This paper relies on a natural experiment to study the short-term consequences of a reduction of the trawler fleet on the economic situation of fisheries. In the context of the Covid pandemic, a scenario of cooperation leading to a weekly rotation of trawlers was set up for four weeks in May 2020 in the port of Le Grau-du-Roi located on the Mediterranean Sea. However, this scenario was not utilized in the nearby port of Sète. Using detailed transaction data, we rely on a difference-in-differences strategy to assess the impact of the large decrease (around 45%) in the number of trawlers selling fish on a daily basis during the cooperation period. We show that the daily sales revenue per active trawler increased more in Le Grau-du-Roi than in Sète (around 20%) due to higher fish catches, presumably due to a decrease in congestion. However, we find that the evolution of the total revenue per trawler was much lower (around 40%) in Le Grau-du-Roi than in Sète because of the cooperation, meaning that the decrease in fishing time had not been offset at all by the increase in daily sales revenue.

本文依靠自然实验来研究拖网渔船船队减少对渔业经济状况的短期影响。在新冠病毒大流行的背景下，2020 年 5 月，在位于地中海的 Le Grau-du-Roi 港建立了为期四周的每周轮换拖网渔船合作方案。然而，这种方案并未在附近的塞特港使用。使用详细的交易数据，我们依靠差异中的差异策略来评估合作期间每天销售鱼类的拖网渔船数量大幅减少（约 45%）的影响。我们发现，Le Grau-du-Roi 的每艘活跃拖网渔船的日销售收入增长幅度高于 Sète（约 20%），原因是渔获量增加，可能是由于拥堵减少。然而，