Preliminary Assessment of Factors Influencing Riverine Fish Communities in Massachusetts

摘要

This report describes the results of a preliminary study of the response of stream fish communities in Massachusetts to flow alteration and other measures of anthropogenic stress, such as impervious cover, relative to the effects of environ-mental characteristics. The report provides bivariate plots among selected fish metrics and measures of flow altera-tion, impervious cover, and area of open water, with quantile regression curves indicating fish response. The report also presents generalized linear model (GLM) equations and plots that indicate relations between selected fish-response variables and multiple environmental and anthropogenic explanatory variables.The scope of the study included small to medium streams across Massachusetts but not streams on Cape Cod, the Islands (Marthas Vineyard, Nantucket), and portions of southeastern Massachusetts where information on simulated streamflows was unavailable. Data on fish samples from the MDFW data-base collected during 19982008 were used in the analysis of fish communities; new fish-sampling data were not collected for this study. Analysis focused on riverine fish communi-ties in free-flowing reaches of streams and rivers. Variables analyzed for the study were restricted to a subset of response and explanatory variables selected from a larger set of data collected for the ongoing study. A review of the literature was used to select fish-community variables, measures of anthro-pogenic stress, and environmental characteristics considered important in determining fish abundance and distribution. Altered and unaltered flows used in the study were simulated for fish-sampling sites using the Sustainable Yield Estimator. The statistical methods employed for analysis were reduced from a larger suite of analytical techniques in order to meet a request by Massachusetts State Agencies for a report on an accelerated timeline.