• Catch and Discards for a Deep-Water Trawl Survey in 1996

      Kelly, C J; Clarke, M; Connolly, P L (Marine Institute, 1997)
      The Fisheries Research Centre has conducted a deep-water survey programme since 1993 and as part of this programme a deep-water trawl survey was carried out in September 1996. The survey fished areas along the continental slope west of Ireland from 52° N to 58° N at depths of 500-1,200m The primary objective was to secure samples of potentially commercial deep-water shark and teleost species in order to examine aspects of their age, growth, reproduction and diet. The survey was conducted on a chartered commercial fishing vessel using a deep-water otter trawl fitted with a small mesh cod-end liner. A total of 26 hauls were made during 87 hours of fishing and yielded a total catch of 29,345 kg. The ground covered ranged from mud to gravel and bare rock and there was no significant gear damage during the survey. Thirteen species of chondrichtian and 33 species of teleost fish were recorded. Length, weight sex and maturity data were taken from some of these species. The most abundant species in the catch were Baird's smoothhead, roundnose grenadier, leafscale gulper shark, black scabbard and orange roughy. Trawl discards expressed as kg discarded per tonne of roundnose grenadier landed were calculated for a broad range of the most abundant species in the catch. During the survey in the Rockall Trough an estimated 16t of deep-water species were discarded and results are compared to estimates for 1995. The main species discarded were smoothhead, squaliform sharks and Lepidion eques. Results indicate up to 16,783t of deep-water species may have been discarded from the deep-water fishery in this area in 1996. This report documents the survey and presents some preliminary results. The data gathered during these surveys are currently under analysis at the PRC and the results will be published in the scientific literature.
    • Deepwater Trawl and Longline Surveys in 1995

      Connolly, P L; Kelly, C J (Marine Institute, 1997)
      Two surveys were carried out in 1995 as part of the continuing deep water fish research programme at the Fisheries Research Centre. The trawl survey fished areas on the eastern slopes of the Rockall Trough and on two seamounts of the mid-Atlantic ridge approximately 300 miles north of the Azores. The deep water longline trip was the first such survey carried out by the Fisheries Research Centre and concentrated on previously fished grounds in the Rockall Trough and on new areas along the slope of the Porcupine Bank. Both surveys were carried out in conjunction with an Bord Iascaigh Mhara (BIM) and the objective was to locate commercial quantities of deep water fish and to obtain samples for biological analyses. The trawl survey was conducted on a chartered fishing vessel using a commercial otter trawl, fitted with a small mesh cod-end liner. Twenty-six trawling operations were carried out in the depth range 750m-1,400m, of which 21 produced fish catches. Longlines were set between 542m and 1,521m and only one line was lost. Thirteen chondricthian and 38 species of teleost fish were recorded from the catches. The most abundant species in the catches were Portuguese shark, roundnose grenadier, black scabbard, Baird's smoothhead, blue ling and orange roughy. Length, weight, sex, maturity and catch data together with samples of otoliths and gonads were collected. Discards were monitored from both fishing methods. In comparison with the trawl, longline catches produced larger specimens of fewer species which were more dominated by sharks. Overall catch rates for the longlines were similar to Norwegian data for the Rockall area. Trawl catch rates showed a decrease since the last Irish survey in this area in 1993.
    • Inventory of Otolith Collections and Ageing Work on North East Atlantic Deep Water Fish Species

      Connolly, P L; Kelly, C J; Gordon, J D M; Bergstad, O A (Department of the Marine, 1995-03)
      The result of a questionnaire sent to 38 institutes, indicate that a broad range of unpublished raw data exist on many of the deep water fish species in the north east Atlantic and Mediterranean. Of the 18 fish classified by ICES as 'primary' deep water species, one or more of the six Coryphaenoides rupestris, Mora moro, Aphanopus carbo, Hoplostethus atlanticus, Phycis blennoides, Helicolenus dactylopterus were common to most of the institutes which completed the questionnaire. Institutes which possessed some form of otolith or ageing data on these primary fish are grouped by species. A table of institutions which have some form of data on other deep water species (including sharks, rays and Chimaerids) is presented. A list of the main deep water species is given with their English, French, and Spanish common names. In general, there was a very positive response to the setting up of an otolith exchange scheme (by correspondence), as an initial approach to the convening of a deep water ageing workshop. The questionnaire did not provide any indications as to the extent or quality of the various data sets.
    • Preliminary Catch, Discards and Selectivity Results of Trawl Survey on Deepwater Slops of the Rockall Trough

      Clarke, M W; Connolly, P L; Kelly, C J (Marine Institute, 1999-10)
      A deepwater trawl survey programme has been operated since 1993 by the Fisheries Research Centre (FRC) in the deep waters of the Rockall Trough and Porcupine Bank. The present survey took place over a period of 10 days in October and November 1997 on the eastern and southern slopes of the Rockall Trough from 54°N to 59°N. Fishing was carried out in five separate areas, in four depth strata: 500-700m, 700-900m, 900-1100m and 1100-1300m. The primary objective of the survey was to obtain samples of chondrichthyan and teleost fish for the FRC deepwater research programme, for contaminant analysis offish by the FRC chemistry section and for food technology analysis at the Teagasc National Food Centre. The survey was carried out on a commercial trawler using commercial deepwater demersal otter trawl gear. In total 15 species of chondrichthyan, 41 species of teleost fish and 5 species of cephalopods were taken. Among the most abundant species in the catch were roundnose grenadier, Portuguese dogfish, leafscale gulper shark, and Baird's smoothhead. Over the entire survey discarding was estimated as 50.5% of the total catch. Discard rates expressed as kg discarded per tonne roundnose grenadier landed and as a percentage of the total catch when compared with those of previous years showed no appreciable change. The main species discarded were rabbitfish, birdbeak dogfish, Baird's smoothhead, roundnose grenadier and Lepidion eques. Catch per unit effort rates expressed as kg caught per hour fished compared with rates for previous trawl surveys showed marked declines. Length frequency distributions for the main chondrichthyan species showed absence of smaller individuals from the samples and sexual dimorphism with respect to length. Attachment of fine-mesh cod-end liner suggested that the commercial gear selects all length frequencies present and that mesh size may not be an effective management measure in this fishery. This leaflet documents the survey and presents some preliminary results. The data from this survey are currently under analysis at the FRC and results will be published in the scientific literature.
    • Results of 1997 Longline Survey of the Rockall Trough

      Connolly, P L; Kelly, C J; Clarke, M; Hareide, N (Marine Institute, 1999)
      The present survey took place over a period of 12 days in August 1997 along the eastern slope of Rockall Trough between 53 and 58ºN including the Northern slope of the Porcupine Bank. Fishing was carried out in six separate areas, in depths between 300 and 2,925 meters. The primary objective of the survey was to obtain samples of chondricthyan and teleost fish for the Marine Institute (MI) deepwater research programme, for contaminant analysis of fish by the MI chemistry section and for food technology analysis at the Teagasc National Food Centre. The survey was carried out on the Norwegian commercial long-liner "Skarheim," using commercial deep-water autoline gear. In total over 70,000 hooks were set during the trip and on average 80% of these were baited. In total 20 species of chondricthyan and 18 species of teleost fish were taken. Among the most abundant species in the catch were leafscale gulper shark Centrophorus squamosus (36%), bird beak dogfish Deania calcea (21 %), Portuguese dogfish Centrascyflium coefofepis (13%), tusk, Brosme brosme (11%) and mora, Mora mora (6%). Over the entire survey, discarding was estimated as 30% of the total catch. The main species discarded were bird beak dogfish and greater lantern shark Etmopterus princeps. Catch per 1,000 hooks showed that highest abundances were found at 600 - 1,100 metres throughout the whole fishing area. Three settings were made at depths between 2,000 and 3,000 meters. These shots gave valuable information about depth distribution of different species and also brought up species that have never been recorded in the Rockall Trough before.
    • Sampling surveys for deep-water demersal fish in 1993

      Connolly, P L; Kelly, C J (Department of the Marine, 1994-09)
      Potential for new developments in deep water fishing have been identified by two sampling surveys carried out in April and September 1993, in the deep waters off the west coast of Ireland and Scotland. The primary objective of the two surveys was to secure samples of a variety of potentially commercial deep water fish species in order to examine aspects of their age, growth, reproduction and diet. These data will be essential in formulating management plans for the expanding deep water fisheries in the area. The surveys were conducted on a chartered fishing vessel using a commercial otter trawl, fitted with a small mesh cod-end liner. Fishing activity concentrated on the depth range 400m-1200m and a total of 81 trawling operations were carried out, of which 75 produced fish catches with limited gear damage. Fifteen species of cartilaginous and 50 species of teleost fish were recorded from the catches. These include the roundnose grenadier Coryphaenoides rupestris, black scabbard Aphanopus carbo, greater forkbeard Phycis blennoides, blue-mouth rockfish Helicolenus dactylopterus and Baird's smooth-head Alepocephalus bairdii. Length, weight, sex, maturity and catch data together with samples of otoliths, gonads and stomachs were secured. In general terms, the fishing ground off the north west of Ireland and west of Scotland caused little problems with gear damage and yielded good catches of deep water species. The two surveys have shown the areas have potential for commercial deep water fishing but the development of this fishery in the area will be contingent on the establishment of suitable markets. This initial report documents the surveys and presents some preliminary results. The data gathered from these surveys are currently under analysis at the FRC and the results will be published in the scientific literature.