Researchers compared spiny lobster populations around California marine reserves after 10 years of protection and found that reserves not only boosted lobster numbers inside by up to 465%, but also substantially increased catches for fishers working just outside reserve boundaries. Researchers repeated a scientific trapping study from 2008, placing scientific traps along gradients from deep inside two Channel Islands marine reserves to reference sites far outside the boundaries, comparing catch rates and lobster biomass after 10 additional years of protection. Legal-sized lobster abundance in traps increased by 125%-465% deep inside reserves over the 10-year period. Catch rates increased by 223%-331% at sites near reserve borders and by nearly 400% just outside reserve borders. Similar large increases were observed in total lobster biomass caught in traps at both study reserves. The spillover effect grew substantially stronger over time as lobster populations built up inside the protected areas. The research provides rare long-term evidence that marine reserves can deliver on their promise to benefit fisheries, showing that short-term costs to fishers can turn into substantial long-term gains as protected populations rebuild and spill over into fishing areas.

Citation

Lenihan, Hunter S.; Fitzgerald, Sean P.; Reed, Daniel C.; Hofmeister, Jennifer K. K.; Stier, Adrian C. (2022). Increasing spillover enhances southern California spiny lobster catch along marine reserve borders. Ecosphere.

"The spillover effect grew substantially stronger over time as lobster populations built up inside the protected areas."

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Lobster catch inside and outside two reserves

Ten years after the 2008 survey, researchers repeated the same trapping at two Channel Islands reserves. Compare how catch per trap changed deep inside each reserve, at its edge, and in fished water at the border and further away.

Change in lobster caught per trap, 2008 to 2018 (%)

Change in mean weight of lobster per trap, 2008 to 2018, from Lenihan et al. (2022), Ecosphere (Results). Out-edge sites are fished water just outside the reserve border; out-far sites are fished water further away.

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Lenihan et al. (2022). Lobster Catches Rose Near California Marine Reserves After a Decade. Ocean Recoveries Lab. https://doi.org/10.1002/ecs2.4110