Designate a Marine Protected Area and prohibit the harvesting of sea urchins
Overall effectiveness category Likely to be beneficial
Number of studies: 2
Background information and definitions
Sea urchins can represent key species within a marine system, with other species crucially depending on their presence to thrive (Coyer et al. 1993; Day & Branch 2002) and to retain balance in the ecosystem (Blamey et al. 2014). Commercial, but also recreational, harvest of edible sea urchins has led to significant ecological changes, not only for sea urchin populations, but also for other species suffering from secondary negative consequences (i.e. a ripple effect; for instance, urchin harvest can negatively affect protected species of abalone; Rogers-Bennett & Pearse 2001). Specific areas can be designated as protected, and specific management measures taken to prohibit the harvest of sea urchins (Béné & Tewfik 2003; Stoner et al. 2012).
Inside protected areas where this activity is prohibited, the threat from sea urchin harvesting to urchin populations and associated communities is removed, and previously impacted populations are, in theory, able to recover over time (Stoner et al. 2012).
When this intervention occurred outside of a marine protected area, evidence for the effects on sea urchin populations is summarised under “Species management – Cease or prohibit the harvest of sea urchin”. Evidence for related interventions is summarised under “Threat: Biological resource use”.
Blamey L.K., Plagányi É.E. & Branch G.M. (2014) Was overfishing of predatory fish responsible for a lobster-induced regime shift in the Benguela? Ecological Modelling, 273, 140–150.
Coyer J.A., Ambrose R.F., Engle J.M. & Carroll J.C. (1993) Interactions between corals and algae on a temperate zone rocky reef: mediation by sea urchins. Journal of Experimental Marine Biology and Ecology, 167, 21–37.
Ceccherelli G., Pinna S. & Sechi N. (2009) Evaluating the effects of protection on Paracentrotus lividus distribution in two contrasting habitats. Estuarine, Coastal and Shelf Science, 81, 59–64.
Day E. & Branch G.M. (2000) Relationships between recruits of abalone Haliotis midae, encrusting corallines and the sea urchin Parechinus angulosus. South African Journal of Marine Science, 22, 137–144.
Rogers‐Bennett L. & Pearse J.S. (2001) Indirect benefits of marine protected areas for juvenile abalone. Conservation Biology, 15, 642–647.
Supporting evidence from individual studies
A replicated, site comparison study in 1996–1997 of six rocky seabed sites off the coast of central and northern California, North Pacific Ocean, USA (Rogers‐Bennett & Pearse 2001) found that marine protected areas prohibiting the commercial harvest of red sea urchins Strongylocentrotus franciscanus had higher abundances of juvenile red abalone Haliotis rufescens and juvenile flat abalone Haliotis walallensis compared to areas where commercial harvesting occurred. Abundances of both species were higher in protected areas (red abalone: 8–139/plot; flat abalone: 0–18/plot) compared to harvested areas (red abalone: 0–39/plot; flat abalone: 0–9). In addition, juvenile abalone abundance was significantly positively related to sea urchin abundance, and inside protected areas 33% of juvenile abalone were found protected under sea urchin spine canopies. In October 1996 and August 1997, three marine protected areas (year of designation unspecified) prohibiting the commercial harvest of red sea urchins and three areas where urchin harvest occurred were surveyed. Juvenile red and flat abalone were counted in 24 x 30 m plots/site (5–8 m depth).Study and other actions tested
A replicated, site comparison study in 2009–2011 of 30 sites around the Northern Channel Islands, southern California, North Pacific Ocean, USA (Teck et al. 2017) found that, six to 33 years after their designations, marine protected areas prohibiting the harvest of red sea urchin Mesocentrotus franciscanus had bigger adult urchins, higher adult total biomass and reproductive biomass, but similar urchin reproductive indices (ratio of reproductive to total biomasses), compared to sites where urchin harvest was allowed. Adult urchins diameter was 6% bigger inside the marine protected areas compared to outside. Adult total biomass was 16%, and reproductive biomass was 23% greater inside the marine protected areas compared to outside. Once a year in summer between 2009 and 2011, eleven sites within seven marine protected areas and 13 sites outside of marine protected areas were surveyed at 6 m and 13 m depths (143 surveys in total). One marine protected area was designated in 1978, and six in 2003. Despite having different levels of activity restrictions, all areas prohibited the harvest of the red sea urchin. Divers counted all urchins >25 mm test diameter along two 60 m2 transects/site/water depth. Fifteen to 20 urchins >50 mm (test diameter) were collected, measured, and their flesh and reproductive glands weighed. For each are. adult total biomass (using total urchin weight) and reproductive biomass (using urchins reproductive gland weight) were calculated from urchins count and weight data.Study and other actions tested