Joan G. Trial

Comparing 1994 Angler Catch and Harvest Rates from On-Site and Mail Surveys on Selected Maine Lakes

Abstract Fishery managers use data on catch and harvest rates collected with both on-site and off-site angler surveys. Many researchers have hypothesized that catch rates from these surveys will differ systematically due to various biases. However, few direct comparisons have been made between the two survey methods using the same waters and seasons. We compared catch and harvest rates for three coldwater species, individually and combined, from concurrent mail and on-site surveys on five Maine lakes during the 1994 ice fishing season. Comparisons were also made for two Maine lakes during the 1994 open-water season. Estimates of catch and harvest from the mail survey exceeded the rates from on-site surveys in 28 of 38 comparisons for individual species. The average on-site to mail survey ratio was 0.40 for catch rates and 0.66 for harvest rates but varied significantly by lake, season, and species. The results suggest that mail surveys do not produce accurate estimate of catch and harvest rates. In situat...

The Effects of Smolt Stocking Strategies on Migratory Path Selection of Adult Atlantic Salmon in the Penobscot River, Maine

Abstract Understanding the homing behavior of Atlantic salmon Salmo salar is vital to the restoration program employed on the Penobscot River, Maine. To produce significant adult returns, managers currently stock hatchery-raised smolts in specific river sections, providing smolts the opportunity to imprint on chemical signals and enabling their return to productive spawning and rearing habitat as adults. In this study, we used observational evidence from passive integrated transponder telemetry to determine whether adults returning from smolt stockings behaved in a way that suggested strong homing to smolt stocking locations. Adults returning from smolt stocking locations located in or at the mouth of the Piscataquis River were more likely to be detected as entering the Piscataquis River than were adults returning from the upper Penobscot River smolt stocking locations. In general, returning adult Atlantic salmon that had been stocked near or in tributaries as smolts chose a path more quickly than those t...

Evaluation of Removal Sampling for Basinwide Assessment of Atlantic Salmon

Abstract Removal estimators for stream fish abundance are widely used but can result in biased population estimates at the site level. We conducted computer simulations to examine how the Carle and Strub (1978) estimator, coupled with variation in catchability, influences the accuracy of population estimates at the site level. Site-level population estimates were then used to examine what effect potential bias in the population estimate at a site had on basinwide abundance estimates. Historic electrofishing data collected from Atlantic salmon Salmo salar in the Narraguagus River, Maine, were used as the baseline for construction of these simulations. At the site level, mean percent bias of population estimates was −23% when catchability was low (0.30–0.40) and when the true population was low (1–20 fish). Bias was reduced as the true population size increased and catchability increased. The negative bias at the site level affected total population estimates for the entire river basin. Under current sampli...

Downstream migratory behavior of hatchery-reared, radio-tagged Atlantic salmon (Salmo salar) smolts in the Penobscot River, Maine, USA

Abstract Migratory patterns and timing of smolt movements of Atlantic salmon ( Salmo salar ) were assessed by placing radio tags on salmon in 1990 and 1991 and releasing fish at Howland, Maine, about 91 km upstream from the mouth of the Penobscot River. Fish movements were tracked by vehicles on streamside roads and by airplanes. Fish released in April moved quickly into the main channel of the river, although 47% of the signals ceased or became stationary within 10 km of the release site, owing to predation, battery failure, or cessation of migratory behavior. Only 3% of smolts were tracked over 40 km downstream. Of those fish actively migrating downstream, the passage rate averaged 3.7 km day −1 , ranging from 0.5 to 15.7 km day −1 .

Use of Riffle and Run Habitats with Aquatic Vegetation by Juvenile Atlantic Salmon

Abstract We examined the use of riffle and run habitats with varying aquatic macrophyte coverage by juvenile Atlantic salmon Salmo salar in the Narraguagus River, Maine, via electrofishing and individual fish observations. At the site level, large and small parr were more abundant in riffle habitats than in run habitats, and the abundance of small parr was lower at sites with heavy aquatic vegetation. At the individual-fish level, parr use of moderately vegetated areas was significantly higher than expected based on availability of such habitats, and use of heavily vegetated areas was lower than expected. The use of vegetated areas was not independent of dominant substrate type. Use of moderately vegetated habitats exceeded expectations for gravel- and sand-dominated areas; for cobble-dominated areas, use of sites with little or no vegetation exceeded expectations. Approximately 95% of the observed parr were found in the vicinity of a discrete cover item (i.e., cobble, vegetation, or other). Parr typicall...

Habitat Selection and Overlap of Atlantic Salmon and Smallmouth Bass Juveniles in Nursery Streams

Abstract Introduced smallmouth bass Micropterus dolomieu have invaded much of the historic freshwater habitat of Atlantic salmon Salmo salar in North America, yet little is known about the ecological interactions between the two species. We investigated the possibility of competition for habitat between age-0 Atlantic salmon and age-0 and age-1 smallmouth bass by means of in situ observations and a mesocosm experiment. We used snorkel observation to identify the degree and timing of overlap in habitat use in our in situ observations and to describe habitat shifts by Atlantic salmon in the presence of smallmouth bass in our mesocosm experiments. In late July 2008, we observed substantial overlap in the depths and mean water column velocities used by both species in sympatric in situ conditions and an apparent shift by age-0 Atlantic salmon to shallower water that coincided with the period of high overlap. In the mesocosm experiments, we detected no overlap or habitat shifts by age-0 Atlantic salmon in the ...

Scale Pattern Analysis Discriminates Atlantic Salmon by River Reach Rearing Origin

Abstract Scale pattern analysis was used to discriminate among juvenile Atlantic salmon Salmo salar reared in different reaches of the Narraguagus River basin. Measurements of parr scales collected during 1990–1999 were used in a principal components analysis and to create linear discriminant functions for seven geographic strata and three river basin strata groups reflecting natural habitat breaks and Atlantic salmon management regimens. Discriminant functions were calculated with both pooled and annual data. Sufficient differentiation existed among rearing habitats of different reaches (or between geographically grouped reaches) in the Narraguagus River basin, particularly for tributary habitats, to allow discrimination to various degrees of possible use in management.

Factors Affecting Baitfish Supply and Retail Prices Paid by Maine Anglers

Abstract Minnows (Cyprinidae) and rainbow smelt Osmerus mordax are the primary baitfishes used for winter sport fisheries in Maine. Anglers buy bait from dealers, who harvest wild fish. The State of Maine licenses dealers and regulates harvests. We investigated trends in real prices of bait in relation to supply, demand, and fisheries regulations. We assumed that supply was related to the number of bait dealer licenses sold each year. Sportfishing license sales, estimates of the number of days fished per angler per year, and the estimated proportion of licensed anglers who participated in ice fishing were used to assess demand. Because price is determined by the interaction of supply and demand, we wanted to determine if supply was meeting demand. Demand for live baitfish and bait license sales have increased since 1973. Between 1985 and 1991, real prices (1985 dollars) for a dozen rainbow smelt fluctuated between US

Growth and Smolting in Lower-Mode Atlantic Salmon Stocked into the Penobscot River, Maine

4.09 and

Effects of Smallmouth Bass on Atlantic Salmon Habitat Use and Diel Movements in an Artificial Stream

4.59. Real prices for minnows were