3 replies to this topic

[jetajockey]

Just a thought I've had.  In the different sampling places I go to, it seems like the most density of specimens turns up in areas where humans frequent, i.e. bridge overpasses, boat launches, public parks, etc.  They seem to be far more productive than a bed of weeds out in the middle of nowhere, anyhow.  

 

So maybe the human presence brings with it a food source and this helps the populations?  Or is this just my run of luck?

[littlen]

I think the coincidence you are noticing is that where there are man-made structures placed in the water---boat launches, bridges, etc----there are more fish.  But there is a direct correlation.  Prey species hang around structure for protection.  Predators hang around the prey.  Think of a coral reef.  The small reef fish hang in/around the coral.  And very few stray far into the open water.  And the larger predators are always looming nearby.    The more suitable habitat we produce in a given body of water, the more potential there is greater number of predator/prey species.

[zooxanthellae]

Just a thought I've had.  In the different sampling places I go to, it seems like the most density of specimens turns up in areas where humans frequent, i.e. bridge overpasses, boat launches, public parks, etc.  They seem to be far more productive than a bed of weeds out in the middle of nowhere, anyhow.  

 

So maybe the human presence brings with it a food source and this helps the populations?  Or is this just my run of luck?

 

You should look to see if you frequent man made structures for collection more often than these middle of nowhere sites, as it is possible you are experiencing some sampling bias. 

That aside, man made structures often work as current breaks, which invite all sorts of fish in. Below are a few images I took of a boat ramp a few years ago, the fish were all there to rest from the higher than normal flow. This may be an extreme example (post hurricane water levels)  but it stands to reason the current break exists year round:

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[Betta132]

It's definitely the structures themselves that fish like, rather than the humans. A never-used bridge in the middle of nowhere will have about the same fish population as a similar bridge in a more active area, possibly more fish due to less disturbances. 

Also, if humans are catching large fish and keeping them, the numbers of small fish in the area will go up. That could be contributing to what you're seeing.