From the University of British Columbia , a fish story inspired by a model:
Fish getting smaller as the oceans warm: UBC research
Changes in ocean and climate systems could lead to smaller fish, according to a new study led by fisheries scientists at the University of British Columbia.
The study, published today in the journal Nature Climate Change, provides the first-ever global projection of the potential reduction in the maximum size of fish in a warmer and less-oxygenated ocean.
The researchers used computer modeling to study more than 600 species of fish from oceans around the world and found that the maximum body weight they can reach could decline by 14-20 per cent between years 2000 and 2050, with the tropics being one of the most impacted regions.
“We were surprised to see such a large decrease in fish size,” says the study’s lead author William Cheung, an assistant professor at the UBC Fisheries Centre. “Marine fish are generally known to respond to climate change through changing distribution and seasonality. But the unexpectedly big effect that climate change could have on body size suggests that we may be missing a big piece of the puzzle of understanding climate change effects in the ocean.”
This is the first global-scale application of the idea that fish growth is limited by oxygen supply, which was pioneered more than 30 years ago by Daniel Pauly, principal investigator with UBC’s Sea Around Us Project and the study’s co-author.
“It’s a constant challenge for fish to get enough oxygen from water to grow, and the situation gets worse as fish get bigger,” explains Pauly. “A warmer and less-oxygenated ocean, as predicted under climate change, would make it more difficult for bigger fish to get enough oxygen, which means they will stop growing sooner.”
This study highlights the need to curb greenhouse gas emissions and develop strategies to monitor and adapt to changes that we are already seeing, or we risk disruption of fisheries, food security and the way ocean ecosystems work.
Note the press release headline: Fish getting smaller as the oceans warm: UBC research – they tout that as if it were measured, it isn’t.
Of course actual field experiments with real data trump models every day of the week and twice on Sunday. For example here’s a graph from the paper The effect of temperature and fish size on growth, feed intake, food conversion efficiency and stomach evacuation rate of Atlantic salmon post-smolts by Handeland et al published in the journal Aquaculture in June 2008:
Fig. 1. Mean weight in Atlantic salmon smolts (±SE, n=23) transferred to seawater at 6 (□), 10 (Δ), 14 (⋄) and 18 (○) °C. The first point (week 0) refers to the freshwater group (control). Different letters indicates significant differences (Student–Newman–Keuls, pb0.05) between temperature groups at same time of sampling, n.s., non significant.
The authors conclude:
In conclusion, the present study shows ontogenetic variation in optimum temperature for growth in juvenile Atlantic salmon smolts, with increased temperature optimum for growth and decreased temperature for feed conversion efficiency as the fish grow bigger.
Temperature tolerance increases with size, but Atlantic salmon smolts are eurythermal (Able to tolerate a wide range of temperatures.) in the size range investigated.
Full paper here (PDF)
Now as Willis would point out, clearly this is tank studies, and not the open ocean, and you can’t duplicate the complexity of the ocean in a tank. But the fish don’t seem to have a temperature issue, in fact they seem to thrive at warmer temperatures. The claim is that as oceans warm, less oxygen will be available, and that will stunt the growth of fish. This claim in the modeling paper comes from the elemental saturation curve for dissolved oxygen (DO) in water, which is much like that of CO2. From a lecture on water chemistry at keystone.edu:
I found this part of the lecture interesting, and was something I didn’t know:
Nota bene: 100% saturation does not mean that no more O2 can be held in solution. I have measured DO >200%. Does this mean that bubbles should be forming? No, not necessarily. Saturation here means that 10.92 mg/l can be held at equilibrium; if 200% is produced by intense photosynthetic activity, the extra amount will be lost (diffused) at the air/water interface.
- a nomogram can be used to determine degree of saturation; use a straightedge to connect the water temperature and DO. Read the % saturation at the intersection of this line with the middle line.
· at 10 meters, with a temperature of 10°C, at surface pressure would hold (at 100% saturation) 10.92 mg, but you may find 15 mg/l.; compared to the surface it would be supersaturated, but at the depth and pressure it’s at, it may be less than saturated.
o How can water be supersaturated?
§ intense photosynthesis
§ entrainment of air falling over a dam or spillway; high pressure of impact drives gases into solution; may lead to gas bubble disease, a problem in TVA dams
§ affects fish if subjected for a few hours to >115% saturation; bubbles form in tissues; emboli collect in gills causing anoxia and death; also affects cladocerans. Other biota, e.g., crayfish and stoneflies are hardier.
So, too much oxygen is also a problem. But what really piqued my interest wad the statement of “intense photosynthesis” as a cause. That made me wonder if photosynthetic algae and diatoms would respond to increased temperature, so I went looking and found this paper: Production and fate of extracellular polymeric substances produced by benthic diatoms and bacteria: A laboratory study by Lundkvist et al.
And the graph showing how photosynthetic oxygen production changes with temperature, again hard data from observation:
Fig. 7. Dose-response curve on light intensity and photosynthesis measured as oxygen production by benthic algae population.
So, it seems to me that the ocean already has this worked out. If O2 can be supersaturated, and “intense photosynthesis” can be a cause, it would seem that warmer water that normally would get oxygen from air-sea interaction and entrainment might be supplemented from increased algal photosynthesis.
Besides, broad differences in oxygen content by latitude are well known:
Image: Wikipedia
And fish aren’t static entities…they move. So I suppose I’m not too worried about global warming shrinking fish. Overfishing is likely a far greater problem for reduced fish size, as are oxygen deprived dead zones due to fertilizer runoff as we’ve seen in the Gulf of Mexico:
Dead zones occur throughout the world and are caused primarily from excess fertilizer and animal manure run-off, as well as, emissions from sewage treatment plants, urban and suburban run-off, and air emissions from vehicles. The largest dead zone in the country occurs at the mouth of the Mississippi River in the Gulf of Mexico each spring. In past years, the dead zone (pictured in the satellite image as the red coastal areas around Texas, Louisiana, Mississippi, Alabama, and Florida) has encompassed some 5,000 square miles. – ewg.org
Looks like they’re going to have to ask the worlds 2nd biggest fish to to change their name from the Basking Sharks then…..
Here we have another model, base upon the output of other, unproven models. We haven’t even established the validity of those models, so how can any of this be called science?
So sad to see climate “science” dragging down other fields of scientific study, in this case marine biology.
I think this little ditty explains it well. Oh, the marine biologist bone is connected to the biology bone, the biology bone is connected to the College of Liberal Arts and Sciences bone, the College of Liberal Arts and Sciences bone is connected to the research University bone, the research University bone is connected to the Federal scientific funding agency bone, the Federal scientific funding agency bone is connected to the Public Sector tax collector bone, the Public Sector tax collector bone is connected to your wallet.
[Emphasis mine]
Here is one of many great dichotomies between the believers and the skeptics. Are the oceans really becoming less alkaline (not more acidic) or are the oceans giving up stored CO2 as they warmed over the last few decades? Both cannot obviously be true.
Oceans tend to absorb CO2 as the cool, and give it up as they warming. Shouldn’t a warming ocean have less CO2 than a cooler ocean?
BTW: We also know there is no evidence to show that the oceans are currently warming.
I have a problem relating this finding to the observed size and population density of marine species around the outflow from power stations, or around the legs of the offshore platforms.
In other words, where the water is warmer it seems to support much more marine life and of larger size.
It therefore seems counter-intuitive to believe that warming oceans result in smaller fish. Perhaps it just means that population growth is such that there are more juvenilles. Perhaps there is a link to fishing…. certainly the fishing around the platforms is better than away from them, or so I have been lead to believe.
At any rate, if the data suggests something that is so completely counter-intuitive and, more importantly, counter to observed patterns elsewhere it suggests that either the data is incomplete or that the science is incomplete. Maybe it rests on an assumption that is wrong or on an accepted belief that on closer inspection will prove to be wrong. For example, the data may be that fish are getting smaller.
Is this mature fish or a proportion of all fish? Is the fish population increasing or decreasing? is it simply an abundance of juveniles?
Or maybe the assumption is that the oceans are warming. Are they warming?
The other aspect,as any of the fishing guides will tell you, is that fish are attracted to the warmer waters causing uneven and changing populations. Quite evidently, fish like warmer waters. Ergo, how can it be bad for them?
But I get it. You can’t publish any scientific report these days nor get good grant money unless you throw in the obligatory “Warming is Bad” message. It is getting so that to extract the science these days you not only have to read the report but also decode it to mine the real data and science from the revenue generating propaganda. If there is still any real science contained in the report that is.
Of course they use clown fish as their example because of emotions evoked in children from popular cartoons. Here is the same blatant attempt only using ocean pH as the harm factor instead:
Ocean Acidification Can Mess with a Fish’s Mind
http://www.scientificamerican.com/article.cfm?id=ocean-acidification-can-m
Similar to the cat toxoplasma infections in mice, pH decrease in seawater, causes clown fish to develop suicide behavior. Ridiculous and demeaning pap for the ideologists. GK
I don’t think the 1000 pound marlin got the memo: http://www.fieldandstream.com/blogs/field-notes/2012/08/angler-lands-half-ton-marlin-just-misses-world-record
Shrinkage! Tell me about it!
Nemo is likely getting smaller, but because of overfishing, particularly of salmon. I might point out that also, the need for less fat in a warmer ocean, particularly salmon again, might also be a factor and finally, if the ocean warmed up a couple of degrees, the Atlantic salmon would just swim 100km or so further up Davis Strait if they didn;t like the warm water. Sheesh – I’m only a geologist, too.
As a matter of fact some of the best spots for catching specimen fish are around or immediately downstream of warm water outlets which raise the water temperature significantly. This is known by anglers all over the world who choose to fish near power station outlets etc.
Shame these ‘modellers’ didn’t bother to check with people who best know fish – the anglers – and get some real-world data rather than working from an unfounded hypothesis.which only serves to highlight their own ignorance.
Mind you I expect there were mega-bucks at stake so they wouldn’t dare disturb the results of their ‘modelling’ with Facts.
Just another waft of the stench of corruption that goes by the name of climate change.
There is another proposition more associated with Darwin than warmin’. It may be that fish are adjusting to the size of catch. Netting size means that the genetically challenged smaller fish are able to persist and mate and the larger species and their genes are eradicated. When one sees the aridity of the majority of our oceans it is s tough proposition to swallow that oxygen in water is under threat. We see the hand of the politicians in all of this; their failure to deliver legislature that preserves stocks is especially damning of the failure of the EU, the general, casual references to a convenient phenomenon that they call AGW is a let-out for all of their awfulness as the blame for anything that is too critical of them or, like the use of Alchemy to derive results beyond the level of current intellectual understanding. When you have organisations such as the BBC demanding that every production has an ethnic diversification content and respectful nods in the direction of AGW then their is little hope that light/fact will illuminate this topic.
And just how much has the North Sea and Atlantic warmed?
Reblogged this on Public Secrets and commented:
As determined by a computer model, while observational data appears to show something different. Surprise, surprise. Be sure to read the whole article.
Will the size of the Fukushima-Daiichi radioactive fish make any difference? All 15 Bluefin Tuna caught by a research vessel off San Diego were contaminated…and the controlled press ignored it.Orwell had the wrong year….
The alternative hypotheses – over fishing and dead areas – are the far more likely cause. Over fishing has certainly shrunk dramatically the size of fish, whether it be the dorado in the River Parana in southern Brazil, or mackerel around the British coastline.
Of course warmer water causes smaller fish. Don’t you remember Hemingway’s famous story of the Cuban fisherman: The old man and the Smelt. Who can forget the epic struggle between Santiago and the sardine?
/sarc
“””””…..AndyG55 says:
October 1, 2012 at 12:48 am
George, I do know whales are mammals.. just very big ones that live in the sea.
There are actually some biggish fish that live down south, I believe some of them even have anti-freeze in their circulatory systems. Whales carry their antifreeze under their skin.
You are right though, the really big fish do prefer warmer waters, although those big whaler sharks are partial to a bit of seal for breakfast, lunch and tea, so a venture into colder waters is often on the cards.
btw, I also can put BSc and BEng on my card, plus MEng and maybe soon, Piled high & Deeper!!…..”””””
Andy, if I was in your shoes, I certainly would do that. I can tell you that I never could have even started my Industrial career in the USA, as aPhysics/Maths graduate, if it had not been for my Radio-Physics, and associated Electronics instruction at UofA; but down through the years, I found that it was my fundamental Physics, that allowed my engineering common sense to know, that I was working in an environment of “you can’t get there from here” restrictions, that they tend to not teach in Engineering courses. Stops a lot of useless thrashing around in the wilderness, trying to solve an unsolvable problem, if you know the finite restraints.
I was working on an MSc almost through to the finish, including having my thesis work done, but due to this’n’that never finished and got the shingle. Got all the learning benefit; but make sure you get the wall art as well, since the Judith Currys of the world demand that there be paperwork behind you.
And my work today is mostly all beholding to a 1926 text book, that very few white folks, and no minorites at all, even know exists.
Good luck with the MEng.
“Note the press release headline: Fish getting smaller as the oceans warm: UBC research – they tout that as if it were measured, it isn’t”
that is so typical LSM – the legacy media is trumpeting any CAGW rant, incredibly often, without any check, taking models as reality.
The warmlist is trying to keep pace with it but…
http://www.numberwatch.co.uk/warmlist.htm
Hey, thinking it over, did they run the study further then 2050? Will in 2100 or 2200 the sharks be smaller then 1 meter? Think at all the beaches we will be able to use without fear of sharks!
I had heard that Greens complain of ‘thermal pollution’ from nuclear powerplants warming the rivers theircooling water comes from. I also read that it should more properly be called ‘thermal enrichment’ in view of the beneficial effects upon all life in the river, particularly in terms of increased fish size.
Does anyone have a link to these River-based measurements?
the person who wrote this is so far out of their depth, it doesn’t matter if the fish are getting bigger or smaller, what matters is if they have little fishing rods or little lights on their heads
There’s potential here for another ‘research’ grant… some savvy ‘researcher’ could ‘research’ how much sea levels drop due to the fact that these shrinking fish are now displacing less water.
The researchers used computer modeling to study more than 600 species of fish from oceans around the world and found….exactly what their models were designed to show, and they were surprised. Confirmation bias at work, no actual evidence being presented.
I am getting tired of seeing my money wasted on propaganda masquerading as science, and even more so I am getting tired of idiots on the left coast.
[tiny bit of research on fish] Do the scientists know that almost all fish have Hemoglobin, except for some Arctic species? Hgb allows much more O2 to be carried to the tissues than O2 only dissolved. And the sigmoid characteristics of the human hgb “saturation curve” means that a large decrease in the pO2 which hgb is exposed to, first leads to a relatively small decrease in the O2 still carried and delivered. For example, in the case of humans a decrease in the normal pO2 the hgb is exposed to in the lungs from pO2 ~100 to 60 still leaves the hgb carrying 90% of its O2 out to the tissues, which is plenty to keep tissue function normal since only about 1/3 of the O2 carried by hgb out of the lungs is used by the tissues during normal activity. Then there’s also the question of whether fish increase their hgb concentration in the face of decreased ambient-gill level pO2 by increasing red blood cell production, which humans normally do at altitude.
Other adjustments by the fish are possible even if Oceanic O2 does decrease. Therefore, I have to trust the fish over the “scientists”.
“We were surprised to see such a large decrease in fish size,” says the study’s lead author
We were aiming for a 10% reduction, but we were surprised to find we could push it to 20%
without being much more unbelievable.
AndyG55 says:
October 1, 2012 at 5:18 am
SAMURAI says:
Q. Do dressed up computer models make my butt look fat?
A. No, your butt always looks fat !…………………………….ps, i’m divorced 😉
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Andy, although your comment is factually true, I think a strong scientific case for increased CO2 levels contributing to Catastrophic Anthropogenic Global Wiggly-butt Syndrome (CAGWS for short) can be made.
As empirical evidence shows, increased levels of CO2 have increased forest and crop yields due to improved photosynthesis efficiencies. With the increased supply of grains and vegetables, food and animal feed prices have fallen, allowing more disposable income available for food expenditures and caloric intake and, voila’, CAGWS.
If a graph was made showing increased CO2 levels compared to increased US obesity rates (aka CAGWS), I’m confident a very strong CO2/CAGWS correlation would be shown…