Trawling has “negligible” effect on soft-bottom

Petrale sole, a flatfish caught by trawling on soft-bottom seafloor. Credit: The Nature Conservancy

A groundbreaking new study recently conducted by California fishermen, The Nature Conservancy and CSU Monterey Bay indicates that bottom trawling only has a “negligible effect” on the seafloor and fish habitat in certain types of soft sea bottom.

Trawling is continually criticised by environmental advocates for the damage it causes to rocky marine habitats and the long-lived animals that occur in them. However, important questions remain about the extent of any damage to sandy and muddy environments.

During the three-year study, fishermen trawled patches of the ocean floor off Morro Bay. Those areas were analysed by underwater photos and video and compared with nearby areas that were untouched.

Their peer-reviewed work, published in the Fishery Bulletin, found that California’s largely soft-bottom seafloor saw little lasting impacts from trawling with a small-footrope trawl.

The researchers say that their study adds to a growing body of literature from around the world showing trawling impacts are context-dependent – the impacts depend on the type of gear used, the types of habitats trawled and how often trawling occurs.

The scientists point out that their study does not imply that all soft-bottom habitats should be open to trawling; but, with new research and technology, “we can fine-tune our fishery regulations to protect truly vulnerable habitats.”

One of the researchers, Dr. James Lindholm has been studying marine ecosystems for 20 years and this autumn he will conduct a similar experiment off Half Moon Bay using trawling nets of different sizes. Commercial fishermen will also be involved.

Read the original post: www.worldfishing.net

Bottom trawling gets a bum rap, CSUMB study finds.

Nic Coury
Local petrale sole, like this dish at the former Alvarado Fish & Steakhouse, may be a more sustainable fish than we thought.

Bottom trawling—dragging nets along the sea floor to catch species like halibut and sanddabs—isn’t always the destructive fishing method it’s made out to be, according to a collaborative study by fishermen, The Nature Conservancy and CSU Monterey Bay.

The study, published in National Marine Fisheries Service’s Fishery Bulletin, found that not all sea floors are created equal. The “soft” sea floor (mostly mud and sand) that comprises up to 85 percent of the continental shelf off the California coast may be able to recover quickly from small footrope trawl gear, the study concludes. Yet most of the state waters and much of the federal waters are closed to bottom trawling.

“Our study adds to a growing body of literature from around the world showing trawling impacts are context dependent—they depend on the type of gear used, the types of habitats trawled and how often trawling occurs,” a press release states. “Trawling in rocky areas with long-lived corals will likely have more long-lasting impacts than trawling in soft-bottom habitats that may be less vulnerable and can recover more quickly.”

Monterey Bay Aquarium’s Seafood Watch guide, which has long shunned much of Monterey Bay’s own local catch because it viewed bottom trawling as environmentally unfriendly, is now picking up on that more nuanced approach. The updated Seafood Watch guide upgraded 21 species of West Coast groundfish from red (avoid) to yellow (good alternative) or green (best choice) rankings, as the Weekly reported last fall.

Also promising: next-generation light-trawl gear that floats just above the sea floor instead of dragging. Environmental Defense Fund consultants Huff McGonigal and David Crabbe developed the technology to allow fishermen to “fish a wider area, travel faster, reduce fuel costs by a quarter and preserve bottom-dwelling fauna,” as the Weekly reported in 2013.

Read the original post: MontereyCountyWeekly.com | by Kera Abraham

Conservation in the Anthropocene: A Breakthrough Journal Debate

In their Breakthrough Journal essay, “Conservation in the Anthropocene,” Peter Kareiva, Michelle Marvier, and Robert Lalasz showed that conservation is losing the war to protect nature despite winning the battle to create parks and game preserves. While the number of protected areas has risen, species in wild places have fallen. Conservationists must shed their 19^th Century vision of pristine nature, the authors wrote, and seek a new vision, one of “a planet in which nature exists amidst a wide variety of modern, human landscapes.”

In a new Breakthrough debate, a host of passionate 21^st Century conservationists, including Kierán Suckling, Paul Robbins, Ray Hilborn, Lisa Hayward, and Barbara Martinez, face off with the authors over the resilience of nature, corporate partners, and the state of conservation today.

Of particular interest is the commentary submitted by Professor Ray Hilborn. You can read his response below, or click here to see Breakthrough Journal’s full debate.

MARINE PARKS ARE FISHY

Ray Hilborn

By Ray Hilborn

In “Conservation in the Anthropocene,” Peter Kareiva, Robert Lalasz, and Michelle Marvier argue that conservation needs to move beyond parks and protected areas. They stress that ecosystems are generally resilient to perturbation, and rather than being irreparably damaged by the slightest anthropogenic impact, ecosystems can both support biodiversity and produce sustainable goods and services. While their arguments and examples are drawn from terrestrial ecosystems, much of their article is relevant to marine ecosystems, my field of study.

Marine ecosystems are the new frontier for conservation. And much of the funding for new scientific work has been directed towards the establishment of protected areas. It’s important to note that while marine and terrestrial ecosystems share much in common, there are differences. One fundamental difference is the nature of human use. In terrestrial ecosystems, a dominant form of use is agriculture, which essentially rips out native ecosystems and replaces them with exotic species: crops, tree plantations, or grasses for grazing. Agriculture makes no pretense about preserving natural ecosystems.

In contrast, in marine ecosystems, we attempt to sustainably harvest the natural ecosystem. We leave the lower trophic levels—primary producers and most of their consumers—untouched, and exploit only the higher trophic levels. This has profound consequences. It means that even if the dreams of protecting 10 percent of the world’s ocean, as set out in the 1992 Convention on Biodiversity, were to come true, most marine biodiversity will remain outside the boundaries. The struggle to maintain biodiversity is in the total anthropocene ocean; it will never be achieved through protected areas.

The marine conservation movement has been slow to grasp this. Similarly, it has failed to see that closing areas to fishing does not eliminate fishing pressure, it simply moves it. When an area is closed, fishing efforts concentrate outside protected areas. Consequently, simple comparisons of abundance inside and outside of reserves as a measure of “success” are meaningless. The salient question to ask is what happens to the total abundance.

One study sought to answer this question by tracking trends in abundance inside and outside of a set of reserves established in the California Channel Islands.¹ Of the species targeted by commercial and recreational fishing, abundance went up inside reserves and down on the outside. Since 80 percent of the habitat is outside of the reserves, the data suggest that the total abundance of the targeted fish species actually declined. The gains inside were more than offset by the decreases on the outside.

In the case of the Channel Islands reserves, the creation of a protected area had a negative impact on abundance. In many other cases, protected areas have little to no impact. Two of the most heralded successes of the marine conservation movement have been the establishment of large protected areas in the Northwestern Hawaiian Islands, and the western Pacific US territories. If the measure of success is the amount of area proclaimed as protected, these are significant achievements. But if the objective is effective protection against real threats, the achievement is less because there was little, if any, human impact in those areas before protection.

There are many threats to marine ecosystems, including oil spills, exotic species, runoff from terrestrial sources, illegal fishing, excessive legal fishing, ocean acidification, and global warming. The marine parks movement does not recognize that most “protected areas” only “protect” from legal fishing, and not much else. Advocates argue that unfished ecosystems are more resilient to environmental perturbations such as exotic species, yet the same argument, if valid, must apply to areas outside of reserves. Since fishing pressure has been redirected to unprotected areas, those ecosystems ought to be more vulnerable to the same perturbation.

Kareiva et al. argue that the new conservation “requires conservation to embrace marginalized and demonized groups,” and perhaps no group has been so demonized by the environmental movement as fishermen. Terms like “roving bandits” and “rapers and pillagers” permeate the public discussion. But luckily this is changing. The new marine conservation movement recognizes that conserving biodiversity requires more than merely controlling fishing. Progressive NGOs are working with fishing groups rather than demonizing them, a transformation that has entered into in marine conservation debates that attempt to find new solutions to the environmental impacts of fishing.

Kareiva et al. close by stating, “Protecting biodiversity for its own sake has not worked. Protecting nature that is dynamic and resilient, that is in our midst rather than far away, and that sustains human communities—these are the ways forward now.” This is as true in the marine world as in the terrestrial. There is certainly a role for protected areas. But the bulk of marine biodiversity will always be in the dynamic areas outside of them, areas that must be sustainably managed as we go forward.

Ray Hilborn is a professor in the school of Aquatic and Fishery Sciences at the University of Washington.

1. Hamilton, S. L., J. E. Caselle, D. P. Malone, and M. H. Carr. 2010. “Incorporating biogeography into evaluation of the Channel Islands marine reserve network.” Proceedings of the National Academy of Sciences of the United States of America. www.pnas.org/cgi/doi/10.1073/pnas.0908091107.