Aspects of the sealworm Pseudoterranova decipiens life-cycle and seal-fisheries interactions along the Norwegian coast

• Published in: Developments in Marine Biology Vol. 4; pp. 557 - 564
• Main Authors: Andersen, Karin, Clers, Sophie des, Jensen, Tor
• Format: Book Chapter
• Language: English
• Published: 1995
• Subjects: Halichoerus grypus; Phoca vitulina; Pseudoterranoua decipiens; seal-fisheries; sealworm; Halichoerus grypus; seal-fisheries; sealworm; Pseudoterranoua decipiens; Phoca vitulina
• ISBN: 0444820701; 9780444820709
• ISSN: 0163-6995
• DOI: 10.1016/S0163-6995(06)80054-5

Demersal fish were sampled from two areas between 1990 and 1993 in order to study the sealworm life-cycle in Norwegian coastal waters, and to assess the current level of seal-fisheries interactions. In both study areas, it is proposed that sealworm transmission revolves around a large and long-lived reservoir of parasites in small benthic non-exploited fish species. This is likely to greatly reduce the scope of sealworm control, either through a seal cull or through increased pressure on commercially exploited fish stocks. In Hvaler Oslofjord, sealworms are transmitted by common seals and infections can reach higher levels locally than at Vega, middle Norway where sealworms are likely to be transmitted mostly by grey seals. However, the level of interaction from seals perceived by fishermen is much higher at Vega. This is probably linked to the larger size and higher visibility of grey seals, the use of fixed gear and the concentration of fishing activities on benthic species close to, haul sites in shallow waters where sealworm infections are highest In Hvaler, the main fishery is currently trawling for uninfected invertebrate in deep waters away from seal haul-out sites, and little interaction is reported. The level of interaction perceived by fishermen is thought to greatly vary, both regionally and historically, with the type of fishing activity.