The Bloater: A Complicated Story

You may recall from my last post that I mentioned a fish species from the recent Tom Simon Fish Collection acquisition, the “Bloater” Coregonus hoyi.  This is a species that in the recent past has been considered endangered, indeed it was known to be extirpated from some of the Great Lakes and thought to perhaps be on its way to extinction across the rest of its distribution.  Herein I’ll detail some of the reasons for which the bloater came to be in such peril.  But for now, allow me to follow a rabbitfish trail (ahem):

Perhaps you have wondered why this fish is named so cruelly?  Perhaps, one might think, the name was given in less politically correct days when short shrift was given to a fish’s feelings, but that is simply not the case.  No, the name actually describes the propensity of the species’ swim bladder to expand and make it look fat when it is trawled from the deep, colder waters that it prefers.  So you see it actually does have to do with the poor fish having a tendency to be gassy.

OSUM 117265 Coregonus hoyi "bloater"

Yes, that bladder does make you look fat! OSUM 117265 Coregonus hoyi 195mm SL 1 of 18 specimens from jar 1 of 3

The rapid ascent from the fairly extreme depths, down to almost 700 feet where the fish resides, and consequent distension of the bladder does cause more than just discomfort for the fish. The complexity of the connection to the gas bladder in the bloaters renders them unable to quickly discharge the air and liable to bursting upon fast ascent from depths.  In many species of fish the swim bladder is directly connected to the gut and the fish can use this connection to directly control the amount of gas in the bladder. This physostomous swim bladder occurs mainly in fish living in shallow waters and swallow air that is passed into the gut and forced into the swim bladder. Not so in the Bloater. Fish in the order Salmoniformes, such as the Bloater, share a character with other advanced fishes: the physoclistous swim bladder. This gas bladder has no direct connection to the alimentary canal but some areas of the membrane separating gut and bladder are very thin and well supplied with capillaries that allow rapid gas exchange. This gas gland secretes oxygen into the swim bladder through the rete mirabile, literally “a wonderful net” of capillaries.

Diagram of the arterial/venous transfer to the gas bladder via the rete mirabile

The Bloater is one of several  “whitefish” species that have become rare and imperiled, some to the point of extinction. Bloaters are invertivores – you guessed right, feed on invertebrates – at all stages of their lives and formerly fed in open water (Many other fish species are invertivores at immature stages and shift their diets to larger prey including vertebrates as adults).  It has been documented that bloaters (and some other fish species) have changed their feeding habits in response to competition from the invasive Alewife Alosa pseudoharengus to feed on benthic invertebrates.  Happily for the bloaters they seem to have benefited, in the long run, from the Alewife invasion.

But there are several other reasons for the drastic declines seen among the bloater populations during the mid-1900’s:  Whitefish provide table fare for many piscivorous people, the fish-eaters among you.  The major upswing of humans in the Midwest region caused concordant increases in demand for food sources, and people began to realize that the Great Lakes could provide fish aplenty to help meet that need.  The lakes and rivers of the Midwest states at one time “teemed with fish”, according to several historians that wrote during that era of expansion and discovery. It seemed that the bounty was inexhaustible, and fishermen quickly capitalized on the surging market, filling their trawl nets to capacity for several decades.

Until, at varying points depending on the species being taken, the catches began to dwindle.  Before long the fishermen began to realize that conservationists were correct in their assessment that the boom wasn’t going to last, and regulations were put in place to husband the resources. However, other influences began to make themselves known, some with alarming results. Compounding the effects of overfishing was the connection of Lake Ontario to Lake Erie via the Welland Canal ca. 1830 that enabled incursion of several invasive fish species:  First to make an impact was the Alewife, a relatively small fish species in the herring family Clupeidae. Alewives compete with coregonids and other fish species for planktonic prey, to the point where diets for some forms shifted from zooplankton to benthic foods, feeding at the lowest level of the water body. Those species that couldn’t adapt their diets disappeared, became smaller or declined in numbers.  The next invader to have a significant impact on bloaters was the Sea Lamprey Petromyzon marinus. Sea Lampreys are piscivorous parasites (or is that parasitic piscivores?) for approximately a year of their several years’ long life cycle.  The invasive lamprey arrived in the Great Lakes in the early 1900’s and by the mid 1900’s had decimated populations of several salmoniform species. It is thought that one reason fish species like Lake Trout, and Lake Whitefish and other coregonids, fared so poorly with the Sea Lampreys is that they tend to inhabit deeper, colder areas of the Great Lakes where the lampreys prefer to feed.  For example, bloaters are most commonly found at a depth of 90 – 680 feet in water temperatures between 34-55 degrees Fahrenheit. Thanks to the monumental efforts of our conservation agencies the Sea Lamprey populations are under reasonably good control to the point where Great Lakes fishes are much safer!



McDonald, M. E., Crowder, L. B., & Brandt, S. B. (1990). Changes in Mysis and Pontoporeia populations in southeastern Lake Michigan: a response to shifts in the fish community. Limnology and Oceanography, 35(1), 220-227.


About the Author: Marc Kibbey is Associate Curator of the Fish Division at the Museum of Biological Diversity.


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Happy Holidays from the Mollusc collection

… and the giant clam, festively decorated for the Holidays.

Caitlin Byrne, collections manager, next to the giant clam

Caitlin Byrne, collections manager, next to the giant clam Tridacna gigas, one of over 98,000 specimens of molluscs at the museum

Below are a couple of photos from a quick visit to the mollusc collection. Note in the foreground in the picture on the left the book “The Freshwater Mussels of Ohio” authored by by G. Thomas Watters, Michael A. Hoggarth, and David H. Stansbery, a unique gift idea for the Holiday season. In addition to detailed accounts of each mussel species found in Ohio, the book provides information on basic biology, human use, and conservation issues of molluscs. Did you know that a recent scientific estimate puts two-thirds of our freshwater mussels at risk of going extinct? Mussels are important though, they naturally filter the water of our rivers, without them the murky waters would be less livable for other organisms.


About the Author: Angelika Nelson is the curator of the Borror Laboratory of Bioacoustics and the social media manager for the Museum of Biological Diversity. All photos taken by the author.

Hoosier Fish

Shown below are photos portraying our work to bring the Tom Simon Collection to Columbus.  We are so thankful to Beth Simon, Tom’s wife of 37 years, for honoring Tom’s wishes to gift the collection to the museum.  Beth was a great source of encouragement (including lots of pizza, subs, cookies and drinks and a great attitude) and brought her daugher Lia and son Zachary to assist in the move.  Tom Simon’s family exhibits the qualities that Tom himself exemplified, a true testimony to his character.  May the arrows from Tom’s quiver always fly true.

The old church that Ichthyologist Tom Simon refurbished and transformed to his laboratory

The old church near Bloomington, Indiana that Ichthyologist Tom Simon refurbished and updated to function as his laboratory and fish repository



Marc Kibbey surveys all that he is now “master” of.  The truck was loaded so heavily on the third trip that Marc and Logan had to dig 1 foot under the lift gate to be able to fold it up.  On one of the steep hills along Indiana Route 46 the truck could only muster 25mph on the nighttime drive back, no doubt making the long line of drivers behind a bit testy.


Load up! Indiana DNR NonGame Fish Biologist Brant Fisher, Indiana University and Tom Simon student Logan Shank fill up the truck

Load up! Indiana DNR NonGame Fish Biologist Brant Fisher, Indiana University and Tom Simon student Logan Shank fill up the truck.


Truck full-o'-fish

Truck full-o’-fish


Bloaters, one of several fish species new to our collection (and one of many reasons i'm excited about this gift)!

Bloaters, one of several rare fish species new to our collection (and one of many reasons i’m excited about this gift)!


These three carts hold what is numerically the biggest portion of the acquisition, approximately 7 million fish larvae

These three carts hold what is numerically the biggest portion of the acquisition, approximately 7 million fish larvae!  These vouchers were used to help develop a six volume series, “Reproductive Biology and Early Life History of Fishes in the Ohio River Drainage“, co-written by Tom Simon.


Logan Shank (aka The Modest Viking), Tom Simon's student ( right of Brant Fisher) is a gentle giant who worked tirelessly on our small crew on the Indiana side.

Logan Shank (aka The Modest Viking), Tom Simon’s student ( right of Brant Fisher) is a gentle giant who worked tirelessly on our small crew on the Indiana side.

Fish Slingers on the Dock

Fish Slingers on the Dock.  Thanks you guys, and to all the rest that helped us in Indiana and at the Museum of Biological Diversity!

Happy Turkey Holiday!

It’s the time of year when ONE BIRD receives all the attention, at least here in the USA: the turkey. Turkeys have been part of the human food chain for a long time, Native Americans hunted them for food and so did the first settlers. Due to unregulated hunting turkeys declined dramatically with the increasing human population. By 1904 turkeys had all but disappeared from Ohio. Today the Wild Turkey Meleagris gallopavo is again a common sight in many metro parks in Ohio. Blendon Woods, for example, has a good population that can be observed easily, often even at the feeders at the nature center.

Note the bristly “beard” extending off the chest of male turkeys and the spurs on their legs as seen in the photos above. The two males on the right are displaying and probably make some “gobbling” sounds.

As a bioacoustician I am of course most interested in the sounds these birds make. You are probably familiar with the famous “gobble” call males make in spring to attract a mate but also in response to other males calling. Here is a recording from our archive (BLB21391):

The gobble is a loud, rapid gurgling sound, it’s the turkey’s version of a rooster’s crow.

Females make quite different calls (BLB12583):

Here is an example of calls given by a juvenile female (BLB13261):

I hope this made you appreciate the diversity of turkey calls and you will listen for their calls next time you visit one of the metro parks.

All recordings are of captive birds at the Ohio Agricultural Research and Development Center, Wooster, Ohio in 1974. You can listen to the full recordings by clicking on the cut numbers above.


angelika_nelson_birdingAbout the Author: Angelika Nelson is curator of the Borror Laboratory of Bioacoustics.


Impacts of Rain Gardens on Urban Bird Diversity

Rain gardens have proven to be a useful tool to mitigate stormwater run-off in cities. They are depressions on the side of the road or sidewalk with plants that absorb rainfall and prevent water from picking up pollutants and carrying them to the nearest stream. The plants and soil also filter the water. But this is not the only service rain gardens provide, the diversity of plants used in them increases habitat for many animals. Many insects and spiders are drawn to the local plants and they in return attract birds and small mammals. Rain gardens can provide nice shelter for these animals too.

As part of project “BluePrint” the City of Columbus plans to install some 500 rain gardens in the Clintonville area to manage stormwater runoff. Dr. Jay Martin, Professor of Ecological Engineering at OSU joined the project to holistically quantify the impacts of stormwater green infrastructure on societal services such as stormwater management, public health, community behavior, economics, and wildlife habitat. Dr. Martin’s PhD student David Wituszynski focuses on the animal aspect and recently contacted the Borror lab to discuss his research idea. David wants to test the hypothesis that implementation of such a large network of rain gardens will increase the diversity of urban bird species.

SongMeter mounted (

SongMeter mounted (

Specifically, he wants to develop automated acoustic methods to track urban bird populations. He will deploy SongMeters, automated recordings units, and program them to record surrounding sounds at certain times of the day. It is easy to record thousands of hours of bird and insect sound, but one needs to analyze them afterwards and identify vocalizing species.

This takes us back to the problem of automated sound recognition raised in Monday’s post. Dr. Martin and David are collaborating with Don Hayford from Columbus Innovation Group who will develop techniques to filter out background noise (such as human voices, machinery, cars, barking dogs – all familiar sounds to our neighborhoods) and produce files of target sounds that can then be analyzed with existing software.

My role will be to provide reference sounds for the software as we need to train the software to recognize known vocalizations of local bird species. This is not an easy task because some bird species have quite varied vocalizations. Our large and diverse archive of sound recordings will come in handy, we have many recordings of local Ohio species. These should cover most of their diverse vocalizations. Our goal is to build classifiers that automatically recognize and label species in the recordings.

map of Clintonville area with proposed rain gardens (project BluePrint, Columbus OH)

Will you get a rain garden on your street? check this map

We have just submitted a grant application to help us fund some of this research. The first SongMeters will be deployed this fall and we will start monitoring the areas to get a baseline level of bird activity. Come spring the city will install rain gardens in the neighborhood and we can compare our recordings before and after the installation. This certainly is a multi-year project. We will keep you updated.

Should you see a rain garden in your neighborhood, take a picture and share it on social media #BLB #raingarden #songmeter!


Further resources:

The project BluePrint was featured in the Columbus Dispatch last January!

Learn more about rain gardens in Central Ohio!


About the Author: Angelika Nelson is the curator of the Borror Laboratory of Bioacoustics at OSU and Co-PI on the project “Determining Impacts of Rain Gardens on Urban Bird Diversity” with Dr. Jay Martin, David Wituszynski and collaborator Don Hayford.

The holy grail of sound recognition: a birdsong recognition app

Listen to the cacophony of bird sounds at dawn. Does it make you want to be able to tell which species chime in? Wouldn’t it be nice to have an app “listen” with you and list all the bird species that are vocalizing? You are not alone, this is what researchers have been and are still working on. If you are somewhat familiar with bird song, you can imagine that it is not an easy task. Every species has its own characteristic sounds. But even within a species every individual most likely sings more than one rendition of the species-specific song and does so with variations.

Listen to the songs of the Yellow Warbler, Chestnut-sided Warbler and Yellow-throated Warbler, three species in the wood warbler family, that commonly sing in Ohio in spring.

Here is an example of two different song types sung by the same Yellow Warbler male:

Training software

To develop a bird song recognition app, software needs to be trained with real bird songs. An animal sound archive that houses thousands of recordings is an ideal resource for this endeavor. The Borror lab has provided many of our 47,000+ recordings to different researchers. Recently, Dr. Peter Jančovic, Senior Lecturer in the Department of Electronic, Electrical and Systems Engineering at the University of Birmingham, UK collaborated with us. He and his colleagues developed and tested an algorithm on over 33 hours of field recordings, containing 30 bird species (To put this in perspective, to-date 10,000 species of birds have been described and half of them are songbirds – so 30 species is really only the tip of the iceberg). But, his results are promising, the developed system recognizes bird species with an accuracy of 97.8% using 3 seconds of the detected signal. He presented these first results at the  International Conference on Acoustics, Speech and Signal Processing in Shanghai.

Sonogram of Yellow Warbler, not Yellow-throated Warbler song

The software correctly identified this sonogram as song from a Yellow Warbler.

Birdsong recognition apps

Some prototypes of birdsong recognition software and apps are already on the market.

bird song recognition apps: Warblr, Chirpomatic, Birdgenie

These are some of the already available bird song recognition apps that you may want to try.


Think of them as the Shazam of birdsong (For those of you not familiar with Shazam, it is an app that identifies music for you). Instead of sampling audio being played you record the bird’s song in question. The software will then compare features of the recorded sound against a database based on pre-recorded, identified sounds, a sound library.


Challenges and problems

This simple sounding process has challenges and problems: You need to get a really good recording of the bird you want to identify, i.e. no other birds singing nearby, no traffic noise, people talking or lawn mowers obscuring your target sound. Once you have managed this, a good app takes into account where in the world, even within the USA and within Ohio you recorded the song. Birds sing with local variations. Research in our lab has focused on this for many years: Birds learn their songs by imitating conspecific adults where they grow up and will incorporate any variations these birds sing in their repertoire. Thus the recorded sounds need to be compared to geographically correct songs of each species. Once the location has been set, the app needs to compare the recording to thousands of songs, because most of our songbirds sing at least 5 types of typical song, some sing over 100. Some like the Northern Mockingbird imitate the sounds of other species.

Geographic variation in song of Yellow Warbler YEWA

Listen to and compare Yellow Warbler songs from Ohio, Maine and Mexico, Baja California and Sonora.

I hope I have not completely discouraged you from trying one of the bird song recognition apps. They truly are an innovative application of the thousands of songs that have been recorded, archived and can be listened to for free. Have you already tried one of these apps? We would love to hear your experiences!


About the Author: Angelika Nelson is the curator of the Borror Laboratory of Bioacoustics.



Jančovic, M. Köküer, M. Zakeri and M. Russell, “Bird species recognition using HMM-based unsupervised modelling of individual syllables with incorporated duration modelling,” 2016 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Shanghai, 2016, pp. 559-563. doi: 10.1109/ICASSP.2016.7471737

Bird song ID apps

Bird Song Id USA Automatic Recognition and Reference – Songs and Calls of America


A comparison of Chirpomatic and Warblr for birds recorded in the UK.

One of these skulls is not like the others

When we receive queries for identification of skulls or specimens, we turn to our large specimen collection to find those that look similar and may help in the identification process. Among other osteological features we can look at the proportions of the skull, along with the size, number and spacing of the teeth. All these features of a recently received picture of a specimen in question led me to suspect that the specimen is foreign to the Great Lakes, and based on the very small size of the specimen I suspected that it may be a Round Goby. Following I will show you some of the specimens I looked at to bolster my conclusion.

Let’s start with a picture of a Round Goby from our collection:

skull of OSUM104702 Neogobius melanostomus Round Goby

OSUM104702 Neogobius melanostomus, Round Goby

Note the width of the skull, and the abundance and spacing of the teeth on this specimen.

The species that I considered to have the skull that would most closely match the proportions of the putative goby skull was the Central Mottled Sculpin.

head of OSUM37269 Cottus bairdii Mottled Sculpin

OSUM37269 Cottus bairdii, Mottled Sculpin








But here you can see that the head of the Mottled Sculpin is actually wider than, and the teeth proportionally not as large as those of the Round Goby (there are several other skeletal differences but those sufficed for this diagnosis).

There are several native fish that are carnivorous and have caniniform or cardiform (small, numerous and closely spaced) teeth that I mused over, but as you can see almost all of those have much narrower skulls and/or have shorter, fewer and more widely spaced teeth than the skull in question.

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Note: The Sauger, very close in appearance to the Walleye, was once abundant in Lake Erie but is now caught very seldom in the lake and its tributaries.

As you can see there is nothing quite like the Round Goby among our native species, and we should no doubt be thankful for that!

head of OSUM104702 Neogobius melanostomus Round Goby

OSUM104702 Neogobius melanostomus, Round Goby

Let us hope that the situation remains the same, and in the meantime, if you find a good use for these little monsters feel free to apply it and let us know your ideas.


About the Author: Marc Kibbey is Associate Curator of the Fish Division at the Museum of Biological Diversity.


What it takes to be a successful Invader

Invasive species have received a lot of bad press, but let’s face it, some of these alien species really have what it takes to make it!  One example of a highly successful invasive species is the Round Goby, a native to central Eurasia including the Black Sea and the Caspian Sea.

Male Round Goby in black spawning coloration

Male Round Goby in black spawning coloration

Identifying an alien

Recently a graduate student in Michigan sent a request for identification of a fish skull.  When I saw the skull on a photo that the student attached to the inquiry my first thought was that this is a species I haven’t seen before.  I was thinking to myself, “in my mind I’ve got a fairly good catalog of all the native species that are found in the Great Lakes, so this one is probably exotic”.  Furthermore, I examined the teeth and the rest of the skull picture, and found features that are similar to the marine blennies and gobies that I’m familiar with; quite possibly a Round Goby.

OSUM 104701, Neogobius melanostomus skull

OSUM 104701, Neogobius melanostomus skull

When one observes the teeth of a Round Goby skull, it becomes readily apparent that they are eminently suited to catching prey: numerous, closely packed and somewhat curved teeth. Once the fangs are sunk into the prey’s body it would be difficult to wriggle out of the goby’s maw.  Speaking of the “maw”, the width of the Round Goby’s head and mouth are somewhat disproportionately large in comparison to the size of the body.  This aspect of the anatomy amplifies the capacity of the fish to suck in its prey.  By opening the mouth quickly a vacuum is created, which when combined with the sudden forward lunge that the goby employs toward the prey, improves the likelihood of successful capture.

Neogobius melanostomus are extremely aggressive and will challenge fishes larger than themselves, outcompeting native fish for preferred habitat as well as preying on other fish’s eggs and young.

What makes the Round Goby so successful?

Round Gobies are found primarily in the benthic zone of the water body, from the bottom of shallow areas down to 70 feet in depth.  They prefer areas where there is plenty of cover such as around rocks, sticks and logs.  The species has been found to tolerate polluted conditions, which enables it to occupy areas that less tolerant species cannot live in. This increases their opportunities to grow into a large population that aids in overcoming the other species in less polluted areas.  Another aspect of their biology that enhances their prowess is a highly developed lateralis system, a fishes’ sensory system conveying environmental information to the brain and making them an effective competitor and predator in dark, murky conditions as well as in clear daylight.

High productivity is a hallmark of an effective invader.  A mature Round Goby female is able to produce over 3,000 eggs, the older the female the more eggs they produce.  The male uses posturing and coloration (see the photo above) to attract females to its nest, often mating with more than one female.  The females spawn up to six times in a season, which lasts all summer long from April through September. Let’s do the math: a female could produce 18,000 young in just one year, that’s a lot of Round Gobies!

Although the deleterious effects of this intruder are considerable in scope, as some research here at OSU has shown, one must nonetheless admire their capabilities.  But we should keep in mind that without our assistance it is doubtful that Round Gobies would have spread so far and certainly not so quickly.  Their ability to tolerate euryhaline conditions, a wide range of salinities, facilitates their natural spread under normal conditions over a much longer time. It has allowed them to survive in the ballast waters of vessels and occupy new areas when the ballast is flushed.

Although they are best known from the Great Lakes they are now found in the lower reaches of larger rivers and have been captured in the Illinois River drainage, presaging their invasion of other Mississippi River tributaries.

map of Round Goby invasion in Great lakes regionBut thus far the most dramatic spread of the Round Goby has occurred in the Great Lakes of North America where a lack of effective competitors facilitated their occupation of new territories.

Northern Europe, too, has suffered from a Round Goby Invasion as shown in these maps and the potential for their spread in Europe is estimated to be much greater. You can follow them on AquaMaps, enter genus “Neogobius” and species “melanostomus” to obtain a map showing their predicted spread.

map of Round Goby invasion in Europe


Because they are not tasty to humans it is hard to truly appreciate this fish from any perspective other than that of their successes as invaders. But to a larger, piscine predator they must indeed be tasty as they have become a substantial part of native gamefishes’ diet.  And for Lake Erie water snakes, as well as aquatic birds like gulls and cormorants, Round Gobies are a major new item on the menu.  Indeed, Round Gobies are so abundant in Lake Erie that frustrated anglers often complain that the pesky little perciforms are the only thing they can catch.

The Round Goby is here to stay, and changes wrought by their incursion will reverberate for decades across the Great Lakes at least. Have you caught one yet?


About the Author: Marc Kibbey is Associate Curator of the Fish Division at the Museum of Biological Diversity.

Freshwater Mussels Vs. The World

Did learning the difference between the lifestyle of the freshwater vs. saltwater mussels whet your appetite? Are you curious whose cousin you are consuming when slurping scallops or opening oysters?  Do you catch yourself wondering at night if sea slugs are really related to land slugs? Is your superpower talking to octopuses and you want to know what other animals you may be able to communicate with? We have got you covered.

This time, we are going to discuss the relationships between all these molluscs, so you can learn just how distinct these organisms really are.  You will finally be able to join the club* of polite pedantic people standing with on the borderlines between clades reminding anyone who will listen that these organisms are distinct! Among our allies are those who pipe up whenever someone calls a spider monkey an ape and folks who visibly wince whenever anyone implies that a spider is a bug. This is the kind of knowledge you can brag about. You’ll never need something to talk about on a date again. Those long thanksgiving dinners with extended family will be a breeze! Shells are easy to carry around as props so you can always be prepared!

*there is no club


(Those of you who already know the difference are also invited to read on but are given explicit permission to feel slightly smug while doing it. It’s a win either way.)

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