Origin of the large burbot (Lota lota (L.)) caught in an Arctic ice-fishing competition: a case study

Recreational ice-fishing and ice-fishing competitions are popular in Finland. In recent years the prizes have become increasingly valuable. One such competition is held yearly at Lake Kilpisjärvi. During the 1998 ice-fishing competition, two participants brought two large burbot (Lota lota (L.)) to the officials for weighing. These two burbot were much larger than the rest of the fish caught. The origin of these two burbot was questioned and subsequently studied by comparing their age-specific size, stomach contents and parasite fauna with those of the smaller burbot caught during the competition. Both the age-specific lengths and weights of the suspected burbot were higher than those of the smaller burbot, and the stomach analysis revealed that the large burbot had eaten roach (Rutilus rutilus (L.)), which are not found in Lake Kilpisjärvi. Moreover, the parasite fauna in these two burbot was not typical of the lake. It was therefore concluded that the suspect burbot could not have been caught in Lake Kilpisjärvi, and the contestants were disqualified.