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100th Occupation of the Seward Line

2020 Field Season Complete

CTD Sampling
Graduate students Hana Busse (WWU) and Annie Kandel (UAF) sample the CTD aboard the R/V Sikuliaq.

Despite challenges and restrictions due to COVID-19, the NGA LTER was able to complete their 2020 field operations. These operations included four planned research cruises, and redeployment of several moorings.

To enable this, we shortened cruise lengths, reduced the number of participating scientist, and transferred on cruise to a different vessel. In the end, the NGA team pulled off the core Gulf of Alaska sampling and so maintained the long-term time series datasets.

Fall Cruise Update

During the first 9 days in September, twelve scientists from the University of Alaska (UAF), Western Washington University (WWU) and U.S. Fish and Wildlife Service (USFWS) sailed aboard the R/V Sikuliaq. Originally, the fall cruise was scheduled to take place on the USFWS vessel R/V Tiglax. Unfortunately, the pandemic forced the cancellation of all 2020 Tiglax sailings. Postponement of other research cruises on the Sikuliaq schedule and a slight shift of fall LTER sailing dates opened a window of availability for a fall expedition.

Fall sampling occurred in Prince William Sound and along the Seward Line. This marks the 100th occupation of the Seward Line using a (nearly) modern suite of vertically profiling sondes! The Seward Line is a 150 nautical mile transect that starts at the mouth of Resurrection Bay and extends offshore into oceanic waters. The first occupation of the Seward Line was in December, 1970. Over the first few years, samples were taken only at discrete depth levels using Nansen bottles and reversing thermometers.

Temperature and salinity
Temperature and salinity anomaly plots from the September 2020 cruise along the Seward Line.


A history of the sampling along the Seward Line includes:

  • First, sampling at Seward Line stations began with a cruise in 1970. Bottles collected water samples from depth.
  • Using profiling dataloggers, 17 full occupations of the Seward Line occurred from 1974 to 1997.
  • Then from 1997-2004, sampling expanded to 6-7 cruises per year as part of the U.S. Global Ocean Ecosystem Dynamics (GLOBEC) program.
  • From 2005 to 2017, cruises occurred in May and September on the Seward Line and in Prince William Sound. The consortium of funding partners include NOAA, the North Pacific Research Board (NPRB), the Alaska Ocean Observing System (AOOS), and the Exxon Valdez Oil Spill Trustee Council (EVOS) via the Gulf Watch Alaska program.
  • Most recently, in 2018 the consortium expanded via funding from NSF’s LTER network. The expansion includes spring, summer and fall expeditions and the addition of survey stations east and west of the Seward Line.

More details and information on the history of our site – https://nga.lternet.edu/about-us/site-history/


Seward Line Sampling Continues Despite COVID-19 Worries

Resilience in Gulf of Alaska Science

Like everyone, scientists world-wide want to reduce the spread of COVID-19. However, for their work, they also need to continue research projects that rely in part on uninterrupted data records. Fortunately, with the support of NSF and University of Alaska, NGA LTER scientists will be able to do both by reducing spring field operations.

A press release by the College of Fisheries and Ocean Sciences at the University of Alaska Fairbanks outlines our plans for the spring cruise: Sikuliaq to embark on limited research cruise in May.

Photo of R/V Sikuliaq at the dock in Seward Alaska
The research vessel Sikuliaq, here in Seward, Alaska, will depart May 4, 2020. [credit: Sarah Spanos]

Evolution forced by COVID-19

Like other research programs, our research plans shifted rapidly in response to the changing situation. Several articles trace this evolution by featuring NGA LTER PIs and research activities.

Importance of the Time Series

Multi-disciplinary monitoring of the Gulf of Alaska ecosystem has occurred every May since 1998. Fisheries managers and research scientists can make informed assessments of Alaska marine ecosystem health and status because of these measurements. This long-term sampling happens along the Seward Line – a set of stations stretching 150 miles across the shelf – and within Prince William Sound. Regular samples at these consistent stations insure the integrity of this time series. Therefore, preserving core physical, nutrient chemistry, phytoplankton and zooplankton data at these stations is a high priority for NGA LTER scientists.

The North Pacific Research Board (NPRB), the Alaska Ocean Observing System (AOOS), and the Exxon Valdez Oil Spill Trustee Council (EVOS) via the Gulf Watch Alaska program all provide additional funding that make this time series possible.

graph of GAK1 data
Nearly 50 years of data have been collected at GAK1, a Seward Line station. This allows the calculation of long-term trends and anomalies. [credit: Seth Danielson]

The Plan

Our planned field work aims to continue the valuable Seward Line time series while keeping personnel safe. Before the cruise, R/V Sikuliaq remained in Seward, AK, staffed by her crew. They have been under quarantine on board since their arrival at the start of April. Three of our Principle Investigators (PIs), Seth Danielson, Ana Aguilar-Islas, and Russ Hopcroft, quarantined at home for 2 weeks. They will join R/V Sikuliaq for the 7 day cruise, May 4-10, 2020. Before the cruise, crew and science party members logged body temperatures twice daily and maintained strict adherence to social isolation protocols in order to ensure a virus-free voyage.

The cruise plan includes sampling of the entire Seward Line with additional stations in western Prince William Sound. Planned measurements include water temperature and salinity using the conductivity-temperature-depth (CTD) instrument; water collections from deep waters to the surface for chlorophyll, nutrient, phytoplankton, and microzooplankton analysis; and net tows for zooplankton.

Other common NGA LTER activities will not be possible due to the short cruise length and limited personnel. Postponed activities include shipboard experiments, seabird and mammal surveys, jellyfish sampling, dissolved iron and other trace metal sampling, carbonate chemistry sampling, and optical measurements. NGA LTER’s other cross-shelf sampling lines will not be visited.

Despite these restrictions, we are fortunate to have the opportunity to continue our work and to contribute to the goal of understanding the Northern Gulf of Alaska ecosystem.