In the early 1990s, ecological and fishery data from the Gulf of Nicoya (Pacific Ocean) were holistically analyzed, and a trophic model was constructed using the Ecopath modeling approach. The results indicated that this tropical estuary, which is a Costa Rican fishery hot spot, was already overexploited by shrimp trawlers and the longline fleet, and recent observations suggest further deteriorations in this system. To evaluate the ecosystem and socioeconomic changes in the Gulf of Nicoya over the last 20 years, the 1993 model was reconstructed with data from 2013 to compare both system states. Although the summary statistics of both states (i.e., 1993 and 2013) suggested that the system maintained its general functionality and even enabled the total harvest to increase by approximately 20%, a more detailed analysis of the levels of the functional groups suggested that the system was further degraded as follows: (1) most shrimp, eel, and catfish species decreased their share in the catches, with severe economic losses for the fishery; (2) of the species that substantially increased their share in the catches, most were short‐lived, low‐value species, such as small pelagic and small demersal fishes; and (3) catches of long‐lived, high‐trophic‐level fish, such as rays, sharks, mackerels, and barracudas, decreased. A picture emerged in which the advancing fishery of low‐trophic‐level species with low economic value enabled the total harvest to increase, while valuable shrimp resources and higher‐trophic‐level species were depleted. These developments caused a tremendous economic loss of approximately 50%.

Please cite this article as: Leitão, F., Alms, V., Erzini, K., A multi-model approach to evaluate the role of environmental variability and fishing pressure in sardine fisheries, Journal of Marine Systems (2014Systems ( ), doi: 10.1016Systems ( /j.jmarsys.2014 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTUnderstanding the fluctuations in population abundance is a central question in fisheries. Sardine fisheries are of great importance to Portugal and are data-rich and of primary concern to fisheries managers. In Portugal, sub-stocks of Sardine pilchardus (sardine) are found in different regions:the Northwest (IXaCN), Southwest (IXaCS) and the South coast (IXaS-Algarve). Each of these sardine sub-stocks is affected differently by a unique set of climate and ocean conditions, mainly during larval development and recruitment, which will consequently affect sardine fisheries in the short term. Taking this hypothesis into consideration we examined the effects of hydrographic (river discharge), sea surface temperature, wind driven phenomena, upwelling, and wind magnitude were negatively related with LPUE, revealing that environmental effects match with the regional peak in spawning time. Overall, results suggest that management of small, short-lived pelagic species, such as sardine quotas/sustainable yields, should be adapted to a regional scale because of regional environmental variability.

The Gulf of Nicoya is a large tropical estuary located on the Pacific coast of Costa Rica and accounts for the country's main fish production. It is increasingly impacted not only by its fisheries, but also by urbanization, tourism developments, the input of pollutants from urban centers and agriculture activities in the catchment areas of large rivers entering the gulf. Similar to other coastal ecosystems, the gulf is particularly sensitive to short-and long-term changes in the climate, such as the precipitation rate, Sea Surface Temperature, wind speed and current regimes. While the gulf has been studied for decades, until now no attempt has been made to combine the analysis of the impacts of fishing and environmental changes on the ecosystem. By following a holistic approach that uses fisheries and environmental time series data from collaborative research and simulation models, this study aims at identifying the main drivers of the observed changes in the Gulf of Nicoya ecosystem. While the model simulations indicate that variations in the catch of some target species (e.g., cephalopods and shrimps) are mainly driven by the fisheries' exploitation rates, several other species (e.g., corvina, snook, small pelagics, and crabs) are also substantially affected by climate variations, particularly during El Niño periods of high Sea Surface Temperature extremes and increased precipitation. During these periods, phytoplankton productivity and zooplankton biomass deceases with bottom-up effects on the entire food chain. Indicators of the environmental state of the system thus have to be considered along with regulations of the fishing pressure to form the basis for the development of appropriate management strategies.

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