An Assessment of Trout Fry and Fingerlings Stocked in Small Southern Maine Streams

Final Report Series No. 02-1

Interim Summaries By John Boland

Final Report Written and Prepared By
Francis Brautigam
Jim Pellerin

Maine Department of Inland Fisheries & Wildlife
Fisheries and Hatcheries Division

March 2002

Abstract

Brook trout (Salvelinus fontinalis) fry and fingerlings, and brown trout (Salmo trutta) fry were stocked in four small southern Maine streams to assess recruitment to the legal fishery; and to examine stocking-related interaction effects on resident fish communities. Brook trout stocked at a rate of 29 fry per habitat unit created a fishery in a fishless stream, but did not appear to increase the abundance of legal-size trout at a stocking rate of 35 per habitat unit in another stream with existing fish populations. Brook trout fry interaction effects in this latter stream consisted of reduced mean lengths for blacknose dace (Rhinicthys atratalus), common shiner (Luxilus cornutus), and creek chub (Semotilus atromaculatus). A reduction in mean weight for creek chub was also noted. Brown trout stocked at a rate of 36 fry per habitat unit created a legal fishery in one of two study streams, where fry stocking appeared to negatively affect brook trout, common shiner, and creek chub populations. Brook trout and creek chub biomass were inversely related to brown trout biomass. Common shiner mean length, weight, biomass, and abundance declined. Fall fingerling brook trout stocked at a rate of 1.1 to 2.9 fish per habitat unit provided little or no contribution to the legal-size fishery in two study streams.

KEY WORDS: BKT, BNT, BIOMASS, ELECTROFISHING, FALL FINGERLING STOCKING, FRY STOCKING, POPULATION ESTIMATE, SURVIVAL, STREAM SURVEY, INTERSPECIFIC COMPETITION, INTRASPECIFIC COMPETITION

Job F-410 FINAL REPORT (1992-2001)

Introduction

Fry and fingerling trout have been stocked in Maine lakes and ponds for many years with success, particularly in habitats with few fish competitors. Trout fry and fingerlings are inexpensive, easy to raise, and require little space in the hatchery. If successful, fry and fingerling stockings could offer an advantageous, low cost opportunity to enhance stream fisheries. In 1989, biologists in southern Maine began stocking fry and fingerling brook trout (Salvelinus fontinalis), and brown trout (Salmo trutta) fry into several brooks and streams. Many streams were stocked on an annual basis, while others were periodically stocked with unscheduled fish. After several years, biologists were uncertain if fry and fingerling trout stockings were contributing legal-size fish to the fishery and an evaluation was initiated.

Two project waters were selected to evaluate each component of the study, which will be reported in three separate sections as follows: I. Brook Trout Fry Assessment, II. Brown Trout Fry Assessment, and III. Brook Trout Fingerling Assessment. The study objectives were (1) to determine the contribution of stocked trout fry and fingerlings to the legal fishery; and (2) to examine the effects of stocking fry and fingerlings on existing fish communities.

For more information or a complete report, please contact:

Francis Brautigam
Maine Fish and Wildlife
Fisheries Division
358 Shaker Road
Gray, Maine 04039
Telephone: (207) 926-2345 x112
Email: francis.brautigam@maine.gov