• Login
    View Item 
    •   Marine Institute Open Access Repository
    • Marine Institute Community of Research Publications
    • Irish Fisheries Investigations
    • Irish Fisheries Investigations
    • View Item
    •   Marine Institute Open Access Repository
    • Marine Institute Community of Research Publications
    • Irish Fisheries Investigations
    • Irish Fisheries Investigations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Marine OARCommunitiesPublication DateAuthorsTitlesSubjectsThis CollectionPublication DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Statistics

    Display statistics

    The abundance of boarfish (Capros aper) along the western shelf estimated using hydro-acoustics

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    IrishFishInvestNo23_Boarfish ...
    Size:
    1.074Mb
    Format:
    PDF
    Download
    Author
    O'Donnell, C.
    Farrell, E.
    Saunders, R.
    Campbell, A.
    Keyword
    Boarfish
    Acoustics
    Shelf edge
    Spawning aggregations
    North Atlantic survey
    Date
    2012
    Publisher
    Marine Institute
    
    Metadata
    Show full item record
    Abstract
    The Boarfish (Capros aper, Linnaeus) is a relatively small deep bodied fish growing up to 23 cm in total length. Typically reddish in colour with large eyes and a highly protrusible mouth boarfish are known to inhabit shallow shelf seas to shelf slopes from 40-600 m. Boarfish are a mesopelagic shoaling species distributed in the eastern Atlantic from Norway to Senegal including the Mediterranean. Exploratory fishing for boarfish by Irish vessels began in the later 1980s when commercial quantities were encountered during the spring horse mackerel (Trachurus trachurus) and mackerel (Scrombrus scomber) fishery in northern Biscay. During the early 2000s the Irish landings were relatively small (<700 t per yr) and it was not until 2006 that a directed fishery developed in earnest. Landings peaked in 2010 at over 137,000 t prior to the introduction of TAC control and interim management plan. This survey represents the first dedicated exploratory acoustic survey for boarfish (Capros aper) undertaken along the western seaboard of Ireland. The survey was timed to coincide with peak spawning time as determined from histological analysis of commercial catch samples. Area coverage was based on the distribution of catches from the IBTS survey time series and from catch data from the pelagic fleet targeting boarfish since 2005. In total 3,160 nmi (nautical miles) of cruise track was undertaken by the MFV Felucca, over 32 transects relating to an area coverage of over 89,500 nmi². Coverage extended from the 50 m contour to the shelf slope (250 m). Transect spacing was set at 15 nmi throughout to make best use of the time available and the large geographical area to be covered. The results presented here are a composite of data collected during this survey and on the northwest herring survey (RV Celtic Explorer). Both surveys were timed to link up and were carried out over 33 days from north (59°N) to south (47°30’N). Acoustic data were collected using a Simrad EK 60 scientific echosounder via a Simrad ES-38B (38 KHz) split-beam transducer which was mounted within a tow-body. This configuration was calibrated on the survey vessel prior to departure. An age length key (ALK) compiled primarily from commercial samples collected during 2010 was applied during the analysis of survey data. Age distribution indicate that the stock was dominated by the following age classes in terms of abundance: 6, 7, 20+ and 9 year old fish and 20+, 9, 7 and 10 years in terms of biomass respectively. Immature fish from 0-2 years were poorly represented in survey catches and this is consistent with a spawning movement of mature stock away from feeding grounds on the shelf. During the survey boarfish shoals were primarily distributed along the shelf edge occurring as aggregations actively spawning or in a state of near readiness to spawn. As a result the abundance estimate is almost exclusively composed of mature individuals (>99%) which is in contrast to the primarily on-shelf distribution of commercial catches. The biomass and abundance estimates presented here were calculated using a modelled TS-length relationship, from as yet unpublished data for boarfish and applied retrospectively to acoustic data.
    URI
    http://hdl.handle.net/10793/787
    Citation
    O’Donnell, C., Farrell, E., Saunders, R. & Campbell, A., “The abundance of boarfish (Capros aper) along the western shelf estimated using hydro-acoustics”, Irish Fisheries Investigations No. 23, Marine Institute 2012
    Collections
    Irish Fisheries Investigations

    entitlement

     
    DSpace software (copyright © 2002 - 2022)  DuraSpace
    Quick Guide | Contact Us | MI Privacy Policy
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.