Saving Seafood

Ray Hilborn: New study provides no new information on global fishing footprint

March 7, 2018 — University of Washington fisheries researcher Ray Hilborn said that a new study using satellite data from industrial fishing vessels to map global fishing effort fails to provide any new insight, despite media reports indicating otherwise.

The study, published in Science in February, used messages transmitted between 2012 and 2016 from the automatic identification systems (AIS) of more than 70,000 industrial fishing vessels to create a global footprint, concluding that “industrial fishing occurs in over 55 percent of ocean area,” according to the abstract.

But Hilborn said the vessels monitored for the study were in large part tuna boats over 100 feet, which have been monitored for decades.

“Most of the footprint data they have is from high-seas tuna fishing, because that’s really the only thing that goes on on the high seas. Maps of the tuna long-lining and seining distribution have been distributed as part of the standard operating procedure by the tuna RFMOs [regional fisheries management organizations] for decades. I remember looking at them 30 or 40 years ago. There’s nothing new about this – that tuna fishing goes on across much of tropical oceans and some of the temperate oceans,” Hilborn told SeafoodSource.

Not only is this not new information, Hilborn said, but it does little to measure the impact of trawling on certain ecosystems, which Hilborn said can be much more severe than high-seas fishing.

“A place that has had one long-line for albacore or big-eye tuna in five years is obviously not very heavily fished, he said. “But if you go to Southeast Asia, we can calculate how often the average piece of bottom is trawled a year. In the U.S., depending on where, it’s about once every three years. In Southeast Asia or India, they are trawled 10 to 20 times a year. That means the impact of fishing there is probably 1,000 times higher than it is on the high seas where someone once visited with a long-line boat.”

Furthermore, the trawling data provided in the new study, Hilborn said, overestimates the proportion of the sea-bed that is affected by 10 times. Hilborn and his team have just completed a five-year study that attempts to provide a finer-grained look at the impact of trawling by aggregating data from vessel-monitoring systems, logbooks, and on-board observations.

Read the full story at Seafood Source

 

Media Fails Again on Fisheries Data; New Maps Don’t Show Intensification of Fishing – Hilborn

February 26, 2018 — SEAFOOD NEWS — The lead article in Science this week, picked up in numerous publications, highlighted data from the AIS vessel tracking system to show the global impact of industrial fishing.

The authors state that vessels are now fishing in 55% of the world’s oceans, which is an area four times larger than occupied by onshore agriculture.

The immediate popular conclusion was that this shows immense overfishing, and Oceana was quoted saying “That means we’re putting more pressure on fish populations.”

But that is not what the data show.  As pointed out consistently by Professor Ray Hilborn of the University of Washington, the comparison with agriculture is simply wrong.

Hilborn says “The comparison to agriculture fails to note that the 50 million square kilometers under agriculture have destroyed the natural ecosystem as the plow or new pasture eliminates the native plants.   The areas fished, particularly for tunas, have changed very little.”

Furthermore,  “Fishing does not impact the primary production (plants), and in very few cases does it impact the species that graze on the primary producers.  So the 50 million square kilometers of the earths’ surface that is used for agriculture is totally transformed,  most of the oceans that are being fished (high seas tuna)  have some changes in top predators abundance. “

Hilborn points out that “High seas fishing for tuna, which constitutes the majority of the “footprint” shown in the Science paper has been mapped for 40 years, and the widespread nature of high seas tuna fishing is well known.  The footprint of bottom trawlers has been mapped in much finer scale already in many places, and the Science paper overestimates the proportion of the seabed impacted by trawls by 10 fold.”

The AIS data is interesting, and allows for specific types of research that was not possible before.  However, the dataset does not give as accurate a picture of global fishing as does the comprehensive database on fish stock surveys and catch records.

Hilborn says “For most of the areas where there are data in this study,  fish stocks are actually increasing and tuna populations are well documented and globally stable.”

Hilborn is a longtime collaborator with Dr. Boris Worm, one of the authors of the paper.  Together they did a groundbreaking study of global fisheries databases, and helped create a standard dataset to measure fisheries catches and stock health.  Neither Worm nor the other authors are claiming that the AIS study shows increased fishing pressure on stocks, they are simply reporting that the tracking data provides a new visualization tool for global fisheries.

This story originally appeared on Seafoodnews.com, a subscription site. It is reprinted with permission.   

 

Can you hear me? NOAA studies boat noise and fish

January 8, 2018 — NOAA scientists studying sounds made by Atlantic cod and haddock at spawning sites in the Gulf of Maine have found that vessel traffic noise is reducing the distance over which these animals can communicate with each other.

As a result, daily behavior, feeding, mating, and socializing during critical biological periods for these commercially and ecologically important fish may be altered, according to a study published in Nature Scientific Reports.

Three sites in Massachusetts Bay included two inside Stellwagen Bank National Marine Sanctuary, a region well known to whale-watchers from the Cape because whales feed in the plankton-rich bank, and one inshore south of Cape Ann. All were monitored for three months by researchers at the Northeast Fisheries Science Center (NEFSC) laboratory in Woods Hole, and at the sanctuary offices in Scituate.

Vocalizations, such as Atlantic cod grunts and haddock knocks, were recorded by bottom-mounted instruments at each site during spawning in winter and spring.

“We looked at the hourly variation in ambient sound pressure levels and then estimated effective vocalization ranges at all three sites known to support spawning activity for Gulf of Maine cod and haddock stocks,” said Jenni Stanley, a marine research scientist in the passive acoustics group at the NEFSC and SBNMS and lead author of the study.

“Both fluctuated dramatically during the study. The sound levels appear to be largely driven by large vessel activity, and we found a signification positive correlation with the number of Automatic Identification System (AIS) tracked vessels at two of the three sites.”

AIS is an automatic tracking system, used on ships and by vessel traffic services. It provides information on a vessel, such as its unique identification number, position, course and speed, which can be displayed on a shipboard radar or electronic chart display.

Read the full story at the Wicked Local