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Biologist discover gizzard shap population explosion at Roosevelt

13K views 47 replies 29 participants last post by  Fishermanjonk 
#1 ·
[FONT=Arial, Helvetica, sans-serif]Arizona Game and Fish Department[/FONT] [FONT=Arial, Helvetica, sans-serif]NEWS RELEASE[/FONT]
[FONT=Arial, Helvetica, sans-serif]Dec. 1, 2008[/FONT]

[FONT=Arial, Helvetica, sans-serif]Biologists discover gizzard shad population explosion at Roosevelt

[/FONT][FONT=Arial, Helvetica, sans-serif]PHOENIX – Arizona Game and Fish Department biologists conducting an autumn fish survey at Roosevelt Lake discovered that a relatively new invader, the American gizzard shad, has experienced a population explosion here at Arizona’s largest inland lake.
“This species looks like threadfin shad on steroids,” said Fisheries Chief Kirk Young. “These wide-bodied invaders from the eastern United States are shaped like footballs and can readily grow past the size where they are available to most sport-fish as forage.”

Young added that it is a wait-and-see proposition to determine if these invasive shad will have positive or negative impacts on Roosevelt or possibly the other popular fisheries along the Salt River.
During the recent fish survey at Roosevelt Lake, most gizzard shad sampled were in the 9- to 14-inch range and the largest two shad measured 17.7 inches long and weighed 2.3 pounds.
“We are still entering all the survey data, but based on what we saw during the sampling process, it appeared that gizzard shad were almost as numerous as the largemouth bass,” said Natalie Robb, the Mesa regional fisheries program manager.
At Roosevelt Lake, gizzard shad were first discovered during water quality sampling during January of 2007. Department biologists at the time recognized that gizzard shad are capable of rapid reproduction – a single female can produce up to 400,000 eggs. But the biologists were not expecting these newcomers to experience such a rapid population expansion.
Gizzard shad, which are native to the eastern United States, will likely compete for space and food with threadfin shad, another nonnative that has become the primary forage fish for sport-fish in the state’s larger impoundments. Immature gizzard shad will also compete for food sources with the larval stages of popular game fish.
However, at about 1-inch in length gizzard shad become more specialized, lose their teeth, exhibit deeper bodies and become filter feeders that consume small invertebrates and phytoplankton (free-floating algae).
“In Texas, they have found that bass can’t generally eat gizzard shad larger than 7 inches long,” said Robb, adding that on the plus side, these large shad can provide a significant meal for bass that do eat them.
Gizzard shad are seldom caught by hook and line and their pungent odor and soft flesh generally render them unsuitable as table fare, but in some parts of the country anglers use them as cut bait for catfish.
Robb explained that in most Arizona lakes, the predominant forage fish is the threadfin shad, which even as an adult is readily fed upon by sport-fish species such as largemouth bass, smallmouth bass and crappie.
However, gizzard shad grow to about 4 inches in length during their first year and readily grow to sizes of 9 to 14 inches in length, yet can exceed 20 inches in length. In Texas, a gizzard shad harvested with a spear gun measured 18.25 inches and weighed in at 2.97 pounds.
Based on the experiences in the Colorado River Basin and other locations where gizzard shad have invaded, biologists said these quick-growing, rapidly-reproducing shad from the herring family will likely spread to the other lakes along the Salt River, such as Apache, Canyon and Saguaro.
Biologists at Lake Powell first noted gizzard shad in 2000 near the San Juan inflow. In netting surveys at Powell in 2006, gizzard shad accounted for almost as much fish flesh as striped bass. These large invasive shad have spread to Lake Mead as well as the headwaters of the Colorado River.

Gizzard shad life history
Gizzard shad feed on both phytoplankton and zooplankton, which are then ground in the gizzard section of the gut.
This species is most often found in large schools. Its common name “skipjack” is derived from the fact that schooling gizzard shad can sometimes be seen leaping out of the water or skipping along the surface on their sides.

Dense schools of young gizzard shad provide forage for predatory fish such as bass, but these wide-bodied shad quickly grow past the primary prey size.
Gizzard shad spawn in the spring, usually in shallow protected water. Eggs and milt are released in the school, seemingly without regard for individual mates. Adhesive eggs attach to submerged objects and hatch in about four days. A single female can produce around 400,000 eggs.
Young gizzard shad feed on microscopic animals and plants, as well as insect larvae. Adults feed by filtering small food items from the water.
Characteristics: Bright silvery blue-green on back, silvery sides and dull white belly. They have a wide body that is stockier than most herring.
Native Range: Extends from the Great Lakes and St. Lawrence River west to eastern South Dakota and central New Mexico.
How to tell gizzard shad from threadfin shad: Gizzard shad have an upper jaw that projects well beyond the lower jaw. If you run your finger underneath the mouth forward and if the fingernail catches on the upper jaw and opens the mouth, you have just become acquainted with a gizzard shad.

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#6 ·
Well that sucks! I am getting a bit pissed off by all the invasive species crap happening in this state lately.
Yep, this state does have some definite issues. We have had lampreys in lake Michigan, now gobies & zebra & quagga mussles. Some asian snakeheads have been found in some inland lakes also. Viral hemorragic septicemia [ vhs] in Winnebago lake, as well as some of the fox river chain of lakes. All in all, I think alot of places are dealing with something that is invasive. Too bad AZ fish & game wont purchase some few thousand gorrilla bass to chow the smaller gizzard shad fry........Anyone google "gorrilla bass" yet ? Pretty interesting stuff :blink:
 
#3 ·
This is not good to hear.
John
 
#8 ·
People were talking bout these gizzard shad a couple years ago in Rosey, I HATE how G&F says they will wait and see if these fish have a positive or negative impact on the salt river chain of lakes, hell do some studies, try to figure it out before its to late into a negative situation. They should just say, Uh, well we dont really want to do anything today so we'll just sit here and see what happens.
 
#9 ·
Kevin that might sound easy, but if you really think about it what really can be done? I mean seriously what can be done.

let say someone dumped a shit load of northerns in a lake, what can be done about it?

posion the lake? drain the lake? put something else into the lake to control that problem? then what controls the problem they just created?



 
#11 ·
Now that i know what a gizzard shad looks like. im pretty sure ive seen one years ago at san carlos.

my dad was throwing a cast net for shad and got about a 9incher we didnt really know what species it was. i think Ghetto was there but we were only guppies at the time
 
#13 ·
I say we get while the gettin is good. Beat the hell outta rosy, create as many memories as possible, release the bigbass to eat what they can, they will survive ok, the smaller ones will have to shift to gills or other panfish & craws for a change. Netting the shad is ok, but sort thru what you bring up. They do make excellent catfish bait. In reality theres nothing we can do. Fish & game has thier agenda & catering to anglers obviously isnt one of thier priorities. Some states rely upon tourism dollars to supplement them, outdoor activities are top priority. The $$ generated by anglers is often overlooked until the shortage is noticed later. This is what we get for a $53.00 conservation license ? jmo........
 
#15 ·
I say we get while the gettin is good. Beat the hell outta rosy, create as many memories as possible, release the bigbass to eat what they can, they will survive ok, the smaller ones will have to shift to gills or other panfish & craws for a change. Netting the shad is ok, but sort thru what you bring up. They do make excellent catfish bait. In reality theres nothing we can do. Fish & game has thier agenda & catering to anglers obviously isnt one of thier priorities. Some states rely upon tourism dollars to supplement them, outdoor activities are top priority. The $$ generated by anglers is often overlooked until the shortage is noticed later. This is what we get for a $53.00 conservation license ? jmo........
I agree its bad but........ Gizzard Shad aren't the end of the world!!!
SWIMBAITS:icon_twis
 
#19 ·
There is really nothing game and fish can do about it. That's why it's called an invasive species. The rest of the fish will adapt or deminish in numbers, that's the way nature works. The only thing that could be done is to sterilize the water and start from scratch, and outlaw all live bait, and I don't think anyone wants that. (except the live bait thing)
 
#21 ·
For those of you that didn't take the time to google Gorilla Bass, this is interesting.

http://www.nighthawkpublications.com/journal/journal166-1.htm
THE TIGER BASS AND THE GORILLA BASS

The Birth of the Super Bass


EDITOR'S NOTE: Barry Smith of Montgomery, Alabama, a longtime fisheries biologist, co-owns American Sport Fish in Pike Road, Alabama, one of the largest private hatcheries in the Southeast, with his partner Don Keller. Smith and Keller have developed several breeds of fish that landowners enjoy stocking in their ponds that may find their way to public waters one day. To keep avid fishermen updated on the newest information and the future of bass fishing, we talked with Smith about the two new strains of super bass that have been developed and now are being stocked into farm ponds, the Tiger Bass and the Gorilla Bass.

QUESTION: Tell me about these super strains of bass that you and your partner, Don Keller, at American Sport Fish have developed. How did they evolve? Why are they super bass? Why are they called the Gorilla and the Tiger?
ANSWER: We've found that even if you can grow a 20-pound bass in a lake, if you can't catch the fish, it has no value. No one wants to hear, "Yep, I've got some 12 or 14 pounders in that pond, but I don't think you can catch one."

We started out stocking the Florida strain of black bass when we got in the stocking business because we knew the Florida bass had good growth rates, especially after year three, and they lived a long time. However, we also knew from the beginning that Florida bass were hard to catch. But we tried to push that thought back in our minds because we really wanted to grow big fish. Seven or 8 years after we stocked the bass, lake owners said they wanted to drain their lakes because they hadn't caught a bass for 2 or 3 years. They thought all of the bass were gone. When we took our electrofishing boat with the monitor out onto the lake, we saw huge quantities of 6- to 10-pound bass. The pond owners were amazed, but they just couldn't catch those bass.

Once Florida bass get bigger and older, they don't want to bite a lure. We knew this was a little bit of a problem, but we didn't realize the scale of the problem. If you want to catch Florida bass, your best bait is live bait and even then catching the older, bigger bass is difficult. When they get older, they're reluctant to bite artificial baits. One thing we tried to determine was how we could grow large bass quickly that would be easier to catch.

To solve this problem, we've been breeding two strains of largemouth bass for 12 years. We call the super-aggressive northern strain the Tiger Bass, and the hybrid, which is a cross between the Tiger Bass and the Florida strain of black bass, the Gorilla Bass. These bass both are subspecies, meaning they are genetically different from the northern strain. The Tiger Bass are much more aggressive feeders and are easier to catch than the Florida bass. You actually can selectively breed these fish to be more aggressive over a period of time.

QUESTION: How did you discover that?
ANSWER: Even during the early days of our work, we learned that certain bass exhibited aggressive feeding behavior in a group. Certain fish would be the first to go after food that you threw out to them. We selected the most-aggressive bass from that group of the northern strain of bass and started breeding them. Then we selected their most-aggressive offspring and bred them. We continued this selection and breeding process over a long time until we developed a super-aggressive bass -- the Tiger Bass.

QUESTION: How long have y'all been doing this selective breeding process?
ANSWER: We've been doing this about 12 years.

QUESTION: So exactly what is the difference between a Tiger Bass and a Gorilla Bass?
ANSWER: The Gorilla Bass is what we call an F1 hybrid. This term is used for what occurs when you take two different subspecies and breed them. When we breed the really-aggressive northern bass that have been selectively bred (the Tiger Bass) with a pure Florida-strain bass we get the Gorilla Bass, which has the Florida strain's genetics, which enables them to grow to very large sizes at a rapid rate and have the aggressiveness of the northern bass. The resulting F1 fish the Gorilla Bass -- is extremely aggressive and extremely fast-growing. So, when Gorilla Bass reach 3 to 5 years old, they weigh anywhere from 6- to 10-pounds each. They'll continue to exhibit that aggressive feeding behavior, and anglers can catch them on artificial lures.

QUESTION: What size bass do you stock?
ANSWER: We stock 2-inch-long bass in new ponds.

QUESTION: How long does an F1 (the Gorilla Bass) take to reach 8 pounds?
ANSWER: They'll weigh 8 pounds in about three years. We've seen some of these fish reach 2-1/2 to 3 pounds in size in one year.

For more information about American Sport Fish, write P.O. Box 20050, Montgomery, AL 36120, or call (334) 281-7703.
 
#24 ·
Theres a post on this from like 2-3 years ago maybe longer. I believe we were all talking about the strongest fight bass and spotted bass came up then someone posted about the tiger and gorilla bass, it was was pretty interesting. its wild what people will do to invent a new species.
I wonder if this is an updated version on it, the old article had some really good details and some pics also I believe a video.
 
#23 ·
I believe that G&F actually do a pretty grreat job in this State. Listen guys, we live in a desert, and we fish for bass. We fish forall kinds of fish in this State and in somecases the fishing is world class. We hunt when we can and our hunting can be world class. Our human population is HUGE compared to our wildlife population but we can all enjoy a bit of it now and then.
This isn't Tennesee where you can't throw a dead cat without it landing in a lake or river or hit a whitetail. But we have 10 big game species, a crap load of small game, and a pretty good diverse population of fish to persue.
Yeah it isn't the best, but Geez, what do you want? Can't get drawn for elk? Quit putting in for rifle rut hunts in unit 1, or Muley Hunts in 13B. Or be patient.
Our fishing and hunting is manged pretty well by G&F, it's mostly us, the users, that screw it all up. Theres what?, a thousand G&F officers and researchers in the State? Theres 100,000 hunters and 1 million water users. They do the best they can, and sometimes I think we can cut them a little slack.
 
#26 ·
Don't put Northerns in the Lakes. A few years ago the Colorado DOW put Northern in lakes to manages the sucker population and now the they are eating the game fish. Last year when I was fishing at Spinney the DOW was gill netting and pulled in a 56 inch Northern that had a complete 36 inch trout in its stomach. Just came up behind it a swallowed it whole. They are great to catch but we have had to drain 3 lakes now to get rid of them.
 
#27 ·
Ridiculous! Northern's will eat the hell out of Stocker trout and an occasional bass but are not worthy of draining a frickin' lake over. They inhabit almost every body of water in Michigan and the Bass and Crappie fishing is second to none. I fish my uncles 35 acre lake that is full of pike and always has been. The Largemouth fishing is unbelievable as is the crappie. I get tired of people thinking the Northerns are some sort of Pirahna or something. Maybe we should drain Sag and Canyon so the Bass can't eat the Stocker Trout.: Jerk-it
 
#29 ·
#32 ·
Muskie and bass in the same lake are a great mix. I have fished some top bass lakes that also had a healthy supply of muskie that makes for some great excitment. It is hard on the top water lures as you pop for bass and all of sudden a giant muskie arches out of the water and slices your line and swallows your top water plug.:)
 
#38 ·
Thats a pretty stout looking gizzard shad. I'll bet my job that there are plenty of bass in rosey easily capable of eating it and others. Stop worrying about the spilt milk per say and lets spool up and go get them 2 lb eating gizzard shad bucket mouths.

who's coming along ???
 
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