I think Bill's post above is one of the all time top posts. So much there. This thread goes to the archives link .
CJ the measure to look at is total mortality which includes natural morts and fishing morts combined. It is highly variable by location , species , human predation efforts and all the biologic factors. It is another "it depends" but can be very high as a % as it would by nature have to be due to fish spawning numbers. I can find some #s but am not sure the significance of them as a measure.
That takes me to Bill's point that measuring carrying capacity is not so important to worry about much. I agree totally. I only keep it in mind as a possible warning factor in ponds that are run or to be run more like a aquaculture operation thus the thread linked early in this thread - Trophic Continuum - natural to aquaculture
http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=6;t=000162;p=1 .
Like Bill I don't think it is wise to run the pond at full tilt. That is like running a motor at high rpm for to long - something is going to break.
We are describing one of the deliminas fisheries science has struggled with since it began - what to look at and how to measure the outcome. Let me suggest the methods developed by early fishery science professors like Swingle. He knew the difficulty of measuring full pond aspects of fish populations so he developed indirect methods. Bill notes them by nature. Learning to do a population analysis can be learned thanks to Swingle and others work. You don't measure carrying capacity or standing crop as its to hard. Instead you measure fish condition as an indicator of pond health. In a natural pond condition is in part a measure of food supply and absence of stress. In crowded circumstances food is usually limited and stress higher and it is reflected in fish condition. Bill noted as follows as the common sense way " Learn how to determine when they are crowded and if your fish are adequately growing. Look and check for those features / characters. " . You can get a good estimate of this by looking at the fish , use RW (Wr) measures , do they look good and by measuring the relationship between the #s( are the numbers balance) - creel surveys , seine surveys , trap results and visual inspection.. This is not perfect but is a good measure. See the links from the archives on population analysis -
http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=92492#Post92492 .
I hope this helps some.
I think the question you ask about what to add or replace is dependent on goals. If you take out big CC you could replace them with HSB as that would be a measure (HSB) that is controlled (no reproduction).
.gif)
