Contrasting decadal recruitment patterns in the sea urchin Strongylocentrotus droebachiensis in the Gulf of Maine

Once a booming fishery in the Gulf of Maine, green sea urchin (Stronglocentrotus droebachiensis) catches declined drastically in the 1990s and have remained low over the past couple decades. To monitor changes in urchin populations, settlement patterns of S. droebachiensis at sites in the northern (Eastport and Frazer Point, ME) and southern Gulf of Maine (York, ME and Isles of Shoals, NH) were recorded. From 1994 to 2019, AstroTurf® panels attached to wire frames were intermittently laid on the ocean bottom at five sites along the Gulf of Maine in late spring and retrieved in the mid to late summer. The present study examined changes in recruitment densities over the 23-year period from 1996 to 2019 and found a drop in recruitment at the southern sites by two orders of magnitude over the time span. Aside from the likely pressure of overfishing, recruitment declines may be influenced by anthropogenic climate change and higher predation rates by Jonah crabs, Cancer borealis.