Effects of a large-scale and offshore marine protected area on the demersal fish assemblage in the Southwest Atlantic

  • Published source details Alemany D., Iribarne O.O. & Acha E.M. (2013) Effects of a large-scale and offshore marine protected area on the demersal fish assemblage in the Southwest Atlantic. ICES Journal of Marine Science, 70, 123-134.


This study is summarised as evidence for the following.

Action Category

Cease or prohibit all types of fishing in a marine protected area

Action Link
Marine Fish Conservation
  1. Cease or prohibit all types of fishing in a marine protected area

    A before-and-after, site comparison study in 1996–2005 of three seabed areas on the Patagonian Shelf, South Atlantic Ocean, off Argentina (Alemany et al. 2013) found a different assemblage of bottom dwelling fish, higher overall abundance and higher abundance of target Argentinian hake Merluccius hubbsi, and particularly of young hake, in a marine protected area in which fishing was banned for up to eight years, compared to two fished reference areas. The whole fish assemblage before the closure was similar in the protected area to one of the two outside areas but differed from both outside areas after the closure (data reported as statistical model results). Before the closure, overall fish abundance was similar inside (0.59 t) and outside (0.45–0.79 t) the reserve, but increased inside the reserve following the closure and was higher than outside in two of four years (inside: 0.73–0.88, outside: 0.27–0.54 t). Hake abundance was similar across areas before the closure (inside: 0.54, outside: 0.26–64 t) but increased inside the reserve and was higher after the closure in all years (0.52–0.89 t) relative to outside (0.13–0.61 t). The proportion of two-year old hake inside the reserve was higher after the closure (36–50%) than before (18%). The Patagonian Closed Area (50–100 m depth) was closed to all fishing in 1997. Data from demersal fish surveys (5 × 30 m trawl with a 2.4 cm codend mesh) before (1996) and after (2000–2003, 2005) the closure were analysed from a selected 28,000 km2 area inside the reserve and two fished areas outside. All fish were counted, identified, and the ages and lengths of hake recorded.

    (Summarised by: Leo Clarke)

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