Effectiveness of the Nordmore grate in the Gulf of Maine northern shrimp fishery

Published source details Richards A. & Hendrickson L. (2006) Effectiveness of the Nordmore grate in the Gulf of Maine northern shrimp fishery. Fisheries Research, 81, 100-106.
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This study is summarised as evidence for the following.

	Action	Category
	Fit a size-sorting escape grid (rigid or flexible) to a prawn/shrimp trawl net Action Link

Fit a size-sorting escape grid (rigid or flexible) to a prawn/shrimp trawl net

A before-and-after study in 1991–1996 of a large seabed area in the Gulf of Maine, North Atlantic Ocean, USA (Richards & Hendrickson 2006) found that the requirement to fit a size-sorting escape grid to shrimp trawl nets in a Northern shrimp Pandalus borealis fishery reduced the capture of non-target fish compared to the period before grids were introduced. During the four-year period after grids were introduced, averages fish catches (by type) were lower with grids for roundfish (after: 5 kg/hr, before: 11 kg/hr) and flatfish (after: 3 kg/hr, before: 7 kg/hr) compared to the previous two-years and indicated reductions of 59% and 61% for each group respectively. Reductions for individual species ranged from 9% to 62% (see paper for full list of species). In addition, average target Northern shrimp catch increased after grids were used (after: 11 kg/hr, before: 8 kg/hr). Fishery observer data were collected onboard Northern shrimp fishing vessels, fishing up to 182 m depths, during December–March of the 1991–1996 Northern shrimp fishing seasons. A total of 140 vessels were sampled after (643 tows with grids) and before (283 tows without grids) grids were made a requirement in April 1992. Regulatory specifications for the grid were that it must include a rigid or semi-rigid grid of parallel bars spaced no more than 2.54 cm apart, a fish escape opening or hole (top or bottom) in front of both the codend and grid, and a mesh funnel to direct objects to the bottom of the grid (optional in 1994–1996).

(Summarised by: Chris Barrett)