70 years of helping people to care for our ocean

New research published on mussels

By: Erika Steyn

Recently, researchers from ORI and the University of Tromsø, Norway used data collected by conservation minded fishermen and bait collectors over a period of more than 17 years to investigate the collection of the intertidal brown mussel Perna perna. These fishermen were asked to report on their shellfish collection activities in postal questionnaires, telephone interviews and more recently on online platforms.

The full research article can be downloaded here and provides the first long-term record of this fishery.

Here are just some of the highlights.

More than 3000 people buy mussel permits each year, and yet only about half of them actually use their permits. As expected, people living along the coast are more likely to be active mussel collectors, as are persons younger than 30 years old.

More people collect mussels during summer when weather conditions are favourable. Mussel flesh is plumper in summer than either winter and spring when the mussels spawn. On average, a permit holder collects mussels three to four times during a three-month period and almost always collects the full bag limit of 30 mussels per day.

The study also found that the catch rate (numbers of mussel collected per day) is unable to track the stock status of individual mussel beds. Although bait collectors reported stable catch rates (30 mussels collected per day) during the study period, field surveys show that mussel densities can vary considerably over time and from location to location.

For sustainable management of the mussel fishery, it is thus necessary to supplement the questionnaire data supplied by the fishers with field surveys of mussel beds.