To give you an idea how fast the LMB can grow, we have stocked fingerling LMB (3"-4") in early May and the customer was catching 2# LMB in late September. If there is enough food in the pond they will grow extremely fast.
esshup,
When I first read I was like "WOW" but this is within what is possible. Those fish appear a little hungrier than Boondoggle's ... but not by much. Boondoggles' are YOY at around 2" stocking in June. 3"-4" LMB are probably not YOY. Definitely not produced in ponds same year and available in early May. These stocker fish could be "runts" that didn't make the growth of siblings in the year prior. It is also possible they were from different cohorts produced by manipulating spawning to occur during a different time of year. Of the two possibilities, I think the most likely is that these were slower growing siblings.
The key component of growth is consumption. So obviously these 3"-4" LMB could not have been runts due to "genetics" of slow growth. There must have been other factors controlling how much they ate when raised with their siblings. One key factor is competition and behavioral traits that support competitive advantage in highly competitive environments (high fish density). Everything a fast growing competitive fish eats is forage/(OR feed) that less competitive fish are not eating. When these slower growing siblings were placed into a pond where they could eat all they would (low LMB density with abundant forage) their growth was just outstanding to say the least.