Originally Posted By: ewest
The most efficient size pellet is one that is about 25% of average mouth gape.

• The pellet size should be approximately 20-30% of the size of the fish species mouth gape. Feeding too small a pellet results in inefficient feeding because more energy is used in finding and eating more pellets. Conversely, pellets that are too large will depress feeding and, in the extreme, cause choking. Select the largest sized feed the fish will actively eat.


Eric, I find this deeply interesting. The fish seem to be disinclined to eat pellets greater than 30% the gape. Is there any reason why the same fish wouldn't be less inclined to eat natural foods whose width is greater than 30% the gape? I consider this important with respect to the size structure of prey fish for optimum predator growth and ultimate standing weight (especially in a two species combination like LMB and BG). If the same rule would apply to LMB it would suggest that optimum forage length is attainable within the first year or year and a half of BG life. Under optimum growth conditions BG YOY could achieve it as well.

LMB have gape width of about 15% their length and bluegill have a height of about 36% their length. For a 20" LMB, a BG that has height of 30% the gape width is 2.5" long. Beyond 20" I think that ratio of gape width and length does increase (same as it does for any LMB whose growth is slowing). But even at 20% gape-width/length for a 25" LMB, the BG whose height is 30% the gape width is less than 4.25" in length.

The problem with this is that these prey only constitute about 0.5% the weight of the predator. At 1%, the most frequent weight of prey, the bluegill height as a percentage of LMB gape width is between 36% and 50%.

These are realized ratios that are based on prey recovered from LMB and sourced to the data of a number of DOW. A realized diet might differ from an optimum diet and it is worth asking whether the LMB might have been inclined to smaller prey than they were eating. Were they, perhaps, forced to eat larger prey than optimum due to the limited availability of smaller prey? At 1/2 the width of realized prey, we would be talking between .18 to .25 for the bluegill height to LMB gape width ratio a number not too dissimilar from the size you reference as "the largest size the fish will actively eat". With pellets the size of the food can be tightly controlled and the weight of pellets consumed determined very accurately. The ratio that you mention above seems to suggest that their exists behavioral inclination with respect to the size of food items.

Last edited by jpsdad; 09/21/19 12:03 PM.
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