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Fish Doctors: A Lesson on Walleye Catchability and Size

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March 22, 2012
Fish Doctors: A Lesson on Walleye Catchability and Size - 1

Ph.D.’s know more about the secret lives of gamefish than any fishing pro might hope to. Outdoor Life sought out some of the biologists whose work is on the leading edge of this revolutionary research. Their startling revelations are guaranteed to make you more successful this season.

Are your chances of fishing success better in a lake that contains a lot of fish or a few fish? Where are your chances best for trophy fish?

If you’re into walleyes, two fascinating studies, one from Cornell University and another from Laurentian University in Ontario, contain some intriguing new information.

The Study
The Cornell team, led by Anthony VanDeValk, sought to explain something of a conundrum taking place on New York’s Oneida Lake: Why is walleye catchability seemingly higher in years when walleye populations are lowest? Since 1957, creel surveys and angler interviews have been used to estimate angler catch rates on Oneida. Fishing success ranged from 0.04 fish caught per angler hour in 1957 to 0.47 in 2003. Meanwhile, walleye population density was estimated at 53.7 fish per hectare (about 2.5 acres) in 1957 and 18.5 in 2003. It hardly seemed to make sense, until walleye growth rates were thrown into the equation. Growth rates ranged from 51.6 mm in 1957 to 16.8 in 2003. So exactly what is happening? A fluctuation in the abundance of prey fish held the key.

Lessons Learned
“In Oneida Lake, the angler catch rate decreased as annual walleye growth increased, suggesting that prey abundance significantly affected angler success and was more important than walleye density in determining catch rate,” the study concluded. “Angler catch rates were not related to walleye population density. However, by combining population density and walleye growth, we were able to explain the variability in angler catch rates. High angler catch rates are likely to occur during years with low prey abundance.”

What It All Means
Although researchers admit that additional information regarding the relationship between anglers, fish, and prey is needed before drawing conclusions with any sort of finality, anglers might well be able to predict their chance for fishing success by gaining information on the relative abundance of prey fish in a particular lake. State fisheries biologists can provide information on prey fish spawning success—offering clues for future fishing success.

They Are What They Eat
Walleyes have eclectic tastes. And some walleye food packs an extra punch. The results of a 10-year study by researchers from Laurentian University indicates that ciscoes are like steroids for wall-hanger fish.

The Study
To assess the effect of ciscoes on walleye bulk, researchers studied 215 lakes across Ontario—60 of which contained yellow perch but no ciscoes and 155 of which contained both yellow perch and ciscoes.

Lessons Learned
According to researchers, data indicated that female walleyes (which are larger than males) had the potential for trophy growth when larger prey—ciscoes—were present. A full 49 percent of the lakes with small ciscoes also featured trophy walleyes.

What It All Means
Doing a bit of homework ahead of time can help you score on a trophy walleye this season. Since ciscoes are critical to trophy walleye growth, start with your state fisheries agency to locate bodies of water with good populations of ciscoes.
“Also, look to larger lakes with lower walleye densities,” says Michael J. Hansen, professor at the University of Wisconsin. “The same is true with muskies.”

Click here for original article.
Learn more about research on bass.
Learn more about research on crappies.
Learn more about research on rainbow trout.

Comments (1)

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from Richard Ziert wrote 2 years 4 weeks ago

Bass/all fish are what they eat – sound familiar? In the face of the never ending debate on predator prey relationships, common threads boil down to “what is eaten”, “who does the eating”, and then, how can this benefit us in catching more bass? I’m sorry for all of us but, in the past, way too much information has been glossed over to our disadvantage. For example, a time worn and “almost” useless statement is: “Bass diets vary with what’s available and its abundance at the time.” It’s not enough. Stay with us and we will expose a little more of those vague undersides, leading to you increasing your catch.

Of the many things eaten in this world, protein is the one essential that provides growth and stamina. Varied diets produce trace elements of all kinds and usually get any creature by as far as those basics are concerned. Except for the algae/plankton (glucose) eaten in the fry stage, and imprinting the young with a life long desire, the food adult bass eat contains very little sugar like substances. Therefore, fast carbohydrate burning is out, and aerobic muscle burning is in. This, and slowed metabolism, are reasons why they eat less, move less in cold water and more in warmer water with a heightened metabolism. But, there is a sweet unknown of life contained here; see if you can find it as we go along.

Protein is special. Too much protein in diets make you smell like a carnivore. Bass are carnivores, and because they largely eat protein to survive and grow, they stink like carnivores. A little known deer hunting secret is to go on a veggie diet a week before you enter the field – so you don’t stink in a way that alarms your prey. Prey fish know what a predator carnivore smells like.

Here are some statements that should help us.

• Protein is an essential part of a healthy diet. It forms the building blocks for muscles, blood, immune system and more. If bass aren't getting enough fuel in the form of carbohydrates and fat to run their body properly, and by and large they don’t, energy from protein is necessary to run their bodies.

• Lack of protein in the diet can lead to loss of muscle mass, stunted growth, impaired immunity and weakening of the circulatory and respiratory systems. This sort of protein shortage is rarely seen in the bass fishing because it is easy for them to get enough protein

• High protein diets call for exercise in order that kidneys and other organs do their job of flushing wastes out of the system effectively. Another issue regarding getting too much protein is leeching of calcium from the bones. The acids released by the body as it digests protein are absorbed with the help of calcium. So if bass aren't getting enough calcium, their body will take calcium from their own bones. Along with the skeletal mass of prey, and other chemical exchanges, is water pH important or what? Hard Water lakes have lots of calcium.

Let’s look at the average estimated amount of protein contained in the things bass eat.

• Shad come in at the low end of the scale of 15-30% for all fish bass eat. Actually there’s a little more fat in shad than other fish.

• Crawfish: About 14% protein

• Earthworms, and other crawly creatures: 60-70% protein; outdoing the pork, chicken, we eat.

• Grasshoppers, and sundry bugs: Ranging to 60%, insects are all over the chart on the amount of protein they contain.

Thinking about energy control vs. loss, bass will generally eat the easiest, most vulnerable meal set before them. But as we will see, that’s not always the case. In view of the amount of protein in earthworms, and the ease of capturing this prey item, it looks like nature takes care of its own.

As with all organisms, energy sources fuel metabolism, growth and reproductive functions such as egg production skin and muscle formation. Protein reproduction occurs best at or near neutral pH. . . resulting in bigger and/or healthier fry and fish.

The dynamic process of balancing nutritional needs responds to many situations that can cause changes in feeding behavior. Dietary needs change as the bass develops and switches from fry to adult stages. Reproductively mature adults exhibit sex-specific changes in setting aside nutritional resources to be used in differing ways. In addition, depending on the adequacy of the diet for direct needs, internal physiological and biochemical processes may again set aside internal nutrient resources to satisfy new requirements. As a result, certain actions, such as egg production or growth, cease if the diet becomes not enough to get the job done.

These shifts happen often in natural settings if only poor-quality food is on hand to meet needs. As a result, internal reallocation of nutrients may alter feeding behavior. Total consumption can increase or decrease or cause switching among available food sources to adjust the intake to meet new nutritional needs. There’s no element of chance involved with when bass switch seasonally available food sources. Along with the easy meal there is a meal type obsession or single mindedness when suitable physiological pathways create them seasonally.

Few bass eat only a single or even just a few prey species. This activity benefits them in many ways including adaptive behavior.
Bass that feed on mixtures of prey typically grow at faster rates than when fed a single source.

A few more essential statements:

• Diet mixing can weaken potentially poisonous chemicals.

• Diet mixing provides a better balance of nutrients if bass can sense the differences between prey species and pick ones whose nutritive profiles correct the basses need. Best diets formed in this fashion would counter incomplete nutrition obtained from single source.

• Evidence supports a variety of additional means that cause dietary mixing, including learning, changes in perception of chemical agents, especially in the sense of smell, and arousal with feeding cues.

• Dietary imbalance often alters feeding behavior to pay the costs for less than best meals. Each meal is unlikely to contain the best possible balance of required nutrients.

• Also, bass cannot regulate the intake of one nutritional grouping without at the same time altering the intake of all others. By varying the intake of prey, bass can control nutrient balance.

• When food is lower in quality, bass typically eat more often for a longer period.

• The time that the food remains in the belly for digestion increases as diet quality increases. As expected, the longer food remains in the gut, the greater is the absorption rate, thus very little is waste.

• In addition, weight gain generally increases as food quality increases, although temperature-dependent metabolic effects can modify this response.

• Bass metabolic rates increase with temperature, thus requiring faster energy intake to maintain a constant energy balance. At higher temperatures, weight gain may decrease because an increased metabolic rate burns off energy otherwise owed to growth. Age and prior food shortage can also exhibit major impact on feeding triggers. An important interaction between tastiness and scarcity exists with the presence of sugar, rather sugar like substances which becomes a feeding stimulus. On cold, cloudy days, metabolism slows. On sunny warm days it speeds up, often sending bass to cooler areas.

• Bass body size also influences meal size. Large bass can eat more than small ones because of the absolute differences in gut volume. Bass can compensate for poor-quality food by increasing the allowance to the belly. This ability results in a larger gut size, which in turn increases the ability to extract resources from food.

• Feeding history can govern bass movement, although few details exist. Bass exhibit lowered activity levels and move shorter distances after feeding on high-quality food. Such behavior may explain why bass densities increase in weed patches, or algae blooms that are healthier than others; a cause of quality prey. At times due to oxygen depletion, and increased phosphorus levels, too much water plant life of any kind is no good for anybody.

• When physiological needs shift, internal controls must shift for that reason. Thus, feeding-control mechanisms balance nutritional needs at several levels, some of which cannot always be satisfied all at once: water, protein, energy, trace minerals, and nutrients such as naturally occurring steroids and fatty acids, specific free amino acids, and vitamins.

• Other chemicals, such as specific amino acids, act as feeding triggers. During crawfish molting, the shell is completely rebuilt. Shell formation requires large levels of the aromatic amino acid phenylalanine, equivalent to Aspartame, an artificial sweetener. I can see the flash bulbs going pop from here. Aspartame on your crawfish baits! Please, not so fast with that idea. There are other things to know before we think about going there. Aside from the fact that you can catch more fish than dreamed of before, we could collectively upset the lakes entire ecosystem, changing habits and life itself as aquatic animals/creatures know it, Please think of this for the informational value here, and be ethical.

• Cold blooded creatures including crawdads regulate there way of life seasonally with air and water temperature. Commonly found shallow, crawdads, without the preferred temperature cover, will migrate deeper during and somewhat after the summer peak. Bottom dwellers mostly, except at night; often climbing the stalks of weeds, and where they may eat some vegetable matter (containing the plant sugar glucose). Along with eating insects and other animals living with them, Crawfish are cannibals, eating there own kind regularly and searching out those that are molting; phenylalanine being the trigger again. Along with fresh, or otherwise healthy green veggies containing sugar like substances as favored food, something to hide under at basin level, and a reasonably good flow of quality water in the area, these are adjunct reasons to find several in specific areas at definite times.

Needless to say, dynamic relationships define food consumption, what triggers come into play thereafter, and require a multidimensional approach can exhibit different effects, but still lead us to a greater catch. Hope you picked up and put together a bunch of stuff here to use on the water. Glad to have you with us today.

Peace

Credit for basic biological, physical, and other vital information contained here can go to myriad professional resources who, have worked and reworked the material over the years. Connecting and weaving the fabric, adapting it to bass fishing however, is the sole responsibility of a perceptive weaver/tailor/fisherman by the name of Richard Ziert If you want specifics, we invite you to send a “letter to the editor”.

-1 Good Comment? | | Report

Post a Comment (200 characters or less)

from Richard Ziert wrote 2 years 4 weeks ago

Bass/all fish are what they eat – sound familiar? In the face of the never ending debate on predator prey relationships, common threads boil down to “what is eaten”, “who does the eating”, and then, how can this benefit us in catching more bass? I’m sorry for all of us but, in the past, way too much information has been glossed over to our disadvantage. For example, a time worn and “almost” useless statement is: “Bass diets vary with what’s available and its abundance at the time.” It’s not enough. Stay with us and we will expose a little more of those vague undersides, leading to you increasing your catch.

Of the many things eaten in this world, protein is the one essential that provides growth and stamina. Varied diets produce trace elements of all kinds and usually get any creature by as far as those basics are concerned. Except for the algae/plankton (glucose) eaten in the fry stage, and imprinting the young with a life long desire, the food adult bass eat contains very little sugar like substances. Therefore, fast carbohydrate burning is out, and aerobic muscle burning is in. This, and slowed metabolism, are reasons why they eat less, move less in cold water and more in warmer water with a heightened metabolism. But, there is a sweet unknown of life contained here; see if you can find it as we go along.

Protein is special. Too much protein in diets make you smell like a carnivore. Bass are carnivores, and because they largely eat protein to survive and grow, they stink like carnivores. A little known deer hunting secret is to go on a veggie diet a week before you enter the field – so you don’t stink in a way that alarms your prey. Prey fish know what a predator carnivore smells like.

Here are some statements that should help us.

• Protein is an essential part of a healthy diet. It forms the building blocks for muscles, blood, immune system and more. If bass aren't getting enough fuel in the form of carbohydrates and fat to run their body properly, and by and large they don’t, energy from protein is necessary to run their bodies.

• Lack of protein in the diet can lead to loss of muscle mass, stunted growth, impaired immunity and weakening of the circulatory and respiratory systems. This sort of protein shortage is rarely seen in the bass fishing because it is easy for them to get enough protein

• High protein diets call for exercise in order that kidneys and other organs do their job of flushing wastes out of the system effectively. Another issue regarding getting too much protein is leeching of calcium from the bones. The acids released by the body as it digests protein are absorbed with the help of calcium. So if bass aren't getting enough calcium, their body will take calcium from their own bones. Along with the skeletal mass of prey, and other chemical exchanges, is water pH important or what? Hard Water lakes have lots of calcium.

Let’s look at the average estimated amount of protein contained in the things bass eat.

• Shad come in at the low end of the scale of 15-30% for all fish bass eat. Actually there’s a little more fat in shad than other fish.

• Crawfish: About 14% protein

• Earthworms, and other crawly creatures: 60-70% protein; outdoing the pork, chicken, we eat.

• Grasshoppers, and sundry bugs: Ranging to 60%, insects are all over the chart on the amount of protein they contain.

Thinking about energy control vs. loss, bass will generally eat the easiest, most vulnerable meal set before them. But as we will see, that’s not always the case. In view of the amount of protein in earthworms, and the ease of capturing this prey item, it looks like nature takes care of its own.

As with all organisms, energy sources fuel metabolism, growth and reproductive functions such as egg production skin and muscle formation. Protein reproduction occurs best at or near neutral pH. . . resulting in bigger and/or healthier fry and fish.

The dynamic process of balancing nutritional needs responds to many situations that can cause changes in feeding behavior. Dietary needs change as the bass develops and switches from fry to adult stages. Reproductively mature adults exhibit sex-specific changes in setting aside nutritional resources to be used in differing ways. In addition, depending on the adequacy of the diet for direct needs, internal physiological and biochemical processes may again set aside internal nutrient resources to satisfy new requirements. As a result, certain actions, such as egg production or growth, cease if the diet becomes not enough to get the job done.

These shifts happen often in natural settings if only poor-quality food is on hand to meet needs. As a result, internal reallocation of nutrients may alter feeding behavior. Total consumption can increase or decrease or cause switching among available food sources to adjust the intake to meet new nutritional needs. There’s no element of chance involved with when bass switch seasonally available food sources. Along with the easy meal there is a meal type obsession or single mindedness when suitable physiological pathways create them seasonally.

Few bass eat only a single or even just a few prey species. This activity benefits them in many ways including adaptive behavior.
Bass that feed on mixtures of prey typically grow at faster rates than when fed a single source.

A few more essential statements:

• Diet mixing can weaken potentially poisonous chemicals.

• Diet mixing provides a better balance of nutrients if bass can sense the differences between prey species and pick ones whose nutritive profiles correct the basses need. Best diets formed in this fashion would counter incomplete nutrition obtained from single source.

• Evidence supports a variety of additional means that cause dietary mixing, including learning, changes in perception of chemical agents, especially in the sense of smell, and arousal with feeding cues.

• Dietary imbalance often alters feeding behavior to pay the costs for less than best meals. Each meal is unlikely to contain the best possible balance of required nutrients.

• Also, bass cannot regulate the intake of one nutritional grouping without at the same time altering the intake of all others. By varying the intake of prey, bass can control nutrient balance.

• When food is lower in quality, bass typically eat more often for a longer period.

• The time that the food remains in the belly for digestion increases as diet quality increases. As expected, the longer food remains in the gut, the greater is the absorption rate, thus very little is waste.

• In addition, weight gain generally increases as food quality increases, although temperature-dependent metabolic effects can modify this response.

• Bass metabolic rates increase with temperature, thus requiring faster energy intake to maintain a constant energy balance. At higher temperatures, weight gain may decrease because an increased metabolic rate burns off energy otherwise owed to growth. Age and prior food shortage can also exhibit major impact on feeding triggers. An important interaction between tastiness and scarcity exists with the presence of sugar, rather sugar like substances which becomes a feeding stimulus. On cold, cloudy days, metabolism slows. On sunny warm days it speeds up, often sending bass to cooler areas.

• Bass body size also influences meal size. Large bass can eat more than small ones because of the absolute differences in gut volume. Bass can compensate for poor-quality food by increasing the allowance to the belly. This ability results in a larger gut size, which in turn increases the ability to extract resources from food.

• Feeding history can govern bass movement, although few details exist. Bass exhibit lowered activity levels and move shorter distances after feeding on high-quality food. Such behavior may explain why bass densities increase in weed patches, or algae blooms that are healthier than others; a cause of quality prey. At times due to oxygen depletion, and increased phosphorus levels, too much water plant life of any kind is no good for anybody.

• When physiological needs shift, internal controls must shift for that reason. Thus, feeding-control mechanisms balance nutritional needs at several levels, some of which cannot always be satisfied all at once: water, protein, energy, trace minerals, and nutrients such as naturally occurring steroids and fatty acids, specific free amino acids, and vitamins.

• Other chemicals, such as specific amino acids, act as feeding triggers. During crawfish molting, the shell is completely rebuilt. Shell formation requires large levels of the aromatic amino acid phenylalanine, equivalent to Aspartame, an artificial sweetener. I can see the flash bulbs going pop from here. Aspartame on your crawfish baits! Please, not so fast with that idea. There are other things to know before we think about going there. Aside from the fact that you can catch more fish than dreamed of before, we could collectively upset the lakes entire ecosystem, changing habits and life itself as aquatic animals/creatures know it, Please think of this for the informational value here, and be ethical.

• Cold blooded creatures including crawdads regulate there way of life seasonally with air and water temperature. Commonly found shallow, crawdads, without the preferred temperature cover, will migrate deeper during and somewhat after the summer peak. Bottom dwellers mostly, except at night; often climbing the stalks of weeds, and where they may eat some vegetable matter (containing the plant sugar glucose). Along with eating insects and other animals living with them, Crawfish are cannibals, eating there own kind regularly and searching out those that are molting; phenylalanine being the trigger again. Along with fresh, or otherwise healthy green veggies containing sugar like substances as favored food, something to hide under at basin level, and a reasonably good flow of quality water in the area, these are adjunct reasons to find several in specific areas at definite times.

Needless to say, dynamic relationships define food consumption, what triggers come into play thereafter, and require a multidimensional approach can exhibit different effects, but still lead us to a greater catch. Hope you picked up and put together a bunch of stuff here to use on the water. Glad to have you with us today.

Peace

Credit for basic biological, physical, and other vital information contained here can go to myriad professional resources who, have worked and reworked the material over the years. Connecting and weaving the fabric, adapting it to bass fishing however, is the sole responsibility of a perceptive weaver/tailor/fisherman by the name of Richard Ziert If you want specifics, we invite you to send a “letter to the editor”.

-1 Good Comment? | | Report

Post a Comment (200 characters or less)