The final leg of the California Current Ecosystem Survey, Leg IV, sailed out of San Diego on September 5 aboard FSV Reuben Lasker. The combined goal of the 80-day, 4 leg survey, is to acoustically survey the 10 mile spaced transect lines for coastal pelagic species (Pacific sardine, northern anchovy, jack and pacific mackerels, market squid) during the day, then sample nightly with a rope trawl for verification of acoustic targets. Leg IV has surveyed transect lines 12-28 within the geographic range of Point Sur to the north and Channel Islands to the south. Acoustics has seen scattered patches of coastal pelagic species schools with higher densities occurring mid transect and offshore.
Trawl catches have been small in stature compared to the northern transect catches of Legs II and III, but large in coastal pelagic species diversity. All five target species appear nightly and seem to correlate nicely with acoustic backscatter data collected during the day. The majority of fish collected have been one-year-olds or younger, a size class rarely encountered on acoustic trawl surveys. The Marine Mammal and Turtle Division is also contributing through observing marine mammals and birds along the route. A valuable data set is in the making for this year.
Leg 3 of the Summer California Current Ecosystem survey departed from San Francisco on August 13, resuming transects off Cape Mendocino and now currently off Monterey Bay. The beginning of leg 3 was relatively quiet, with scant coastal pelagic species backscatter in the acoustics; low densities of jack mackerel and sardine eggs in the Continuous Underway Fish Egg Sampler, predominately in the offshore portions of the northern transects; and minimal catches in the trawls, from which the only coastal pelagic species caught were small numbers of jack mackerel.
But that all changed just south of San Francisco Bay, where significantly higher densities of acoustic coastal pelagic species backscatter were associated with enormous hauls of pure anchovy in the trawls and low densities of anchovy eggs in the Continuous Underway Fish Egg Sampler. Jack mackerel eggs continue to be seen on the offshore ends of the transects and the marine mammal lines.
A large catch of mainly Jack mackerel and some Pacific sardine. photo: NOAA Fisheries.
During the day, sampling is performed along transects using a continuous underway fish egg sampler, an underway CTD profiler, and multiple acoustic instruments. At night, surface trawls are directed to locations where coastal pelagic species were observed acoustically during the day. The trawls serve to estimate the species composition and respective demographic structure of the fishes sampled acoustically. These data will be used to estimate the abundance of Pacific sardine, Jack mackerel, Pacific mackerel, Northern anchovy, and Pacific herring in the California Current.
A juvenile sardine recently ingested by a Jack mackerel hints at one of the many causes of last years’ poor sardine recruitment. Photo: NOAA Fisheries.
On leg 2, Lasker resumed sampling off the coast of Washington. During this second leg, Jack Mackerel has dominated the catches, followed by Pacific mackerel, Pacific sardine, Pacific herring, and Northern anchovy. Sardine, mostly large, were found in the same areas as large aggregations of Pacific and Jack mackerels (see image below, left). There are no indications yet of a substantive 2017 sardine recruitment.
Leg 2 will continue to sample the waters off Oregon and Northern California until August 9.
July 13, 2018
The 2018 California current Ecosystem Survey, a joint Fisheries Resources Division/Marine Mammal and Turtle Division mission aboard NOAA Ship Reuben Lasker, has finished transects off West Vancouver Island and Washington, and is now sampling off Oregon. At the present rate of progress, transects north of Tillamook Bay should be completed before the end of the first 20-day leg, on July 16, when Lasker arrives to Newport, OR.
Owing to the efforts of the ship’s Captain, officers and crew, and Fisheries Resources Division Scientists (David Demer, Dan Palance, Dave Griffith, Lanora Vasques del Mercado, Anne Freire, Megan Human, and Kevin Runge), the acoustic and trawl sampling continues to proceed as planned, with only two trawls missed due to a hydraulics failure. All data-collection systems continue to be operational and morale remains high. See Marine Mammal and Turtle Division Field Work for a summary of their operations and preliminary results.
The potential sardine habitat was optimal off the west coast of Vancouver Island (Fig. 1). Underway CTD casts along each transect confirmed satellite-sensed sea-surface temperatures in the range of 12-14.5 ºC, with surface-mixed layer depths less than 40 m.
Figure 1. Satellite-sensed potential sardine habitat (left) and sea-surface temperature (SST; right), averaged from 6 to 11 July 2018 (https://swfscdata.nmfs.noaa.gov/AST/sardineHabitat/habitat.asp). There is a filament of optimal/good potential habitat off Washington and Oregon, near the shelf break, with SST ranging from 12-14.5 ºC. Mostly, however the sardine potential habitat is south of Cape Mendocino.
Acoustic backscatter from small pelagic fishes, species in trawl catches, and eggs in the Continuous Underway Fish Egg Sampler (Fig. 2) indicate that herring are nearshore off Vancouver Island, Pacific mackerel is spawning near and beyond the western ends of the transects, and northern anchovy is south of Westport, WA.
Although the ship has extended most of the transects east into 20-m water depths, most of the backscatter from the northern sub-population of anchovy was mapped farther offshore, close to the shelf break. Continuous Underway Fish Egg Sampler data, however, indicate some anchovy are spawning close to shore. Backscatter from krill was highest in the nearshore area off the northern end of Vancouver Island, concentrated towards the south of the island near the Strait of Juan de Fuca, and in a continuous band along the shelf break.
Figure 2. The preliminary, unverified distribution of 38-kHz integrated volume backscattering coefficients (sA; m2 nmi-2), from 5 to 70-m deep and averaged over 2 km distance intervals, ascribed to coastal pelagic species (a); 120-kHz sA attributed to krill (b); Continuous Underway Fish Egg Sampler egg density (eggs m-3) for jack mackerel, anchovy, and sardine (c); and proportions of coastal pelagic species in trawl catches (d).
The acoustic sampling has also revealed the locations of methane seeps and associated biota reliant on chemosynthetic primary production, along the continental margin (Fig. 3). This aspect of the California Current Ecosystem has been recently added to the list of studies by the Advanced Survey Technologies group, included in the acoustic-trawl surveys.
Figure 3. Krill swarms (red) over the seabed (rust) and near methane seeps (blue spires), detected acoustically in 150-200 m depths, near Astoria. A layer of unidentified plankton (green) at the base of the surface mixed layer, extends off the shelf.
In an associated mission, two Saildrones (www.saildrone.com), fit with dual-frequency (38- and 200-kHz) echosounders, have surveyed ~13 transects from the north end to the middle of Vancouver Island, averaging roughly one transect per day. After mitigating noise in the 200-kHz echosounders, two other Saildrones launched from Alameda, CA to survey Lasker’s transects south of Cape Mendocino. However, one of those had to return to Alameda for repairs. A fifth Saildrone will sail from Alameda to replace the fourth while it is repaired. In mid-August, the repaired Saildrone will again launch from Alameda and will focus on sampling nearshore areas between San Francisco and Point Conception. It will then repeat CalCOFI Line 80 throughout the period of coastal pelagic species southern migration, until approximately February 2019.
July 7, 2018
The 2018 California current Ecosystem Survey, a joint Fisheries Resources Division/Marine Mammal and Turtle Division mission aboard NOAA Ship Reuben Lasker, has finished transects off West Vancouver Island and is now sampling off Washington. At the present rate of progress, transects north of the Columbia River should be completed before the end of the first 20-day leg, on July 16, when Lasker arrives to Newport, OR. The acoustic and trawl sampling has proceeded as planned, and only one day of marine mammal and seabird observations has been lost to inclement weather. All data-collection systems are operational.
The potential sardine habitat was optimal off the west coast of Vancouver Island (Fig. 1). Underway CTD casts along each transect confirmed satellite-sensed sea-surface temperatures in the range of 12-14.5 ºC, with surface-mixed layer depths ranging from 40 to 10 m.
Figure 1. Satellite-sensed potential sardine habitat (left) and sea-surface temperature (SST; right), averaged from 11 June to 4 July 2018 (https://swfscdata.nmfs.noaa.gov/AST/sardineHabitat/habitat.asp). Potential habitat off the west coast of Vancouver Island is optimal, with SST ranging from 12-14.5 ºC.
Acoustic backscatter from small pelagic fishes was mapped mostly on the eastern ends of the transects and near the Strait of Juan de Fuca (Fig. 2). Backscatter from krill was highest in the nearshore area off the northern end of the island, continuous in a band along the shelf break, and concentrated towards the south of the island where humpback whales were observed feeding.
The continuous underway fish-egg sampler found Pacific mackerel eggs on the western ends of the transects, mostly in the southwest portion of the area surveyed. Trawl catches of coastal pelagic species throughout the area were almost entirely Pacific herring. Herring catches near Strait of Juan de Fuca also included one anchovy, a sardine, and a Pacific mackerel.
Figure 2. The preliminary, unverified distribution of 38-kHz integrated volume backscattering coefficients (sA; m2 nmi-2), from 5 to 70-m deep and averaged over 2 km distance intervals, ascribed to coastal pelagic species (a); Backscatter attributed to krill (b); Continuous Underway Fish Egg Sampler egg density (eggs m-3) for jack mackerel, anchovy, and sardine (c); and proportions of CPS species in trawl clusters (d).
In an associated mission, two Saildrones (www.saildrone.com), fit with dual-frequency (38- and 200-kHz) echosounders, surveyed five transects near the north end of Vancouver Island, averaging one transect per day. After mitigating noise in the 200-kHz echosounders, two more Saildrones will soon be launched from Alameda, CA to survey Lasker’s transects farther south. A fifth Saildrone will sail from Alameda in mid-August and will focus on sampling nearshore areas between San Francisco and Point Conception.
June 29, 2018
At 1430 on Tuesday, June 26, 2018, NOAA Ship Reuben Lasker sailed from Pier 15, San Francisco, to begin the first of four 20-day legs of the 2018 California current Ecosystem Survey. The 2018 California Current Ecosystem Survey is a joint project between the Fisheries Resources Division and the Marine Mammal and Turtle Division to survey populations of coastal pelagic fish species, marine mammals, their prey, and their environment along the West Coast of the U.S. and Vancouver Island, Canada. Equipment was readied for marine mammal and seabird observations, trawl and plankton net sampling, and a variety of acoustic measurements. The ship headed west-northwest into ~ 20-kt wind and ~ 3-m swell, en route to the northwest end of Vancouver Island. West of San Francisco, schools of small pelagic fishes were observed in the sonar and echosounder displays. Sardine eggs were sampled in the Continuous Underway Fish Egg Sampler.
The MS70 stopped functioning shortly after departing San Francisco, due to a faulty programmable Ethernet switch and power strip. ET Brian Thomas installed a spare switch and the imaging sonar is functioning again. All data-collection systems are now operational.
Drills and welcome aboard presentations followed the turbulent first night. Proceeding at < 5 kts for most of Wednesday, sea-conditions improved, and Lasker fetched waters ~210 nmi off Oregon on Thursday. Lasker increased speed to ~12 kts overnight and was parallel with Newport, Oregon by midday Friday. Friday afternoon, the new Nordic 264 rope trawl was untied and crew were trained on its deployment. Trawling and transects off Vancouver Island are expected to begin late Sunday.
Throughout most of the daytime transit, Marine Mammal and Turtle Division observers were on effort. Meanwhile, the Fisheries Resources Division has been sampling around the clock with the Continuous Underway Fish Egg Sampler, EK60s, EK80s, ME70, and SX90. New software is being used to analyze data from the SX90 sonar and EK60 echosounders, to quantify behaviors of near-surface fish schools. Observations closer to shore that the ship can safely navigate will be made using Saildrone unmanned surface vehicles fit with dual-frequency (38- and 200-kHz) echosounders.