Overview of the biological characteristics of Alewife (Alosa pseudoharengus) spawning runs on the Isthmus of Chignecto, New Brunswick, Canada

Abstract

Alewife (Alosa pseudoharengus) are an anadromous species of river herring that are found in the Atlantic Ocean, ranging from the coasts of North Carolina, USA to Newfoundland, Canada. Age-structured population models and other aspects of populations have not been determined for all Alewife populations in the Maritime Provinces. To inform population models, background information are examined including biological characteristics such as age, growth patterns and condition factor. Alewives were aged by enumerating annuli on scales. Alewife weight, fork length, total length and sex were collected in the field as a part of a preexisting project from 2013 to 2019 the Inner Bay of Fundy region. Here, the presence of spatial-temporal differences in fish size, condition factor, sex ratio or ages and potential changes or biases across river systems are identified. The results indicate that length-weight relationships and growth rates did trend upward between 2013 to 2019, with female Alewife growing at a faster rate than male Alewife. The determination of age revealed that the distribution of ages per sex during the spawning run was similar, with both sexes having a mean age of four. Similarly, average proportion of virgin spawners per age was four years of age for both sexes. The variance of Fulton’s condition factor revealed that there is little difference in health for Alewife across the sample years and the four river systems. This information will help inform population management and protection for anadromous fish in Atlantic Canada, which will help researchers understand the influencing processes and biological characteristics driving alewife spawning runs. This thesis documents the validity of anecdotal observations on Alewife spawning run composition and provides resource managers with research recommendations and an improved understanding the ecological significance of run timing in the Inner Bay of Fundy.