Marine Conservation Biology Institute Marine Conservation Biology Institute
Marine Conservation Biology Institute

Shifting Gears: Addressing the Collateral Impacts of Fishing Methods in US Waters

shifting gears
Relative severity of fishing gear classes 0 = least severe and 100 = most severe. Numbers in parentheses are impact scores. The impact score for midwater trawls also represents that for purse seines and hook-and-line.

There is broad recognition that overexploitation of targeted fish species threatens marine biodiversity and fisheries in the USA and elsewhere, but there has been far less recognition in the regulatory and conservation advocacy communities of the "collateral damage" caused by the various types of gear that commercial fishermen use.

Aside from possible overfishing, there are two kinds of collateral damage from fishing, namely "bycatch" (the killing of nontarget species caught by fishing gear) and "habitat damage" (physical disturbance that kills seafloor life that is not retained in fishing gear).

Some fisheries, such as trolling for salmon and harpooning swordfish, are selective, causing virtually no bycatch or habitat damage. Other gears are nonselective. Shrimp trawls bury or crush nontarget invertebrates and fishes, and pelagic longlines drown large numbers of sea turtles and seabirds.

The fact that Fishery Management Councils do not discriminate among fishing gears ranging from environmentally "clean" to devastating is bad policy because it puts potentially sustainable fisheries at the mercy of methods that undercut sustainability.

In view of growing evidence that habitat damage from fishing gear contributes to the decline in biodiversity and fisheries, there is a pressing need to broaden the national debate to examine all impacts of fishing on marine species and ecosystems.

MCBI addresses this issue of how fishing gears affect biodiversity and fisheries by producing a rigorously researched, scientifically credible report on the impacts of various types of commercial fishing gears used in US waters. This study, titled "Shifting Gears: Addressing the Collateral Impacts of Fishing Methods in US Waters," shows remarkable consensus among fishermen, regulators, scientists and conservationists, who seldom share the same point of view on fishing matters. There was consistent agreement about which fishing gears are the most and least harmful to marine resources. Bottom trawls, dredges, bottom gillnets and midwater gillnets were considered to have a relatively "high" ecological impact, while midwater trawls, purse seines and hook-and-line gear were considered to have a "low" impact on the marine environment. The impacts of longlines and pots and traps were rated as relatively "moderate."


Download the Shifting Gears report [4 MB PDF] and its executive summary [PDF]. Also see the following related articles:




Download the "Shifting Gears" report in full text [4 MB PDF] and its executive summary [PDF]

Download the "Shifting Gears" paper [PDF] published in the journal "Frontiers in Ecology and the Environment"