-finders - an inexpensive alternative to scientific echo-sounders for unravelling the links between marine top predators and their prey TI - Recreational fish-finders - an inexpensive alternative to scientific echo-sounders for unravelling the links between marine top predators and their prey UR - http://hdl.handle.net/11427/16169 ER - en_ZA
dc.identifier.urihttp://dx.doi.org/10.1371/journal.pone.0140936en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/16169
dc.identifier.vancouvercitationMcInnes AM, Khoosal A, Murrell B, Merkle D, Lacerda M, Nyengera R, et al. Recreational fish-finders - an inexpensive alternative to scientific echo-sounders for unravelling the links between marine top predators and their prey. PLoS One. 2015; http://hdl.handle.net/11427/16169.en_ZA
dc.language.isoengen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.publisher.departmentPercy FitzPatrick Institute of African Ornithologyen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_ZA
dc.rights.holder© 2015 McInnes et alen_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/4.0en_ZA
dc.sourcePLoS Oneen_ZA
dc.source.urihttp://journals.plos.org/plosoneen_ZA
dc.subject.otherMarine fishen_ZA
dc.subject.otherPredationen_ZA
dc.subject.otherPenguinsen_ZA
dc.subject.otherTransducersen_ZA
dc.subject.otherMarine ecologyen_ZA
dc.subject.otherLinear regression analysisen_ZA
dc.subject.otherMarine environmentsen_ZA
dc.subject.otherMarine biologyen_ZA
dc.titleRecreational fish-finders - an inexpensive alternative to scientific echo-sounders for unravelling the links between marine top predators and their preyen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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