The major fishery effects on the ecosystem

Modern fishing fleets are capable of causing a very significant reduction in demersal deepsea fish biomass in just a few years, this as resulted in the collapse of several fisheries (Koslow et al., 2000). Along the MAR, fishery for roundnose grenadier depleted the stock in the 70s (Merrett and Haedrich, 1997). However, Polish fleets have been exploiting the same species over recent year on the MAR, it is not know if the fishing areas in the 70s and the 90-00s were the same.

It is likely that large predators populations on oceanic bathymetric features are particularly sensitive to overfishing, due to low productivity and in some cases high catchability. On the southern part of the MAR and adjacent seamounts, populations of alphonsinos were depleted too in the 70s. More recently, longline fisheries seem to have depleted seamounts populations of giant redfish of seamounts of the northern MAR (Hareide and Garnes, 2001).

These depletions of dominant species induce major changes to demersal deepsea fish communities that loose their larger predators and the corresponding ecological functions. In addition to catching target species, deepwater fisheries by-catch unwanted species that are either too small or unpalatable. Discarding rates are often high (in the order of 50%) and the bulk of the discards is made of smoothheads (Alepocephalidae) because of their high abundance (Allain et al., 2003).

Deep-water trawling impacts deepsea benthic communities. Over recent years attention was particularly drawn to the impact of trawling on Lophelia reefs. Measures to reduce the impact and protect some areas were taken. Fishery impact to such communities are ancient (Joubin, 1922) and extent shallower than what we currently term "deepwater", the original extend and role of these reefs in the fish production is unknown. At least under some conditions (long soaking time, operation of hundredths km of nets, deployments over coral reefs) deep-water set nets was also shown to have severe impact mainly on the fish community by generating ghost fishing and targeting more vulnerable species such as sharks. High discards of monkfish may also occur (Hareide et al., 2005). As a result deepwater netting is banned in ICES

ICES WGRED Report 2006 | 105

divisions VIa,b, VIIb,c,j,k and part of sub-area XII in 2006, based on the annual TAC regulation (COUNCIL REGULATION (EC) No 51/2006) and is subject to further introduction of management measure.

2 .9 .9 Con cl u d in g r em ar k s

Over the last 15 to 20 years, the deep-water ecosystem was significantly impacted by fishing as and when fishery extended deeper partly as a result of overexploitation of shelf stocks.

Deepwater stock are typically low productive and their sustainable levels of exploitation are much smaller than those of shelf stocks.

Towed fishing gears have severe impacts on benthic communities; this is a major problem on structurally complex habitat including biogenic reefs. On the same kind of reefs netting is also considered undesirable as it can generate (i) habitat disturbance because of lots nets and dumping of used nets and (ii) ghost fishing. Therefore deepwater trawling should be restricted to primarily sedimentary bottoms and where possible fisheries should shift to longlining and closely managed netting (out of coral areas) as was successfully done in some southern hemisphere fisheries (fishery for Patagonian toothfish, Disostichus eleginoides, in the South Georgia and South Shetland Islands).

Although this is probably improving thanks to the Data Collection Regulation (Council Regulation (EC) No 1543/2000 of 29 June 2000) and on-board observers programs (Council Regulation (EC) N° 2347/2002 of 16 December 2002) there are serious gaps in the knowledge of exploited stocks structure and biomass. Better reporting of catches and effort data is necessary especially in International waters (NEAFC regulatory area). VMS (Vessel Monitoring System) data should be made available to National Research Institutions.

2 .9 .1 0 References

Allain V., Biseau A., Kergoat B., 2003. Preliminary estimates of French deepwater fishery discards in the Northeast Atlantic ocean. Fish. Res., 60, 185-192.

Freiwald, A., Wilson, B.J., 1998. taphonomy of modern deep, cold-temperate water corals reefs. Mar. Biol., 13, 37-52.

Gage J.D., Tyler P.A., 1991. Deep-sea biology. A natural history of organisms at the deep-sea floor. Cambridge University Press, Cambridge, pp 263-273.

Genin, A., Dayton, P.K., Lonsdale, P.F., Spiess, F.N., 1986. Corals on seamount peaks provide evidence of current acceleration over deep-sea topography. Nature, 332, 59-61.

Gordon J.D.M., 1979. Lifestyle and phenology in deep sea Anacanthine Teleosts. Symp. Zool.

Soc. London 44, 327-359.

Gordon, J.D.M., 1986. The fish populations of the Rockall Trough. Proc. R. Soc. Edinb., 191-204.

Gordon J.D.M., Bergstad O.A., 1992. Species composition of demersal fish in the Rockall Trough, north-eastern Atlantic, as determined by different trawls. J. mar. biol. Assoc. U.

K. 72, 213-230.

Gordon J.D.M., Duncan J.A.R., 1985. The ecology of deep-sea benthic and benthopelagic fish on the slopes of the Rockall Trough, northeastern Atlantic. Progress in Oceanography 15, 37-69.

Gordon, J.D.M., Merrett, N.R., Haedrich, R.L., 1995. Environmental and biological aspects of slope-dwelling fishes of the north Atlantic. In: Hopper A.G. (eds) Deep-water fisheries of the North Atlantic oceanic slope Kluwer Academic Publishers Dordrecht/Boston/London, p 1-26.

106 | ICES WGRED Report 2006

Hareide N.-R., Garnes G., 2001. The distribution and abundance of deep water fish along the Mid-Atlantic ridge from 43°N to 61°N. Fish. Res., 51, 2-3, 297-310.

Hareide, N.-R., Garnes, G., Rihan, D., Mulligan, M., Tyndall, P., Clark, M., Connolly, P.L., Misund, R., Mcmullen, P., Furevik, D., Humborstad, O.B., Høydal, K., Blasdale, T., 2005. A preliminary investigation on shelf edge and deepwater fixed net fisheries to the west and north of great Britain, Ireland, around Rockall and Hatton Bank 47 pp. Available at: http://www.bim.ie.

Husebo, A., Nottestad, L., Fossa, J.H., Furevik, D.M., Jorgensen, S.B., 2002. Distribution and abundance of fish in deep-sea coral habitats. Hydrobiologia, 471, 91-99.

ICES, 2004. Report of the working group on biology and assessment of deep-sea fisheries resources International Council for the Exploration of the Sea Copenhagen ICES CM 2004/ACFM:15 Ref. G. ICES CM 2003/ACFM: 25. 308 pp.

ICES, 2005a. The Annual ICES Ocean Climate Status Summary 2004/2005. ICES Cooperative Research Report, No. 275. 37 pp.

ICES, 2005b. Report of the working group on marine mammal ecology (WGMME). ACE: 05, 137pp.

Joubin, M.L., 1922. Les coraux de mer profonde nuisibles aux chalutiers [Deepsea coral harmful to trawlers]. Office Scientifique et Technique des Peches Maritimes, Notes et Memoires, 18, 5-16.

Koslow J.A., 1997. Seamounts and the ecology of deep-sea fisheries. Am. Sci. 85, 168-176.

Koslow, J.A., Boehlert, G., Gordon, J.D.M., Haedrich, R.L., Lorance, P., Parin, N., 2000.

Continental slope and deep-sea fisheries: implications for a fragile ecosystem. ICES J.

Mar. Sci., 57, 3, 548-557.

Lorance, P., Latrouite, D., Seret, B., 2000. Observations of chondrichthyan fishes (sharks, rays and chimaeras) in the Bay of Biscay (North-eastern Atlantic) from submersibles. Proc.

3rd European Elasmobranch Association Meeting, Boulogne-sur-Mer, 27-29 May 1999, 29-45.

Lorance, P., Dupouy, H., 2001. CPUE abundance indices of the main target species of the French deep-water fishery in ICES Sub-areas V-VII. Fish. Res., 51, 2-3, 137-149.

Lorance P., Uiblein F., Latrouite D., 2002. Habitat, behaviour and colour patterns of orange roughy Hoplostethus atlanticus (Pisces: Trachichthyidae) in the Bay of Biscay. J. mar.

biol. Assoc. U. K. 82, 321-331.

McClatchie, S., Thorne, R.E., Grimes, P., Hanchet, S., 2000. Ground truth and target identification for fisheries acoustics. Fish. Res., 47, 2-3, 173-191.

Merrett N.R., Haedrich R.L., 1997. Deep-sea demersal fish and fisheries. Chapman & Hall, London, 282 p.

Merrett N.R., Haedrich R.L., 1997. Deep-sea demersal fish and fisheries. Chapman & Hall, London, 282 p.

Mortensen, P.B., Hovland, M., Brattegard, T., Farestveit, R., 1995. Deep water bioherms of the scleractinian coral Lophelia pertusa (L.) at 64 degree N on the Norwegian shelf:

Structure and associated megafauna. Sarsia, 80, 2, 145-158.

Rogers, A.D., 1999. The biology of Lophelia pertusa (Linnaeus 1758) and other deep-water reef-forming corals and impacts from human activities. International revue of hydrobiology, 84, 4, 315-406.

ICES WGRED Report 2006 | 107