Modeling an Interdisciplinary Early Warning System for Future Fisheries Scenarios: A socio-bio-economic value-chain evaluation, JANUS

The Janus project examined the impact of Periphylla periphylla on the socio-ecological systems of Norwegian fjord systems (especially the Trondheimsfjord) and the potential that this jellyfish species has as a resource. This project explored the impact P. periphylla blooms have had on fishers in North and South Trøndelag, improved understanding of P. perifylla and its interaction with other species, developed an interdisciplinary (bio-economic) model for these species and laid the foundation for the creation of an "early-warning system" that might help managers and stakeholders anticipate an outbreak of a P. Periphylla bloom. Project status The Janus Project has now completed its active research phase and is now officially ended, although analysis of data from the project continues. Eleven full-week research cruises were completed. These updated the history and status of Periphylla stock biomass, its regional distribution in the Trondheimsfjord and reproduction biology. This knowledge is essential to understanding the impact of P. Periphylla in the fjord's ecosystem. Of particular interest has been the competition for prey species between Cod-like fishes and P. periphylla. Data indicates a conspicuous pattern of decline in cod Catch Per Unit Effort (CPUE). Combined with other data (such as data indicating temperature increases in the Trondheimsfjord, which are assumed to be beneficial for the jelly but not so for the cold-adaped species in the cod family), it can be speculated that a climate-induced historically low abundance of cod facilitated the take-over by Periphylla as top predator in the inner Trondheimsfjord ecosystem. Janus researchers worked to estimate the energetic and economic cost of Periphylla proliferation in terms of lost production of traditional harvest in the fjord and to understand the behavior of fish there. Two participatory stakeholder workshops with full- and part-time fishers in the Trondheimfjord were carried out. These mapped the experiences of fishers from Trondheim and North Trøndelag with jellyfish. P. perifylla is most relevant to consider as a possible resource for N. Trøndelag fishers, but lack of research, processing technology and infrastructure such as landing sites and adequate transportation (among other factors) make this impractical at present. The workshops identified fisher income as a critical factor for adaption and identified those factors most likely to impact income for both groups. Fishers sought a "livable" income rather than income maximization. The workshops also produced many other observations and recommendation useful for management. Janus researchers conducted a comprehensive survey of artisanal fishers in Trondheimsfjord, collecting basic information including about fishing gear, fishing area and season, catches, price, costs, and effects of jellyfish on fishing activities and behavior. Results indicate that jellyfish have moderate to severe effects on fishing gear and season; to adapt to the jellyfish situation, fishers choose to shift fishing from cod to other species such as crab, hake and haddock, or mussel farming;, the biggest challenge facing fishers is not the jellyfish, but market price and fishing cost. A bioeconomic model has been developed to capture the interactions between cod and P. periphylla in the Trondheimsfjord. A coupled physical-biological ecosystem model (www.sinmod.no) has been applied to the Trondheim fjord in order to estimate the potential impact of P. periphylla on fish prey (redfeed). Simulations over the period 2002-2005 indicate that P. periphylla might exert differentiated effects on redfeed according to season. The model results suggest that whereas redfeed is mainly found in the outer fjord during late summer- late winter, it is in the early spring and the summer that P. periphylla is likely to prey on redfeed when it features its highest growth and is available for the outward migrating gadoid fish larvae. The project developed and implemented a model for P. periphylla, analyzed the tropic relationship between redfeed (C. finmarchicus)and P. periphylla, analysed the dispersion/retention mechanisms in P. periphylla in relation with circulation patterns and light dependent dial vertical migration and qualitatively compared scenarios of population growth to the historical observations throughout the last decade. Test scenarious simulating the potential of future climate warming based on IPPC scenario A1B on the C. finmarchicus ? P. Periphylla relationship were done. In its final phase, the Janus project explored factors relating to P. perifylla blooms that might make for an "early warning system" for the outbreak of P. perifylla blooms. The project compared key characteristics of fjords that have experienced such outbreaks.Results suggest that three northern fjords, the Skjerstadfjord the Holandsfjord, and Stordjupna in the Vestfjord are particularly vulnerable.

This project addresses the interaction between the socio-economic system and the marine ecosystem by focusing on the serious problem in several Norwegian fjords including the Trondheimsfjord: the recent superabundance of the jellyfish species Periphylla p eriphylla. The question addressed here is how to manage this jellyfish in manner that is rational from both ecological and socio-economic perspectives. By using a relatively delimited ecosystem, developing interdisciplinary models, incorporating stakehol der input, and focusing on a single policy question (Periphylla-redfeed management), this project will create an interdisciplinary model for these species and move towards creation of a decision support tool to help make rational management choices based on both ecological and socio-economic criteria. WP 1 will collect relevant available biological, economic and social data, define variables and prepare the data for integration into models by subsequent WPs. WP 2 will assess the adaptive capacity of th e community to resource situations by determining stakeholder perceptions of socio-ecological and economic aspects of jellyfish and redfeed in the Trondheimsfjord region. This will be done in a series of highly interactive stakeholder workshops employing Systems Thinking and Baysesian Belief Network modeling techniques. The workshops will explicate shared mental models of probable causal relationships among key variables. Information and models from these workshops will inform the model building in WP 3 and WP 4. WP 3 will develop a population model for the jellyfish P. periphylla that is implemented in the SINMOD ecosystem model, and develop a cod larvae model for studying the interaction between C. finmarchicus, P. periphylla and cod larvae. WP4 wi ll integrate the variables defined in WP1, the scenarios from WP2, and the ocean-ecology model developed in WP3 to further develop economic scenarios and to simulate their associated implications.