Paula Chainho Warns of the Urgent Need to Regulate the Harvesting of Japanese Clams

The recent collision between a fishing boat and a catamaran on the River Tagus has raised a number of questions about the harvesting of the Japanese clam, which, despite earning millions of euros for the catchers, can be a danger to public health. MARE researcher Paula Chainho, who leads the team studying this bivalve, has completed the National Action Plan for the Japanese clam, which has yet to be implemented. ​

The Japanese clam (Ruditapes philippinarum) is a species of bivalve that was introduced to Portugal in the 1980s to be cultivated in the Ria Formosa. Since then, the species has spread to the estuaries of the Tagus, Mondego, Sado and elsewhere, and was classified in 2019 as an invasive species, which prohibited its commercialization unless there is a management plan. 

There are two bivalve production areas in the Tagus: one downstream of the Vasco da Gama Bridge and another upstream, where the quality of the bivalves is strictly monitored. In the downstream zone, the harvesting of lambujinha is prohibited due to high levels of lead, but the Japanese clam can be caught, provided it goes through a purification or processing process. In the upstream zone, clams cannot be caught, as the species has not yet been classified for consumption.

In Portugal, there are no specific regulations for harvesting Japanese clams, which are only regulated by the rules of the areas where the bivalve is caught, such as in the Tagus estuary. It can be harvested in two ways: with a recreational fishing license, allowing up to five kilos a day to be caught without the possibility of selling it, or with a professional license, which requires the use of legal fishing gear and takes place in areas defined by the National Bivalve Monitoring System of the IPMA (Portuguese Institute for the Sea and Atmosphere).

In order to better manage harvesting and control populations of this bivalve, a team of researchers led by Paula Chainho drew up the National Action Plan for the Japanese Clam, which is currently awaiting review by the Institute for Nature Conservation and Forests (ICNF) before being implemented. This plan, which was drawn up in conjunction with researchers, fishermen, captaincies, inspection bodies and decision-makers, “defines what measures need to be implemented, both in terms of regulation and monitoring, in order to legally fish for this clam as a way of controlling populations”.

Paula Chainho, in an interview with Público, explained that one of the measures included in the plan is a change in the daily clam catch limits. This measure was eventually implemented through regulations published in the meantime, but even so, the researcher believes that it needs the legal framework provided by the plan. Despite this, this daily limit allows anyone with a professional license to catch around 80 kilos of clams a day in the Tagus River.

Other measures proposed in the plan include the creation of a study on juvenile Japanese clams, to assess the impact of illegal harvesting for export, and the development of solutions for the treatment of clams that need prolonged purification. The plan also suggests limiting catches in recreational fishing and creating mechanisms for disposing of seized clams, which are often returned to the estuary.

In order to be implemented, this plan still needs to be approved by the Council of Ministers, but is currently under review by the ICNF.

The situation calls for urgency, as the Tagus' Japanese clams may not be in suitable condition for consumption. As Paula Chainho points out, “I don't buy Japanese clams because I know where they're caught. It may be fine and it may not.” The problem persists and, until the action plan is implemented, the solution remains distant.

To access the article in Públicor click HERE