Alison I. Feibel1, Jean-Sébastien Lauzon-Guay1, Raúl A. Ugarte1
1Acadian Seaplants Limited, 30 Brown Avenue, Dartmouth, Nova Scotia B3B 1X8, Canada
Ascophyllum nodosum (L.) Le Jolis dominates the rocky intertidal zone across most of its distribution in the North Atlantic and is widely harvested at a commercial scale in North America and Europe. Common harvesting techniques are a walk-on harvest using a knife, a specialized manual cutting rake from a boat, and mechanized vessels with hydraulic cutter heads (mechanical harvesters). The walk-on harvest and mechanical harvesters traditionally conduct a pulse harvest at higher exploitation rates than the boat and rake. After the harvest, beds are left fallow for multiple years to regrow. To examine A. nodosum recovery rates and the impact on associated invertebrate communities following a mechanical harvest, we established two control and two experimental harvest plots at two sites in Maine (USA) in August 2018. A second harvest was conducted in 2021 to reproduce a three-year pulse harvest. Data collection on A. nodosum and invertebrates (second harvest only) was collected prior to harvesting, immediately post harvesting, and at one-year intervals for three years. The harvests removed 53% and 41% of the A. nodosum biomass respectively, resulting in a significant decrease in biomass and length but no difference in snail populations. The impact of the harvest was short, after one year there was no significant difference between our control and experimentally harvested plots for biomass or length. Our initial results indicate that the impact of mechanical harvesting has only a short-term impact on A. nodosum architecture. Further results will provide data on the effects of a repetitive mechanical harvest.