Governor Phil Murphy • Lt.Governor Tahesha Way, Esq.
NJ Home | Services A to Z | Departments/Agencies | FAQs  
State of New Jersey Department of Environmental Protection
DEP Home | About DEP | Index by Topic | Programs/Units | DEP Online 

Fish Monitoring Sections


Bureau of Freshwater & Biological Monitoring

Northern Fish IBI

(High Gradient)

The Fish IBI data is used in concert with available macroinvertebrate data to assess the status of aquatic life designated use in state waters as required by the CWA section 305(b) 106 (e) (1). These data are used to identify impaired waters under section 303(d) 106 (e) (1). The data help to measure water quality use attainment and the Department's success in attaining the Clean Water Act goal of "fishable" waters as elaborated in the New Jersey Integrated Water Quality Assessment Report.

The northern fish IBI uses resident fish communities to measure the health of high gradient wadeable streams north of the fall line which are greater than 4 square miles in drainage size.  Fish assemblage analysis is accomplished using a regional modification of the original IBI (Karr 1981), developed by Kurtenbach (1994) and later recalibrated by the Bureau of Freshwater and Biological Monitoring (BFBM) (2005; 2013).

The IBI incorporates richness, trophic composition, abundance, and overall health of the fish assemblage into a single ecologically based index. The index is comprised of several attributes (metrics) of a healthy fish assemblage, which are selected based on their sensitivity to anthropogenic impacts.  Each metric is scored based on its deviation from reference condition.  Metrics are averaged to generate an overall score and rating for each stream sampled. Fixed sites are sampled on a five year rotating basis, with monitoring focused on one of the State’s five major Water Regions each year.

Detailed information related to the methods used to collect fish assemblage, chemical, and physical habitat data for Northern high gradient streams can be found in the Fish Monitoring Standard Operating Procedures (SOP). This document provides information on fish metrics and the associated scoring methodology for the Northern Fish IBI. In addition, the SOP outlines safety training and procedures as it pertains to electrofishing in wadeable streams.


nibi region map

If you are interested in more information about the Northern Fish IBI, please contact John Vile at 609-292-0427.

large brown trout in livewell

brown trout on measuring board

chain pickerel on measuring board

furnace brook

northern pike passaic river

brown trout mulhockaway creek

clinton brook

Photo credits - NJDEP

Department: NJDEP Home | About DEP | Index by Topic | Programs/Units | DEP Online
Statewide: NJ Home | Services A to Z | Departments/Agencies | FAQs

Copyright © State of New Jersey, 1996-2023

Last Updated: October 26, 2018