Musings on the balance of nature and it's effect on the Delaware River trout

Finally got around to adding up Aprils catch and comparing it to those of the last twenty-five years. This year ranked fourth for number of fish caught. It is clear that the best April fishing occurs when the reservoirs aren't spilling and there is plenty of sunshine to warm up the lower water flows.  This of course gets the bugs going sooner
which results in better early fishing.

Exactly fifty percent of the fish caught this April were at least seventeen inches long.  This percentage fluctuates quite a bit from year to year especially with rainbows as they are comparatively short lived and a large year class can cause big swings in the percentages.

Back in the nineties the percentage of big fish usually ran about fifteen to twenty percent.  In recent years the percentage usually runs between forty five and sixty five percent. Assuming my fishing ability has remained fairly constant, this would indicate that there are either more big fish now in the river or less small fish or a
combination of both.

What has caused the change?

 Over the years I have observed a number of factors that could impact the make up of the fish population. A "no kill"  section was created. Creel limits were reduced throughout the system. Peer pressure to release fish has increased along with the increase in the number of fishermen. Regulations have been put in place closing major spawning areas to fishing after October fifteenth and opening day on rainbow spawning streams has been pushed back to protect spawning fish.  All of these things should result in an increase in the number of fish.

 On the negative side ,however, there has been a marked increase in the predators that now call the river home.  Great Blue Herons continue to patrol the shallows.  Large striped bass follow anglers around in some pools and either take fish that are hooked or as soon as they are released.  Eagles that only wintered here twenty-five
years ago now raise families all along the river.  Mergansers take a tremendous toll on yearling trout throughout the system. River otters are now commonly seen running along the banks of the river. Perhaps the predator that has the greatest impact on the decline in the young trout population are the big trout themselves who dine on their
offspring throughout the year (who hasn't hooked a yearling trout and had it end up cross ways in a nineteen incher's mouth)..

In the end, the biomass in the river is probably determined by low flow rates that concentrate both predator and prey in a smaller arena. The increased flow rates we now have have most likely allowed an increase in the biomass over what it was in the early nineties.  The big difference is that it is made up of more bigger fish with fewer
young fish reaching catch able size.

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