Seasonal movements, age and size statistics, and food habits of upper Cook Inlet northern pike during 1994 and 1995
By: by David S. Rutz.
Contributors: Alaska. Division of Sport Fish.
Series: Fishery data series -- no. 96-29.
Publisher: Alaska Dept. of Fish and Game, Division of Sport Fish, Research and Technical Services
Published: 1996
Place of publication: Anchorage
Language: eng
Number of pages: 54
Subjects: Pike -- Alaska -- Cook Inlet -- Statistics.; Fishery resources -- Alaska -- Cook Inlet -- Statistics.; Fishes -- Alaska -- Cook Inlet -- Statistics.; Fish populations -- Alaska -- Cook Inlet -- Measurement.
Other titles: Seasonal movements, age and size statistics, and food habits of northern pike in upper Cook Inlet during 1994 and 1995.
Description: Fourteen lakes and two tributaries of the Susitna River drainage, supporting northern pike Esox lucius, were sampled during 1994 and 1995 to assess seasonal migrations and distributions, age and size compositions, and food habits. Seasonal migrations and distributions of northern pike were investigated using radiotelemetry. Based on radiotelemetry information spawning migrations appeared to begin during the last week of April for Trapper, Ding Dong and Alexander lakes, and during the first week of May for Whiskey Lake, and continued through late May or early June. The greatest distance a radio-tagged fish traveled from capture location was 13 km; the least distance traveled was less than 1 km. Some northern pike remained within the lakes they were captured in while others moved into outlet streams or adjacent connecting lakes. Selected Susitna River drainage lakes were sampled using modified hoop nets, gillnets, and hook and line during the spring and summer of 1994 and 1995. Northern pike captured with hook and line were generally larger and older than northern pike caught in hoop nets or gillnets. Northern pike captured with hoop nets in the spring of 1994 from Alexander Lake were divided among the relative stock density categories of stock, "quality," and "preferred" (40%, 35% and 22%, respectively), while northern pike captured from Trapper Lake in the spring of 1994 were primarily in the stock and quality categories (77% and 20%, respectively). During 1995, stomach contents were analyzed from northern pike captured in selected Susitna River drainage lake systems and three area stocked lakes to assess dietary trends of northern pike by two major habitat types. Of the 237 stomachs examined, 24% were empty. Of nonempty stomachs of northern pike caught in systems with fast clearwater streams and deep lakes with little aquatic vegetation, 73% contained salmonids and 11% contained invertebrates. In contrast, of the nonempty stomachs of northern pike caught in systems with well established northern pike populations and having slow-moving streams and shallow lakes with abundant vegetative mats, 96% contained invertebrates and 3% contained salmonids. Of nonempty stomachs examined from northern pike caught in three area stocked lakes, 59% contained rainbow trout O. mykiss, 26% contained other fish species, and 26% contained invertebrates. Several lake systems within the Susitna River drainage that were historically productive coho O. kisutch and sockeye O. nerka salmon streams are now believed to contain only northern pike. To document the presence or absence of juvenile coho salmon in these systems, we sampled five systems: Fish Creek (Kroto Slough), Witsoe Creek (Kroto Slough), Trapper Creek (Deshka River), Fish Creek (Nancy Lake System) and Fish Lake Creek (Yentna River). Two-hundred fifty wire mesh minnow traps baited with salmon roe were set for a period of 24 hours in these systems, supposedly barren of coho salmon. Catch per unit of effort (CPUE) was 0.25 juvenile coho salmon per trap set. Coho salmon juveniles were completely absent in two of the five systems sampled. In the remaining three systems, juvenile coho salmon were found in low numbers and only in the immediate vicinity of the stream's confluence area. Juvenile salmon captured near these confluence areas most likely originated from other parent streams, because juvenile salmon seek out confluence areas for short-term rearing during outmigration.
Notes: "September 1996"

Includes bibliographical references (p. 26-28)

Also issued online.