Impact of sampling efficiency on the performance of data-driven fish habitat models

Although lakes and rivers are intimately connected, more effort is needed to develop conceptual approaches accounting for lake–stream interactions within the drainage network. Lakes can buffer the impacts of environmental variability in streams and facilitate stream fish recolonization processes. However, lakes have rarely been incorporated in habitat models for stream fish. We examine whether including the presence of lakes in habitat models can improve our understanding of brook trout (Salvelinus fontinalis) abundance in streams. We quantified brook trout relative abundance in 36 streams over 3 consecutive years by single-pass electrofishing. Relative abundance of brook trout in streams was greatest when lakes were present in the stream network. Lakes had greater influence on relative abundance in headwater streams than in larger streams. These results emphasize the importance of considering lakes as a critical attribute in landscape fish habitat models, many of which focus on terrestrial landscape variables. We discuss potential gains from incorporating the presence of lakes in (i) multiscale habitat models, (ii) analyses of spatiotemporal distribution of thermal refuges, and (iii) metrics of habitat connectivity in lake–stream networks.

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Effect of the spatial arrangement of habitat patches on the development of fish habitat models in the littoral zone of a Canadian Shield lake

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f05-249 ◽

2006 ◽

Vol 63 (4) ◽

pp. 737-753 ◽

Cited By ~ 7

Author(s):

Anik Brind'Amour ◽

Daniel Boisclair

Keyword(s):

Littoral Zone ◽

Predictive Power ◽

Fish Habitat ◽

Spatial Arrangement ◽

Canadian Shield ◽

Habitat Patch ◽

Constant Multiple ◽

Habitat Models ◽

Habitat Patches ◽

Multiple Approach

We developed fish habitat models in a Canadian Shield lake using (i) a sampling-site approach based on analytical units having a surface area equal to that of sampling sites (S ~ 200 m2), (ii) a constant-multiple approach in which the analytical units constituted grouping of adjacent sampling sites in units of increasing sizes (e.g., 2S or 3S), and (iii) a habitat-patch approach in which only contiguous sampling sites with similar environmental characteristics were merged. The best models explaining within-lake variations in fish density, biomass, and community structure on the littoral zone were obtained using the constant-multiple approach, but the predictive power of these models was highly variable (0 < R2 < 0.9) compared with the habitat-patch approach (0.27 < R2 < 0.49). For these approaches, intrinsic variables (estimated inside the analytical units) explained on average 16%27% of the variations of fish descriptors compared with 6%32% for extrinsic variables (observed outside analytical units or related to the spatial arrangement of habitat characteristics). Our study suggests that habitat patches are reliable analytical units with which to develop fish-habitat models. Our study also indicates that inclusion of variables that refer to landscape characteristics may significantly improve the predictive power of fish habitat models.

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Are trout populations affected by reach-scale stream slope?

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f99-272 ◽

2000 ◽

Vol 57 (2) ◽

pp. 468-477 ◽

Cited By ~ 13

Author(s):

Daniel J Isaak ◽

Wayne A Hubert

Keyword(s):

Species Composition ◽

Spatial Scale ◽

Relative Abundance ◽

Cross Sections ◽

Fish Habitat ◽

Rocky Mountain ◽

Mountain Streams ◽

Habitat Models ◽

High Slope ◽

Rocky Mountain Streams

Reach-scale stream slope and the structure of associated physical habitats are thought to affect trout populations, yet previous studies confound the effect of stream slope with other factors that influence trout populations. We isolated the effect of stream slope on trout populations by sampling reaches immediately upstream and downstream of 23 marked changes in stream slope on 18 streams across Wyoming and Idaho. No effect of stream slope on areal trout density was observed, but when trout density was expressed volumetrically to control for differences in channel cross sections among reaches in different slope classes, the highest densities of trout occurred in medium-slope reaches, intermediate densities occurred in high-slope reaches, and the lowest densities occurred in low-slope reaches. The relative abundance of large trout was reciprocal to the pattern in volumetric trout density. Trout biomass and species composition were not affected by stream slope. Our results suggest that an assumption made by many fish-habitat models, that populations are affected by the structure of physical habitats, is at times untenable for trout populations in Rocky Mountain streams and is contingent upon the spatial scale of investigation and the population metric(s) used to describe populations.

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