URI professor part of a worldwide study on impacts of bottom trawling on health of seabeds
A worldwide study on the impacts of bottom trawling, which accounts for a quarter of the world’s seafood harvest and can negatively affect marine ecosystems, has found that seabeds are in good health where trawl fisheries are sustainably managed.
The
research published in Proceedings of the
National Academy of Science (PNAS) by a
team including co-author Jeremy
Collie, Professor of Oceanography at the University of Rhode Island,
builds on recent international collaboration in this field and is the first
worldwide study of its kind. It brings together data from 24 large marine
regions around the world to establish a relationship between distribution and
intensity of trawling activities and the biological state of seabeds.
Researchers,
led by CSIRO, Australia’s national science agency, assessed the status of
seabed biota, or marine organisms, on a scale from 1 (unimpacted) to 0 (fully
impacted) and found that 15 regions studied had a status greater than 0.9,
while three had a status less than 0.7, and 1.5% of all seabed areas studied
had a depleted status of 0.
Lead author and CSIRO marine scientist Roland Pitcher said that the study shows that good management of fisheries contributes to better outcomes for the broader ecosystem.
“The
results show that effectively managed and sustainable trawl fisheries are
associated with regions having high seabed status of 0.95 or more,” said
Pitcher. “Regions that had low seabed status scores were places where fish
stocks typically are over-exploited and have ineffective management regimes.
“Detailed
data were not available for all jurisdictions where bottom trawling occurs, but
importantly, this study provides the world’s first statistics to estimate the
impact of global trawling and provides an evidence base to inform effective
improvements to trawling practices worldwide.”
Data
from the northwest Atlantic—the coastal and offshore waters extending from the
Carolinas to Greenland—were not available for this study but the results are
relevant to the region, where bottom trawls and dredges account for much of the
fisheries catch.
In
U.S. waters the Sustainable Fisheries Act of 1996 mandated the protection and
restoration of essential fish habitat. The New England Fisheries Management
Council uses the Fishing Effects Model to calculate the percentage
of seafloor habitat that is disturbed by bottom fishing.
“Between
1996 and 2017, total habitat disturbance from all gears combined declined from
35% to 20%,” said Collie. “Bottom trawls accounted for about 90% of total
habitat disturbance, hence the decrease in disturbance largely reflects the
reduction in bottom-trawl fishing effort during this time.
“These
trends indicate that maintaining fishing effort at sustainable levels has the
added benefit of reducing impact to the seabed animal life that sustains
fisheries production.”
University
of Washington, Seattle, fisheries scientist Ray Hilborn said the research
demonstrated the power of global collaboration for fisheries research.
“By
bringing these data together from across 24 large marine regions of the world
we are able to establish foundational statistical relationships between
trawling activities, their impacts and ecosystem status, including implications
of trawl-gear choices and spatial distributions of trawl intensity,” said
Hilborn.
“This
research is a critical step in moving towards an overall estimate of the global
impact of trawling, and understanding the steps required to improve fisheries
management, reduce exploitation, improve stock sustainability and the status of
the seabed environment.”
