The ecosystem approach to fisheries, encouraged since the 1980s’, nowadays has still not been put in practice for an effective ecosystem based fishery management (EBFM). The use of ecosystem models in fishery science allows an integrated approach to study and quantify the potential effects of management scenarios or environmental changes on biological resources and fishery socioeconomics and can represent the core of an EBFM approach. The adoption of such ecosystem models, and especially Ecopath with Ecosim and/or Atlantis, for management is slow, have not yet become operational, have high development costs and are not always thoroughly validated. In this thesis, an ecosystem model was developed for the North East Adriatic Sea (NEAS), as a tool possibly used to support fisheries management in the area. The developed ecosystem model integrates 33 functional groups, 10 fishing fleets and an aquaculture activity. The initial conditions and main parametrization are coherently embedded in a mass-balanced Ecopath model for the year 2005. The time-dynamic simulations in Ecosim for the period 2005-2015, was preliminary fitted to collected reference data and it was tested for sensitivity to the variation of initial parameters and forcing functions using Monte Carlo analysis. The results of the Monte Carlo analysis validated initial conditions and main parameters used for the model structure. Additionally, the largest variations in Ecosim simulations are produced by changes in production and consumption rate parameters. The sensitivity analysis indicated that fishing effort had a minor influence on the NEAS model, which was primarily influenced by primary productivity. An ensemble of models was created to account for variability in food web interactions by implementing different fitting strategies for each model, without changing the mass-balance parameter settings or forcing functions. For each model in the ensemble, the vulnerability values were estimated by minimizing discrepancies between the predicted and observed data (reference time series). Although the area and the open boundaries represent model limitations, the model reproduced the observed dynamics of data by functional group with a good degree of accuracy. The NEAS model was used to simulate the impacts of the latest Common Fishery Policy directive (2015-2030) and results used as a proxy for other areas of Mediterranean hosting multi-target multi-gear fisheries. A management scenario applying the EU Landing Obligation was simulated to assess the regulation’s ecological and socioeconomic impacts. Additional scenarios aimed at reducing the Landing Obligation-subjected discards were also assessed and evaluated as alternative solutions for the discarding issue. Results suggest that the combined direct and indirect effects of this regulation have globally a negative ecological and economic impact. The increase in landed biomass consequent of the regulation (approx. +13%) will cause an increase in fishermen workload, a small decrease in revenue (approx. -0.50%) and indirectly reduce biomasses at sea (approx. -0.20%) of both marketable and non-marketable species. Economic losses will not be compensated even with the possibility of selling landed discards for uses other than human consumption (e.g., fishmeal). Improving selectivity and introducing quotas resulted as the best alternatives, however none of the adaptation scenarios completely compensated the negative effects of the regulation. Results suggest the landing obligation is a management measure with several negative effects for systems characterized by mixed fisheries and the absence of output control (quotas), such as the Mediterranean Sea.

L'approccio ecosistemico alla pesca, incoraggiato sin dagli anni '80, non è stato ancora effettivamente applicato in forma di gestione ecosistemica della pesca (EBFM). L'uso di modelli ecosistemici nella scienza della pesca consente un approccio integrato per studiare e quantificare gli effetti potenziali di scenari gestionali o delle modifiche ambientali sulle risorse biologiche e sulla socioeconomia della pesca e possono rappresentare il nucleo di un approccio EBFM. L'adozione di modelli ecosistemici per la gestione è lenta, i modelli Ecopath con Ecosim e Atlantis non sono ancora operativi, hanno costi di sviluppo elevati e non vengono sempre accuratamente convalidati. In questa tesi è stato sviluppato un modello ecosistemico del Nord Est Adriatico (NEAS), quale potenziale strumento utilizzato per sostenere la gestione della pesca locale. Il modello integra 33 gruppi funzionali, 10 flotte di pesca e un'attività di acquacoltura. Le condizioni iniziali e la parametrizzazione sono coerentemente integrate nel modello Ecopath a bilancio di massa (2005). Le simulazioni dinamiche in Ecosim (2005-2015) sono state adattate (fitting) preliminarmente ai dati di riferimento raccolti e testate per la sensibilità alla variazione dei parametri iniziali e forzanti mediante l'analisi Monte Carlo. I risultati hanno validato le condizioni iniziali e i parametri utilizzati per la struttura del modello. Inoltre, le variazioni maggiori nelle simulazioni di Ecosim sono dovute dai cambiamenti dei parametri di produzione e di consumo. Il modello risulta poco sensibile a variazioni dello sforzo di pesca, invece influenzato principalmente dalla produttività primaria. Un insieme di modelli creato tiene conto della variabilità delle interazioni trofiche nella rete alimentare implementando strategie di fitting diverse per ogni modello, senza modificare le impostazioni dei parametri a bilancio di massa o le forzanti. Per ogni modello dell'insieme, i valori di vulnerabilità sono stati stimati riducendo le discrepanze tra i dati predetti e osservati (serie temporali di riferimento). Sebbene l'area ed i confini aperti rappresentano i limiti di modello, esso riproduce la dinamica osservata dei gruppi funzionali con un buon grado di precisione. Il modello ha simulato gli impatti dell'ultima direttiva della Politica Comune della Pesca (2015-2030) e i risultati sono utilizzati come proxy per altre aree a pesca multi-specie multi-attrezzo nel Mediterraneo. L’applicazione della normativa UE sull'obbligo di sbarco di scarti da pesca è stata simulata all’interno di un scenario, valutando gli impatti ecologici e socioeconomici. Scenari aggiuntivi volti a ridurre i scarti da pesca regolamentati sono stati valutai come soluzioni alternative per il problema dello scarto. Effetti diretti e indiretti combinati di questo regolamento hanno un impatto ecologico ed economico negativo a livello globale. L'aumento della quantità sbarcata conseguente al regolamento (circa +13%) aumenterà il carico di lavoro dei pescatori, ridurrà le entrate (circa -0.50%) e ridurrà le biomasse in mare (circa -0.20%) sia di specie di interesse commerciale che non. Le perdite economiche non saranno compensate nemmeno dalla possibilità di vendere i rigetti sbarcati per usi diversi dal consumo umano (farine di pesce). Il miglioramento della selettività e l'introduzione di quote risultano le alternative migliori, tuttavia nessuno degli scenari alternativi compenserà del tutto gli effetti negativi del regolamento. I risultati suggeriscono che l'obbligo di sbarco è una misura di gestione con effetti negativi per i sistemi caratterizzati da pesca mista e l'assenza del controllo delle catture (quote), come il Mar Mediterraneo.

Development of an ecosystem model of the northern Adriatic Sea / Celic, Igor. - (2017 Dec 18).

Development of an ecosystem model of the northern Adriatic Sea

CELIC, IGOR
2017-12-18

Abstract

The ecosystem approach to fisheries, encouraged since the 1980s’, nowadays has still not been put in practice for an effective ecosystem based fishery management (EBFM). The use of ecosystem models in fishery science allows an integrated approach to study and quantify the potential effects of management scenarios or environmental changes on biological resources and fishery socioeconomics and can represent the core of an EBFM approach. The adoption of such ecosystem models, and especially Ecopath with Ecosim and/or Atlantis, for management is slow, have not yet become operational, have high development costs and are not always thoroughly validated. In this thesis, an ecosystem model was developed for the North East Adriatic Sea (NEAS), as a tool possibly used to support fisheries management in the area. The developed ecosystem model integrates 33 functional groups, 10 fishing fleets and an aquaculture activity. The initial conditions and main parametrization are coherently embedded in a mass-balanced Ecopath model for the year 2005. The time-dynamic simulations in Ecosim for the period 2005-2015, was preliminary fitted to collected reference data and it was tested for sensitivity to the variation of initial parameters and forcing functions using Monte Carlo analysis. The results of the Monte Carlo analysis validated initial conditions and main parameters used for the model structure. Additionally, the largest variations in Ecosim simulations are produced by changes in production and consumption rate parameters. The sensitivity analysis indicated that fishing effort had a minor influence on the NEAS model, which was primarily influenced by primary productivity. An ensemble of models was created to account for variability in food web interactions by implementing different fitting strategies for each model, without changing the mass-balance parameter settings or forcing functions. For each model in the ensemble, the vulnerability values were estimated by minimizing discrepancies between the predicted and observed data (reference time series). Although the area and the open boundaries represent model limitations, the model reproduced the observed dynamics of data by functional group with a good degree of accuracy. The NEAS model was used to simulate the impacts of the latest Common Fishery Policy directive (2015-2030) and results used as a proxy for other areas of Mediterranean hosting multi-target multi-gear fisheries. A management scenario applying the EU Landing Obligation was simulated to assess the regulation’s ecological and socioeconomic impacts. Additional scenarios aimed at reducing the Landing Obligation-subjected discards were also assessed and evaluated as alternative solutions for the discarding issue. Results suggest that the combined direct and indirect effects of this regulation have globally a negative ecological and economic impact. The increase in landed biomass consequent of the regulation (approx. +13%) will cause an increase in fishermen workload, a small decrease in revenue (approx. -0.50%) and indirectly reduce biomasses at sea (approx. -0.20%) of both marketable and non-marketable species. Economic losses will not be compensated even with the possibility of selling landed discards for uses other than human consumption (e.g., fishmeal). Improving selectivity and introducing quotas resulted as the best alternatives, however none of the adaptation scenarios completely compensated the negative effects of the regulation. Results suggest the landing obligation is a management measure with several negative effects for systems characterized by mixed fisheries and the absence of output control (quotas), such as the Mediterranean Sea.
18-dic-2017
29
2015/2016
Settore BIO/07 - Ecologia
Università degli Studi di Trieste
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2927172
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