Age, Growth, Year Class Strength, and Survival Rates of the White Perch, Morone americana (Gmelin) in the Delaware River in the Vicinity of Artificial Island

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Abstract
More than 1400 white perch were studied to determine growth, year class strength and survival rates in a section of the Delaware River. Except for young of the year, all specimens were collected with trawl and trap nets. There was no difference in size selection using these two methods. The annulus is a valid year mark. Most individuals had completed the annulus by mid-June. However, the period of annulus completion extended from at least the first week in May to the end of July with older individuals completing the annulus later. In their first year white perch attained approximately 40% of the length attained by the eighth year. Young-of-the-year continue growth through the month of November while older fish grew little after September. Up to their fifth year, females grew somewhat faster than males. Based on the 1960 through 1964 year classes males had higher survival rates than females. In general, growth rates were lower in this section of the river than was previously reported for the Patuxent or Delaware Rivers. For both sexes growth rates were greater in the east side of the river than in the west. This was not due to differences in mean temperatures. The 1964 and 1966 year classes were relatively strong compared with others. The relatively good growth in 1965 probably contributed to a higher number of recruit spawners in 1966. The number of fish older than age group III increased in July and August collections and decreased progressively from September through November. Very few fish older than age group VIII were captured.

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