Saving Seafood

New Study Puts Hard Numbers on Impacts of Bottom Trawling

July 24, 2017 — Roughly a fifth of all fish eaten globally are caught using nets towed along the bottom of the ocean. There’s long been concern that this method – known as trawling – destroys or severely damages the ecosystems where it’s used. Now, a new meta-analysis of the science available on this topic offers some quantification of the impacts of different type of trawls.

Previous studies have found that the mud plumes from some trawls can be seen from space, and that “bottom trawling related to commercial fisheries leaves a greater physical footprint on the seafloor than the combined effects of all other human activities, including scientific research, fossil fuel recovery and waste disposal.”

While it is undeniable that dragging metal gear across the seafloor impacts the ecosystems there, a new analysis of seventy different studies finds that not all trawls are equal, and that some do significantly less damage than others.

In particular, otter trawls – the type most commonly used in New England – have the least impact of the four types compared. Otter trawls scrape, on average, just under an inch off the seafloor and remove about six percent of the animals living there. In contrast, hydraulic dredges squirt water into the sediment to release buried animals, reaching about six inches into the sea floor and removing more than forty percent of animals.

Read the full story at WCAI

Helping Fishermen Catch What They Want, and Nothing Else

May 3, 2016 — Heather Goldstone, of NPR affiliates WGBH and WCAI, discusses bycatch reduction in fisheries on a recent episode of “Living Lab.” Her guests were veteran gear designer Ron Smolowitz of the Coonamessett Farm Foundation, who has worked with the southern New England scallop industry; Steve Eayrs, a research scientist at Gulf of Maine Research Institute, who has worked with groundfishermen in Maine; and Tim Werner, a senior scientist with the New England Aquarium, who put acoustic pingers on gill nets to warn away dolphins. An excerpt from the segment is reproduced below:

It’s the holy grail of commercial fishing: catch just the right amount of just the right size of just the right species, without damage to the physical environment. It’s a tall order, and few fisheries are there yet.

Leaving aside the issue of straight up over-fishing, the Food and Agriculture Organization of the United Nations estimates that, each year, fishermen around the world accidentally catch more than seven million tons of marine life – everything from whales and turtles, to sea cucumbers – that they weren’t even after. Such by-catch, as it’s known, is essentially collateral damage.

And fishing has other environmental impacts. In some parts of the ocean, the scars left by trawls dragged across the sea floor can be seen for years.

But, it doesn’t have to be that way. Over the past decade or so, a lot of effort has gone into designing fishing gear and related equipment that allows fishermen to catch more of what they do want, and less of what they don’t, while also minimizing damage to the environment. For example:

  • Veteran gear designer Ron Smolowitz and the Coonamessett Farm Foundation have worked with the southern New England scallop industry over the past several years to develop a trawl that excludes loggerhead sea turtles. It turns out, it’s also better at capturing scallops, with the end result that scallopers can use smaller areas and less fuel – 75% less – to make their catch.

Read the full story and listen to the segment at WCAI