Effect of closed areas on populations of sea star Asterias spp. on Georges Bank

Abstract

High sea scallop abundances such as those in the closed areas of Georges Bank may cause predators, including sea stars, to aggregate and cause increased natural mortality rates for sea scallops. We hypothesized that sea stars are aggregated and are of larger size in areas of Georges Bank that are closed to fishing. within the open areas was not always smaller or larger than those in the closed areas; however, average arm length estimates were influenced by the abundance of sea star recruits. Sea scallop densities were independent of sea star densities. Sea star predation influenced sea scallop densities in specific locations, as instantaneous natural mortality rates were high.

Estimating similarity in benthic communities over decades and in areas open and closed to fishing in the central Gulf of Maine, USA

“…The marked increase of sea stars between 2013 and 2014 (x = 0.16 ± 0.02 to x = 0.51 ± 0.08) correlated with high scallop abundance on Fippennies in 2014 (≈1.81 × 10 8 ind.). Sea stars are a major predator of scallops, particularly smaller juvenile scallops (Marino et al 2007); sea stars respond to increased prey abundance by increasing individual consumption rates and by increasing in number (Barbeau & Scheibling 1994, Barbeau et al 1996, Marino et al 2007, and they tend to aggregate in high density in closed areas (Marino et al 2007). Interestingly, Platts Bank, the one continuously open area, had fewer scallops than expected but a higher concentration of sea stars (Table 5).…”

Quantification of echinoderms (Echinodermata) on Georges Bank, and the potential influence of marine protected areas on these populations

“…Reducing the impacts of fishing disturbance may enhance recruitment of sea stars in this area. This hypothesis is supported by the presence of smaller individuals inside closed areas compared to open areas (Marino et al., ; Rosellon‐Druker, ). As with sand dollars, sea stars were also persistent and abundant in open areas, indicating natural resilience.…”

“…Spatial resolution of these studies was on the scale of tens to hundreds of kilometers. More recent studies have generally investigated echinoderm abundance and distribution as part of benthic assemblages (i.e., phylum taxonomic resolution) or are focused on specific areas of the bank (e.g., Collie, Escanero, & Valentine, ; Hermsen, Collie, & Valentine, ; Link, ; Link et al., ; Marino, Juanes, & Stokesbury, ; Marino et al., ; Packer, Watling, & Langton, ; Thouzeau, Robert, & Ugarte, ).…”

“…Several studies indicate that the establishment of MPAs leads to significant differences in invertebrate populations after a period of time, with a general consensus that abundance, biomass, and diversity are modified as a result of diminishing the impacts of fishing disturbance (Ashworth, Ormond, & Sturrock, ; Collie et al., ; Hermsen et al., ; Marino et al., ; Stokesbury, ). The types of fishing disturbance include direct removal of invertebrates by fishing gear, body breakage, enhanced predation and migration rates, along with modification of sediments via re‐suspension of finer particles or dispersion of coarser sediments (Asch & Collie, ; Prena et al., ; Stokesbury & Harris, ).…”

Spatial distribution, biomass and size structure of Ctenodiscus australis (Echinodermata: Asteroidea) in shelf-break areas, Argentine

“…On the other hand, Asterias spp. from Georges Bank was registered in higher densities in closed than open areas to fishing, condition not attributed to fishing impacts (Marino et al 2007). Previous work conducted in the whole MU 2 (Reclutas bed, 1893 km 2 ) showed a decreasing trend in the biomass of Ctenodiscus australis between 1998 and 2002 (Schejter et al 2008).…”