Systems approach modelling of the interactive effects of fisheries, jellyfish and tourism in the Catalan coast

Abstract

a b s t r a c tDespite the large fluctuation in annual recordings of gelatinous plankton along the Catalan coast in the north western Mediterranean and the lack of long term data sets, there is a general perception that jellyfish abundances are increasing. Local authorities are concerned about the stranding events and arrivals of jellyfish to beaches and believe it could reduce the recreational appeal of the beaches e a valuable ecosystem service for the regional tourist industry. Previous studies also demonstrate the predation of jellyfish (Pelagia noctiluca ephyrae) upon some small pelagic fish larvae (Engraulis encrasicolus). Small pelagics are the principal source of revenue for the local fisheries. A social-ecological model was created in order to capture the effects of changes in abundance of P. noctiluca upon the local fisheries, the tourist industry and the wider economy. The following sub-models were constructed and connected following the systems approach framework methodology: an age-class based fisheries model; a jellyfish population matrix model; a jellyfish stranding model; a study on the impact of jellyfish strandings on beach users; and an economic inputeoutput matrix. Various future scenarios for different abundances of jellyfish blooms were run. The "Expected blooms" scenario is similar to the quantity and size of blooms for 2000e2010. For a hypothetical "No blooms" scenario (standard background level of jellyfish but without any blooms) landings would increase by around 294 tonnes (5.1%) per year (averaged over 10 years) or approximately 0.19 MV in profits per year (4.5%), and strandings would decrease by 49%. In a "Frequent blooms" scenario, landings would decrease by around 147 tonnes per year (2.5%) and decrease profits by 0.10 MV per year (2.3%), and strandings would increase by 32%. Given the changes that these scenarios would cause on the regional gross domestic product and employment, this study concludes that the overall impact of either of these scenarios on the economy would not be significant at the regional scale.

Atmospheric indices allow anticipating the incidence of jellyfish coastal swarms

“…Attempts at modelling the presence of jellyfish swarms on the coast have usually faced difficulties, such as the scarcity of available data, limited sources of information and constraints in the model used (Tomlinson et al, 2018). For example, Berline et al (2012) compared six Mediterranean zooplankton time series from 1957 to 2006 and found no significant correlations between climate indices and local temperature or zooplankton abundance.…”

VECTORS of change in the marine environment: Ecosystem and economic impacts and management implications

“…Climate change may increase metal contamination of mussels, but not to any critical level at the relatively unpolluted sites. Tomlinson et al (2018) developed a socio-ecological model to capture the effects of changes in abundance of the Pelagia noctiluca on local fisheries, tourism and the wider economy. Scenarios of different abundance/frequency of jellyfish blooms projected significant positive and negative changes to regional gross domestic product (GDP) and employment in the Mediterranean.…”

Jellyfish Swarms and Degree of Exposure and Vulnerability of Recreational and Tourist Activities on Beaches. Methodological Approach to Their Assessment in the Lagos-Ferrara Sector (Málaga, Spain)

“…If jellyfish can be considered a threat, the risk to humans is given by the probability of damage (physical, such as stings, and in the form of a drop in economic activity, in case of a decrease in economic activity) or loss (mainly due to the consequences of a hypothetical drop in visits to beaches that are affected by jellyfish). Progress has already been made with regard to the impact of jellyfish stings on human health [6,12,14], also at the socio-economic level in certain sectors such as fishing [17,23] and in tourism [11,13,21]. The interest of this study is to consider all the possible aspects in which their appearance on the coasts can imply an effect on the human activity on the beaches, both recreational and tourist.…”