NPR/NGS Radio Expeditions
11 Feb 1997
- Monterey; Monterey Bay Aquarium
- 36.61825 -121.90148
Stereo=1; Decoded MS stereo
NPR/NGS RADIO EXPEDITIONS
Barbara Block -in CA -Monterey Bay Aquarium
Feb. 11, 1997
BB = Barbara Block
CF = Charles A. Farwell
AC = Alex Chadwick
G 00:46-2:14 -ambi kids @ monterey aquarium, music in bg
2:44 BB -what is neat what is going on is that the tuna here are patrolling waiting for the first bite of food to come in and once they finish feeding -what you are going to see is we are going to drop in the water column to the bottom of the tank and what is going to happen -and what's going to happen is that one the food hits the water they are going to establish the normal pattern that we think they feed in nature with -and then watch them come up -(AC -here they are) there they go. and they are going to come up from the bottom from the depths (?) (AC -they are dropping in what? squid?) they are dropping in squid -lots of squid (AC -ah!)
3:18 AC -tell me what the fish are doing -what the tuna are doing ¬
BB -what the tuna are doing is coming up from almost the bottom of the tank to head up and hit the squid from below. so what they do is silhouette the squid with a light at the top of the tank. they are actually coming up as they feed in nature -from deeper in the tank and then coming up towards the squid. so watch a large tuna. get your eyes on a large tuna. now what they are doing is coming down and then coming back up -and it is sort of hard to see. and almost all of the approaches to the squid are coming from below and then up at the squid.
AC -there they go
G 3:55-4:14 ambi -kids watching with music in bg
4:16 AC -they are amazingly fast (BB: they are) for big animals
BB -they are -they are actually quite deep in the tank now ¬
let's see if they come up now -there is a lot of food on the surface -there you go -there are some large tunas on the surface. ok. they leave their pectoral fins out and they are actually flying through the water like airplanes getting lift from the pectoral fins. and despite their large size and bulk they are very maneuverable. now you are getting a beautiful view. this is not any different from perhaps what you would see
in nature. coming out of the murky depths and picking off the squid 4:52
4:53-5:00 ambi bed
5:01 AC -do they like to feed near the surface like this?
BB -well actually this particular species of yellow fin tuna ¬what we have noticed in the wild is that they like to be down at depths and then come up quickly to the surface and then go back down again. think of them as being a bit skittish of the surface. and if you watch in here, even in the tank you've got that phenomenon happening. you don't see yellow fin tuna right at the surface. what you have are the big yellow fin tunas down lower in the tank in about 6 to 10 feet and then coming back up to get the squid...and so for the public what you get is a real view of how this system works in the open ocean. you've got mixed groups -bonitos (?) and tunas, barracuda along with the sea turtles and molas and the interactions here at a feeding frenzy are probably similar to what one might see in the open ocean. 5:50
G 5:51-6:06 ambi -kids, music in bg -esp. good bc child saying FISH, look at the FISH (I think -a bit faint)
6:07 BB-the goal here at the aquarium this spectacular view ¬this window onto the open ocean (good bc of the music in bg) to get an idea at what these animals are doing so that we have an appreciation for the organism that is distinct from its view in a can.
6:26 AC -i have been to the Boston aquarium for instance, and others, but i have never seen tuna at an aquarium.
BB -in japan there are tuna in an aquarium. in north america this is the first exhibit that features tuna in a large venue such as this. we are going to have a curator -the original person who built this come down and talk to you so that you can get his impression on what it takes to build a container for tunas. 6:57
6:58-7:01 ambi -kids, etc
7:02 BB -so the hard part is that these are athletes and basically the open ocean is their realm (woman talking in bg ¬distracting) and to be contained in a million gallon tank is part of the challenge of keeping tuna. so it is a combination of diet...open ocean is an environment without lots of particles in the water -there's not a lot of food out there so they need extremely clear water and that clarity is due to the lack of organisms in the water and the aquarium has built that in their filter system here. 7:47 now what the tunas have done that is pretty phenomenal is that they drop almost behaviorly right after the feeding again what i think for this particular species, the yellow fin tuna, it is a lot like what they do in the wild, they are not surface tunas, they like to be down above right where the warm water changes to cold, called thermacline....the yellow fin tuna is sustaining most of the fishing pressures in the oceans. it is a warm water tuna, it's strategy is to take the high metabolism and endothermy, the warm bloodiness of tunas go back to tropical environs and be very efficient at catching food and reproducing. and it is that high reproduction rate the allows fisherman to catch millions of metric tons of this particular species. the 2 species that we have on display, the skipjack and the yellowfin are both the species that sustain the largest pressure but bc of their evolutionary strategies they are able to handle that by putting out lots of young. it is the cold tempered species such as the blue fin, the albacore that are more susceptible to overfishing in part bc of their strategy of how it is they go back to individual spawning grounds. 9:08
9:09 AC -is it possible ........
BB -.... it is yellow fin that we think of when we think of the porpoise dolphin issue....what species of tuna you catch is very much dictated by what you are after -the particular market you are trying to supply. canned tuna is traditional skip jack, yellow fin and albacore. yellow fin tuna also serves as our fresh meat tuna that we might see as ahi on a menu. and blue fin tuna -most of us as americans rarely eat blue fin tuna... and that is bc they are shipped in containers almost like coffins in a jet right over to Japan where it is seen as fresh fish in the Japanese fish market as sashimi suguro where a single slice of tuna can sell for extraordinary amounts of money....
10:55-12:08 aquarium ambi
13:02 BB-... they are actually camouflaged, if you take a look at how they are built, when you look up at a tuna from bellow like we can do right now, they are silver; when you look down they are dark blue. and so what that is is nature's way of trying to camouflage a tuna -when you look up in the ocean you see down welling light, when you look down you see dark colors, and that is part of how they actually disappear.. 13:25 tunas are spectacular animals to look at. they have all these specializations we were talking about to swim efficiently. their pectoral fins, the finlets on the back of their tails. and what they do differently from all other fish is that they are stiff throughout most of their body and then they wag their tail to swim. it is more like a dolphin on its side. 13:44
13:43 AC -look at the size of those things
13:45 BB -that's one of our oldest tunas. he is at least 4 years in captivity and probably 5 to 6 yrs of age, probably running about 80 pounds. yellow fin tuna the males can get as large as 400 lbs. the females, their weights are much less ¬maybe 150 to 200 lbs.....
14:30 AC -before you put the tuna in this tank had you ever seen that feeding behavior before
BB -no that is the joy of this tank, as a biologist we are used to viewing these fish with acoustics. we are used to listening
to the pulses of sound that came back from our data recordings... so we could see the fish moving up and down and get a feel of what the water column -the water structure was like in terms of temp and oxygen. but we couldn't really see what they were doing. so for me and the post docs it was really a joy to walk in here the first day...and watch what it was they were doing. and 2 particular behaviors stood out: out in the sea these fish moves in a fashion that we call yo-yos. they go up and down and the up and down movt is a powered movt with their tail followed by a glide. and if you look carefully at the tank you can see them -although they just ate and they may not be in gliding mode. but when they glide they are saving energy by not having to thrust their tail and use their muscles.... the second thing was the feeding....
16:06 AC -why don't they eat the smaller fish in the tank?
BB -the fish in the tank are all distantly related. it is as if we are keeping cousins in the tank. the bonitos are the closest living relatives to the warm blooded tunas that are actually cold blooded. and the barracudas are very ancient relatives of the tuna. these are compatible species in nature. they are actually not known to eat each other.... 17:12 in nature people have long been interested in the difference btwn warm and cold blooded animals and that has been popularized most often amongst mammals -were dinosaurs warm? what my lab is focused in on is using tunas as a model to actually study the advantages of being warm, and having their living relatives, the bonitos as available study specimens to compare what are the advantages to having a warm body. so we can do living experiments on performance questions ¬how fast a tuna goes vs. its cold cousins... and one can't really do that in a living mammal or bird with its dinasourian relatives. and that is one of the things that we are studying over at the tuna research ctr. 17:58
18:20-19:25 -ambi in room
ac-can you id the tuna?
BB -only some -the large ones -we have hand reared ¬
20:54 BB -i look at these animals, and what i see is nature's finest invention for a swimming machine. if you look at the tail region there are all sorts of specializations or adaptations that we see there that we to this day don't know what they are doing. and engineers at MIT as well as elsewhere are building things such as ROBOTUNA in which they are trying find out by building a man made device what they are that tuna are doing. and what we hope in the future is put sensors on these tunas and find out how does flow go over surfaces and how it is that they are using natures evolutionary structures to basically do what they are doing, which is swim efficiently through the water column.
21:39 AC -they are so sleek. you can't see individual scales on
them it is asthough they have this silver skin.
bb -well that is a great observation. it turns out that part of the tuna strategy to move through the water efficiently is to actually have what we call a naked skin. and thy have reduced their scales that are found in most fish to a very fine level only in certain places. and most of that surface you are seeing is without scales. and it has that naked appearance. and one thing that's something that we have learned in captivity is that if you touch a tuna, if we handle the tuna inappropriately we can leave the tuna bruised very easily. and so part of our success... that we have here is to handle the tunas with slings that barely allow us to manipulate the animal with our hands so that we don't interfere with anything on their body surface. bc nature didn't make them to bump into things in the open ocean
AC -how old do tuna get?
22:48 bb -tuna is basically depending upon their species have different ages. so blue fin tunas -the ones that get very large in the atlantic oceans -they can be over 30 yrs of age when they are in the 1000 pound class. the yellow fin tuna...is a fast growing relatively short lived tuna and the males can be 8-10 yrs and the females can live 4 to 6 years....
23:21 AC -you said that the male yellow fin tuna can get up to be 400 pounds -the largest specimen here are about 80 pounds ¬are these going to get bigger?
bb -well we would think based on the what the wild data says that these animals would continue to grow and then plateau. one of the things that we are doing in captivity is each of these tunas are carrying a radio chip that allows us to individually identify when the tuna was collected and how old the tuna is and what we can do is measure their growth rate and pay attention to how many calories it takes to be a tuna and how much growth they are putting on ¬
25:13 -(in another area with tuna) keeping tuna is a challenge bc they've got the metabolism of a mammal of their size which means that they consume a lot of oxygen and water doesn't have as much oxygen as air. so to have a school of tuna in a tank of any size...requires that we have lots of pumps, lots of aeration... for this particular species we have to heat the water and....it costs a lot of money to actually keep a school of tunas... this building was built in collaboration with stanford U. and Monterey Bay Aquarium......to put them on display, bc a big part of the project was to bring people in contact with tuna so they know the beauty of the organism...... also built for research ... so that people like me ....can find out how tuna work, their physiology, their biomechanics and their behavior....
26:33-27:23-ambi in tuna room
28:09 BB-this is what it is all about. being a researcher, being so close to tunas is not something that you can do. i spend extraordinary amounts of effort, and the nation has helped fund us with their federal grants to put us out at sea to see what tunas do in the wild. what most of us can't do is everyday come in contact with an open ocean fish. and this is what the tuna research and conservation ctr is helping us do. we can come in here daily, see what the tunas are doing and most importantly physically handle the tunas, try our instruments on the tunas, study the tunas and learn how this marvelous machine really works. in the middle of the tank we have one of our tags, this is a pop-up satellite tag...the way this tag works is the implantable archival tag is this years focus but bc of the inability to get the tags back we want to begin to package the unit together with small satellite transmitters and the hope is that we can actually archive lots of data and then send it back through the satellite system. and the problem for doing that is that we are going to have to attach a device on a tuna for a long period of time. so in addition to using these tanks for practicing surgery, and our group has been in here almost every Sunday of the last several months you can see stitches for the implantable tags and what has happened there is that our surgery team is literally building their confidence by putting in stitches and practicing 29:41 ¬
29:40 SPLASH! in tank
29:46 AC -that is unbelievable!
BB -that is a burst activity
ac -but that thing was -if i hadn't seen it i would never believe that a fish could move that fast
29:55 bb -well tunas are renowned for being continuous swimmers they keep their mouth open to get the oxygen they do what we call ram ventilation and they are continually going. and part of the reason they are warm is that they capture the heat -the muscle locomotory generates heat as they move and they are able to capture that heat and that helps them improve their performance as swimmers. warmer muscle means they get to go faster with a higher output. and what you just saw was a burst of speed. and that burst of speed is one of the fastest bursts of speed that we see in the fish world. none of us have had recorders on a tuna that actually has been able to measure that burst of speed but we are building a set of recorders that we hope will allow us to measure how fast a tuna goes.
30:40 ac -you mean the instruments can't keep up with the speed?
bb-actually what we have done is basically gone out and measured how fast a marlin goes with true measurements like a speedometer and found out that like many pelagic fish most of the time they go slowly. their effort isn't in going fast, 90% of the time they go slowly. but when they do go fast our instruments pretty much bought them out. they can't keep up with the speed of the marlin and at this point we have found that the tuna cruise faster than their cold-blooded relatives. they cruise at about 3 to 5 miles per hour. and at some cases 5 to 7 miles per hour and many of us might think that is not fast but when we go swimming we would have a hard time swimming continuously for 24 hours times 365 days at those types of speeds. so what these fish are deigned for is low speed cruising but what they are capable of is short very frenetic bursts -if the predator was coming to get them i would but my bet on a tuna who is built like a Ferarri and can basically zoom right out of the region of the ocean that the predator might be coming to attack them in. the way the tag works is that the tag is carried by the fish, and on a predetermined day a corrosable linkage in which a piece of metal is actually corroded through that is forming the attachment through the tuna, literally releases and the pack comes up to the surface. this experiment went on this weekend here and that package right now in the middle of the tank is transmitting data via Argo satellites. 32:19
AC -notes: the little transmitter -stock base w/a yellow cone top and an antenna sticking out of it which is 6 or 7 inches long -black antenna
32:42 bb -what that is a carbon covered tube shaped like a torpedo -the top of it is a float -a syntactic foam float and an antenna which is coming out of the syntactic foam float and with the creative design of Paul Howie we have been able to put together the 2 teams of researchers who have been able to come up with this technique of keeping the tag on the fish to the preset date and then having it pop off. and our goal now is to go into the field and put 50 of these tags on giant bluefin tuna in which the big question is on what should we pop off the tags and our plan is to put them on the large breeding fish and then pop all 50 off at a time that we consider to be the peak breeding in the gulf of Mexico and the Mediterranean sea and what we hope to have are 50 data points from this year alone in which we will see is where do these large tunas go to breed.33:35
33:36 ac -and what is that date?
bb -we think that the best plan is to pop the tags off 3 months from when we are at Cape Hatteras. and we hope to hit May, June and a little bit of July. the peak of breeding in the gulf of mexico from reading the literature should be late april and may and into early june. the peak of breeding in the med. sea is the month of june. so the pop-off tags will have their micro¬processor programmed to come off 3 to 4 months from the cape hatteras deployment date...we will know the results of this project by june and july of this year....the whole story is if the tag makes it out there in the final stages of development.
35:53 let me just show you one archival tag -archival tags come out of the belly...what we have to look for is a stalk coming out of the ventral (?) region and that stalk has a beat at the end of it...here is one right here. that is wearing a wildlife computer archival tag, and the stalk comes out and that is the light sensor at the tip of the stalk. so in essence the fish is carry its sensor through out the water column which is picking up the data on ambient temperature, pressure, light, and inside there is a thermostat that picks up the body temp. 35:38 we know and have built confidence that mortality is extremely low if non-existent in our captive environment, and that gives us confidence when we go to the wild environment that fish that are 10 or 20 times the size of these fish will have no trouble carrying a tag or having a tag implanted in them
36:07 ac -how are you going to surgically implant in the field?
bb -well that is quite a site alex. basically what we do is pull the blue fin tuna through an opening we call the tuna door we pull it right onto the deck of the ship and in the cockpit of the sport fishing boat we flip the tuna on its side and put ina once inch incision and replay the exact experiment that we have been doing here over 100 times. so we stick the tag in, put in 2 stitches and working as a team we turn around this 3 to 400 pound animal and send it back out the door of the boat.
ac-how do you catch the fish? ..
36:45 bb -we rely on the expertise of the sport fisherman and they use a circle hook which is a special hook that helps to catch the fish just in the jaw region only, and while the fish is on board we quickly remove that hook we use heavy tackle which allows us to get these large fish to the boat in less than 15 mins. so we are going to do some survival studies in order to make sure the tunas are all surviving from the experiments that we are doing..........SHE WANTS TO BE CAREFUL WHAT SHE SAYS bc people get made reo using animals for experiments ......OFF THE RECORD: we know from our work here that tunas are surviving these procedures and are feeding the next day -that's actually a good line -and from that knowledge we walk out to the atlantic with confidence that if you're 10 to 20 times the size of a yellow fin tuna and in some cases 30 times the size that just adding the procedure of hook and line when done right will give us a fish that survives the procedures. now the good news is that we did acoustic studies and others have in the hatteras arena and others have we are making sure that our handling techniques are insuring the survival of the fish. 38:30
38:31-40:06 room ambi-alex talks in middle for a sec -can hear ac and bb in bg -but faint
44:48 AC -why are tuna warm blooded, when fish -all the other fish that i know aren't warm blooded?
BB -well that is a good observation. there is probably 25,000 species of fish on earth and only a handful -a few tunas as well as some sharks are warm. and when we think about why tunas are warm we are really thinking about why is that a mammal is warm, why is it that a bird is warm. it is the same sort of question. and as a physiologists that are 2 answers -one is that warming your muscles or warming your brain or warming your viscera usually improves the performance of that tissue, so we are built of ...........45:33 so it improves performance, our tissues are effected by small rises or temperatures and the enzymes and the proteins .........
45:51 ac -why are tuna warm blooded when all the fish that i know are not warm blooded?
bb -that is a good observation bc there are really 25,000 species of fish and only a few are warm and that includes tunas and a couple of sharks such as the white shark. and when we think about why tunas are warm we are really addressing the same question we think about why are mammals or birds warm and we often have to go back to dinosaur relatives to get the answer. in the case of the tunas what we like to offer as an idea is that its warming of the muscles or warming of the tissues that actually improves their physiological performance and is a benefit the animal gets by having the warm tissues. so we could take the muscle and say that a tuna that warms its muscles by 10 degrees is faster than any other fish in the sea. there is another way to answer the question: that is by being warm these animals get to where they want on earth. they have the advantage of what i call niche expansion. so by being warm they can move into polar seas and take advantage of forage that would not be available to them if they were not able to move into these cold waters. so that they can go at anytime where they want to go w/o temp. being a limitation. 47:01
47:02 ac -is that why the tuna can swim as fast as it can -as fast as i saw it go in that tank?
bb -i think so -i think that burst of speed is really unique to the tuna endothermic condition.
47:14 ac -in the work that you are doing -you are very interested in tuna and the preservation of tuna -for conservationists to succeed i think you have to get people to some how connect with animals. so we are interested in saving whales bc somehow we have connected with whales, and we are interested in preserving habitats bc we connect with bears and wolves. how do you get people to connect with tuna?
47:47 bb -well i think we are just beginning and i think that one of the key things that one has to do when ones observes a tuna.... is you have to be fascinated with the beauty of form, mov't and color that you can see right in front of you that you can see as they swim by. natures finest invention is a swimming tuna. we as humans are trying to model devices that actually move through the water with the efficiency that a tuna does. so i think that their large size, their incredible beauty as a swimming animal is something that most of us have just not come in contact with and so the trick will be to get people to take advantages of these opportunities to see a tuna and to help interpret their biology which is a fascinating biology. 48:33
48:33 ac -and when you call them nature's finest invention you mean what?
bb -i think that when it comes to making a living sea what a tuna does in terms of moving lOs of thousands of miles in search of its food and doing that relatively efficiently in something that very few animals are able to do -to move across from the Bahamas to Norway in 50 days as some of the tag recapture data has already shown. or to go from cape hatteras to the adriatic sea in a short period of time is something that we can't even begin to fathom in terms of what we know about swimming in the water. and a tuna in its lifestyle is using the whole ocean in many cases several oceans as their own home range. and it is interesting to me to find out really is the ......49:45 -they have enormous ranges and it is interesting to me to find out really how they work and how it is that they are able to get from place to place -how it is that they are able to navigate when we ourselves have taken 100s of yrs to figure out how to give a sub its position underwater. and yet these animals are holding a course finer than any navigational compass that we can build. and we know this -we can observe this.50:07
50:08 ac -they can hold a course better than a compass that we can build?
bb -what i would like to say is that when we follow a tuna often times we don't have to look at our computers any more to say where is the fish we just have to say check out course 122 degrees it is probably on that course. and what the fish is doing is taking a course in the ocean we don't know really what are the cues that the fish are using -whether it is a magnetic compass whether it has something to do with light -how it is they find their way.50:39
50:39 ac -but you draw point a on the ocean and point b 100s of miles a way and the tuna can swim in a straight line btwn them?
50:48 bb -we haven't observed tunas over 100s of miles w/our instruments. we observe tunas on a daily basis for maybe as long as 8 days. and we have done a lot of that and we have been fascinated by the fact that buoys many miles apart off the island when we are following big ahi, big yellow fin tuna, buoys that we have to look at a chart to figure out where they are, the tuna swims from one buoy to the next s if they have a chart and a navigational aide right in their head. on a bigger picture map if you look at the atlantic ocean and some of the tracking that has gone on by frank kerry and i as a student what we found was that animals would stay on a course for day after day and we weren't sure how it was that they were able to navigate along those courses. whether it was geomagnetic, whether it was a compass, whether it was light from the sky -51:42
51:43 ac -do you think you will ever know the answer to that question?
bb -i think that questions that we are trying to get the answers for are straight forward questions, what is the advantage of being warm? where do these tuna go? where do they breed? and how is it that they travel so efficiently from one side of the ocean to the next. i think we will get the answer to some of those questions with some of the new technology that we are putting to use with tunas, but there will always be new questions that we will dig up and want to know future answers to 52:10
ac -....what does telemetry mean to you...
52:37 bb-i am fortunate -i was schooled in telemetry from the day i was a college student working at woods hole ocean. inst. so i have been listening to what tunas do for 2 decades. so telemetry for me having been on the ocean at night following tunas with a full moon and dolphins at the bow of our boat ¬telemetry is the way that the biologists really gets into the head of the animal and understand what is it tat the animal does rather than what is it that the human does. so we really get a perspective on how it is that a tuna navigates and moves through its 3 dimensional environment. and i think that it connects all of us to why we are interested in biology in the first place. we want to know how animals work. we want to know how they behave. we want to know whatthey do. and only by getting out their in their environment to we begin to understand what it is that they are doing
53:30 -where we are now moving from acoustics to data storage technology and now to remote telemetry by sending data to sky and then down loading that data back in our laboratories is we are going to open up the migratory paths of a host of organisms that have been inaccessible to study. and the pelagic environment -the open ocean environment thatwe work on is one of those places that much like the deep sea has been a challenge for biologists to go get any info about. we know more about perhaps what is happening on the moon than we know about certain places here in our ocean environment. and yet the ocean makes up a large portion of our planet and yet these techniques, these technologies are finally going to allow us to really get some of the secrets from some of the organisms that have bene the hardest to study. 54:21
54:22 ambi outside place of interview
54:53 TOUR OF AQUARIUM with
last march opened up part of aquarium that is devoted to the open oceans ...describing the aquarium -the philosophy of aquarium
1:02:17 CF (chuck farwell) this is the tank that we were looking at this morning during the feeding alex. it is 90 feet long, 52 feet wide and 36 foot deep and the water volume is approx 1 million gallons. and as you look down you will notice that the tank is this really nice rich royal blue color that comes from a small ceramic tile. and the entire inside of the tank has been lined with tiles to give it the blue color ... 1:03:11 now we are looking down and we have several different species of fish. right at this point we have a school of b~rracuda, california barracuda. and below us are the yellow fin tuna. and on the very bottom of the tank you can see a few soup fin sharks swimming around. and we have 2 different sea turtles ... there is also bonito. the fish with the smaller pectoral fins and a few skipjacks. so it is a community tank that we have set up primarily with open ocean fishes that you find 50 to 100 miles off ¬
1:03:44 AC -what is the great round flat fish? ...
CF -....oh! that is a mola-mola. it's called an ocean sun fish -it is absolutely an amazing fish. you will find them out under floating kelp patties -out away from the shore, maybe 1 or 2 mola per kelp patty....very fast growing fish. they can increase their body weight by about 5 times in one year. very fast growing. and i think the largest animal that has ever been caught is about 1,200 pounds. so they can get up to the extremely large size ....
AC -they are amazing to look at.
CF -they are great. and they are very popular with or visitors.
1:05:01 AC 0 how many fish are youkeeping inhere now?
CF -right now there are about 68 yellow fin tuna, about 100 bonito, 30 barracuda. 6 shookfin shark, 2 turtles and 1 sun fish -mola molas ....1:05:43 there is one interesting fact that we learn about keeping tuna early on in some of our off-site holding areas and it is that they have a very high respiration rate, the utilize a lot of 02, and you have to design your water system or your life support system to accommodate your collection of tunas. but what we didn't realize is the same time they are using 02 they are giving off a large quantity of carbon dioxide which changes the water chemistry and lowers the acid content or the PH of the water. and if proper measures aren't taken you can end up lowering the PH to a level that is dangerous ... so we had to figure out a way 'to get rid of the excess carbon dioxide from the water. we have done that and it has worked out very well for us.
1:06:41 ac -what do you do with the fish waste? it just winds up in the filtration system?
CF -we have a very huge filtration system. all of the water is passing through 6 sand filters. there is biological activity in the filters that breaks down the waste ....so the water system has to be designed to take care of the waste products. it is a very important part of the exhibit. and one that the people don't see, but it is import as any other part of the exhibit ....the water temperature is the same from top to bottom and we are keeping it 68 degrees F, 20 degrees C, which is the lower range that you find yellow fin tuna in. so that was our driving force of setting the temp -was the physiological requirements of the tuna
1:08:06 ac -all this water is filtered in 2 hours. every 2 hours? (CF -yes) 1 million gallons?
CF -and you have to do it.
1:08:27 AC -is there any other aquarium like this in the world?
1:08:31 CF -i don't know of any other aquarium that has an exhibit of tuna and other open ocean fishes of this size or magnitude .....other places have holding tanks of this magnitude ... for whales, for orca ....but something that is dedicated for solely this use -this is probably the largest ...1:10:34 i am going to guess that we are feeding this tank about 200 pounds of food at each feeding -roughly at that amount. and when you consider that all that food has to be digested, metabolized, and then a large amount of waste gotten rid of ....so the filtration system runs 24 hours a day. you can't turn it off.
LEO -how do you get the fish in the tank?
1:11:13 CF -(IN MY WORDS) tuna put into a stretcher -one at a time -with water and lifted by crane and lowered into tank. they are very heavy, 2 people disconnect the stretcher and let the fish free in the tank. tuna swims off a makes a couple of exploratory laps and then settle in. and then as they settled in, and they got more and more fish they formed a school ....which is a key to keeping this fish on display is to have enough to form a school. you take a schooling fish and keep them by themselves or in very small number and they don't do very well
1:12:07 ac -you mean for their health -it is important for the health of the fish ....
CF -yes. i believe so ..... .
1:13:07 END of interview with him
1:13:08-1:15:58 ambi in place of interview -top of tuna tank
CHANNELS MIGHT BE REVERSED (leo says)
1:16:17-1:21:35 general ambi inside aquarium