Survival of Tagged Striped Bass in the Hudson River

Striped bass are a popular and economically important recreational fish species on the eastern seaboard of the United States. The Hudson River estuary provides a valuable overwintering ground for this fish, and there has been a need to monitor the striped bass population in response to a coast-wide decline observed beginning in the 1970s and the collapse of the commercial fishery in the 1980s.

A population of overwintering striped bass has been monitored in the Hudson River since 1984. The monitoring program has included tagging and releasing of fish caught between November and April of each year. The main objective of this monitoring program is to estimate annual population size, but a large database of biological parameters is also available from this ongoing study. One useful aspect of the ancillary data is the ability to calculate survival parameters of the population. In particular, starting with the 1991-1992 program, striped bass that were alive but not in good condition were tagged to determine if the presence of certain gross anatomical abnormalities (such as blindness or bacterial infection) affected their survival. The nature of the particular abnormality of each striped bass was recorded prior to release. In monitoring program years before 1991-1992, only striped bass in good condition were tagged and released.

The historical database will be mined for data pertaining to these fish, and the survival rate will be compared to that of fish tagged in good condition (no abnormalities or injuries observed). The frequency of occurrence of specific abnormalities and injuries will be explored and the implications of any disparity between survival rates will be analyzed as it pertains to the annual fish population estimation and health of the Hudson River striped bass population in general. Because mortality is presumably high during overwintering, a better estimation of the survival rate and causes of mortality will be helpful to add to our knowledge base on the biology of this species.