Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-10T13:23:10.620Z Has data issue: false hasContentIssue false
  • English
  • Français

Effect of discards on roundnose grenadier stock assessment in the Northeast Atlantic

Published online by Cambridge University Press:  20 October 2009

Lionel Pawlowski  and
Pascal Lorance
Lionel Pawlowski
Affiliation:
Ifremer, 8 rue François Toullec, 56100 Lorient, France
Pascal Lorance
Affiliation:
Ifremer, rue de l'île d'Yeu, BP 21105, 44311 Nantes Cedex 3, France
Get access

Abstract

In the Northeast Atlantic fishery for roundnose grenadier Coryphaenoides rupestris, discards account for about 30% of the catch in weight. Data on discards are scarce; however, length distributions and discard rates appear to be relatively stable from year to year. In contrast, landings data available since 1990 show that the average pre-anal fin length has decreased from 20.7 cm in 1990 to 15.2 cm in 2008, resulting in a 58% reduction of the mean individual weight (850 g in 2008) and an increasing occurrence of overlapping class sizes between landings and discards in recent years. For stock assessment, the method of separable virtual population analysis (SVPA) was used. However, because of the lack of discard data for many of the years covered by the study, the catch data used as input to the assessment model had to be reconstructed from the available information (landings, discards, fishing effort and bathymetric distribution of the stock) using two methods. The first method relied on the assumption that the recent length distributions of discards were applicable to the earlier years (1990-1997). It resulted in unrealistic bimodal length distributions, suggesting a change in discarding practices through time, with larger individuals being discarded in the early days. The second method, based on the fishing effort and length distribution by depth strata, produced unimodal distributions for the whole period and confirmed that the average length of discarded fish was higher in the early days of the fishery. In both cases, the estimates of biomass follow parallel trends, suggesting a strong decline in the population. The available information and methods are discussed.

Keywords

Stock assessmentFishing effortDiscardsTime seriesMacrouridaeCoryphaenoides rupestrisAtlantic Ocean
Type
Research Article
Information
Aquatic Living Resources , Volume 22 , Issue 4 , October 2009 , pp. 573 - 582
Copyright
© EDP Sciences, IFREMER, IRD, 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Allain V., 1999, Ecologie, biologie et exploitation des populations de l'Atlantique du Nord-Est. Thèse dr, Univ. Bretagne occidentale, Brest.
Allain, V., 2001, Reproductive strategies of three deep-water benthopelagic fishes from the Northeast Atlantic Ocean. Fish. Res. 51, 2-3, 165–176. CrossRef
Allain, V., Biseau, A., Kergoat, B., 2003, Preliminary estimates of French deepwater fishery discards in the Northeast Atlantic Ocean. Fish. Res. 60, 185–192. CrossRef
Atkinson D.B., 1995, The biology and fishery of roundnose grenadier (Coryphaenoides rupestris Gunnerus, 1765) in the North West Atlantic. In: Hopper A.G. (Ed.) Deep-water fisheries of the North Atlantic oceanic slope, Series E: Applied Sciences, Kluwer Academic Publishers, Dordrecht, pp. 51–111.
Basson M., Gordon J.D.M., Large P.A., Lorance P., Pope J.G., Rackham B., 2002, The effects of fishing on deep-water fish species to the west of Britain. Joint Nature Conservation Committee (JNCC), JNCC Rep. No. 324, Peterborough http://www.nhbs.com/
Bergstad, O.A., 1990, Distribution, population structure, growth and reproduction of the roundnose grenadier Coryphaenoides rupestris (Pisces: Macrouridae) in the deep waters of the Skagerrak. Mar. Biol. 107, 25–39. CrossRef
Bergstad, O.A., Gordon, J.D.M., 1994, Deep-water ichthyoplankton of the Skagerrak with special reference to Coryphaenoides rupestris Gunnerus, 1765 (Pisces, Macrouridae) and Argentina silus (Ascanius, 1775) (Pisces, Argentinidae). Sarsia 79, 33–43. CrossRef
Bridger J.P., 1978, New deep-water trawling grounds to the west of Britain. Lab. Leaf., Ministry of Agriculture Fisheries and Food (MAFF), Directorate of Fisheries Research, Lowestoft.
Charuau A., Dupouy H., Lorance P., 1995, French exploitation of the deep-water fisheries of the North Atlantic. In: Hopper A.G. (Ed.) Deep-water fisheries of the North Atlantic oceanic slope. Ser. E: Applied Sciences, Kluwer Academic Publishers, Dordrecht, pp. 337–356.
Clark, M., 2001, Are deepwater fisheries sustainable? The example of orange roughy (Hoplostethus atlanticus) in New Zealand. Fish. Res. 51, 2-3, 123–135. CrossRef
Ehrich, S., 1983, On the occurrence of some fish species at the slopes of the Rockall Trough. Arch. Fischwiss. 33, 3, 105–150.
Gordon, J.D.M., Bergstad, O.A., 1992, Species composition of demersal fish in the Rockall Trough, Northeastern Atlantic, as determined by different trawls. J. Mar. Biol. Assoc. UK 72, 213–230. CrossRef
Gordon J.D.M., Merrett N.R., Bergstad O.A., Swan S.C., 1996, A comparison of the deep-water demersal fish assemblages of the Rockall Trough and Porcupine Seabight, eastern North Atlantic: continental slope to rise. J. Fish Biol. 49, Suppl. A, 217–238.
Gordon J.D.M, 1979, Lifestyle and phenology in deep sea anacanthine teleosts. Symp. Zool. Soc. London 44, pp. 327–359.
Gordon J.D.M., Hunter J.E., 1994, Study of the deep-water fish stocks to the west of Scotland. Report presented to. Highlands and Islands Enterprise and other sponsors. The Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll, Vol. 2.
ICES 2007, Report of the Working Group on the Biology and Assessment of Deep-Sea Fisheries Resources (WGDEEP), May 2007. Int. Counc. Explor. Sea, ICES CM 2008/ACOM 14.
ICES 2008, Report of the Working Group on the Biology and Assessment of Deep-Sea Fisheries Resources (WGDEEP), March 2008. Int. Counc. Explor. Sea, ICES CM 2008/ACOM 14.
ICES 2009, Report of the Working Group on the Biology and Assessment of Deep-Sea Fisheries Resources (WGDEEP), March 2009. Int. Counc. Explor. Sea, ICES CM 2008/ACOM 14. 504p.
Kelly C.J., Connolly P.L., Bracken J.J., 1996, Maturity, oocyte dynamics and fecundity of the roundnose grenadier from the Rockall Trough. J. Fish Biol. 49, Suppl. A, 5–17.
Kelly, C.J., Connolly, P.L., Bracken, J.J., 1997, Age estimation, growth, maturity and distribution of the roundnose grenadier from the Rockall Trough. J. Fish Biol. 50, 1–17. CrossRef
Knutsen H., Jorde P.E., Skogen M., Stenseth N.C., 2009, Large-scale population structure in roundnose grenadier. ICES International Symposium, Issues confronting the deep oceans: the economic, scientific and governance challenges and opportunities of working in the deep sea, Horta (Azores), 27-30th April 2009.
Lorance, P., Dupouy, H., Allain, V., 2001, Assessment of the roundnose grenadier (Coryphaenoides rupestris) stock in the Rockall Trough and neighbouring areas (ICES Sub-areas V-VII). Fish. Res. 51, 151–163. CrossRef
Lorance P., Large P.A., Bergstad O.A., Gordon J.D.M, 2008, Grenadiers of the Northeast Atlantic – Distribution, biology, fisheries, and their impacts, and developments in stock assessment and management. In: Grenadiers of the world oceans: biology, stock assessment and fisheries, Bethesda, MS, USA, Am. Fish. Soc. Symp. 63, pp. 365–397.
Mauchline, J., Gordon, J.D.M., 1984, Diets and bathymetric distributions of the macrourid fish of the Rockall Trough, northeastern Atlantic Ocean. Mar. Biol. 81, 107–121. CrossRef
Rochet, M.-J., Trenkel, V.M., 2005, Factors for the variability of discards: assumptions and field evidence. Can. J. Fish. Aquat. Sci. 62, 224–235. CrossRef