Northern Snakeheads in Two New York City Lakes Over Four Years

A population of northern snakeheads was discovered in two connected lakes in Queens, New York in 2005 and monitored by electrofishing over several years.  While there is evidence of reproduction, catch per unit effort of snakeheads has remained relatively constant and that of most other fish species has remained the same or increased.  The northern snakehead length-weight relationship is identical to that reported from the Potomac Basin population of snakeheads. Compared with these fish, New York City snakeheads are greater in length per age class using fish scales to determine age.  Despite being in suitable habitat, the New York City northern snakehead population has not increased as has been observed in other areas and the ratio of juveniles to adults caught has remained uncharacteristically low, suggesting low reproduction or recruitment but good post-recruitment success.  Potential causal factors in this lack of or delay in population increase include the water quality characteristics of salinity and acidity and presence of other fish species, although the exact reasons for slow population growth are unknown.