Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques

2010 ◽  
Keyword(s):  
Brown Trout ◽  
Brook Trout ◽  
Fish Assemblages ◽  
Smallmouth Bass ◽  
Fish Abundance ◽  
Forage Fish ◽  
Data Sets ◽  
Biotic Factors ◽  
Habitat Factors ◽  
Habitat Variables

<em>Abstract</em>.—In regional survey studies of habitat and fish assemblages, potentially important biological interactions can be masked by strong gradients in habitat variables and associated collinearities among biological variables. We used structural equation modeling to compare the causal influences of local habitat and biotic factors on fish density in rivers and to determine the extent to which the set of sites chosen for analysis influenced their apparent importance. When all sites in our Michigan data set were used, spatial patterns in brook trout <em>Salvelinus fontinalis </em>biomass were 28 times more sensitive to habitat variables than brown trout <em>Salmo trutta </em>biomass. However, when the sample was restricted to trout streams, then brook trout biomass patterns were twice as sensitive to brown trout biomass as habitat variables. In a similar analysis for smallmouth bass <em>Micropterus dolomieu</em>, habitat factors had the strongest effects on fish densities when the analysis was based on all samples available. However, when the sample was limited to steams in which smallmouth bass actually occurred, direct effects of forage fish abundance and indirect effects of habitat via forage fish abundance were more prominent. In both the trout and smallmouth bass analyses, regional data sets (which included sites where the species of interest was absent) overemphasized the importance of habitat factors on fish abundance, but restricting the sample to sites having the species of interest elevated the importance of biotic factors. In reality, both habitat and biotic factors are important to these species, but the variance structure of the sample being analyzed had an overriding influence on the statistical importance of one versus the other. These findings help to resolve apparently conflicting results of previous studies assessing the relative influence of habitat and biotic factors on population abundance.

scholarly journals Automating the analysis of fish abundance using object detection: optimising animal ecology with deep learning

2019 ◽  
Author(s):  
Ellen M. Ditria ◽  
Sebastian Lopez-Marcano ◽  
Michael K. Sievers ◽  
Eric L. Jinks ◽  
Christopher J. Brown ◽  
...  
Keyword(s):  
Deep Learning ◽  
Object Detection ◽  
Fish Assemblages ◽  
Aquatic Ecology ◽  
Video Data ◽  
Fish Abundance ◽  
Data Sets ◽  
Seagrass Meadows ◽  
Learning Techniques ◽  
Better Than

AbstractAquatic ecologists routinely count animals to provide critical information for conservation and management. Increased accessibility to underwater recording equipment such as cameras and unmanned underwater devices have allowed footage to be captured efficiently and safely. It has, however, led to immense volumes of data being collected that require manual processing, and thus significant time, labour and money. The use of deep learning to automate image processing has substantial benefits, but has rarely been adopted within the field of aquatic ecology. To test its efficacy and utility, we compared the accuracy and speed of deep learning techniques against human counterparts for quantifying fish abundance in underwater images and video footage. We collected footage of fish assemblages in seagrass meadows in Queensland, Australia. We produced three models using a MaskR-CNN object detection framework to detect the target species, an ecologically important fish, luderick (Girella tricuspidata). Our models were trained on three randomised 80:20 ratios of training:validation data-sets from a total of 6,080 annotations. The computer accurately determined abundance from videos with high performance using unseen footage from the same estuary as the training data (F1 = 92.4%, mAP50 = 92.5%), and from novel footage collected from a different estuary (F1 = 92.3%, mAP50 = 93.4%). The computer’s performance in determining MaxN was 7.1% better than human marine experts, and 13.4% better than citizen scientists in single image test data-sets, and 1.5% and 7.8% higher in video data-sets, respectively. We show that deep learning is a more accurate tool than humans at determining abundance, and that results are consistent and transferable across survey locations. Deep learning methods provide a faster, cheaper and more accurate alternative to manual data analysis methods currently used to monitor and assess animal abundance. Deep learning techniques have much to offer the field of aquatic ecology.

Segregation of resident trout in streams as predicted by three habitat dimensions

1992 ◽  
Vol 70 (5) ◽  
pp. 886-890 ◽  
Author(s):  
Michael A. Bozek ◽  
Wayne A. Hubert
Keyword(s):  
Rainbow Trout ◽  
Brown Trout ◽  
Rocky Mountains ◽  
Brook Trout ◽  
Elevation Gradient ◽  
Cutthroat Trout ◽  
Individual Species ◽  
Habitat Features ◽  
Central Rocky Mountains ◽  
Habitat Variables

We assessed the relation of three measures of habitat to the distribution of four species of Salmonidae, cutthroat trout (Oncorhynchus clarki), brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Oncorhynchus mykiss), in streams of the central Rocky Mountains. We examined whether single measures of three habitat dimensions (climate, stream energy, and stream size) could account for current distribution patterns of four resident trout species in Wyoming. The three habitat dimensions were represented by three habitat variables: elevation, channel gradient, and wetted stream width. Considerable overlap in the ranges of elevation, gradient, and wetted width was observed among reaches where the four species were found, but differences in the mean values of these habitat features were observed among species. Using discriminant analysis, we categorized the presence and absence of individual species in stream reaches by the three habitat variables. We successfully predicted the presence of brook trout (87%), cutthroat trout (59%), brown trout (50%), and rainbow trout (39%) in streams, but the absence of each species was predicted more successfully (rainbow trout (94%), brown trout (94%), cutthroat trout (90%), and brook trout (57%)). The three habitat features were useful in describing the segregation of trout species in streams of the central Rocky Mountains.

Multispecies and Watershed Approaches to Freshwater Fish Conservation

2019 ◽  
Keyword(s):  
Fisheries Management ◽  
Brown Trout ◽  
Brook Trout ◽  
Cape Cod ◽  
Land Protection ◽  
Trout Population ◽  
Waquoit Bay ◽  
Coastal Estuary ◽  
Air Force Base ◽  
Trout Fishery

<em>Abstract</em>.—Waquoit Bay is a coastal estuary located on the south side of Cape Cod. The primary rivers feeding the bay, the Quashnet and Childs rivers, are small, coldwater, groundwater-fed streams. Most of the watersheds of both rivers were originally set aside in the 1600s as a plantation for the Native American Mashpee Wampanoag tribe. The rivers were heavily modified in the late 1700s by the building of mill dams and later in the 1800s by cranberry agriculture. The anadromous Brook Trout <em>Salvelinus fontinalis </em>fisheries in both rivers were acclaimed in the early 1800s. Anadromous river herring <em>Alosa </em>spp. runs were created on both streams by connecting the streams to Johns Pond, a natural kettle hole pond. After anadromous Brook Trout populations declined due primarily to habitat loss, efforts were initiated in the 1950s to restore anadromy to Brook Trout in Cape Cod rivers by overstocking with hatchery Brook Trout. After this project, land protection along the river started with the purchase of abandoned cranberry bogs. Both rivers were heavily stocked with Brown Trout <em>Salmo trutta </em>in the 1970s and 1980s to create a sea-run Brown Trout fishery. In 1976, Trout Unlimited began an ongoing habitat improvement project in the Quashnet River. In the 1970s and 1980s, the rapid development of Cape Cod threatened the watershed. In 1988, the Waquoit Bay National Estuarine Research Reserve was formed and the Commonwealth of Massachusetts purchased land in the watershed to preserve it as open space. As part of the purchase agreement, a potential well site was reserved, which led to studies by the U.S. Geological Survey on the hydrology of the Quashnet River and the impact of potential wells. In the early 1990s, fisheries management shifted away from the stocking of Brown Trout to focus on the native Brook Trout fishery. The Mashpee National Wildlife Refuge, a consortium of landowners centered on Waquoit Bay, was formed in 1995. In 1997, the contaminant ethylene dibromide from the former Otis Air Force Base Superfund site was found to be entering the upper Quashnet River. This led to the creation of a system of berms and groundwater extraction systems. The failure of part of the berm system led to concerns about fisheries impacts, and a restoration plan was developed. A Brook Trout passive integrated transponder tagging project was initiated on the Quashnet River in 2007, and the Brook Trout population has been annually sampled since 2000. In 2008–2010, adult wild Brook Trout from the Quashnet River were transplanted to the Childs River and a wild Brook Trout population was reestablished. Nitrogen loading from the watershed has become a major issue for the Waquoit Bay estuary, causing algae blooms and water-quality impacts. The fisheries of the Waquoit Bay tributaries have been protected and enhanced by an ongoing combination of land protection, fisheries management and research activities, and habitat improvements involving a wide variety of partners. Watershed development and potential climate change continue to threaten both the estuarine resources of Waquoit Bay and the native freshwater and diadromous fisheries of its tributaries.

scholarly journals Brook trout (Salvelinus fontinalis) extinction in small boreal lakes revealed by ephippia pigmentation: a preliminary analysis

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Alexandre Bérubé Tellier ◽  
Paul E. Drevnick ◽  
Andrea Bertolo
Keyword(s):  
Brook Trout ◽  
Fish Assemblages ◽  
Salvelinus Fontinalis ◽  
Sediment Cores ◽  
Experimental Studies ◽  
Cost Effective ◽  
Fish Predation ◽  
Boreal Lakes ◽  
Predation Pressure ◽  
Trout Population

<p>Ephippium pigmentation is a plastic trait which can be related to a trade-off between visual predation pressure and better protection of cladoceran eggs against different types of stress. Experimental studies showed that planktivorous fish exert a greater predation pressure on individuals carrying darker ephippia, but little is known about the variation of ephippium pigmentation along gradients of fish predation pressure in natural conditions. For this study, our experimental design included four small boreal lakes with known fish assemblages. Two of the lakes have viable brook trout (<em>Salvelinus fontinalis</em>) populations, whereas the other two lakes experienced brook trout extinctions during the 20<sup>th</sup> century. Cladoceran ephippia were extracted from sediment cores at layers corresponding to the documented post- extinction phase (1990's) and from an older layer (1950's) for which the brook trout population status is not known precisely. Our first objective was to determine whether brook trout extinction has a direct effect on both ephippium pigmentation and size. Our second objective was to give a preliminary assessment of the status of brook trout populations in the 1950's by comparing the variation in ephippia traits measured from this layer to those measured in the 1990's, for which the extinction patterns are well known. Cost-effective image analysis was used to assess variation in pigmentation levels in ephippia. This approach provided a proxy for the amount of melanin invested in each ephippium analysed. Our study clearly shows that ephippium pigmentation may represent a better indicator of the presence of fish predators than ephippium size, a trait that showed a less clear pattern of variation between lakes with and without fish. For the 1990's period, ephippia from fishless lakes were darker and showed a slight tendency to be larger than ephippia from lakes with brook trout. However, no clear differences in either ephippium size or pigmentation were observed between the 1990's and 1950's layers within each lake. This suggests that brook trout extinction already occurred before the 1950’s, or that brook trout population abundance was already extremely low before and after the 1990’s. Our preliminary study shows that ephippium pigmentation can be used as a tool to quickly assess present and past predation levels on zooplankton when only sediment samples are available.</p>

scholarly journals Seabird‐induced natural mortality of forage fish varies with fish abundance: Evidence from five ecosystems

2020 ◽  
Author(s):  
Claire Saraux ◽  
William J. Sydeman ◽  
John F. Piatt ◽  
Tycho Anker‐Nilssen ◽  
Jonas Hentati‐Sundberg ◽  
...  
Keyword(s):  
Fish Abundance ◽  
Forage Fish ◽  
Natural Mortality

scholarly journals Do native brown trout and non-native brook trout interact reproductively?

2008 ◽  
Vol 95 (7) ◽  
pp. 647-654 ◽  
Author(s):  
J. Cucherousset ◽  
J. C. Aymes ◽  
N. Poulet ◽  
F. Santoul ◽  
R. Céréghino
Keyword(s):  
Brown Trout ◽  
Brook Trout

Effects of Proposed Passamaquoddy Power Project on Anadromous Fishes in Canadian Waters

1960 ◽  
Vol 17 (5) ◽  
pp. 713-720 ◽  
Author(s):  
C. J. Kerswill
Keyword(s):  
Atlantic Salmon ◽  
Brown Trout ◽  
Brook Trout ◽  
High Potential ◽  
Bay Of Fundy ◽  
Tidal Power ◽  
Potential Production ◽  
Sport Fishery ◽  
Potential Value ◽  
Power Project

Atlantic salmon, smelt, alewives, shad, eastern brook trout, and introduced brown trout occur in waters that will be affected by the Passamaquoddy power project. The first four species are taken occasionally in herring weirs but total annual landed values did not exceed $6,000 in the period 1937 to 1956. Salmon and trout have high potential value for angling, subject to improvements in local river management.Construction of tidal power dams should overcome the present lack of typical estuarine conditions in the Passamaquoddy area and favour production of anadromous species. An improved sport fishery for sea-run trout could develop. Realization of the potential production of Atlantic salmon, alewives and shad, but possibly not sea-run trout, would depend on satisfactory access from the Bay of Fundy to the impounded areas.

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