The fidelity of wolffish towards feeding area in fjord


Movements and migration behaviour of common wolffish (Anarhichas lupus) were studied in Fjord Hvalfjordur W-Iceland throughout June 2010 ÔÇô March 2012. Sampling on the geographical distribution and depth of the wolffish during their stay in Hvalfjord was carried out by tagging fish in June 2010 and May 2011. Using ultrasonic transmitters and by monitoring by logging the dwelling of those fish within detecting area of stationary listening stations throughout the fjord area. Main aim of the study was to map the movements and migration patterns of wolffish in infjord area in relation to time of the year and environmental factors. 
The information received represent the first data on migration behaviour of wolffish individuals in Icelandic waters including data covering period of 34 months. The dwelling of wolffish (67-77 cm in length) within detection area of the receivers and their movements between them has given information on how they utilise the fjord area and on their travelling speed. The wolffish forage in Hvalfjord from January until end of August but are in outer areas in-between due to spawning and the migration involved before and following spawning. Following spawning the wolffish entered the feeding grounds of Hvalfjord in January - April where most of them stayed until June - August when they migrated out of the fjord in the beginning of the spawning migration or just before.  The recorded depth of wolffish in Hvalfjord was ranging from 22 to 49 m and their mean travelling speed when moving between stations where mainly 0,2-0,4 km with instances of higher mean speed, up to 2.5 km/hour. During the summer the wolffish showed generally fidelity to narrow feeding areas as reflected by their staying within detection area of receivers (0,5 km2 +/- 0,3 km2), with examples of such dwelling of individual within range of one station for 20-63% of its time every week for 3 months. The annual monitoring of wolffish in Hvalfjord showed that they entered this feeding area year after year.  The best example of this fidelity of wolffish towards their feeding grounds in the fjord area is the dwelling of two wolffish there for 3 years in a row. This first tagging of wolffish with electronic tags in Icelandic waters have given new information on behaviour ecology of wolffish that are valuable to improve further research on the fish and serve as important references when decisions concerning utilisation of wolffish are taken. In December 2012 report was published (in Icelandic with English abstract) revealing results of the wolffish study 2010-2012 that can be accessed here: G├Ânguheg├░un steinb├şts ├ş Hvalfir├░i

The wolffish study was carried out parallel to study on migration behaviour of haddock (Melanogrammus aeglefinus) in Fjord Hvalfjord where same technology was used. These research were the first to use electronic tags to study haddock and wolffish in Icelandic waters. The  study on haddock in Hvalfjord showed annual fidelity of the haddock to the feeding grounds in the fjord and their spawning migration out of the fjord inbetween, as was shown for the wolffish. Detailed information received in the study on haddock migration in Hvalfjord is put forward in report published in May 2012 (in Icelandic with English abstract) that can be accessed here: G├Ânguheg├░un ├Żsu ├ş Hvalfir├░i

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