Harvesting seaweed in France: what quantity of biomass is harvested?

The French coasts, including Brittany, represent an important part of the seaweed harvest in Europe, for bottom seaweed, as well as for shore seaweed.

France is a country that harvests a large amount of seaweed. In particular, the Brittany coasts are an essential area for seaweed growth. Scientists have identified more than 700 seaweed species in the Iroise Sea, around the Molène archipelago as well as around Roscoff or off the coast of Bréhat. It is an important ecosystem for all fauna, an abundant and varied resource; but what is the situation exactly for the harvesting of this biomass for processing? The latest figures show stable production over the last ten years dominated by the harvesting of laminaria and fucales.

Bottom seaweed

France is the second largest producer of seaweed in Europe after Norway. Each year it produces between 70,000 and 90,000 tonnes of fresh seaweed from the harvest of natural populations.

This harvest is mainly done by boats to harvest laminaria. At the last Idealg forum held in Roscoff in November 2019, Martial Laurans from Ifremer presented the updated data of this vessel-based, mechanised harvest.

Currently around thirty active boats fish 50,000 to 60,000 tonnes of fresh Laminaria digitata and 15,000 to 20,000 tonnes of fresh Laminaria hyperborea. This harvest is concentrated in the Iroise sea, the border between the temperate hot and cold waters, with little exchange with the coastal waters and concentrating most of the algae resource in France.

In addition, there is still some seaweed harvesting activity in the Basque Country. Red seaweed, Gelidium sesquipedale, ripped by the elements, which is collected in the sea when it is drifting (cutting it is forbidden) or gathered from the shore when it is washed up (conditions for collection and gathering set by Prefectural Decree). Ten or so boats remain active for this collection. Relatively recent press articles refer to 1,000 to 1,600 tonnes fresh/year unloaded in France in Saint-Jean de Luz, to be sent to Spain to an agar extraction plant.

Shore seaweed

The other seaweed exploited in France is gathered on foot by professional shore seaweed gatherers and for a few years have accounted for around 4,500 to 5,000 tonnes harvested annually in Brittany.

In Brittany, this fishing is strictly governed by the Brittany regional fishing committee (http://www.bretagne-peches.org/) to control and manage this wild biomass and therefore increase sustainability of the environment and companies. Fishing and harvesting days as well as the number of harvesters have been determined to avoid over-exploiting seaweed, adjust the harvest according to growth and to leave areas fallow. In 2018, 79 shore seaweed harvesting licences were issued on a professional basis, which is the maximum number of licences determined by deliberation of the Brittany CRPMEM and the harvest was carried out by 277 harvesters of which 136 were seasonal harvesters.

More recently, to support the development of this activity along the Atlantic coasts, decrees regulating the harvest of shore seaweed were also issued or submitted to a public consultation for the Pays de la Loire region as well as Charente Maritime. The harvesting of shore kelp is also regulated in the Atlantic Pyrenees. The volumes harvested in these areas nevertheless remain much lower than those harvested in Brittany.

Recently, the compilation of harvesting data provided monthly by professional harvesters to the Brittany DDTM (Department for Land and Coastal Management) was published. It enables you to find out the species of seaweed harvested and the tonnages available for processors. This data is presented in the summary report of the 2016-2019 Seaweed Biomass programme ‘Evaluation et gestion de la biomasse exploitable en algues de rive’ (Assessment and management of the shore seaweed biomass that can be exploited) (http://www.bretagne-peches.org/?titre=programme-biomasse-algues&mode=peche-a-pied&id=366). The authors of this report do however emphasise that this information must be taken with precaution given certain limitations in the declaration data: co-harvested and/or co-declared species, dried weight/fresh weight mixtures, location problems, etc.). The use of data must therefore take all these limitations into account, but does give a good overview of the harvests.

In 2018, the harvest of shore seaweed in Brittany reached 4,553 tonnes of fresh seaweed. Finistère accounts for 58% of the tonnes harvested with production of more than 2,622 tonnes of fresh seaweed. Second is the Côtes d’Armor with a production of 1,931 tonnes of fresh seaweed. Activity is on a small scale in Ille-et-Vilaine and in Morbihan.

Most of the seaweed harvested (79% in 2018) comprises fucales (A. nodosum, Fucus spp., H. elongata). In more detail, the authors of the biomass report present the different species of seaweed harvested

                                     In tonnes of fresh seaweed

  • Ascophyllum nodosum                            2,359
  • Himanthalia elongata and Fucus spp.    1,251
  • Palmaria palmata                                   333
  • Chondrus crispus                                    316
  • L. digitata, Saccharina latissima            151
  • Ulva spp.                                                 90
  • Porphyra dioica                                      30
  • Other seaweed                                         22

This tonnage of seaweed harvested has been quite stable for several years. However the demand for biomass is increasing. To make seaweed exploitation activities sustainable and plan for future developments, professionals are implementing different strategies to provide tomorrow’s seaweed: estimate of biomass available to identify harvests in areas that are not yet exploited, optimisation of harvest methods to enable better regrowth/growth, sea and land seaweed farming facilities, development of methods to farm seaweed that is in shortage, exploitation of biomass captured naturally in oyster leases, etc.

Although seaweed is one of the solutions for the sustainable food of the future, it is vital to be able to sustainably harvest or grow this seaweed.

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