Table 1. Characteristics of the five potential cohort structures for eastern oyster examined with the R package mixtools.

There were four year classes with either one or two cohorts, except in 2003 when spatfall and oyster abundance were too low to distinguish more than one cohort. Nominal = starting values entered into mixtools for mean size of each cohort; μ, σ and proportion = estimates of cohort mean size, standard deviation, and proportion of the population in each cohort generated by mixtools.

Number of cohorts	Estimates	Annual cohorts
		2004		2003	2002		2001
		Jul	Aug	Jul	Jul	Aug	Jul	Aug
7	nominal	20	45	55	80	90	100	110
	μ	21.9	43.6	61.7	78.3	89.3	91.1	100.5
	σ	7.2	3.5	0.8	7.8	1.5	17.8	3.7
	proportion	0.36	0.05	0.02	0.14	0.04	0.34	0.06
6	nominal	20	40	70	90	100	115
	μ	21.8	43.6	61.6	85.2	102.3	118.2
	σ	7.2	3.7	0.7	13.0	3.0	8.5
	proportion	0.36	0.05	0.01	0.49	0.04	0.04
5	nominal	25		55	85	110	130
	μ	21.9		43.6	85.1	102.3	119.4
	σ	7.2		3.3	14.1	2.9	8.2
	proportion	0.36		0.05	0.52	0.04	0.03
4	nominal	15		45	90		110
	μ	21.7		67.3	89.9		121.8
	σ	7.1		25.5	12.8		4.7
	proportion	0.34		0.23	0.42		0.02
3	nominal	25			70		100
	μ	21.9			43.5		88.0
	σ	7.2			3.2		16.3
	proportion	0.36			0.04		0.59