LobStAR (Stock assessment and management of Eastern Scheldt Lobster)

Collaboration between researchers and fishers

The small-scale, seasonal lobster (Homarus gammarus) fishery in the Eastern Scheldt is unique in the Netherlands. The lobster stock fluctuates as a result of natural factors. In recent years, however, some fishers and recreational divers are seeing fewer lobsters. It is unclear whether the stock is showing a structural decline, and if so, for what reasons. Through the Association of Professional Fishers Oosterschelde, Westschelde and Voordelta (OWV), fishers have launched their own fishing plan to improve fisheries management. To do so, an adequate stock assessment is essential, but insight into the lobster stock status is lacking. The OWV also wants to start a dialogue with the government and other stakeholders on the development of the lobster stock and base possible additional management on scientific data.

An adequate stock assessment is the foundation of sustainable fisheries. Funding for such a scientific assessment is, however, beyond the reach of a small fisheries niche such as that of East Scheldt lobsters. Project subsidies have the disadvantage of being temporary, while stock assessments should be conducted annually. The key to future-proof stock assessments thus lies with a method by which fishers themselves efficiently and practically can gather data that feed into a simple data management system. This system will then automatically generate annual reports on the development of the catches over time. The LobStAR project’s primary goal is to develop an innovative Stock Assessment knowledge system through intensive collaboration with East Scheldt lobster fishers. This system can then be continued by OWV against low costs once the project is concluded. This system will provide data to support sustainable management (Regulatory approaches).

What are the project’s key questions?

1. What does biology of the East Scheldt lobster look like?
2. How do we design a simple system for automatic catch registration?
3. What does a simple stock estimate for the East Scheldt lobster look like?
4. What does a data management and calculation application that the sector can operate on its own look like?
5. What knowledge do lobster fishers have, and how can we apply this knowledge to the stock assessment and management?

These questions are addressed in separate, interlinked action packages.

Biology of the lobster

Information on the growth, reproduction and mortality of East Scheldt lobsters is of crucial importance to the stock assessment. This information also benefits lobster fishers in planning and conducting their fishery activities.

Laboratory and field experiments enable us to map the lobsters’ biology. In the lab, for example, we study the animals’ basic energy use and the relation between their activity level and water temperature. In the field, lobsters are tagged and released with help from fishers. Thus, when a tagged lobster is caught, we can monitor the individual growth and gain insight into the migration of lobsters in the East Scheldt.

CatchCam for automatic catch registration

We need adequate information on the catch to produce a stock assessment. For example, how many lobsters are caught, how many are male and how many are female and what is their size? Aboard the small vessels, measuring and determining the sex of each individual lobster is difficult for the fishers. Therefore, we develop an onboard catch monitoring system capable of registering the fishing efforts and catch information. The lobsters are placed under a camera which then takes a picture and registers the precise location. Automatic image recognition software then enables a computer to determine the size and sex of the lobster. The camera registers only the catch and not the personnel aboard the vessel. This so-called "CatchCam" operates autonomously to ensure the fisher is not required to take additional actions that may interfere with the fishing activities on board.

Stock assessment

We map what data is already available and how, and what extra efforts are required to achieve a dataset that can be used for a stock estimate. Moreover, we study what stock assessment methods are suitable for use with these existing data. Next, we assess the historical development of the stock based on existing data and the current status as revealed by the data that is collected within the project.

Data storage and application

In the setup of the project, the sector is the initiator and driving force behind the data supply for this project; a unique concept compared to conventional government-driven monitoring programmes. With the aid of technology, we support the shift in ownership and responsibility for monitoring and management from the government to the sector. We investigate whether the onboard automatic catch registration can be stored within a database managed by the fisheries association OWV. Furthermore, we consider the possibility of developing an application that can generate reports on stock development. And finally, we consider what preconditions are needed to enable the Zeeland lobster fishing sector to maintain a novel concept (a fisheries information system managed by the sector) in the long term.

Using the knowledge of fishers

Sustainable lobster fishing in the East Scheldt calls for accurate information on stock developments. To this end, biological data and catch data of all the various lobster sizes that are caught must be linked to the actual fishing effort. Building a time series of quantitative data for a stock assessment will take several years. However, fishers also have a wealth of knowledge on the lobsters’ biology, historical development and changes. This local experience is a crucial source of information that can be used to improve insight into stock development. Combining the knowledge of fishers and scientists enables us, in a much shorter-term, to generate a qualitative assessment of the stock development . The knowledge the fishers have can also be included in the scientific data and can be used for comparison and interpretation purposes. The fishers’ knowledge will be gathered through interviews, work sessions and an annual survey on the developments in the composition of the catch.

Supervisory committee

Other parties may also benefit from systematically gathered information on the development of the lobster stock. The dialogue on stock development and management strategies benefits from shared, validated knowledge. To this end, a supervisory committee has been set up for the project, which includes the following parties: Stichting Anemoon; Stichting Promotie Oosterscheldekreeft; United Fish Auctions; and Stichting Nationaal Park Oosterschelde.