Modelling the ecology, dynamics and assessment of Nephrops norvegicus (Linnaeus 1758) in the waters around Ireland

Simple item page
dc.availability.bitstreamopenaccess
dc.contributor.advisorRogan, Emeren
dc.contributor.advisorexternalLordan, Colmen
dc.contributor.advisorexternalCodling, Edward A.en
dc.contributor.authorBenchikh, Hocine Amine
dc.contributor.funderMarine Instituteen
dc.date.accessioned2022-09-30T11:05:57Z
dc.date.available2022-09-30T11:05:57Z
dc.date.issued2022-06-23
dc.date.submitted2022-06-23
dc.description.abstractNephrops norvegicus is a valuable market species in the North-East Atlantic and it is of economic importance to Ireland. The present study investigated the status of the Aran ground stock, frequently ranked within the top two commercially valuable “fish” landed. Since 2002, under water TV surveys have been developed to provide a fishery independent estimate of burrow abundance in areas that exhibited a steady decrease in Nephrops over two decades contrasting with the increasing landings. In order to identify stock status and provide reliable information to management, we used a number of different approaches in the fields of time series analysis, spatial analysis and fisheries stock assessment. We examined the temporal fluctuations in a 16 year time series of landings in Aran grounds and found fluctuating cycles within an overall decreasing trend. This stock dynamic was also compared with the other main areas of harvest off the coast of Ireland (Smalls ground, Porcupine Bank, and the west Irish Sea) disclosing a regional common trend in the pattern of the stocks for connecting areas. Regional climatic influences (e.g NAO, AO and AMO) have been detected on various time scales ranging from month to years and the time series analysis method appears effective for detecting changes in fishing behaviours. Spatial analysis of the burrow density over the stock area revealed patchy distribution varying in size and intensity over the years with a spatio-temporal trend marked by a depletion of abundance in midfield with noticeable consequences for fishing vessel activity at a regional level. This spatial approach enabled the evaluation of the influence of the mud content of the seabed on the density of burrows and to explore the potential impact of the prevailing current circulation pattern during the planktonic stage of Nephrops on the level of recruitment by using remote sensing data. For an optimal fisheries management strategy, demographic information for the exploited species is necessary and for Nephrops, effective stock assessment is hampered because of the difficulty in age determination. A biomass model with a Schaefer surplus yield component and a data limited CMSY method were chosen to address the lack of age data and to predict biomass and related key fisheries reference points. Both approaches underline the ongoing decline of Nephrops abundance and reveal warning signals of unsustainable fishing exploitation.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationBenchikh, H. A. 2022. Modelling the ecology, dynamics and assessment of Nephrops norvegicus (Linnaeus, 1758) in the waters around Ireland. PhD Thesis, University College Cork.en
dc.identifier.endpage378en
dc.identifier.urihttps://hdl.handle.net/10468/13714
dc.language.isoenen
dc.publisherUniversity College Corken
dc.relation.projectMarine Institute, Ireland (Sea Change strategy scheme with the support of (Grant Aid Agreement No. PHD/FS/07/005) and the Marine Research Sub-programme of the National Development Plan 2007–2013, Ireland)en
dc.rights© 2022, Hocine Amine Benchikh.en
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/en
dc.subjectFisheryen
dc.subjectStock assessmenten
dc.subjectSpatial analysisen
dc.subjectTime series analysisen
dc.titleModelling the ecology, dynamics and assessment of Nephrops norvegicus (Linnaeus 1758) in the waters around Irelanden
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD - Doctor of Philosophyen
Files
Original bundle
Now showing 1 - 2 of 2
Thumbnail Image
Name:
BenchikhHA_PhD2022.pdf
Size:
50.83 MB
Format:
Adobe Portable Document Format
Description:
Full Text E-thesis
Download
Thumbnail Image
Name:
3a. 108222871 - Hocine Benchikh, Submission for Examination form - remaining signatures.pdf
Size:
447.48 KB
Format:
Adobe Portable Document Format
Description:
Submission for Examination Form
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
5.2 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Research Theses Submission
Biological, Earth and Environmental Sciences - Doctoral Theses
College of Science, Engineering and Food Science - Doctoral Theses