Bottom trawling is good

Last updated 15:56 30/11/2010

In a study sure to enrage extreme greenies everywhere, scientists in California have discovered that bottom trawling may not be systematic environmental pillage.

In fact, it may even be good for the seabed.

As reported in the latest issue of New Scientist, a five-year study by The Nature Conservancy is looking at the impact of bottom trawling on a strip of seabed 23km off Morro Bay, between Los Angeles and Monterey.

The scientists marked out eight plots, each 1km by 330m, that had not been trawled for a decade or more. Four would remain untouched and four would be trawled.

Last year the trawling zones were hit twice and  photographs of the seabed taken after each trawl. More photographs were taken six and 12 months later.

"Early signs indicate that marine life survived, even thrived, after last year's trawls," the New Scientist wrote. "Donna Kline, a fish ecologist at California State University in Monterey Bay, thinks that far from destroying a habitat, the trawl may have created a new one by etching grooves into the flat bottom."

This would be a remarkable conclusion, but it is way too early to be sure. A more intensive series of five trawls in each zone took place last month and time must pass before the impact can be assessed. Any conclusions may also be inapplicable to New Zealand seas.

Still, it is an interesting study.

In New Zealand's exclusive economic zone bottom trawling is banned in 17 deep sea areas totalling 1.2 million sq km, as well as around several underwater features such as seamounts.

This is a wise precaution, but it's also clear we know woefully little about our marine ecology.

Part of the deal with the fishing industry to close those areas involved industry paying a third share of costs to research deepwater seabed environments - ie, a maximum of $330,000 a year.

That's not a lot, frankly. Given the industry's strong financial interest in understanding the sea, I would have thought one third of research costs was woefully inadequate.

However, let's keep things in perspective. Many people think of farming as a clean green countryside activity, whereas farming has obliterated the natural environment almost completely. A farm is not countryside, it is a factory without a roof.

Is this a bad thing? No. We need farms to feed us. With farms we can sustain ourselves using less land than we'd need if we were all hunter gatherers.  

There's a lesson there for the fishing industry. If it's not prepared to invest in researching wild fisheries, aquaculture should be a priority.


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Peter T   #1   04:19 pm Nov 30 2010

That headline is a leading Tui billboard candidate. Not sure why you have to be an "extreme greenie" to be bothered by a such a headline when the story goes on to confess that this is a single study in a single location and that it is "way too early to be sure". Another case of the media trumpeting dubious science just for the sake of a stir. Do journalists get paid by the click these days?

Jim   #2   04:29 pm Nov 30 2010

Maybe the human race could stop breeding like rabbits and requiring all this food in the first place.

Nick   #3   04:43 pm Nov 30 2010

LOVE the headline. Second para even better. Careful, or Forest and Bird will revoke your membership.

James   #4   04:51 pm Nov 30 2010

Its not so much about sea life in general, but the rare species of coral, sponges and other invertebrates that are destroyed during trawling, and since they are not saturated in the environment, they cannot re-establish and survive. Plus some corals can take thousands of years to establish themselves and grow to an adequate size, to be wiped out in mere minutes.

Space availability is one of the biggest limiting factors in a marine environment, so it makes sense that any recently cleared area would be quick colonised by organisms capable of doing so.

So in summary, trawling is never a good thing in my book. It may help the species that are specialised for quick establishment in a cleared environment, but it comes at the cost of too many rare species.

Senthil   #5   05:14 pm Nov 30 2010

All the referenced study shows is that marine life returns quickly after a muddy bottom has been freshly ploughed. It's a bit far fetched to say the test environment was 'pristine' because it hadn't been ploughed for at least 10 years.

Richard Wells   #6   05:27 pm Nov 30 2010

The fishing indusstry puts millions of dollars in researching the status of the stocks it wishes to catch as well as the effects of any interactions with other species caused by the fishing activity. Line that up against the amount paid by any other primary sector, directly, to look at their externalities....... say research on turbidity abd fertiliseers in rivers, wildling pines, monoculture and impacts on native bird, plant, reptile and insect life.

RhinoD   #7   01:05 am Dec 01 2010

New Scietist is not a science journal and this study is therefore not peer-reviewed, so who would believe it. I wish journalists (i.e. Tim Hunter) could read science properly before writing their own headlines to sell their stories. You need a better education Mr. Hunter

Dallas Weaver   #8   05:40 am Dec 01 2010

It so happens that The Nature Conservancy owns bottom trawling licenses and has a financial stage in the results. Their study didn't include the impacts of the suspended solids.

Randle   #9   06:19 am Dec 01 2010

The thing is though Tim, in productive areas certain areas can be fished over hundreds of times a year, often 4-6 times a day. If an area produces a lot of fish a boat will keep towing back and forth over that area until catch's begin to drop and then move on. Then there is nothing stopping another boat hitting that same area the next day based on historical data. Your reporting of this study fails to understand how fishing actually works in practice.

Natalie   #10   07:55 am Dec 01 2010

Hi Tim,

This is absurd. In New Zealand waters they have bottom trawled 100 year old coral. To suggest that bottom trawling is good is obscene - the findings from the study are not even complete.


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