Tag: swordfish assessment survey

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Geoff Goodenow, May 20, 2004

NOAA Teacher at Sea
Geoff Goodenow
Onboard NOAA Ship Oscar Elton Sette
May 2 – 25, 2004

Mission: Swordfish Assessment Survey
Geographical Area: Hawaiian Islands
Date: May 20, 2004

Time: 1600

Lat: 19 15 N
Long: 157 06 W
Sky: Beautiful day; lots of sunshine with scattered cumulus clouds
Air temp: 26.6 C
Barometer: 1015.2
Wind: 132 degrees at 15 knots
Relative humidity: 62%
Sea temp: 26.7 C
Depth: 3116.6 m
Sea: Swells less than a meter offering up a very smooth and pleasant ride.

Science and Technology Log

Several escolar, 2 snake mackeral, 2 sharks and 2 swordfish on the line today. The sharks were both silky sharks. One was tagged and released. The same treatment was intended for the other but it broke free of the hook before we got it on board. Both swordfish were dead.

The last of the swordfish was the biggest we have seen: 185 cm plus a sword of over 60cm and weighing in at 90kg. A couple skipjack tunas were landed with troll lines.

We are staying in the same area for the longline set tonight. We didn’t even bother to check Cross seamount as things are pretty good here and we would probably have had to turn away from there out of respect for others’ presence.

In reviewing Kylie’s presentation (see personal log), Rich commented that we know what the movements of the animals are, but we don’t know so well why they make various vertical movements nor how they are able to deal with the stresses imposed by those movements. The temperature/cardiac function relationship described yesterday adds a bit to the puzzle as do studies of tolerance to oxygen reduction. I found this quite interesting and hope I can condense the story to something meaningful for you.

At depths reached by bigeye tuna oxygen levels are far lower than levels experienced by skipjack and yellowfin tunas at the depths they are normally found. Tunas characteristically have high metabolic rates which might seem impossible to maintain at low ambient oxygen levels experienced by the bigeye. Fishes tolerant of low oxygen levels are typically very sluggish, have low metabolic rates and have blood with a higher affinity for oxygen than less tolerant species. In exchange for that high oxygen affinity (a benefit at the gills), they sacrifice maximum delivery of that oxygen to their tissues; their blood just doesn’t want to let go of it.

Bigeyes then, as you would expect, have blood that grabs oxygen more readily than blood of skipjacks and yellowfin. So how are bigeyes able to remain so active when their fellow fishes with high oxygen affinities just can’t keep the pace? Recall those heat exchange units we’ve mentioned before??? Bigeyes’ blood loses much of its grasp on the vital gas as it is warmed by those heat exchange units. And remember that at the gills the blood is “cold” again. What a great system — readily grab and hold oxygen at the gills even in low ambient oxygen environments, and readily release it in the muscles. Pretty cool, I think.

To conclude, I quote from the summary section of my source as to the value of these studies. I presume that what is stated here specifically with respect to bigeye applies more broadly. “Understanding the vertical movements and depth distribution of bigeye tuna, as well as the physiological abilities/tolerances and oceanographic conditions controlling them, has been shown to be critical to improve longline catch-per-unit effort analysis and long term population assessments in the Pacific.”

Goodenow 5-20-04 oceanic white tip
Geoff with a small oceanic white tip shark

Personal Log

Following the line retrieval, I managed to get some time on the upper deck in my favorite shady spot with my book. Reading, snoozing and enjoying the view passed the afternoon along with an interruption to assist with a troll line catch. This was very nice after such a gloomy yesterday that was topped off with another late night at the movies (Pirates of the Caribbean).

Just before supper Kylie did a rehearsal of a presentation she will be making in Australia about her vision studies. Rich and Kerstin made comments and suggestions to help her polish the presentation. It was interesting to hear them address content and presentation issues much as I do with my own students.

Kerstin asked me today if it is getting tough coming up with material for the log. I suggested that indeed it is becoming more of a challenge. Perhaps out of sympathy, she called me to her lab early this evening to share with me some details related to the eye socket of a swordfish. Thanks, Kerstin, and keep ’em coming!

Questions:

Many native plants and animals of the Hawaiian Islands have suffered due to the introduction of non-native species to their environment. The green cover of the islands is very different in most places than what Polynesian settlers saw. Mongooses and ginger are two introduced species. See if you can find out how they got here, why they were introduced and specific impacts they have had on native species. (There are others for which you could do the same investigation including many in your home area).

Geoff

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Geoff Goodenow, May 11, 2004

NOAA Teacher at Sea
Geoff Goodenow
Onboard NOAA Ship Oscar Elton Sette
May 2 – 25, 2004

Mission: Swordfish Assessment Survey
Geographical Area: Hawaiian Islands
Date: May 11, 2004

Time: 1600

Lat: 18 49 N
Long: 158 03 W
Sky: A gray overcast morning with a couple of showers. Brightened through the late morning and stayed mostly(thin)overcast but enough sun to cast shadows and feel pretty intense. 90% cloud cover through most of daylight hours. Tonight the sky is star-filled — beautiful.

Air temp: 26.3 C
Barometer: 1011.9
Wind: 100 degrees at 8 knots
Relative humidity: 66.9%
Sea temp: 26.7 C
Depth: 3333 m

Sea: A bit of chop especially this morning when wind seemed stronger. There were a couple of splashes onto the deck as we brought in the line this morning. Still some whitecaps this afternoon; well settled this evening.

Salinity: 34.4 (I thought some might be wondering; it has been consistent throughout.)

Scientific and Technical Log

This morning we brought in several escolar (none scoring better than 4 as they belly flopped to the surface), a yellowfin tuna which was tagged and released, and three blue sharks (one was kept and two were returned after blood samples and a couple remoras were secured). Shark wrestling is getting to be routine. Since then we have been steaming northeast beyond Cross Seamount. At 2000 we are at Lat 19 10N and Long 157 45 W as we begin the set.

On minor correction: sharks and other big fish brought on board are hoisted by human muscle using a block and tackle (not a mechanical winch as stated previously)

Kerstin Fritsches from the University of Queensland in Brisbane, Australia is working on vision studies of the fish. Her husband, Steven Evill (often affectionately referred to as Dr. Evil) assists as do three graduate students, Rickard and Eva from Sweden, and Kylie, also from Brisbane. It is for these studies that the eyes are taken from the animals. I will attempt to explain some practical applications of their studies and give you a sense of the kinds of work being done on board. I will do this in several editions of the log — not all at once. So to start —

Fishes, depending on species may use a variety of senses to know their environment. Scent, for example, may allow them to home in on prey.   While research goes on by others to analyze other sensory structures and abilities, Kerstin’s work is about vision. The attempt is being made to find out just what these different fishes are able to see. Do they see differently and, if so, how so? The practical application for longline fisheries, a very indiscriminate practice, is to eliminate by-catch. This can help protect endangered species and make longlining more cost and time efficient by finding ways to attract only economically valued species.

The water column is visually quite a varied environment. Longer wavelengths of red light are essentially filtered out and gone within the first 50 meters below the surface while shorter wavelengths in the blue range penetrate the depths. But imagine hanging out, living, and hunting at 600 meters as some of these fish do, in daytime light levels the equivalent of a starry night at the surface. Some such as swordfish and bigeye tuna come toward the surface at night keeping their exposure to light levels constant. Imagine your life spent in light levels no greater than that of a starlit night. What adaptations do these animals have to accommodate such a lifestyle? What are different parts of the visual apparatus doing in these animals? In order to help uncover answers to these and other questions, three kinds of projects are going on here.

When a live fish of desired species comes aboard, it is first killed then its eyes are taken. Kerstin and Rickard must have living tissue from the retina for their studies. They have about 20 minutes in which to get the tissue they need into a special oxygen-rich solution in which the tissues will be good for 6-8 hours. Steven works with lenses which do tend to cloud over time, but he is able to easily accomplish his work before that happens. For Eva and Kylie there is no rush as their samples, retinas and eyes with only lenses removed, are destined to be preserved for later study at home. I’ll pick up from here tomorrow with details about specific aspects of the work on vision. In preparation you might look up what the retina and lens of the eye do.

Personal Log

I observed our hitchhiking birds in a new feeding maneuver this morning. A bunch of flying fish took to the air and were happily gliding along. Our friends took after them and approaching from the rear snatched them out of the air.

Filling in the non-fishing time gaps: Last night I interviewed Eva about her part of the vision studies and this afternoon Rickard took me through his experiments. At home in Sweden he does vision studies on insects, moths and butterflies in particular. I am also reading Adam’s Navel which I can recommend to those with an interest in human biology written in an interesting non-technical and often humorous style. And it is often nice to find some shade, a comfortable deck chair and with a beverage in hand stare across that wide, blue expanse of water.

The days pass quickly.

Goodenow 5-11-04 sunset
Sunset from NOAA Ship OSCAR ELTON SETTE.

Questions:

I am happy to report that we are eating quite well on our voyage, but that was not the case for early voyagers across the seas. At times they might have had plenty to fill their stomachs, but at the same time lack a balanced diet. Because of this, one condition the mariners suffered was scurvy. What are the symptoms/problems associated with that condition? What can be done to prevent it? See if you can find out when and how the solution to the problem was discovered.

Geoff

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Geoff Goodenow, May 10, 2004

NOAA Teacher at Sea
Geoff Goodenow
Onboard NOAA Ship Oscar Elton Sette
May 2 – 25, 2004

Mission: Swordfish Assessment Survey
Geographical Area: Hawaiian Islands
Date: May 10, 2004

Time: 1600

Lat: 18 41 N
Long: 158 19 W
Sky: Sunshine with scattered cumulus; beautiful day.
Air temp: 27.3 C
Barometer: 1010.92
Wind: 68 degrees at 8 Knots
Relative humidity: 47.9%
Sea temp: 27.1 C
Depth: 1674m (at 1800 hours, Lat 18 25N, Long 158 27W)
Sea: A few white caps tonight. What might they foretell?

Science and Technology Log

Pretty good day on the line. We tagged a yellowfin tuna (on board) and a broadbill swordfish (in the water). In the latter case, the tag was attached by sort of harpooning it into the animal from deck. We also pulled in a snakefish (head only), a big eye tuna, 2 escolar, a barracuda (of no interest so simply cut off the line) and 3 blue sharks. One was too large to safely bring aboard; it was cut loose. The two others were brought on board. From one we took blood and fin clips after which it was released. One fish was brought in by trolling today.

As you have noticed water temperature here would be quite comfortable for us (but we are not taking afternoon swims). Rich explained to me that here there is mixing of the surface layers such that the surface temps. I have been reporting would apply to a depth of about 100 meters. Then between there and 400 meters we would see about a 10 degree C drop. While some fish stay in the upper layers others hang in the depths or make regular vertical transgressions across these zones.

Fish are generally regarded as having body temperature at or very near ambient. Any heat produced in the muscles by aerobic respiration is picked up by the blood and circulated through the gills where that heat is dumped efficiently to the environment. Some saltwater fish (no freshwater ones) including tunas and some sharks have developed a kind of heat exchange system. Heat from venous blood is passed to arterial flow in order to keep certain muscles and organs above ambient temp. by as much as 20 degrees C in large fish. This allows body tissues and organs to work more efficiently.

Billfish such as swordfish also have a heat exchange system but it is located only around the eye and brain. Here certain eye muscle is reduced to little more than a container for mitochondria which generate lots of heat. The heat exchange system then only serves this region of the body keeping it above water temp. Still busy at Cross Seamount. The fishermen must be having a big time up there. We are setting at Swordfish again tonight. (Lat 18 17N Long 158 22W at finish of set)

Personal Log

Those oily escolar are not being kept for consumption. This morning we took one’s eyes and made a short incision along the belly just to take some muscle tissue In returning the escolar bodies to the sea I have scored their diving entries 1-10 as in competitive events. Most have been dropped straight in, but this morning I thought of trying something with a higher difficulty factor — a one and half back flip with tail entry. But on its first rotation, a bit of the entrails was ejected shipward striking me on the shoulder before falling to the deck. Unfortunately, this was not captured on film for replay tonight on “Funniest Ship Videos”, but for those present, it provided a good bit of humor to start the morning. Hereafter, we might just stay with the less ambitious dives. Spectators were glad it was I and not they.

Later I made my debut as a shark wrestler. As a rookie I was given the tail end. Even though the blues are comparatively tame once on board, the strength in the animal’s body was very evident as it tried to move – – not so sure I care to deal with the other end of these babies!

Goodenow 5-10-04 blue shark
TAS Geoff Goodenow and a blue shark.

Questions:

This question relates to paragraph two of the science log. What is the thermocline within a body of water? How would you expect a temperature profile to change through the seasons in a deep lake in central Pennsylvania?

Any questions from you folks???

Geoff

Posted on

Geoff Goodenow, May 9, 2004

NOAA Teacher at Sea
Geoff Goodenow
Onboard NOAA Ship Oscar Elton Sette
May 2 – 25, 2004

Mission: Swordfish Assessment Survey
Geographical Area: Hawaiian Islands
Date: May 9, 2004

Time: 1600

Lat: 18 39 N
Long: 158 17 W
Sky: A few more cumulus clouds around today (40% cover) but they didn’t seem to get in the way of the sun too often. Some thin stratus and cirrus around too.
Air temp: 26 C
Barometer: 1011.5
Wind: 120 degrees at 3.5 Knots
Relative humidity: 56 %
Sea temp: 27.1 C
Depth: 959.3 m

The sea was very,very smooth throughout the day.

Science and Technology Log

The line last night was put out at Swordfish Seamount (500 meters deep), about 35 miles south of Cross. It was a bit longer than usual. Longline retrieval began 0800 and was not complete until 1130. Both the length and our better fortune accounted for the longer effort. We brought in 7 on the line today including 4 sharks. Species included the following: 1 snakefish (Gempylus serpens – 104 cm long and about 7 cm wide with a big eye, pointy snout and lined with very sharp teeth– dead), oceanic white tipped shark (Carcharhinus longimanus) alive, 157 cm and nasty; a blue shark (Prionace glauca), alive, 132 cm and 32.5 kg, rather docile onboard, very pretty coloration — grayish belly softly blending to a blue dorsally; a big eye thresher shark (Alopias superciliosus — love that name) a bit of life in him but not much, 136 cm + tailfin, 51 kg, its curved tail fin nearly the length of his body; a silky shark (   ?   ) alive; an ono or wahoo, a dolphinfish and an escolar. I took some samples of blue shark and thresher shark teeth. A pretty exciting and busy morning. For most of these fish their fate in our hands was the same as usual.   But the real excitement was bringing on the live sharks. As they are drawn near the ship, netting held in place on a 3 foot by 6 foot rectangular metal frame is lower to the water by a winch. The fish is brought onto it and hoisted aboard. There are a few seconds of near terror as this thrashing animal hits the deck wielding danger at both ends of its body. A mattress like cover is thrown over each end and weighted down by human bodies (mine was not one of them today, but I’ll take my turn eventually; how many people do you know who have ridden a shark?).

The oceanic white and the silky were tagged with the pop ups. To do this a hole is drilled through the base of the dorsal fin. Line looped through that hole attaches the pop up to the animal. Fin clips and blood samples (if possible) are taken as are any remoras attached to the sharks. Then another moment of fear — restraints are withdrawn and animal is sent overboard as quickly as possible. Description of the satellite pop up tags: Each is about 12 inches tall. At the base is a light sensor, above that a cylindrical housing about 1 inch diameter, next a swollen area about 1.75 inch diameter (the pressure sensor) above which is an antenna about 6 inches long.   Each costs about $4000.00 including about $300 satellite time to upload data. Since a signal cannot be sent through seawater to the satellite, the units acquire and store data until a preset pop up date (8 months is about max given battery power of the unit). Then they are released automatically, pop to the surface, find a satellite and dump info to it. The system allows us to track fishes vertical movements (by pressure changes) and horizontal movements by measuring ambient light levels. The latter tells us daylength which can be used to estimate latitude to perhaps within a degree and time of dusk and dawn, which when compared to Greenwich can indicate longitude.

But what if the animal dies before the 8 months are passed? If the animal is headed to the depths, at 1200 meters pressure causes release of the pop up. If no vertical change is detected over 4 days (animal has died in shallow water), they release. Other things can happen that disable the pop ups. They might get broken or eaten by other animals. Only about i in 3 tagged swordfish and big eye thresher sharks are heard from if tagged. Those animals go surface to 600 meters often and rapidly subjecting tags to quick temperature and pressure changes that might disrupt operation of the device. In spite of the obstacles, data is gathered from about 60% of the pop up tags deployed. An alternative is small archival tags that get implanted right onto the animal. These cost only $800 and have much greater storage capacity than pop ups so can provide much more data. However, these must be recovered — the fish have to be recaught in order to get the info from the tag. That’s a tough order in this big ocean and recovery rate is indeed low. Setting longline again tonight in same area. At 2042 we are at lat 18 16 N and long 158 27 W.

Personal Log

Last night was spectacular. Brilliant stars horizon to horizon — a star show above, including the Southern Cross, that was equaled in beauty and wonder by the light show in the water. Bioluminescent organisms were ablaze off stern. It looked like the Milky Way in the water but with the stars turning on and off and swirling about in a frenzy. Some were mere points of light, sometimes things flashed as a light bulb going quickly on and off, and once in a while a ghostly basketball sized sphere tumbled through the view. It was hard to know whether to look up or down for fear of missing the next dazzling event.

And yes, there was a small crowd at the bow to admire the moonrise at about 2345. The ship as always held its position near the longline set. As such we are sort of at the mercy of the sea, just rocking and rolling as it moves beneath us. It is to me a very pleasant motion, one that just rocks you gently to sleep. I have never been on a cruise ship, but friends who have tell me there is no (or little) sense of motion to the ship. Perhaps this is comforting to some, but I like the total experience (within reasonable limits, of course) and these last two nights have been perfect in all respects. I am handing off my duties as brake and bait man to others this evening so that I might digest and organize some of the info passed to me by Kerstin and others in the last couple days.

Questions:

Here are a couple relating to ocean currents. Look at a chart that shows ocean currents along the US east coast (southern and mid-Atlantic states) and for the US west coast (Washington to California). What is the general direction of the flow along each coast? Along which coast, especially in summer, would you expect ocean water to be warmer? Why?

I have given you daily temperature readings for the sea water here at about 18 degrees north. The Galapagos Islands straddle the equator far to the east of here off the west coast of South America. You would most likely expect the water there to be warmer on average than around the Hawaiian Islands. Is it? If not, what accounts for the difference?

Happy Mother’s Day,

Geoff