Mobile fishing gear reduces benthic megafaunal production on Georges Bank

Published source details Hermsen J., Collie J. & Valentine P. (2003) Mobile fishing gear reduces benthic megafaunal production on Georges Bank. Marine Ecology Progress Series, 260, 97-108.
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This study is summarised as evidence for the following.

	Action	Category
	Cease or prohibit all towed (mobile) fishing gear Action Link

Cease or prohibit all towed (mobile) fishing gear

A before-and-after, site comparison study in 1994–2000 of four sites of sandy and gravelly seabed on Georges Bank, North Atlantic Ocean, USA and Canada (Hermsen et al. 2003) found an increase in invertebrate biological production in shallow and deep sites closed to towed fishing gear compared to adjacent fished sites approximately five years after closure. Biological production (a measure of biomass regeneration over time) from invertebrates at shallow (45–62 m) sites closed to fishing increased following closure (before: 17; after: 215 kcal/m²/year), and was higher than at shallow fished sites where production did not vary over time (before: 32; after: 57 kcal/m²/year). Production at deep (80–90 m) sites closed to fishing also increased following closure (before: 174; after: 256 kcal/m²/year), and was higher than at deep fished sites where production did not vary over time (before: 52; after: 30 kcal/m²/year). In January 1995, a combined area of approximately 10,000 km² of Georges Bank was closed to all bottom towed fishing gear. Invertebrates (>5 mm) were sampled with a dredge (6.4 mm mesh) at four sites across the two depth ranges (‘shallow’ and ‘deep’). Shallower sites are subject to more intense and regular fishing. At each depth, one closed and one fished site were sampled. Animals were identified, counted and weighed. Individuals from the 20 most abundant species were measured. Biological production was estimated from a combination of biomass and length-frequency distribution data.