The 27th Iceland Groundfish Survey (IGFS) took place for the 1-19 March 2011. Five trawlers participated: The commercial trawlers Bjartur NK, Ljósafell SU and Jón Vídalín VE, respectively and the research vessels Árni Friðriksson and Bjarni Sæmundsson. Around 600 fixed trawl stations were investigated allround the country (Fig. 1) . The main aim of IGFS is to monitor between-year changes in stock sizes, distribution and biological status of demersal fish stocks around Iceland and study variability in sea water temperature on the fishing grounds. Following is a brief summary of preliminary results available.
The mean bottom temperature was rather high in 2011 as it has been in recent years. In the warm ocean water at the south and west coasts of Iceland, the temperature was similar to the recent nine years. At the north coast the bottom temperature was also rather high, however, somewhat lower than during the spring surveys 2003-2006 (Fig. 2) .
The geographical distribution of cod was relatively even and the main changes in distribution since 2010 were higher abundance at the southeast and northwest coasts, while lower abundance was found at the continental edge off Northeast Iceland (Fig. 3) .
As during the last three years, the biomass index for cod increased between years, measuring now at a similar level as in 1998 and 2004 (Fig. 4) . The increasing trend of the index in recent years is mainly due to higher proportion of large cod (larger than 70 cm). This is well demonstrated by the length distribution, where we also see that middle sized fish, i.e. 35-60 cm long, is lacking compared to the average for the period 1985-2010 (Fig. 5) . The first estimate of the size of the 2010 year-class indicates it is weak. The year-classes 2008 and 2009 have been estimated as of average strength if compared to the average year-class sizes in the survey since during 1985 - 2010.
The youngest cod age groups (1-3 years of age) measured below average in weight as has been the case the last 6-7 years. However, the mean weight at age for 4-9 year old cod has shown increasing trend in recent two years and is now around or above the average for the period 1985-2010. At the south coast the body condition index (measured gutted weight at length) for these age groups and the liver index are the highest since 1993, when such weighing started.
The good body condition of the cod stock is in accordance with greater stomach fullness than in recent years, where capelin was far the most important prey species for cod as often is the case at this time of the year (Fig. 6) . Capelin occurred in cod stomachs allround the country, but the greatest stomach fullness was found in Breidafjord (W Iceland), at the grounds off the Westfjords and in shallow waters off the northern coast of Iceland (Fig. 7) .
The biomass index for haddock has shown a decreasing trend in recent years and was now only ¼ of the average for the 2003-2007 when it was at maximum level (Fig. 8) . The length distribution for haddock show all length classes below average in numbers (Fig. 9) . Length distribution and age data indicate that all haddock year-classes after 2007 are weak, but most of the haddock catch was 35-50 cm long, most of which are 4 year old haddock.
The haddock was caught at the continental shelf allround the country (Fig. 10) . The decreasing abundance of haddock in most recent years is therefore not limited to certain areas. However, the distribution has shown dramatic shifts since the years just before the turn of the century when relatively small proportion of the haddock catch was taken north and east off Iceland. The body condition of the haddock was around average both south and north of Iceland, while the liver index was near minimum compared to earlier years. Despite this, more capelin was found in haddock stomachs than in recent years (Fig. 11) .
The biomass index for halibut in the IGFS collapsed dramatically during the 1986-1990 and has been at minimum level ever since. In no year has fewer halibut been encountered in the IGFS than during the last two surveys and the biomass index now is approximately 1/20 of what it measured during the period 1985-1986 (Fig. 12) .
The biomass index for plaice was similar to last year and somewhat higher than during the years 2004-2009, although it measured only 1/3 of the index in 1985 when the IGFS started. The biomass index for the lemon sole and witch flounder have stayed at relatively high level since 2003 after a decade of low level abundance (Fig. 12). The biomass index of common dab has stayed low in recent 8 years.
Other species and stocks
The biomass index for the Golden redfish measured high as has been the case since 2003 (Fig. 13) and as usually greatest occurrence was in deep waters off the Faxabay and the Breidafjord (W Iceland). Only small catches were made of small Golden redfish, i.e. redfish less than 30 cm.
The stock biomass index for saithe was relatively low like it was in recent four years and is now at similar level as it was during the period 1996-2003 (Fig. 14). The saithe at the size range of 35-50 cm was in somewhat greater numbers.
The biomass index for the catfish was relatively low as in the last years survey (Fig. 14) . Relatively small catches of 20-60 cm catfish were made compared to earlier years, which indicates relatively poor recruitment in the coming years. The occurrence of catfish larger than 70 cm was above average .
The ling biomass index increased during the years 2003-2007 after a ten year period of low values (Fig. 14). The 2011 index is the second highest since 1985 and 40-80 cm ling was predominant in the catch.
The tusk biomass index has remained high since 2004 at a similar level as during the years 1985-1992. The 2011 index is similar to the years 2006-2008 (Fig. 14). However, small tusk (less than 30 cm) has shown a decreasing trend.
As in most recent years considerable amount of monkfish occurred south and west of Iceland with a few fish even caught off North Iceland (Fig. 14). However, the year-classes 2008 and after are rather weak if compared with the years since 1998.
The lumpsucker abundance in the IGFS increased during the years 2001-2006, but has decreased since. The biomass index is now at the lower range since the monitoring started but similar to the period 1995-2001 (Fig. 14).
The current provisional results of the IGFS presented here are important part of the annual assessment of the Marine Research Institute of the status of exploited fish stocks off Iceland. The final results of the annual stock assesment with recommendations on allowable catches for the next fishing year (starting 1. September 2011) will be presented in early June 2011.
The Marine Research Institute, Reykjavik, 13 April 2011