Northwest Fisheries Science Center

2017 West Coast Groundfish Bottom Trawl Survey

This portal tracks the 2017 groundfish survey conducted on chartered West Coast fishing vessels by the Fisheries Research Survey (FRS) Team from NOAA's Northwest Fisheries Science Center. During the first half of the survey (May - July) we will conduct sampling from onboard the F/V Excalibur and the F/V Last Straw. The vessels are relatively small (65 - 76 ft in length) and usually host three scientists: a chief scientist from FRS and two back deck biologists. Many of the back deck biologists are volunteers without whose assistance we could not conduct the survey. The vessel personnel includes the Captain, two crewmembers and sometimes a night watch person. Follow us as we use trawling and oceanographic sampling to learn about the California Current ecosystem and the health of many West Coast fish populations. The survey traverses the entire area from U.S.-Canada to U.S.-Mexico at depths from 55 m to 1280 m twice during the sampling season (May - October). The survey is the primary source of fisheries independent information used in the management of 40+ groundfish along the U.S. West Coast. Although communications are often spotty while the team is at sea, chief scientists will post updates during periodic port calls as the vessels sample throughout the survey season.

Excalibur Haul Out Mob
test 3
Galley Table Mob
test 2
Sunrise on the Excalibur

Marine Debris Blog

By Melissa A. Head
September 12, 2017

pic of calendar with date September 12

The Northwest Fisheries Science Center (NWFSC) began monitoring benthic marine debris (anthropogenic waste found on the ocean floor) encountered in sample tows conducted by the West Coast groundfish bottom trawl survey (WCGBTS) in 2007. Since then we continue to record, catalogue, and weigh all debris related objects encountered, and categorize them into broad groups such as plastic, metal, rubber, fabric/fiber, glass, Styrofoam, and unsorted debris. In addition, to these groups we also record if objects are related to fishing or military activities. We determine this by markings on objects (Fig. 1), or by easily distinguishing some items as derelict fishing gear, such as crab pots and fishing line. We previously recorded data on debris on paper while at sea and transferred information manually to a database after the field season. In 2016, we updated our back deck software to include marine debris entries. This streamlined at sea data collection, and reduced time spent on data transfer during the off-season.

Figure 1 AFigure 1B

Fig 1. Images taken off Southern California, on leg 5 of the first pass of the 2017 WCGBTS (July 10 - 17) showing spent missile tubes, a common form of benthic debris collected in the southern California bight.


The impact of benthic debris has been sparsely studied, simply because it is easier to study debris that floats at the surface layer or washes ashore. The WCGBT survey is unique in this research venture with ongoing debris collections since 2007 (Keller et al. 2010). We now have a time series from 2007 through 2017 that covers the entire U.S. West Coast region. This allows us to observe frequency and distribution patterns of marine debris settlement, as well as remove debris from the ocean. From 2007 - 2011, benthic marine debris was present in 1315 of 3776 tows and weighed a total of 11,507 kg (Head et al. 2016). One of the more obvious patterns of debris distribution, that survey scientists recognized before we conducted analysis of data, was the high occurrences of military related debris off Southern California (Fig 2.). Survey scientists and the chartered commercial fishermen often dread the final leg of the trawl survey where we are sampling off S. California, simply because of the high amounts of garbage we end up sorting. In fact, we found that 92% of all military related benthic debris occurred South of Pt. Conception, CA (Head et al. 2016). Since we are primarily interested in marine life and not debris, these tows can be demoralizing at times (Fig. 3). That being said, all of us recognize the importance of collecting data on trash encountered in the ocean. We also realize that we are lucky to be a part of the groundfish survey team since we also get the opportunity to see some beautiful coastline, observe many marine mammals, and see some amazing fish (Fig. 4)!

Figure 2. orange circles on map of west coast indicating location of debris
Fig 2. Distribution of marine debris along the U.S. West Coast from 2007 -  2010 by weight (kg).


Figure 3
Fig 3. Captain Mike Retherford Sr. of the F/V Excalibur, expressing disgust at the level of trash present in a sample tow on leg 5 of the WCGBT survey.

Figure 4 AFigure 4B

Fig 4. Peter Frey, WCGBT fisheries scientist, on leg 5 of the 2017 survey aboard the chartered F/V Excalibur, pictured with a whipnose angler fish, family Gigantactinidae. Seeing this specimen lifted morale and cheered the entire crew!


In addition, to the military related debris we encounter off S. California, we also found that 16% of all tows analyzed from 2007 -  2010 contained derelict fishing gear (Head et al. 2016) (Fig. 5). While this does not seem like a huge number of tows, it is much higher than the number with military related items along the coast (6%). While plastic objects are more frequently encountered (31% of total count), metal debris items are close behind and contributed to the majority of the total debris by weight (35 %). Derelict fishing gear can range from large metal crab pots to small 5-gallon slime eel buckets. Pots can be lost at sea due to lost or damaged buoys, which are attached by line to the pots. These fishing pots inevitably sit on the ocean floor and continue to fish, often referred to as "ghost fishing."

Figure 5
Fig 5. Typical Slime eel, or Pacific hagfish, fishing pots caught during a sampling tow.  Many types of fishing pots can be lost at sea and potentially continue to fish.


The importance of monitoring and understanding the impact of marine debris is apparent, and we hope to continue to collect these additional data on the survey along with oceanographic and fisheries related information. All data recorded are crucial to our mission of promoting sustainable and productive fisheries, communities, and ecosystems. Streamlining our at sea efforts and collecting as much information from every aspect of our field sampling, allows us to effectively manage our marine resources.

Below are more interesting debris related photos taken over the years of trawl survey sampling:

Figure 6A. picture of a packaged ham pulled out of the water Figure 6 B. picture of an old corroded oil barrel

Figure 6 C. red hazardous bag with words 'asbestos' picked upFigure 6 D. buckets full of small debris on boat

Figure 6 E. large rusted metal debrisFigure 6F. upclose photo of small debris, including caution tape

Figure 6G. scientist saluting jovially after picking up ocean debrisFigure 6H. scientist taking off litter wrapped around fish


Keller, A.A., Fruh, E.L., Johnson, M.M., Simon, V., and McGourty, C. 2010. Distribution and abundance of anthropogenic marine debris along the shelf and slope of the US West Coast. Mar. Pollut. Bull. 60, 692 ¿ 700. Head, M.A., Keller, A.A., Simon, V., Buchanan, J., Bosley, K., Kamikawa, D., Harms, J., Draper, D., Frey, P.H., Chappell, A.C., Fruh, E., and Bradburn, M. 2016. Benthic marine debris along the U.S. West coast. NWFSC Ecosystem review, Seattle, WA, May 2016.



Tagged: marine, debris, blog, fram, survey, west coast, nwfsc, groundfish, bottom, trawl, anthropogenic, waste

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