Recruitment of blue mussels, Mytilus edulis L., on suspended collectors in Finnmark, North Norway (70–71°N)

Abstract

In order to investigate Mytilus edulis settlement in two North Norwegian fjords (70–71°N), short-term collectors were suspended at six different stations at intervals of 2–4 weeks during spring–autumn of 2002 and 2003. At the same stations, long-term collectors were deployed monthly from May to August 2002 and sampled the following autumn. Settlement occurred between early July and late October and peaked between mid-July and mid-September. Settlement peaked in inner Porsangerfjord, with the average mean daily settlement (MDS) up to 1408 m⁻¹ day⁻¹, and decreased towards the coast, where the maximum MDS was 3.8 m⁻¹ day⁻¹. In Altafjord, maximal mean MDS were between 47 and 168 m⁻¹ day⁻¹. Fjords apparently function as retention areas for larvae, whereas at the coast larvae are effectively dispersed. Eighty-nine per cent of the mussels recruited in October/November were <2 mm. Long-term collectors deployed in inner Porsangerfjord had the highest recruitment (mean density 47,537 m⁻¹). Inner Altafjord had very low recruitment (mean density 46 m⁻¹), perhaps due to freshwater discharge. Collectors deployed in late August had lower recruitment than those deployed earlier, but there was no evidence of recruitment differences between collectors deployed earlier. At densities above ca. 5000 m⁻¹, intraspecific competition controlled the level of recruitment.

Keywords:

• Blue mussels
• Mytilus edulis
• North Norway
• recruitment
• settlement

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgments

Many people have assisted me on my many journeys around Finnmark. I particularly thank Frank Lund for 2 years of Finnmark tours and for measuring mussels; Mona Isaksen for measuring mussels; Knut Bergly, Gunnar Mathisen and Kyrre Olsen for their hospitality and for letting me use their mussel farms; Knut Sivertsen for repeatedly reviewing the manuscript and good advice; Hans Christian Eilertsen for reviewing the manuscript and encouraging words; and Arne Duinker for a very helpful review of the manuscript.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark