Comparison of Day Snorkeling, Night Snorkeling, and Electrofishing to Estimate Bull Trout Abundance and Size Structure in a Second-Order Idaho Stream

Thurow, Russell E.; Schill, Daniel J.

doi:10.1577/1548-8675(1996)016<0314:codsns>2.3.co;2

Cited by 65 publications

(73 citation statements)

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“…The sampling technique used (underwater observation) can also be responsible for biased data, especially when conditions are less than ideal. For example, limited application is associated with deep areas, dark substrate, high presence of LWD, bad underwater visibility or the counting of organisms in dense populations (GRIFFITH et al, 1984;THUROW and SCHILL, 1996). However, underwater observation is a valid technique to estimate abundance, size structure (WILDMAN and NEUMANN, 2002;JOYCE and HUBERT, 2003) and habitat use (FLEBBE and DOLLOFF, 1995;DOLLOFF et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

Habitat Use by Native and Stocked Trout (Salmo Trutta L.) in Two Northeast Streams, Portugal

Teixeira¹,

Cortes²,

Oliveira³

2006

Bull. Fr. Pêche Piscic.

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Habitat use by stocked and native brown trout (Salmo trutta L.) was assessed in two headwater streams of North-eastern Portugal. Underwater observations were made during the summer season in three successive years to evaluate the effect of supplemental trout stocking. Multivariate analysis techniques applied to data sets on microhabitat use were exploited to identify the focal elevation (distance of fish from the bottom), total depth and cover as the variables that contribute most to the discrimination between stocked and native trout. Preference curves computed for native and stocked trout of the same age (1 + ), showed a distinct pattern in their ability to explore the available microhabitat resources. Stocked trout tended to occupy deeper pools (total depth > 100 cm vs. 60-100 cm for native trout), holding higher focal elevations (140-160 cm vs. < 20 cm for native) with lower water column velocities (< 10 cm.s -1 vs. 10-20 cm.s -1 for native) and no specific preference for cover. In contrast, native trout displayed a clear preference for microhabitats with coarse substrate (particle size > 22.5 cm) and cover (combination of boulders and overhanging vegetation or undercut banks). Furthermore, a high poststocking movement of 80% hatchery-reared fish was verified just one month after their release, suggesting that stocking did not contribute to the sustainable populations in either stream, and is far from being an adequate management technique. Key-words:Salmo trutta, snorkelling, restocking, microhabitat, preference curves. UTILISATION DE L'HABITAT PAR LA TRUITE COMMUNE (SALMO TRUTTA L.) SAUVAGE ET CELLE D'ÉLEVAGE, DANS DEUX RIVIÈRES DU NORD-EST DU PORTUGAL RÉSUMÉL'utilisation de l'habitat par la truite de repeuplement et par la truite commune (Salmo trutta) a été évaluée dans deux rivières du Nord-Est du Portugal. Des observations en plongée ont été faites en période estivale pendant trois années successives pour évaluer l'efficacité des repeuplements. Des techniques d'analyses multivariées appliquées à l'ensemble des données du microhabitat ont permis d'identifier la position Article available at

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Section: Discussionmentioning

confidence: 99%

Habitat Use by Native and Stocked Trout (Salmo Trutta L.) in Two Northeast Streams, Portugal

Teixeira¹,

Cortes²,

Oliveira³

2006

Bull. Fr. Pêche Piscic.

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“…We excluded age-0 fish because of the difficulty involved in accurately assessing their numbers. Recent field studies have confirmed that underwater observations made with snorkeling gear provide unbiased estimates of the relative abundance and size structure of stream salmonid fishes [18,19]. Differences in densities and fish size between species and among the sections were tested by KolmogorovSmirnov tests.…”

Section: Methodsmentioning

confidence: 98%

Differences in longitudinal distribution patterns along a Honshu stream of brown trout Salmo trutta, white-spotted charr Salvelinus leucomaenis and masu salmon Oncorhynchus masou

et al. 2010

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Brown trout Salmo trutta were first introduced into Japan in 1892, and they currently naturally reproduce in several rivers in Honshu and Hokkaido, Japan. Although negative impacts of brown trout introductions on native salmonid fishes have been documented in some Hokkaido rivers, studies of ecological interactions between brown trout and native salmonid fishes on Honshu are limited. In this study, we describe the longitudinal distribution patterns of introduced brown trout, white-spotted charr Salvelinus leucomaenis and masu salmon Oncorhynchus masou in a 4 km stretch of a stream in central Honshu. Underwater observations were conducted in all pools within upstream, middle and downstream sections (190-400 m in length) of this stretch in order to estimate the densities of these species. Only white-spotted charr was observed in the upstream section, while brown trout and masu salmon were observed in the middle and downstream sections. Masu salmon densities, however, were much lower than brown trout densities. In the downstream section, white-spotted charr was absent. These results are consistent with results from previous studies of Hokkaido rivers, where it was found that white-spotted charr in low-gradient areas tend to be displaced by brown trout.

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“…This is a direct method usually employed in the evaluation of habitat use by fish in small streams (Thurow & Schill, 1996). The stream segments (defined for telemetry experiments) were surveyed and the data observations distributed by 140 small native (<20.0 cm), 26 big native ( ‡20.0 cm) and 208 stocked trout to assess the microhabitat used.…”

Section: Field Surveysmentioning

confidence: 99%

PIT telemetry as a method to study the habitat requirements of fish populations: application to native and stocked trout movements

Teixeira

Cortes

2007

Hydrobiologia

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Comparison of Day Snorkeling, Night Snorkeling, and Electrofishing to Estimate Bull Trout Abundance and Size Structure in a Second-Order Idaho Stream

Cited by 65 publications

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Habitat Use by Native and Stocked Trout (Salmo Trutta L.) in Two Northeast Streams, Portugal

Habitat Use by Native and Stocked Trout (Salmo Trutta L.) in Two Northeast Streams, Portugal

Differences in longitudinal distribution patterns along a Honshu stream of brown trout Salmo trutta, white-spotted charr Salvelinus leucomaenis and masu salmon Oncorhynchus masou

PIT telemetry as a method to study the habitat requirements of fish populations: application to native and stocked trout movements

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