ICES Living Resources Committee ICES CM 2004/G:13, Ref. D Report of the Study Group on the Biology and Life History of Crabs (SGCRAB) By Correspondence This report is not to be quoted without prior consultation with the General Secretary. The document is a report of an Expert Group under the auspices of the International Council for the Exploration of the Sea and does not necessarily represent the views of the Council. International Council for the Exploration of the Sea Conseil International pour l’Exploration de la Mer H. C. Andersens Boulevard 44–46 · DK-1553 Copenhagen V · Denmark Telephone + 45 33 38 67 00 · Telefax +45 33 93 42 15 www.ices.dk · [email protected] Contents 1 INTRODUCTION...................................................................................................................................................... 5 1.1 Background of the Study Group ..................................................................................................................... 5 1.2 Terms of Reference......................................................................................................................................... 5 1.3 Attendance at the Study Group ....................................................................................................................... 5 2 PROGRESS IN RELATION TO THE TERMS OF REFERENCE........................................................................... 6 2.1 TOR a: compile data on landings, discards, effort and catch rates (CPUE) for the most important crab fisheries in the ICES area................................................................................................................................6 2.1.1 Cancer pagurus landings..................................................................................................................... 6 2.1.2 Cancer pagurus Ireland, Inshore ......................................................................................................... 7 2.1.3 Cancer pagurus Ireland offshore......................................................................................................... 7 2.1.4 Chaceon affinis Ireland........................................................................................................................ 8 2.2 TOR b: standardise methods for the acquisition, analysis and interpretation of CPUE, size frequency and research survey data........................................................................................................................................ 8 2.2.1 Investigating assessment methods for Cancer pagurus....................................................................... 8 2.3 TOR c: define stock structure / management units for crab stocks................................................................. 9 2.3.1 Estimation of crab meat content by measurement of blood protein in Cancer and Maja..................... 9 2.3.2 Seasonal changes in condition (blood protein) of Cancer pagurus ................................................... 10 2.3.3 Size at maturity of Cancer pagurus (Ireland) .................................................................................... 11 2.3.4 Hematodinium infection in Cancer pagurus in Ireland ..................................................................... 12 2.4 TOR d: assess environmental effects including diseases on crab fisheries;.................................................. 13 2.5 TOR e: assess the interaction between net/dredge fisheries and other anthropogenic activities and crab stocks 13 2.5.1 Larval surveys – Cancer in the English Channel ............................................................................... 13 2.6 TOR f and g: assess the effects of fishing on the biological characteristics of crab stocks and review the methods for estimating recruitment to crab stocks........................................................................................ 14 3 VENUE AND DATES FOR NEXT MEETING...................................................................................................... 15 1 Introduction 1.1 Background of the Study Group The first meeting of the Study Group on Crab met in Jersey, UK, in 1993 to review progress on the research and fishery management of two commercially important Majidae species, the spider crab (Maja squinado) and the snow crab (Chionoecetes opilio), fished on the two sides of the Atlantic and in the Pacific, as reported in C.M. 1993/K:3. The Study Group recognised the need for more intensive coverage of the life history characteristics of the two species, and a better geographic representation of carcinologists. This lead to a second meeting at La Coruña, Spain, which reviewed new information available on the life history and fishery management of the Spider crab and Chionoecetes species (opilio, bairdii, tanneri), as reported in C.M. 1996/K:1. It was recommended that the SGCRAB should meet on a 3 years basis and that the remit be enlarged to include other commercially important crab families (notably portunid and cancrid crabs which are not covered by ICES assessment working groups or study groups. Subsequent meetings of SGCRAB was convened in Brest, France (4–7 May, 1998), in Copenhagen 25–29 March 2001 and Tromsø (2–4 June 2004) respectively. The 2004 report was produced by correspondence and in preparation for a meeting in Galway, Ireland in May 2005. 1.2 Terms of Reference The Study Group on the Biology and Life History of Crabs [SGCRAB] (Chair: O. Tully, Ireland) will work by correspondence in 2004 to prepare for a meeting in 2005: a) compile data on landings, discards, effort and catch rates (CPUE) for the most important crab fisheries in the ICES area; b) standardise methods for the acquisition, analysis and interpretation of CPUE, size frequency and research survey data; c) define stock structure / management units for crab stocks; d) assess environmental effects including diseases on crab fisheries; e) assess the interaction between net/dredge fisheries and other anthropogenic activities and crab stocks; f) assess the effects of fishing on the biological characteristics of crab stocks; g) review the methods for estimating recruitment to crab stocks. 1.3 Attendance at the Study Group The following members contributed to the 2004 report: Tully, O. (Chair) Ireland Fahy, E. Ireland Robinson, M. Ireland Addison, J. United Kingdom Eaton, D. United Kingdom Latrouite, D. France Other members were contacted by e-mail and asked for submissions to this report. ICES SGCRAB Report 2004 5 2 Progress in relation to the Terms of Reference 2.1 TOR a: compile data on landings, discards, effort and catch rates (CPUE) for the most important crab fisheries in the ICES area 2.1.1 Cancer pagurus landings 2.1.1.1 Landings in England and Wales Total landings for England and Wales vessels are given in Table 1.1. Landings (provisional) in 2003 from all areas were the second highest on record surpassed only in 1998. The majority of landings come from areas 104B, 104C, 107D and 107E. Table 1.1. Total landings (tonnes) of edible crab by ICES region by E&W vessels, all gears, all ports. 2003 landings are provisional Year 104A 104B 104C 106A 107A 107B 107C 107D 107E 107F 107G 107H 107J 107K 108B Total 1990 1953 1152 0 219 926 4047 806 178 0 9282 1991 1839 1325 210 751 4084 400 184 0 8793 1992 2208 617 4 146 1392 3562 295 318 3 8546 1993 0 978 747104 1220 3032 644021 106640 1994 0 872 1397 0 1797 4024 484 0 0 8576 1995 0 918 1495 67 1948 4941 397 71 0 9837 1996 0 1234 1440 1 6 1283 4761 326 1 2 9055 1997 1 1448 1263 1 100 1 1457 5868 367 322 1 0 10830 1998 1754 1295 223 82 4 0 1324 9778 557 367 5 2 15391 1999 16 1994 1292 0 77 0 1121 6485 700 159 2 11847 2000 12 3312 1406 3 107 0 0 764 4909 680 112730011315 2001 7 3425 1676 188 119 1 0 749 4859 881 143 31 11 12091 2002 2983 1804 4 214 1 0 876 4784 502 244 59 3 0 11474 2003 0 3808 1524 4 131 0 809 5564 543 127 14 2 12525 2.1.1.2 Landings in Ireland Total landings of Cancer pagurus by Irish vessels was over 10,000 tonnes in 2002. Landings have been increasing by 590 tonnes per annum since 1990 (Figure 1.1) 12000 y = 590.62x - 1E+06 10000 8000 6000 4000 2000 0 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 Figure 1.1. Landings (tonnes) of crab by Irish vessels 1990–2002. The average annual increase in landings is 590 tonnes. 6 ICES SGCRAB Report 2004 2.1.2 Cancer pagurus Ireland, inshore A voluntary logbook scheme was launched in Ireland’s inshore crab and lobster fishery in 2002 by BIM (The Irish Sea Fisheries Board). Catch rates of Cancer pagurus are recorded as target or as by-catch (of the lobster fishery). Gear is targeted at one or the other species. Landings are recorded as number of boxes per day and the amount of fishing gear targeting crab or lobster is indicated. Table 1.2 shows the landing per unit effort (kgs per trap) and discards per unit effort in four counties in 2003. Table 1.2 Landing (LPUE in kgs per trap hauled) and discard rates (DPUE) of crab in four counties in Ireland in 2003. LPUE DPUE County N Mean S.d. Mean S.d. Clare 24 0.80 0.24 0.45 0.13 Cork 14 2.39 0.69 0.86 0.56 Donegal 118 1.24 0.60 0.82 0.48 Kerry 195 1.88 0.99 0.75 0.60 2.1.3 Cancer pagurus Ireland offshore A database of fine spatial scale catch and effort data for the Irish offshore Cancer pagurus fishery continues to be updated. This database holds DGPS position and associated catch information for every string of pots from all vessels (5) involved in the fishery since it was established in 1990.