• 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 longline survey of the slopes of Porcupine Bank and Porcupine Seabight

      Clarke, M; Hareide, N; Hoey, S (Marine Institute, 2001)
      This survey took place over a period of 12 days in November and December 1999 on the western slope of the Porcupine Bank and the western and eastern slopes of the Porcupine Seabight. Fishing was carried out in five separate areas, in depths between 400 and 2,000 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 Teagase National Food Centre. The survey was carried out on a commercial long-liner, using commercial deep-water autoline gear. In total 18 species of chondricthyan, 24 species of teleost fish and 1 species of cephalopod were taken. Among the most abundant species in the catch were bird beak dogfish, leafscale gulper shark, Portuguese dogfish and mora. Over the entire survey, discarding was estimated as 42% of the total catch. The main species discarded were birdbeak dogfish, black mouth dogfish and greater lantern shark. Catch per 1,000 hooks (CPU E) was highest abundances were found in the western and northwestern slope of the Porcupine Bank. The catch rates in the slopes of the Porcupine Seabight were considerable lower. CPUE compared with rates from previous years in the northwestern slope, showed a reduction for the commercial species Portuguese dogfish and leafscale gulper shark.
    • Deepwater longline survey on the continental slopes of Porcupine Bank, Rockall Bank and Hatton Bank

      Clarke, M; Moore, S J (Marine Institute, 2002)
      A deepwater survey programme has been operated since 1993 by the Marine Institute (MI), in the deep waters of the Rockall Trough and Porcupine Bank. The first leg of the present survey took place over a period of 12 days in August 2000 on the Western slope of the Porcupine Bank and the western slopes of Rockall Bank and Hatton Bank. The second leg took place on the slopes and shelves of the Porcupine Bank. Fishing was carried out in depths between 150 and 1,800 meters. The primary objective of the survey was to obtain biological samples of chondricthyan and teleost fish, for contaminant analysis of fish by the MI chemistry section and for food technology analysis at the Teagase National Food Centre. The survey was carried out on the commercial long-liner "An Capall Bán," using commercial deepwater autoline gear. In total 26 species of chondricthyan and 24 species of teleost fish were taken. Among the most abundant species in the catch were birdbeak dogfish (22%), leafscale gulpershark (14%), Portuguese dogfish (8%), tusk (17%) and mora (8%). Over the entire survey, discarding was estimated at 43% of the total catch. The main species discarded were bird beak dogfish and greater lantern shark. Catch per unit effort showed that highest abundances were found in the northwestern slope of the Porcupine Bank at 600 - 700 metres and in the western slopes of Rockall Bank and Hatton Bank at 1,000 to 1,200 metres depths.
    • 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.