The European lobster (Homarus gammarus) occurs along the entire Swedish west coast down to the northern part of the Sound, and lives mainly on rocky substrates in crevices and dugouts between rocks and gravel. The lobster population along the Swedish coast is considered to be one single stock, but large local differences in density may occur. Fishing for European lobster is extensive, but catch per effort (the number of lobsters caught per pot) decreased sharply during the 1950s and 1960s and has since remained at a stable low level according to catch data from lobster fishermen in Bohuslän. New legislation limiting the lobster fishery was passed in 2017, yet the stock is still considered to be overfished: The overall stock analysis (Fish Barometer 2024) indicates high fishing mortality over long periods, and low productivity, with the result that the stock is not within safe biological limits. To provide management with a strong basis for decision-making, we are working to increase the knowledge of European lobster biology and behavior.
Every year, the Department of Aquatic Resources (SLU Aqua) conducts a lobster survey in both no-take and fished areas to provide fisheries independent data on biological parameters of the Swedish lobster population. In addition to SLU’s survey, volunteer fishermen participate in the citizen science project; LOBSERVE, which enables the collection of catch data and size along a larger geographical area. Lobster catch can be used as an index of density, and thus of stock status, and can be compared between areas and over time if the fishing is standardized and carried out at the same time of year. If a pot is left fishing (soaked) for a longer period, the pot will eventually be saturated as lobsters are no longer attracted to the bait or choose not to enter due to e.g., competition. CPUE needs to be standardized to soak time to be comparable. With the help of a camera study, we want to find out what happens at and around the cage. We want to investigate questions such asks and gravel. The lobster population along the Swedish coast is considered to be one single stock, but large local differences in density may occur. Fishing for European
lobster is extensive, but catch per effort (the number of lobsters caught per pot) decreased sharply during the 1950s and 1960s and has since remained at a stable low level according to catch data from lobster fishermen in Bohuslän. New legislation limiting the lobster fishery was passed in 2017, yet the stock is still considered to be overfished: The overall stock analysis (Fish Barometer 2024) indicates high fishing mortality over long periods, and low productivity, with the result that the stock is not within safe biological limits. To provide management with a strong basis for decision-making, we are working to increase the knowledge of European lobster biology and behavior.
Every year, the Department of Aquatic Resources (SLU Aqua) conducts a lobster survey in both no-take and fished areas to provide fisheries independent data on biological parameters of the Swedish lobster population. In addition to SLU’s survey, volunteer fishermen participate in the citizen science project; LOBSERVE, which enables the collection of catch data and size along a larger geographical area. Lobster catch can be used as an index of density, and thus of stock status, and can be compared between areas and over time if the fishing is standardized and carried out at the same time of year. If a pot is left fishing (soaked) for a longer period, the pot will eventually be saturated as lobsters are no longer attracted to the bait or choose not to enter due to e.g., competition. CPUE needs to be standardized to soak time to be comparable. With the help of a camera study, we want to find out what happens at and around the cage. We want to investigate questions such as:
- What influences a lobster to enter a pot?
- At what rate is a pot getting saturated?
- At what point do lobsters stop entering the cage?
- Do lobsters’ propensity to enter a cage with other lobsters differ between fished and
no-take areas?
We offer the opportunity to do a degree project with focus on European lobsters, using camera-rigged pots to study the behavior of lobsters around pots and also factors leading to saturation of pots. We are looking for a highly motivated student with an interest in fisheries ecology and animal behavior. Experience with dynamic modelling and R is an advantage. The work includes fieldwork, analysis of collected video material and data analysis. SLU’s lobster survey occurs in Lysekil in August 2024, and the student will be part of the crew while deploying the lobster pots rigged for video.
Contact: Hege Sande, hege.sande@slu.se or Andreas Sundelöf, Andreas.sundelof@slu.se
For more information:
https://www.fiskbarometern.se/rapport/2023/species/Europeisk%20hummer
https://artfakta.se/artinformation/taxa/Homarus%20gammarus-217764/detaljer
https://www.slu.se/ew-nyheter/2024/1/bra-ar-for-hummerfiske–daligt-ar-for-hummern/
https://www.slu.se/lobserve