Northwest Fisheries Science Center

The Main Deck

Acoustic and trawl adventures in the Northeast Pacific

Blog Entries for January 2016

Measuring hake

By Sandy Parker-Stetter
Posted on January 31, 2016


Hake on the electronic measuring board.  Photo credit Sandy Parker-Stetter (NWFSC)

After a midwater trawl catch comes on board, the hake are divided into males and females and measured for length (from snout to tail). Our wet lab team uses electronic measuring boards that are interfaced with a computer program – no paper for us. The computer program tracks every measurement, weight, and sample (like stomach content, otolith bone, or genetic collections) that is taken from an individual fish, and even has a bar-code reader for scanning labels on bags or vials! This crazy efficient system allows us to link all the attributes of an individual fish. Alicia Billings, on the NWFSC-FRAM Fisheries Engineering and Acoustic Technologies team, is constantly fine-tuning and developing this system to be easier to use, faster, and even more powerful. Thanks, Alicia!

A range of hake sizes caught in the trawl.  Scissors and quarter for scale.  Photo credit Sandy Parker-Stetter (NWFSC).  Fish styling by Allen Shimada (OST).

Every trawl contains a range of fish sizes, but the average and the largest/smallest lengths can be very useful. We’re interested in knowing if there are length differences within an aggregation (large on one side, small on the other?) or if there are length differences across aggregations (large fish in one aggregation, small in another?). 

We’ve had a few opportunities to sample an aggregation more than once. We’ve been a bit surprised at how consistent lengths have been from trawl to trawl, making us think that hake of different sizes may mix within a single aggregation. 

We’ve also had the opportunity to sample multiple aggregations spaced along the coast.  Again, the mixing of sizes has been a bit unexpected.  We’re now down in the Southern California Bight, so our sampling (and comparisons of lengths) continues.


Tagged: Winter hake survey

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Are they spawning?

By Sandy Parker-Stetter
Posted on January 30, 2016


Early on, we referred to this survey as the “Spawning Hake Survey” and said we were looking for spawning hake. Over time, we shifted to calling it the “Winter Hake Survey” and talked about looking for adult hake. Let’s talk about hake biology and what it means for the survey, and its name.

In the summer, Pacific hake are spread between southern California and Alaska or British Columbia. In the fall, they move southward and aggregate for spawning. Where they go, the size of the spawning area, and the size(s) of the aggregation(s) are not well understood. 

Over the fall and early-winter, the gonads of male and female adult Pacific hake (those that are older than age-2) develop gradually. After some time, their gonads are fully developed and the fish are ready to spawn. How long they can stay ready-to-spawn isn’t known. At some point, the hake release their sperm and eggs into the water and they are, technically speaking, spawning at that time. How this timing works, and how long spawning lasts, isn’t clear.

Saying that we’re looking for “spawning hake” sounds like we’re hoping to catch them in the act of releasing eggs and sperm. If we step back to the original survey goals, we’re not specifically interested in the act of spawning itself, although biologically that’s the important part. 

Instead, we’re more interested in finding the winter aggregations of adults regardless of whether they are preparing to spawn, are spawning, or have recently spawned. We want to know if they are all found in one giant aggregation, if males and females are in the same aggregation, and whether spawning occurs in a smaller geographic area than in summer. Shifting our language to say that we’re looking for adult hake during their spawning period is more consistent with what we’re trying to learn.

To tie this back to the survey and what we’ve found so far – we have found hake with developing gonads (pre-spawn) and some that are fully developed and ready-to-spawn. We have not yet caught any aggregations in the act of spawning, or found any fish that have already spawned (spent or post-spawn).  The search continues.

Female hake who isn’t ready to spawn.  Photo credit Pete Frey (NWFSC)

Female hake who is ready to spawn.  Photo credit Sandy Parker-Stetter (NWFSC)

Male hake who is ready to spawn.  Photo credit: Sandy Parker-Stetter (NWFSC)

Tagged: Winter hake survey

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Day versus night

By Sandy Parker-Stetter
Posted on January 29, 2016


A few of our original winter survey questions focused on Pacific hake “aggregations” (referring to a group of fish that aren’t necessarily behaving/swimming in an organized way as they do in a “school”) and what they do at night. We wondered if they stayed at the same depths during day and night. Further, if they did move up/down, we wondered if it was just males, just females, or both. We wonder about a lot of things.

Wondering aside, we are conducting 24-hour operations so have had lots of chances to see what hake do in the darkness and in the daylight. 

We see the adult hake on the acoustic displays both day and night, but the aggregations change. On the echogram, you can see that during the day the adults are in a tight layer down deep. During the night, they are much more spread out, but still identifiable, in shallower water. This is different than during the summer when the hake are very dispersed, and difficult to identify, at night. During the dusk period, the hake move up. During the dawn period, the hake move down. 

Acoustic echogram showing adult hake deep in the water during the day (left) and much shallower at night (right).  Image credit NWFSC-FRAM-FEAT

The dawn/dusk movement takes place over several hours, but the layer stays intact. The compound echogram shows the hake shallow at night (where we fished them), their migration back down at dawn, and the hake down deep during day (where we again fished them). You can also see the layer being disrupted by a piece of equipment that was lowered down to 500 m. Our trawls suggest that both males and females are doing this day/night migration.

Compound echogram showing the hake layer (in white) at night, moving down, and then during day.  Note that when we lowered a temperature sensor in the water, the layer was disrupted and briefly disappeared!  Image credit Sandy Parker-Stetter (NWFSC)

Tagged: Winter hake survey

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Winter Hake Leg 2

By Sandy Parker-Stetter
Posted on January 27, 2016


Leg 2 of the winter hake survey left beautiful San Francisco on January 26.  We’ll pick up the survey where leg 1 left off, just north of Monterey Bay, CA, and continue to work our way south toward San Diego.  Reports from our colleagues on the NOAA Ship Rueben Lasker suggest that the hake may be more mature, and some may even be spawning, in the survey area where we’ll be next working.

Sailing board for the Shimada with our 26 January sailing!  Photo credit Rebecca Thomas (NWFSC)

 

Going under the Golden Gate Bridge.  Photo credit Sandy Parker-Stetter (NWFSC)

We’re fortunate to have another superstar science party on board. The Acoustics Lab (aka Mission Control) is staffed by Rebecca Thomas (Acoustic Phenom), Steve de Blois (Field Party Chief), Sandy Parker-Stetter (Chief Scientist), and Lucy the Lucky (a stuffed duck who is secretly in charge of this whole operation, sent to sea by Rebecca’s daughters). The Wet Lab will continue to run like a well-oiled machine under the care of Doug Draper (Lead Biologist, day), Tom Holland (Lead Biologist, night), Allen Shimada, Mike Gallagher, Carlos Godinez-Perez, and Jenni Hood. In the Chem Lab, Anthony Odell (University of Washington) and Ben Simpson (Highline College) will again work their magic in sampling for harmful Algal Blooms (HABs), phytoplankton, and bacteria. 

Weather looks good for next few days and we’re looking forward to seeing whether the hake have started to spawn in southern CA. The science party on leg 1 left with lots of interesting biological questions (Why are hake found at these locations? Is temperature a factor in how close they are to spawning condition? Will we find larger fish in southern CA?) and on leg 2 we’ll gather more information to help generate some answers.


Tagged: Winter hake survey

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Highlights from Leg 1

By Sandy Parker-Stetter, et al
Posted on January 23, 2016


We are at the end of leg 1 of the winter hake survey and got a lot accomplished. We found adult hake, and we found juvenile hake. We caught midshipmen. We ate a lot of ice cream, and drank a lot of coffee. We calibrated. We collected >2,300 nmi of acoustic data. We did 18 zooplankton tows. We changed the design 4 times. We are ending on a high note!

I asked each of the science party members to share a highlight (or a few) from leg 1.

Aaron – I have taken an interest in what appears to be a diet and maturity relationship in the hake we've caught so far. Most of the immature hake we've sampled have had food in their stomachs, while nearly all mature hake have had nothing, signaling a possible relationship between digestion and spawning.

Working in the wet lab (Photo credit Anthony Odell, UW)

Anthony – Finding a dinoflagellate whose known distribution is “tropical to warm temperate” off of southern Oregon in early January. El Nino? Or random mini-gyre spun amuck? Finding out what it’s like to be to be a human pinball/cosmonaut in training in a boat that is known to “roll a bit” in 20+ ft. seas. It’s all about “no hands for me, two for the boat” and “controlled falling.”

Ben – The highlight of the first leg for me, besides the thrill of doing something new, was Cliff’s cooking. That, and his help getting me on a protein shake (3 eggs, milk, ice cream) and peanut butter regimen after he found out I was trying to gain as much weight as possible from all the free food on this cruise.

Cassandra – Seeing whale blows during marine mammal watch from the flying bridge on a beautiful sunshine-y afternoon off of Trinidad Head. Hake 'enhanced samples' - the most sampled fish ever. Best boat food ever - thanks Cliff! Weird little clear, spiny, gummy bear sized critters from zooplankton sample. Measuring swim bladders on plainfin midshipman. Being the first to use the Shimada's new sorting belt setup - great design Alicia! Seal pup cavorting next to the boat during calibration attempt.

Pete extracting otoliths (bones used for ageing) from hake (Photo credit Anthony Odell, UW)

Chu – Before the survey, if people were asking me about the spawning hake distribution, I would have said I had no idea about it. Now I have learned a lot about it although the observations may not be conclusive. In addition, working with people from so many different groups is such a pleasurable experience.

Kayleigh – This has been my first time out on a NOAA “White Boat,” and I've really enjoyed seeing how the boat crew and scientists work together as one big team to complete our mission at sea. My other highlight was when we saw a pod of 3 or 4 humpback whales, who spouted and fluked before diving deep and out of our sight!

Nick – Sorting hake at 2:00 am and finishing in time for the 3:00 ice cream break. Trying to decide the correct plural for plainfin midshipman... mans... men…?

Pete – My favorite thing about this cruise has been the straightforward investigative approach to answering a really important question. Hey, where do you think adult hake go in the wintertime to have their babies? Let's go find out! Nice to participate in well-designed and executed research that will almost immediately add to our knowledge of this valuable stock.

Sandy – My favorite moment of leg 1 was seeing the first trawl on deck and realizing that we had actually caught adult hake! I came into this survey saying that we’d be successful if we caught adult hake even once (but secretly hoping it would be more than once). Seeing those adult hake on the second day of the survey was shocking, in a good way.

Steve – Adapting to a new regime of nighttime trawling and filling out “net configuration” forms on a darkened bridge with only the illumination of a red headlamp (and perhaps a realization that stronger reading glasses would be appreciated…).

Victor – I would say that the highlight for me was watching everyone work together. From the most basic part of being a floating island, to the highly evolved technological wonder that is the Shimada and her crew. The scientists working together with the crew to answer questions about our oceans, using technology's both sophisticated and blunt. The combined experience of everyone involved and how we made it all look so easy. There is a place for everyone here and everyone has a job and a place. 

On the flying bridge of the Shimada (Photo credit Anthony Odell, UW)

Tagged: Winter hake survey

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Calibration

By Sandy Parker-Stetter
Posted on January 23, 2016


Today we calibrated our acoustic echosounders in beautiful Monterey Bay, CA. Compared to our previous attempt, which involved 30 knot winds and 10’ combined seas (5’ swell + 5’ wind waves), conditions today were perfect. Winds <3 knots, 1’ seas, sunshine, and 200+ common dolphins (Delphinus delphis) that swam around us feeding on a large school of fish that passed under us. Perfect!

A calibration sphere (Photo credit Sandy Parker-Stetter)

A precision-machined 38.1 mm tungsten carbide sphere, which reflects a known amount of acoustic energy, is used to calibrate the echosounders. Three downriggers—two on the starboard side and one on the port side—are mounted onto the Shimada’s railing. Each downrigger lets out a very thin line, and the three lines are attached together at a swivel below the Shimada.  The sphere is then suspended below the swivel, and—with skill and some good luck—below the echosounders as well. We can control the location of the sphere in the acoustic beam by having Chu’s computer program instruct each downrigger to let out, or take in, line.

After the sphere has been moved around the acoustic beam, we analyze the data to see if we have to adjust settings based on the calibration results. Calibrations of the Shimada echosounders are done several times a year to ensure that systems are running correctly and that we have high quality data for our analyses. Today’s calibration was the first of the year for the Shimada and it was a success. Mission accomplished.

Sandy


Tagged: Winter hake survey

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Always learning

By Sandy Parker-Stetter
Posted on January 21, 2016


The wet lab and acoustic science party members have over 150 combined years of fisheries experience.  People have studied a range of species, in an array of ecosystems, using most available types of scientific equipment.  This is a crazy amount and diversity of experience to have on board.

Even though the group has a lot of experience, it still happens that we make a prediction about something and the result is a bit different than we expected.  Sometimes we’re in the ballpark, like thinking we’ll catch adult hake but finding juveniles.  But other times our predictions miss the mark.  Below are a few examples of how we continue to learn, and sometimes be surprised.

(1) We saw an acoustic pattern that we thought could be juvenile hake mixed with other species.  We put in the midwater trawl, watched fish go into the net on the sonar, and hauled it back on board. 

Prediction: Juvenile hake with squid

Actual: Plainfin midshipmen and squid

Explanation: On the acoustic echograms, squid and juvenile hake can be similar.  The midshipmen were a surprise!

A basket of plainfin midshipmen. Photo credit Sandy Parker-Stetter.

(2) The midwater trawl was set on another aggregation.  We watched the sonar during fishing, seeing hake go into the net and noting that the net was not fishing near the bottom (we always watch for this).

Prediction: Juvenile hake

Actual: Juvenile hake plus 24 other species, including flatfish and rockfish (that live on/near bottom)

Explanation:  If we fish near the bottom, even if we don’t touch the bottom, the large weights and disturbance from the trawl can spook on-bottom species up and into our net!

A 38 kHz echogram showing a track (red line is the top of the net) for a midwater trawl that was not on the bottom, but contained many common bottom species. Image credit NWFSC/FRAM/FEAT.

Tagged: Winter hake survey

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Watching while we fish

By Sandy Parker-Stetter
Posted on January 20, 2016


Cartoon image of a midwater trawl catching fish (Source: https://teacheratsea.files.wordpress.com/2012/08/trawl-net.jpg)

An important part of the winter survey sampling is our ability to verify that fish we see on the echograms are indeed Pacific hake. We do this using a “midwater trawl,” a large fishing net that the Shimada pulls through the water. Using a sonar system, we’re able to monitor how deep the net is below the surface and get a sense of whether a lot, or very few, fish are going in. We’re interested in the latter because we want a sample that is just large enough to collect the information we need.

Image from sonar used to monitor the net during fishing, showing the opening of the net and the sneaky fish below us! (Photo credit: Phil Manougian)

Before the midwater trawl reaches our “target depth,” it filters a lot of water, potentially catching other fish or invertebrates (like squid or jellyfish) on the way down.Critters can also be caught as the net is hauled back up to the ship. To give us a way to tell whether something unusual was caught in with our hake, or whether it came into the net on the way up or down, we strap a camera inside a waterproof housing and light system onto the net. Although we can’t see the video in real-time, we can replay it once the trawl is back on board.

A King-of-the-salmon caught during summer 2015 (Photo credit Sandy Parker-Stetter)

During a recent trawl, we caught a “King-of-the-salmon” (Trachipterus altivelis, http://www.fishbase.org/summary/3264). These “ribbonfish” can be found as deep as 900 m! Fish of the size in the photo can eat krill, squid, and small fishes – which might explain why we catch them deep down in the acoustic layer that contains small lanternfish.Watching the King-of-the-salmon swim in this video provides a rare glimpse of this fish in action.

Sandy

 

 

 

 

Video credit NWFSC/FRAM/FEAT

Tagged: Winter hake survey

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The NOAA Ship Bell M. Shimada

By Ensign Phil Manougian, Sandy Parker-Stetter
Posted on January 19, 2016


The NOAA Ship Bell M. Shimada is a world-class research vessel.  I asked Ensign Phil Manougian to tell us a bit about what makes the Shimada such a great ship to use for scientific work.

Fun NOAA Ship Bell M. Shimada facts!

The Bell M. Shimada is a Fisheries Survey Vessel (FSV) - a highly specialized, technically advanced research vessel used for investigating fisheries biomass, collecting data on ocean currents, buoy operations, Remotely Operated Vehicle operations, and other acoustic surveys.  We typically sail in the Pacific waters between San Diego, CA to the southern regions of Alaska.  General info on Shimada can be found here!

But what about some unique facts about the ship?  It’s 208.6 feet long, yes, but what makes it such a good ship for surveys like the winter hake survey?  What’s so special about its propeller?  Let me tell you!

Looking up the exhaust stack on the Shimada.  Note the spring in the lower left that attach the stack to the metal bracing (Photo credit Phil Manougian)

Bell M. Shimada is a very quiet ship.  Quieter than most ships that transport cargo, carry passengers, and fish commercially.  This is a requirement because Shimada has very specialized advanced acoustic sonar sensors affixed to the bottom of the ship which are constantly mapping the water below the ship at various frequencies.  If the ship made too much noise from loud machinery, pipe vibrations, or propeller cavitation, the acoustic images returned from the sonar would be full of “noise” (errors in picture or data that reduce the quality).  To help make the ship quiet, Shimada has rubber vibration dampeners on almost every item onboard that vibrates, rattles, or is generally loud while operating.  This greatly reduces the noise that reaches the hull of the ship, potentially ruining good data.  The propeller onboard is a very big, precisely engineered, acoustically quiet propeller.  It is so advanced in its design that exact specifications are classified and pictures aren’t even available to the public!

Ensign Phil Manougian

 

Rubber vibration dampeners (Photo credit Phil Manougian)


Tagged: Winter hake survey

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First time on a NOAA ship

By Ben Simpson, Sandy Parker-Stetter
Posted on January 18, 2016


Being at sea aboard the NOAA Ship Bell M. Shimada is an incredible experience for a seasoned scientist, but what is it like for someone out for the first time? Ben Simpson, a sophomore at Highline College in WA, was recruited by Dr Vera Trainer (NWFSC) to assist with Harmful Algal Bloom (HABs) sampling. I asked Ben about his experiences and first impressions. (Sandy)

First time at sea, in winter, aboard a research vessel

Chemistry lab on the NOAA Ship Bell M. Shimada, where the HABs sampling is done (Photo credit Anthony Odell, University of Washington)
 

When asked to describe my at-sea experience so far, several words came to mind: exhilarating, engrossing, inspiring, rewarding, validating (in reference to my studies as a Biology major, where my research experience internship is studying the domoic acid/Pseudo-nitzschia system). The chance to take a break from classes to work on a project relevant to my studies is one that not many people have so early in their schooling.

Sampling HABs down the West Coast, under the guidance of Anthony Odell (University of Washington), is my first real experience with large scale data collection. In a short seven days, I have had invaluable practice multitasking efficiently, managing changing conditions/circumstances, as well as working with a crew of intelligent and driven scientists, experience that will undoubtedly serve me well in my goals of medical school and becoming a physician.

The chemistry lab I am working in is a dream setup. I have spent the last week of night shift (1800 to 0600) listening to music and filtering water to acquire data on the residual effects of the largest harmful algal bloom we've seen in decades (during an El Niño year no less!). Small hiccups in the filtration rig have cultivated my inner MacGyver. The Shimada’s Survey Technicians are always on the ball ensuring our equipment is working at peak capacity, and their CTD piloting has been crucial to the sampling process.

I overestimated my sea legs on day 2, thinking that I no longer needed the seasickness patch I had been wearing. Unfortunately, this was a few hours prior to our night of 70 knot winds and >25’ swells – but fortunately, my body equilibrated after only one rough night, and I can honestly say I have enjoyed bouncing around on our journey to San Francisco since then. When things have slowed down, it has been great hanging out with the nighttime wet lab crew (Pete, Aaron and Nick), and I’ve gotten a couple good tours of the bridge from the junior officers Phil and Niki.

I hope that this is not the last survey I find myself aboard. If things keep going this way, I might have to reconsider med school!

Ben Simpson


Tagged: Winter hake survey

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Adapting the design

By Victor Simon, Sandy Parker-Stetter
Posted on January 16, 2016


The modified survey design, showing the Simon Extension (Photo credit Sandy Parker-Stetter)

If you’ve been watching our location using the link on the left (“Track the NOAA Ship Bell Shimada”), you may have seen us deviating from the original survey design. We knew from the start that our design would be “adaptive,” meaning that we’d make changes on the fly if we had biological or weather-related reason to do so. From the attached figure you can see that we shortened a long offshore diagonal due to weather but, more interestingly, added a series of zig-zag transects over the Mendocino. Victor Simon from the Northwest Fisheries Science Center made the suggestion to spend more time surveying the Mendocino Ridge area (note: we named the new section of transect the “Simon Extension”), so I’ll let him explain the rationale – take it away, Victor!  (Sandy)

 

Why the Mendocino Ridge?

When I saw the survey design for the winter hake survey, I immediately thought that the Mendocino Ridge/Gorda Escarpment would be an interesting area to survey if time permitted. The Mendocino Ridge is formed by three merging tectonic plates (Gorda, Pacific, and North American Plates) which form a south facing ridge that is 1000’s of meters high. This incredible topography, coupled with winter currents that run south to north, creates a region with high nutrient concentrations, which can in turn result in a great deal of food for newly hatched fish like Pacific hake. My 17 years’ experience with the West Coast Groundfish Survey has fueled my fascination with this geological area and the role it plays in the California Current Ecosystem. I asked myself, “What would I do if I was a hake?” and, knowing how unique and food-rich the Mendocino Ridge area can be, I realized this is definitely a place where the winter survey would be likely to find “us”.

Victor Simon

The Mendocino Ridge is formed by the junction of three tectonic plates and is an area of high ecological value (source: NOAA Ocean Explorer)


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Last years young hake

By Sandy Parker-Stetter
Posted on January 15, 2016


Fish are often referred to by their “age” relative to when they hatched.  An age-0 fish has not yet reached its 1st birthday (hatchday?), an age-1 fish hasn’t yet reached its 2nd birthday, and so on.  For Pacific hake, age-1 and age-2 fish are considered to be “juveniles.”  Even though the age-1s and age-2s aren’t spawning yet, and aren’t the target of this survey, knowing where juveniles are is still important information if we ultimately want to count fish.

During summer 2015, many people remarked on the high number of age-1 hake.  While planning the winter 2016 survey, we wondered where we would find those age-1s, who would now be (almost) age-2s.  There are many hypotheses on where juveniles hang out during winter, but no one really knows.  Would they be found with the spawning adults or somewhere else?

Newsflash!  We have now picked up the (almost) age-2 juveniles in four midwater trawls.  They have been in diffuse layers, strong schools, and somewhere in between.  At least once we were sure that they would be the spawning adults we’re looking for, but were not!  Because the schools can be quite small catching them has been tricky, but the fishing crew is doing a great job in spite of the wind, waves, and rain.  In the catches we’re also seeing a handful of other fish species, such as rockfish, and some squid.

Sandy

Age-2 juvenile hake (Photo credit Sandy Parker-Stetter)

Tagged: Winter hake survey

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What's the weather like?

By Sandy Parker-Stetter
Posted on January 13, 2016


Full disclosure - we came out to sea in January knowing that the weather and sea state could be bad.  We knew.  We were right.

On January 12 we had wind gusts that reached 70 knots (that’s faster than you drive on some highways), seas of 25’ (a 2.5 story building), and it rained (hard). The consensus was that we were at a Beaufort sea state of 9. Cool. This video is a view out of a porthole that is 8-10' above water, except when it's hit by one of the waves I just mentioned!

Video credit Sandy Parker-Stetter

These seas make it difficult to move around – the mantra of “a hand for you and one for the ship” applies more than ever, and sometimes it’s easier to slide along the side of a passageway rather than try to walk down the middle.  With this kind of sea state, all objects are in motion – imagine the galley staff trying to prepare and serve food in this.  Imagine us trying to eat!  Even every-day common tasks (such as standing by a sink and brushing your teeth) become quite challenging and sometimes require wedging yourself into a corner.

We take comfort seeing the twitter feed from our colleagues on the NOAA Ship Reuben Lasker, who are offshore of San Diego doing the CalCOFI survey.  They are reporting “conditions calm sunny” and we’re heading that direction.

Sandy


Tagged: Winter hake survey

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Hake!

By Sandy Parker-Stetter
Posted on January 13, 2016


Two days into the winter hake survey and we found our first adult Pacific hake.  We were ~75 miles offshore, near Coos Bay, OR, when we noticed a new pattern on the acoustics.  We fished the aggregation using our midwater trawl and confirmed that it was hake.  Score!  These hake were found over 3,000 m bottom depth, much further offshore than we see them during our usual summer surveys.  The catch was 99.1% hake, so a very clean catch.

We used the acoustics to identify the hake we fished.  Our systems are like high-tech versions of fish finders.  The acoustic “echogram,” shown below for our 38 kHz unit (we have 18, 38, 70, 120, and 200 kHz), gives us many pieces of information:

  1. How deep fish or invertebrates (referred to as “targets”) are in the water below us (these hake were at 375-400 m)
  2. How long the aggregation is (this aggregation was >6 nmi long)
  3. A sense of how many are there using color, where grey is a weak return and red is a strong return (the hake were much stronger than the small fish above them)

Photo credit Sandy Parker-Stetter

Using the echograms, we can decide if we think these are hake, if we think there are enough to catch with the trawl, and where we need to put the midwater trawl to catch them.  For this survey, the most important job in the acoustics lab is to watch the acoustic echograms to identify targets for fishing – and hopefully we’ll see more aggregations like this and find more hake!

Sandy


Tagged: Winter hake survey

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Placing our bets

By Sandy Parker-Stetter
Posted on January 13, 2016


Colored magnets show guesses of where we will find our first hake – note that the guesses span from latitudes 32° to 43°23’, but most people think we’ll see hake before we hit San Francisco. (Photo credir Sandy Parker-Stetter)

 

The second most common question I am asked about the survey is, “Where will you find hake?”  This is a great question, but we really don’t know the answer!

When we were designing the 2016 winter hake survey, we had little information to work with.  The adults could be in southern CA as is conventionally thought, or they could be further north as other observations suggest, particularly since this is a strong El Niño year.  We’re really not sure when we’ll first encounter spawning hake, but the science party and ship’s crew are placing their guesses on the large survey map in the acoustic lab.  Some say we’ll see them soon and others say it will be later in the survey down south.  My guess is the orange mark just west of Eureka, CA.

Sandy


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Why winter?

By Sandy Parker-Stetter
Posted on January 13, 2016


When telling people about this survey, I am most often asked the question, “Why would you want to be at sea during the winter?!” Sure, the weather isn’t the best - but winter is when Pacific hake spawn, and our goal is to learn more about what hake are doing in the winter when they think no one is watching.

We know a lot about what Pacific hake do during the summer (in this picture, hanging out with red tuna crabs), but what do they do in the winter? (Photo credit Sandy Parker-Stetter)

Hake are considered to be a 'migratory' species, which means that the adults spawn in winter in a different location than they feed in the summer. The current Pacific hake survey, that estimates the population size, occurs during summer when hake are spread from southern CA northward to BC or AK. The survey takes 110 days aboard 2 research vessels and involves dozens of scientists and crew.

Unlike the extensive summer surveys, some migratory species are surveyed during the winter, when they are spawning when the adults are expected to be in a smaller geographic area. This way, it takes fewer ship days to estimate the number of fish. Unfortunately, so little is known about Pacific hake during their spawning season that we don’t even know if a winter survey is feasible. That’s why we’re at sea this winter - to collect data that will help us to determine if a winter survey might be a better option compared to the existing summer surveys.

During this winter survey, we’ll determine: whether spawning hake are really in a smaller geographic area; whether we can predict where they are based on environmental conditions; whether males and females are found in the same location, and whether we find the immature fish nearby. Observations and data collected that allow us to understand even a few of these questions will make this survey a success!


Tagged: Winter hake survey

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The winter hake survey begins

By Sandy Parker-Stetter
Posted on January 12, 2016


On January 9 we left the dock aboard the NOAA Ship Bell M Shimada to start leg 1 of the winter hake spawning survey.  Scientific equipment and personal gear were all tied down before we left.  We knew that, once we crossed “the bar” (the point where the shallow waters of Yaquina Bay meet the deep waters of the Pacific Ocean),  that we would encounter large swells and everything that wasn’t secured would be in motion.  We were right, but fortunately we did a good job of tying everything down!

We have a great scientific party for leg 1 of the survey - the Acoustics Lab and survey epicenter are staffed by Sandy Parker-Stetter (Chief Scientist), Steve de Blois (Field Party Chief) and Dezhang Chu (Acoustic Wizard) of the NWFSC.  The Wet Lab is under the all-star control of Victor Simon (Lead Biologist, day), Pete Frey (Lead Biologist, night), Cassandra Donovan, Kayleigh Somers, Aaron Chappell, and Nick Tolimieri, all of NWFSC.  The Chem Lab is in full-swing with Anthony Odell (UW) and Ben Simpson (Highline College) doing Harmful Algal Bloom (HABs), phytoplankton, and bacterial sampling.

We’ve just started our acoustic, zooplankton, oceanographic, and HABs sampling off Newport and we’ll use upcoming posts to discuss the survey goals, our sampling, and what we’re seeing.  Stay tuned. 

Sandy

The science party for leg 1 of the winter hake survey aboard the NOAA Ship Bell M Shimada. (Photo credit Lawrence Hufnagle, NOAA, NWFSC, FRAM)

Tagged: Winter hake survey

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Follow us on the winter hake survey!

By Sandy Parker-Stetter
Posted on January 8, 2016


Our home for the next month- the 209’ NOAA Ship Bell M Shimada.

Little is known about what hake do during the winter, so the NWFSC Fisheries Engineering & Acoustic Technologies (FEAT) team will be conducting a first time winter survey of spawning hake.  We’ll be aboard the 209’ NOAA Ship Bell M Shimada from 9 Jan to 9 Feb.

Since this is a research survey, we don’t know when or where we’ll find hake, but we have a base design to work with (see map below).  Follow us as we sample between Newport, OR and San Diego, CA.

 

Our focal species, the hake (Merluccius productus).

 

 

 

 

Check back for posts on why we’re doing this survey, how this exploratory approach works, interesting findings, and posts on what life at sea is like!

Map of our study area showing the transect lines (black lines)
we'll be sampling over the next month. (Photo credit Sandy Parker-Stetter)

Tagged: Winter hake survey

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See more blog entries:

July 2017
June 2017
February 2017
January 2017
February 2016
January 2016