Northwest Fisheries Science Center

West Coast Groundfish Bottom Trawl Survey

This portal tracks the 2018 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.

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Excalibur Haul Out Mob
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Galley Table Mob
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Sunrise on the Excalibur

Demobilization - Pass 1

By John Buchanan
August 6, 2018


Calendar with dates July 23-25

Demobilization for the first pass (May 18-July 16) of the 2018 west coast groundfish bottom trawl survey occurred in Newport Oregon from July 23-25, once the vessels Excalibur and Last Straw returned from southern California. This involves the dismantling of the many electronics, and offloading of the multitude of equipment and supplies needed to make this coast wide survey a success. This also includes, sampling equipment, fishing gear (nets, trawl doors, trawl wire, sensors), samples, sampling tables, and the few living comforts for at sea biologists spending 1-3 weeks from home at a time. NOAA divers remove acoustic transducers mounted on the bottom of the research vessels during demobilization. Survey team members Victor Simon, Doug Draper, Peter Frey and John Buchanan undertake the diving in Yaquina Bay with the help of support personnel. The custom-built transducer units (100-200 lbs ea.) are detached, dropped from the hull of the vessels and hauled out of the bay. 

The trawl wire is wound off the boats onto spools for storage until next year. This steel cable is 5/8" thick and 7500 ft (1.42 mi) long. As the cable is spooled off, survey biologists measure each sections and note any stretch that has occurred during fishing operations. The nets and fishing gear are loaded onto trucks and sent north to Seattle and Bainbridge Island for repairs and certification for use in future surveys. Everything is gone through by survey staff in Newport and Seattle to get ready for the next pass occurring a short 2.5 weeks away! This includes little details like all new sampling supplies, clean bedding, testing of safety gear, repair/calibration of electronics, etc. In addition, the multitude of first pass samples are distributed to the end users, and/or prepared for analysis.  All the sampling tables are repainted anew, ready for the next sweep down the coast. Most importantly, the data are amassed and readied for stock assessment use.

The vessels, free of the government encumbrance, are readied for return to commercial fishing. The crews and biologists say goodbye until next year, safe fishing!

Figure 1.  Offloaded sampling gear and equipment ready for transport north.

 

Figure 2. Nets, footropes and cables shortly after removal from vessles.

 

Figure 3. John Harms and Melissa Head remove cables from trawl doors prior to shipping.

 

Figure 4. Wire being removed from Last Straw and prepared for measurement at Englund Marine.

 

Figure 5. John Buchanan, Peter Frey and Doug Draper prepare to remove transducers from the F/V Last Straw during demobilization on July 24, 2018 at the dock.

 


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Are fish picky eaters?

By Doug Draper
August 6, 2018


We do a lot while at sea, but one important aspect of the Groundfish Trawl Survey, sometimes overlooked, is the collection of numerous specimens and samples. These collections range from entire fish or invertebrates to various tissues and organs. Quite a few of the collections are collaborative efforts amongst various parties, such as universities and other scientific institutions within the U.S. and abroad. However, a good portion of these collections are for ongoing Northwest Fisheries Science Center (NWFSC) internal projects integral to stock assessments and overall management of NE Pacific fisheries, such as fish otoliths (ear bones used for age determination), and gonads (organs used to determine maturity levels and reproductive life histories).

One ongoing project undertaken by several on the survey team is research into the diet habits of fish. Significant effort goes towards collecting stomachs from a multitude of groundfish species to understand their predator-prey dynamics and food web associations (i.e. types and amount of prey consumed, where feeding occurs, and how predators and prey interact). We also study how prey varies in response to geography (e.g. latitude, depth), environment (e.g. temperature, dissolved oxygen content, acidification), climate fluctuations (e.g. El Niño-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the recent "warm blob" anomaly in the NE Pacific Ocean), and anthropogenic influences (e.g. fishing, pollution).

Species of interest include lingcod, sablefish, arrowtooth flounder, Pacific sanddab, and many of the rockfish species found in the NE Pacific. This information is of particular value to ecosystem modelers and managers, as well as stock assessors, since changes in prey preference and availability directly relate to the health and status of recreationally and commercially important groundfish species and the economies dependent upon them. We investigate the feeding habits of groundfish by comparing short-term diet composition (via stomach contents) and long-term trophic relationships (via stable isotope analysis). Stable isotope analysis is a tool for studying diet history by identifying the ratios of certain stable isotopes and chemical elements within fish tissue. The goal of our research is to gain an understanding of the types of prey consumed and the effects of varying influences upon these populations.

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Figure 1. Staring down a sablefish gullet (longline hook with ganion visible).
 

 

Sablefish montage
Figure 2. Extracting a stomach from a sablefish (clockwise, starting upper left): pulling the stomach from the cavity and finding the forward end of the esophagus; cutting at the esophagus to retain all stomach contents; cleaning up the stomach by removing viscera, e.g. liver, gall blader, connective tissue; placing stomachs individually into cloth sample bags, which are then stored at sea in 10% buffered formalin.

 

Pacific sanddad montage
Figure 3. Extracting the stomach from a Pacific sanddad (clockwise from upper left): cutting into gut cavity, removing stomach, and excising stomach at forward end of esophagus; cleaning off viscera and conective tissue; placing in cloth sample bag for storage; collecting ~1 cm cube tissue sample for stable-isotope analysis, which is done for every stomach collected.

 

Figure 4. Now that's a full lingcod stomach!

 

Figure 5. Photomontage of a variety of prey items collected from fish stomachs.

 


Tagged: diet, picky eaters, travel, tracked, survey, blog, Pass 1, f/v excalibur, southern extent, west coast, bottom, trawl Fisheries, team, groundfish survey, at-sea biologists, pyrosomes, mobilization, volunteers, US-Canada to US-Mexico, California current ecosystem, port calls, cooperative research

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