A Statistical Analysis of the Impacts of Management Decisions on the Distribution of Catch in the California Commercial Dungeness Crab Fishery

Abstract

Harmful algal blooms happen all along coasts around the world. During harmful algal blooms, sea life can absorb toxins emitted by the algae found in these blooms. Many of these events occur within areas of interest for high-value fisheries. Here, I examine the effect of management decisions to open or close Dungeness crab fishing areas due to domoic acid levels during and after the 2015 harmful algal bloom in California on the ratio of catch by small to large vessels. Using a difference-in-differences statistical analysis, I examine whether small vessels in California were negatively affected by the special closures, using Washington as a control group. I find no statistically significant difference between the catch ratio before the start of the harmful algal bloom (fall 2010 to spring 2015) and after (fall 2015 to spring 2017). Additionally, the trend of the ratio of catch by smaller vessels to larger vessels increased slightly in California after the harmful algal bloom. When considering just the 2015-16 season in this analysis, California as a whole increased the ratio of catch going to smaller vessels, but the Bodega Bay area ports showed a decreased statistically significant difference in the catch ratio. This analysis illustrates that while on the whole, California small vessel fishermen might have a slight, not statistically significant increase in catch ratio, there are some small vessel fishermen who are negatively affected with the change in the timing of open areas for the commercial harvest of Dungeness crabs.