COVID-19 lockdowns reveal the resilience of Adriatic Sea fisheries to forced fishing effort reduction

www.nature.com/scientificreports OPEN COVID‑19 lockdowns reveal the resilience of Adriatic Sea fisheries to forced fishing effort reduction Gianpaolo Coro1*, Anna Nora Tassetti2, Enrico Nicola Armelloni2,3, Jacopo Pulcinella2, Carmen Ferrà2, Mario Sprovieri4, Fabio Trincardi5 & Giuseppe Scarcella2 The COVID-19 pandemic provides a major opportunity to study fishing effort dynamics and to assess the response of the industry to standard and remedial actions. Knowing a fishing fleet’s capacity to compensate for effort reduction (i.e., its resilience) allows differentiating governmental regulations by fleet, i.e., imposing stronger restrictions on the more resilient and weaker restrictions on the less resilient. In the present research, the response of the main fishing fleets of the Adriatic Sea to fishing hour reduction from 2015 to 2020 was measured. Fleet activity per gear type was inferred from monthly Automatic Identification System data. Pattern recognition techniques were applied to study the fishing effort trends and barycentres by gear. The beneficial effects of the lockdowns on Adriatic endangered, threatened and protected (ETP) species were also estimated. Finally, fleet effort series were examined through a stock assessment model to demonstrate that every Adriatic fishing fleet generally behaves like a stock subject to significant stress, which was particularly highlighted by the pandemic. Our findings lend support to the notion that the Adriatic fleets can be compared to predators with medium-high resilience and a generally strong impact on ETP species. Large-scale collectors of vessel data (i.e., international agencies and industries) have estimated that the 2020 March–April lockdowns, imposed by several governments, reduced fishing activities by about 10% in the world and by about 50% in E urope1. In fact, on the one hand lockdowns introduced practical difficulties on board of vessels to applying social distances and, on the other hand, they caused a collapse of demand for seafood due to the closure of fish markets and restaurants and the reduction of direct sales, which in turn contributed to decrease fishing activities2. Both large and small-scale fisheries were affected, in different ways depending on the area3,4. Initially, the global reduction of fishing activity was due to the asynchronicity of the lockdown start time and fishing seasonality. Now, about two years into the pandemic, the time when this period began is becoming less and less relevant. Understanding the response of fisheries to fishing hour reduction during the pandemic requires interpreting the information that vessels transmit via satellite and terrestrial devices, e.g., Automatic Identification Systems (AISs). To do this, fishing locations should be either extracted from the AIS records directly (when this information is available) or estimated from the sequences of coordinates embedded in these data (as in the case of the present experiment). Statistical and machine learning models are commonly used for these estimation t asks5–7 (Section 1.1 of Supplementary Information reports an overview). Although their operational error makes them better suited to large-scale and big data analysis8,9, they allow identifying fishing activity patterns over time. During the COVID-19 pandemic, fisheries suffered a powerful stress due to the consequences of the sanitary restrictions. Quantifying this stress can allow gaining a greater understanding of the response of fisheries to regulations. We present a study of fisheries’ response to the reduction of fishing hours from 2015 to 2020, which was the result of a combination of factors, including the pandemic. A major hypothesis, which was verified by 1 Institute of Information Science and Technologies (ISTI), National Research Council of Italy (CNR), 56124 Pisa, Italy. 2Institute for Biological Resources and Marine Biotechnology (IRBIM), National Research Council of Italy (CNR), 60125 Ancona, Italy. 3University of Bologna, Department of Biological, Geological and Environmental Sciences, 40126 Bologna, Italy. 4Institute of Anthropic Impacts and Sustainability in the Marine Environment (IAS), National Research Council of Italy (CNR), 91021 Torretta Granitola, Italy. 5Department of Earth System Science and Environmental Technologies, National Research Council of Italy (CNR), 00185 Rome, Italy. *email: Scientific Reports | (2022) 12:1052 | https://doi.org/10.1038/s41598-022-05142-w 1 Vol.:(0123456789) www.nature.com/scientificreports/ General factors Low stock availability due to depletion Biological seasonality of the stock Regulatory seasonality due to monthly fishing hour limitations Vessel decommissioning Response of the fish market to restrictions and diminished fish supply Fishers’ reaction and low compliance with unpopular regulations COVID-19 dependent factors Fish market closure Restaurant closure Reduction of intermediate and wholesaler activities Reduction of purchase for domestic use Consumption of frozen food instead of fresh food Sanitary restrictions on board Unsold catch Lowering of prices Liquidity requirements to manage money loss Forced stop of fishing activities Obligations of shifts for active vessels Fisheries’ self-fishing-activity limitation to reduce the offer Table 1.  List of general and COVID-19 dependent factors that negatively affect the fisheries in the Adriatic Sea. our approach, is that a fishing fleet can be modelled as a predator species exposed to external stress factors that reduce its abundance. Such factors include (Table 1-General factors) (i) low stock availability due to depletion; (ii) biological seasonality of the stock; (iii) regulatory seasonality due to monthly fishing hour limitations (like the summer fishing ban in the Adriatic Sea); (iv) vessel decommissioning, which reduces fleet capacity; (v) the response of the fish market to restrictions and the diminished fish supply; (vi) fishers’ reaction and low compliance with unpopular regulations. In this scenario, the COVID-19 dependent factors act as additional stress factors (Table 1-COVID-19 dependent factors) that may be viewed as equivalent to the effect that fishing pressure exerts on large predators. This hypothesis was tested using a stock assessment model (AMSY10). A spatial analysis was also performed, to identify the response of some fleets to the high stress level experienced due to the 2020 lockdowns and the sanitary restrictions. The fleets selected for this analysis were the large-scale fleets of the Adriatic Sea, the area with the highest regional bottom trawling footprint in the world11. In the Adriatic Sea, most of the fishing activity is carried out by four fleets targeting small pelagic and demersal fish species—pelagic pair trawlers, purse seiners, bottom otter trawlers and beam (or Rapido12) trawlers—which currently account for more than 70% of revenues13 (Section 1.2 of Supplementary Information reports an overview). Demersal t (...truncated)