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At least 343 records · Page 19Linked to original sources

Summer habitat use by Columbia River redband trout in the Kootenai River drainage, Montana

The reported decline in the abundance, distribution, and genetic diversity of Columbia River redband trout Oncorhynchus mykiss gairdneri (a rainbow trout subspecies) has prompted fisheries managers to investigate their habitat requirements, identify critical habitat, and develop effective conservation and recovery programs. We analyzed the microhabitat, mesohabitat, and macrohabitat use and distribution of Columbia River redband trout by means of snorkel surveys in two watersheds in the Kootenai River drainage, Montana and Idaho, during the summers of 1997 and 1998. Juvenile (36&ndash;125 mm total length, TL) and adult (>=126 mm TL) fish preferred deep microhabitats (>=0.4 m) with low to moderate velocities (<=0.5 m/s) adjacent to the thalweg. Conversely, age-0 (<=35 mm) fish selected slow water (<=0.1 m/s) and shallow depths (<=0.2 m) located in lateral areas of the channel. Age-0, juvenile, and adult fish strongly selected pool mesohabitats and avoided riffles; juveniles and adults generally used runs in proportion to their availability. At the macrohabitat scale, density of Columbia River redband trout (35 mm) was positively related to the abundance of pools and negatively related to stream gradient. The pool: riffle ratio, gradient, and stream size combined accounted for 80% of the variation in density among 23 stream reaches in five streams. Our results demonstrate that low-gradient, medium-elevation reaches with an abundance of complex pools are critical areas for the production of Columbia River redband trout. These data will be useful in assessing the impacts of land-use practices on the remaining populations and may assist with habitat restoration or enhancement efforts.

Montana

Water quality and bed sediment quality in the Albemarle Sound, North Carolina, 2012–14

The Albemarle Sound region was selected in 2012 as one of two demonstration sites in the Nation to test and improve the design of the National Water Quality Monitoring Council’s National Monitoring Network (NMN) for U.S. Coastal Waters and Tributaries. The goal of the NMN for U.S. Coastal Waters and Tributaries is to provide information about the health of our oceans, coastal ecosystems, and inland influences on coastal waters for improved resource management. The NMN is an integrated, multidisciplinary, and multi-organizational program using multiple sources of data and information to augment current monitoring programs. This report presents and summarizes selected water-quality and bed sediment-quality data collected as part of the demonstration project conducted in two phases. The first phase was an occurrence and distribution study to assess nutrients, metals, pesticides, cyanotoxins, and phytoplankton communities in the Albemarle Sound during the summer of 2012 at 34 sites in Albemarle Sound, nearby sounds, and various tributaries. The second phase consisted of monthly sampling over a year (March 2013 through February 2014) to assess seasonality in a more limited set of constituents including nutrients, cyanotoxins, and phytoplankton communities at a subset (eight) of the sites sampled in the first phase. During the summer of 2012, few constituent concentrations exceeded published water-quality thresholds; however, elevated levels of chlorophyll a and pH were observed in the northern embayments and in Currituck Sound. Chlorophyll a , and metals (copper, iron, and zinc) were detected above a water-quality threshold. The World Health Organization provisional guideline based on cyanobacterial density for high recreational risk was exceeded in approximately 50 percent of water samples collected during the summer of 2012. Cyanobacteria capable of producing toxins were present, but only low levels of cyanotoxins below human health benchmarks were detected. Finally, 12 metals in surficial bed sediments were detected at levels above a published sediment-quality threshold. These metals included chromium, mercury, copper, lead, arsenic, nickel, and cadmium. Sites with several metal concentrations above the respective thresholds had relatively high concentrations of organic carbon or fine sediment (silt plus clay), or both and were predominantly located in the western and northwestern parts of the Albemarle Sound. Results from the second phase were generally similar to those of the first in that relatively few constituents exceeded a water-quality threshold, both pH and chlorophyll a were detected above the respective water-quality thresholds, and many of these elevated concentrations occurred in the northern embayments and in Currituck Sound. In contrast to the results from phase one, the cyanotoxin, microcystin was detected at more than 10 times the water-quality threshold during a phytoplankton bloom on the Chowan River at Mount Gould, North Carolina in August of 2013. This was the only cyanotoxin concentration measured during the entire study that exceeded a respective water-quality threshold. The information presented in this report can be used to improve understanding of water-quality conditions in the Albemarle Sound, particularly when evaluating causal and response variables that are indicators of eutrophication. In particular, this information can be used by State agencies to help develop water-quality criteria for nutrients, and to understand factors like cyanotoxins that may affect fisheries and recreation in the Albemarle Sound region.

North Carolina, Virginia

Demographic characteristics of an adfluvial bull trout population in Lake Pend Oreille, Idaho

Introductions of nonnative species, habitat loss, and stream fragmentation have caused the Bull Trout Salvelinus confluentus to decline throughout much of its native distribution. Consequently, in June 1998, the Bull Trout was listed under the U.S. Endangered Species Act as threatened. The Bull Trout has existed in Lake Pend Oreille and its surrounding tributaries since the last ice age, and the lake once supported a world-renowned Bull Trout fishery. To quantify the current status of the Bull Trout population in Lake Pend Oreille, Idaho, we compared the mean age, growth, maturity, and abundance with reports in a study conducted one decade earlier. Abundance was estimated by mark–recapture for Bull Trout caught in trap nets and gill nets set in Lake Pend Oreille during ongoing suppression netting of Lake Trout S. namaycush in 2007–2008. Bull Trout sampled in 2006–2008 were used to estimate age structure, survival, growth, and maturity. Estimated Bull Trout abundance was similar to that estimated one decade earlier in Lake Pend Oreille. Bull Trout residing in Lake Pend Oreille between 2006 and 2008 were between ages 4 and 14 years; their growth was fastest between ages 1 and 2 and slowed thereafter. Male and female Bull Trout matured at a similar age, but females grew faster than males, thereby maturing at a larger size. Our findings suggest that management has effectively addressed current threats to increase the likelihood of long-term persistence of the Bull Trout population in Lake Pend Oreille.

Idaho

Surgical insertions of transmitters and telemetry methods in fisheries research

Use of electronic transmitter and monitoring systems to track movements of aquatic animals has increased continuously since the inception of these systems in the mid-1950s. The purpose of the present report is to provide information about veterinary principles and their incorporation into surgical implantation procedures for fish. We also intend to provide insight into the unique challenges of field-based aquatic surgical studies. Within this context, 4 aspects of the process for surgical implantation of transmitters in fish (ie, handling, aseptic technique, anesthesia, and implantation) will be described. Effects of surgical insertion of transmitters (ie, tagging) and aspects of the surgical implantation process where collaboration and professional exchanges among nonveterinarian researchers and veterinarians may be most fruitful will be discussed. Although this report focuses on surgical implantation, the principles and protocols described here (other than incision and suture placement) are also applicable to studies that involve injection of transmitters into fish.

American Journal of Veterinary Research

Real-time piscicide tracking using Rhodamine WT dye for support of application, transport, and deactivation strategies in riverine environments

Piscicide applications in riverine environments are complicated by the advection and dispersion of the piscicide by the flowing water. Proper deactivation of the fish toxin is required outside of the treatment reach to ensure that there is minimal collateral damage to fisheries downstream or in connecting and adjacent water bodies. In urban settings and highly managed waterways, further complications arise from the influence of industrial intakes and outfalls, stormwater outfalls, lock and dam operations, and general unsteady flow conditions. These complications affect the local hydrodynamics and ultimately the transport and fate of the piscicide. This report presents two techniques using Rhodamine WT dye for real-time tracking of a piscicide plume—or any passive contaminant—in rivers and waterways in natural and urban settings. Passive contaminants are those that are present in such low concentration that there is no effect (such as buoyancy) on the fluid dynamics of the receiving water body. These methods, when combined with data logging and archiving, allow for visualization and documentation of the application and deactivation process. Real-time tracking and documentation of rotenone applications in rivers and urban waterways was accomplished by encasing the rotenone plume in a plume of Rhodamine WT dye and using vessel-mounted submersible fluorometers together with acoustic Doppler current profilers (ADCP) and global positioning system (GPS) receivers to track the dye and map the water currents responsible for advection and dispersion. In this study, two methods were used to track rotenone plumes: (1) simultaneous injection of dye with rotenone and (2) delineation of the upstream and downstream boundaries of the treatment zone with dye. All data were logged and displayed on a shipboard laptop computer, so that survey personnel provided real-time feedback about the extent of the rotenone plume to rotenone application and deactivation personnel. Further, these strategies facilitate adjustment of rotenone application and deactivation strategies in real time if necessary based on the observed advection and dispersion of the rotenone plume. Two large-scale and complex applications of rotenone in the Chicago Area Waterway System (CAWS) in 2009 and 2010 to combat invasive Asian carp are documented in this report. The application in Chicago Sanitary and Ship Canal (CSSC) in December 2009 involved more than 1,800 gallons of rotenone injected at multiple stations through a 6.2-mile reach of the canal near Lockport, Illinois. The rotenone plume was encased in Rhodamine WT dye so that two survey boats provided real-time feedback to shore personnel regarding the plume extent as it advected downstream. Real-time tracking of the rotenone was essential in this large-scale application because of the multistage injection strategy and the numerous deactivation points required to minimize collateral damage to fisheries in surrounding and receiving water bodies. All timing of application and deactivation operations relied on dye tracking. A second application of rotenone in May 2010 to the Little Calumet River near O’Brien Lock and Dam (Illinois) provided another opportunity for dye-tracking support operations; however, application and deactivation strategies were designed considering zero-flow conditions within the reach of interest. Therefore, dye was injected at the upstream and downstream boundaries of the rotenone application reach and was used to track movement of water in and out of a treatment reach, allowing proper deactivation to occur and avoiding unnecessary damage to fisheries downstream. The data collected during the real-time tracking operations for both applications allowed full documentation of the rotenone treatment for archival purposes and provided information for future applications. The methods presented in this report for real-time tracking and documentation of piscicide applications in riverine environments worked exceptionally well and allowed the multiagency Asian Carp Rapid Response Workgroup to carry out large-scale rotenone applications in urban waterways in an environmentally responsible manner with minimal collateral damage to fisheries outside the treatment reach. Traveltime information extracted from the boat-mounted and fixed-position fluorometers agrees well with empirical predictions from a preliminary dye study (mock rotenone injection) on this system completed in November 2009 on the CSSC and with previously published methods for estimating traveltimes of the peak, leading edge, and trailing edge of the plume. Although the rotenone application strategy called for zero-flow conditions on the Little Calumet River in 2010, downstream advection of treated water did occur, and dye tracing combined with velocity mapping allowed this advection to be documented and exposed the unique hydrodynamics and mixing within this reach. The large volumes of data collected during the operations allow documentation and visualization of the rotenone applications, thus providing feedback to planners and archival of the treatments for future reference. The methods developed in this report are directly transferrable to piscicide applications in water bodies in other locations, including rivers, ponds, or lakes, and can be used for real-time tracking of any passive contaminant that may enter a water body.

Illinois

Monitoring fine-sediment volume in the Colorado River ecosystem, Arizona: construction and analysis of digital elevation models

Digital elevation models (DEMs) of eleven 2–5 kilometer reaches of the Colorado River ecosystem (CRE) in Grand Canyon were constructed from repeat bathymetric and topographic surveys collected between August 2000 and December 2004. The DEMs will be used by researchers to study the effects of Glen Canyon Dam (GCD) operations on the sediment resources of the CRE in Grand Canyon by quantifying morphological changes and sediment transfer within and among the study reaches. Airborne surveys collected light detection and ranging (lidar) and photogrammetric data, whereas ground topographic and bathymetric data were collected simultaneously on river trips. Surveys were conducted in August 2000, September 2000, May 2002, May 2004, November 2004, and December 2004. The aerial lidar and photogrammetric data were merged with the ground topographic and bathymetric data to create DEMs of the study areas with a grid resolution of 1 meter. For each survey period, the vertical component of uncertainty (specifically, reproducibility or precision) was estimated for each data type (lidar/photogrammetry, ground surveys, bathymetry) and for two different types of bed-surface texture (smooth and rough). The resulting DEMs from this study are a valuable contribution to ongoing efforts in assessing the effects of GCD operations on the CRE. The DEMs can be used to map the spatial characteristics of geomorphic change within the study reaches and to estimate sediment budgets for different time periods by calculating the difference in sediment volume between surveys. In addition, the DEMs provide essential boundary conditions for numerical models of sediment transport and deposition, as well as help define the spatial distribution of habitat for fisheries investigations.

Arizona

Status and trends in the Lake Superior fish community, 2019

The Lake Superior fish community was sampled in 2019 with daytime bottom trawls at 76 nearshore and 35 offshore stations distributed throughout the lake. In the nearshore zone, 25,131 fish from 24 species or morphotypes were collected. The number of species collected at nearshore stations ranged from 0 to 15, with a mean of 5.6 and median of five. Nearshore mean biomass was 5.7 kg/ha which was similar to the past twenty-year average of 5.2 kg/ha and less than the 42-year period-of-record mean of 8.5 kg/ha. Lake Whitefish, Rainbow Smelt, Longnose Sucker, Bloater, lean Lake Trout, Cisco, Burbot, and siscowet Lake Trout had the highest total collected biomass. In the offshore zone, 13,145 fish from 11 species or morphotypes were collected. The number of species collected at offshore stations ranged from two to six, with a mean 3.6 and median of four. Deepwater Sculpin, Kiyi, and siscowet Lake Trout made up 99% of the total number of individuals and biomass collected in offshore waters. Mean and median offshore biomass for all species in 2019 was 7.0 kg/ha which was greater than the past eight-year average of 6.6 kg/ha. Recruitment, as measured by age-1 densities, was near the period-of-record lakewide average for Lake Whitefish (7 fish/ha) and Rainbow Smelt (137 fish/ha) and was lower than the period-of-record lakewide average for Bloater (4 fish/ha), Kiyi (1 fish/ha), and Cisco (<1 fish/ha). Lakewide average age-1 Cisco densities have been estimated at <1 fish/ha in twelve of the last twenty years. Survival of Coregonus species to age-1 continues to be a major concern of fishery managers.

Lake Superior

Status and trends in the Lake Superior fish community, 2021

The Lake Superior nearshore fish community was sampled in May-June 2021 with daytime bottom trawl tows at 45 stations located in USA waters. The 45 locations sampled were long-term monitoring sites that had been annually sampled since 1978. All comparisons to 2021 results were limited to past collections from USA waters, as compared to previous years, where comparisons included USA and Canadian sites. In 2021, the number of species collected at each site ranged from 0 to 15, with a median of 5 species. Average fish biomass was 6.3 kg/ha, which was higher than the average observed over the past 10 years (4.7 kg/ha), similar to the average observed from 2001-10 (6.7 kg/ha), and less than the averages observed in 1991-2000 (14.8 kg/ha), and 1981-1990 (11.9 kg/ha), but higher than the average from 1978-1980 (5.2 kg/ha). Average biomass in 2021 was highest for Lake Whitefish ( Coregonus clupeaformis , 3.2 kg/ha), Bloater ( C. hoyi , 1.4 kg/ha), Rainbow Smelt ( Osmerus mordax , 0.5 kg/ha), and Cisco ( C. artedi , 0.3 kg/ha). Coregonus spp. year-class strength, as measured by densities of age-1 fish, was 8 fish/ha for Bloater, 11 fish/ha for Cisco, and 41 fish/ha for Lake Whitefish. The age-1 Bloater estimate was in the range observed for the 2014, 2015, and 2016 year-classes (7-9 age-1 fish/ha) and greater than that observed in other years over the past decade (<1 age-1 fish/ha). The age-1 Cisco estimate was the highest estimate since the 2009 year-class. Average Lake Whitefish age-1 density was the second highest estimate observed over the past 44-years. Cisco survival to age-1 has been low since 2009 and near zero since the 2014- and 2015-year classes. This lack of survival has yet to be adequately explained and continues to be a major concern of fishery managers due to Cisco’s importance in ecosystem dynamics and value to the commercial fishery.

Lake Superior

Genetic population structure of muskellunge in the Great Lakes

We quantified genetic relationships among Muskellunge Esox masquinongy from 15 locations in the Great Lakes to determine the extent and distribution of measurable population structure and to identify appropriate spatial scales for fishery management and genetic conservation. We hypothesized that Muskellunge from each area represented genetically distinct populations, which would be evident from analyses of genotype data. A total of 691 Muskellunge were sampled ( n = 10&ndash;127/site) and genetic data were collected at 13 microsatellite loci. Results from a suite of analyses (including pairwise genetic differentiation, Bayesian admixture prediction, analysis of molecular variance, and tests of isolation by distance) indicated the presence of nine distinct genetic groups, including two that were approximately 50 km apart. Geographic proximity and low habitat complexity seemed to facilitate genetic similarity among areas, whereas Muskellunge from areas of greater habitat heterogeneity exhibited high differentiation. Muskellunge from most areas contained private alleles, and mean within-area genetic variation was similar to that reported for other freshwater fishes. Management programs aimed at conserving the broader diversity and long-term sustainability of Muskellunge could benefit by considering the genetically distinct groups as independent fisheries, and individual spawning and nursery habitats could subsequently be protected to conserve the evolutionary potential of Muskellunge.

Great Lakes

Antimycin A species sensitivity distribution: Perspectives for non-indigenous fish control

The global transfer of aquatic biota outside their native geographical range has resulted in dramatic changes to biological communities. Many nonnative species introductions are facilitated by human activity and then spread intra-continentally through connected watersheds once established. Resource managers therefore utilize multiple control technologies, such as management chemicals, for fisheries management to remove non-indigenous fishes. Antimycin-A (ANT-A) is a management chemical, previously registered in the United States, that has been extensively studied and used to control non-indigenous fishes. The present study examines ANT-A species sensitivity among fish and aquatic invertebrates and summarizes factors that influence toxicity. ANT-A species sensitivity distributions 20th percentile hazard concentrations (HC20) for acute studies ≤ 24 h demonstrated fish (0.088 µg/L) are 174-fold more sensitive to ANT-A than invertebrates (15.35 µg/L). Similar to previous reports, toxicity was demonstrated to be influenced by water pH, temperature, and fish mass. Therefore, the present study and results characterize ANT-A toxicity for aquatic resource managers and future use in fisheries management.

Management of Biological Invasions

Characterization of deep-sea coral and sponge communities in Greater Farallones National Marine Sanctuary: Point Arena South Essential Fish Habitat Conservation Area and New Amendment 28 Areas

This report summarizes samples collected during a remotely operated vehicle (ROV) cruise conducted in October 2019 on board E/V Nautilus. Areas sampled in Greater Farallones National Marine Sanctuary included areas proposed for fisheries management zoning in the Point Arena South (PAS) Essential Fish Habitat Conservation Area (EFH). Dive planning targeted habitats and biological communities of corals, sponges, and fishes in relation to the new, 2020 configuration of PAS EFH (hereafter referred to as PAS), which includes areas once closed to commercial bottom trawling and now opened to bottom trawling, once opened to bottom trawling and now closed, or that remain closed to commercial bottom trawling. Particular interest was given to enumerating deep-sea corals and sponges (DSCS) in these areas as they are long-lived, slow-growing species that are vulnerable to impacts from bottom trawling. Fish species were also enumerated. These data provide the most recent assessment and characterization for a portion of these areas before the final ruling on Amendment 28 went into effect on January 1, 2020 (50 C.F.R. part 660). A total of seven sponge specimens were collected on this mission, some of which could potentially be new species, such as the large yellow ‘plate’-shaped sponge and the ‘palm frond’ morphology of the predatory sponge Asbestopluma , documented on both dives. Six coral collections were made, including three types of red Swiftia sp. gorgonians (two had fan-shaped morphology and one had branched morphology) with different polyp colors. A high diversity of fishes, particularly groundfish, were documented across the entire PAS area. The findings from this cruise will be provided to NOAA’s National Marine Fisheries Service to help them identify biologically complex areas of the seafloor that are most sensitive to bottom trawling and aid in the ongoing management of this designated essential fish habitat conservation zone. Habitat data from these surveys will be used to confirm substrate prediction models that can be used to predict DSCS habitats where there is a dearth of visual observations.

California

Distribution, migration behavior, habitat use, and species interactions of fall-released juvenile hatchery spring Chinook salmon on the Deschutes River, Oregon, 2002, Annual report 2002

In a review of National Fish Hatcheries (NFH), the U.S. Fish and Wildlife Service (USFWS) identified the need to assess the fate of hatchery-reared fish and their potential effect on the aquatic community (USFWS 1998). Additionally, in the Columbia River Biological Opinion, the National Marine Fisheries Service (NMFS) recommended monitoring and evaluating ecological interactions between hatchery and wild fish (NMFS 1999). In 2002, a study was designed to investigate the fate of hatchery-reared fish and to assess habitat use and fish interactions in the Deschutes River, Oregon.

Oregon

Preliminary volcano-hazard assessment for the Katmai volcanic cluster, Alaska

The world’s largest volcanic eruption of the 20th century broke out at Novarupta (fig. 1) in June 1912, filling with hot ash what came to be called the Valley of Ten Thousand Smokes and spreading downwind more fallout than all other historical Alaskan eruptions combined. Although almost all the magma vented at Novarupta, most of it had been stored beneath Mount Katmai 10 km away, which collapsed during the eruption. Airborne ash from the 3-day event blanketed all of southern Alaska, and its gritty fallout was reported as far away as Dawson, Ketchikan, and Puget Sound (fig. 21). Volcanic dust and sulfurous aerosol were detected within days over Wisconsin and Virginia; within 2 weeks over California, Europe, and North Africa; and in latter-day ice cores recently drilled on the Greenland ice cap. There were no aircraft in Alaska in 1912—fortunately! Corrosive acid aerosols damage aircraft, and ingestion of volcanic ash can cause abrupt jet-engine failure. Today, more than 200 flights a day transport 20,000 people and a fortune in cargo within range of dozens of restless volcanoes in the North Pacific. Air routes from the Far East to Europe and North America pass over and near Alaska, many flights refueling in Anchorage. Had this been so in 1912, every airport from Dillingham to Dawson and from Fairbanks to Seattle would have been enveloped in ash, leaving pilots no safe option but to turn back or find refuge at an Aleutian airstrip west of the ash cloud. Downwind dust and aerosol could have disrupted air traffic anywhere within a broad swath across Canada and the Midwest, perhaps even to the Atlantic coast. The great eruption of 1912 focused scientific attention on Novarupta, and subsequent research there has taught us much about the processes and hazards associated with such large explosive events (Fierstein and Hildreth, 1992). Moreover, work in the last decade has identified no fewer than 20 discrete volcanic vents within 15 km of Novarupta (Hildreth and others, 1999, 2000, 2001; Hildreth and Fierstein, 2000), only half of which had been named previously—the four stratovolcanoes Mounts Katmai, Mageik, Martin, and Griggs; the cone cluster called Trident Volcano; Snowy Mountain; and the three lava domes Novarupta, Mount Cerberus, and Falling Mountain. The most recent eruptions were from Trident Volcano (1953–74), but there have been at least eight other, probably larger, explosive events from the volcanoes of this area in the past 10,000 years. This report summarizes what has been learned about the volcanic histories and styles of eruption of all these volcanoes. Many large earthquakes occurred before and during the 1912 eruption, and the cluster of Katmai volcanoes remains seismically active. Because we expect an increase in seismicity before eruptions, seismic monitoring efforts to detect volcanic unrest and procedures for eruption notification and dissemination of information are included in this report. Most at risk from future eruptions of the Katmai volcanic cluster are (1) air-traffic corridors of the North Pacific, including those approaching Anchorage, one of the Pacific’s busiest international airports, (2) several regional airports and military air bases, (3) fisheries and navigation on the Naknek Lake system and Shelikof Strait, (4) pristine wildlife habitat, particularly that of the Alaskan brown bear, and (5) tourist facilities in and near Katmai National Park.

Alaska

A characterization of the deep-sea coral and sponge community along the Oregon Coast using a remotely operated vehicle on the EXPRESS 2022 expedition

Deep-sea coral and sponge (DSCS) communities serve as essential fish habitat (EFH) by providing shelter and nursery habitat, increasing diversity, and increasing prey availability (Freese and Wing, 2003; Bright, 2007; Baillon et al., 2012; Henderson et al., 2020). Off the U.S. West Coast, threats to these long-lived, fragile organisms from bottom contact fishing gear, potential offshore renewable energy development, and ocean warming and acidification have been the subject of recent research (Gomez et al., 2018; Salgado et al., 2018; Yoklavich, et al., 2018; Gugliotti et al., 2019). Other DSCS studies have reported new species (Yoklavich and Love, 2005), analyzed species distribution and abundance (Tissot et al., 2006, Watters et al., 2022), developed predictive distribution models (Huff et al., 2013; Rooper et al., 2017; Kreidler, 2020), and discovered medicinal uses for corals and sponges (Essack et al., 2011; Shrestha et al., 2018). Due to the vast area of unexplored seafloor within the territorial waters and the U.S. exclusive economic zone (EEZ; 12-200 nautical miles off the coast) and the technological requirements and expense of deep-sea research, there is still much to learn about the distributions and biology of DSCS. This information is critical to resource managers for effective conservation and management of DSCS habitats. In order to minimize the adverse impacts of fishing on EFH, the Pacific Fishery Management Council (PFMC) and National Marine Fisheries Service (NMFS) designated several seafloor habitat areas as EFH conservation areas (EFHCA), first in 2006 (as part of Amendment 19 to the Pacific coast groundfish fishery management plan) and then again in 2020 (as part of Amendment 28). These areas are closed to bottom trawl fishing at a minimum, and in some cases to all bottom contact fishing gears. In addition to protections afforded by EFH-related regulations, the National Marine Sanctuary Program prohibits certain non-fishing activities within areas designated as national marine sanctuaries, such as oil and gas exploration or extraction, cable laying, and other forms of seabed alteration or construction that disturb benthic communities. NOAA’s Deep-Sea Coral and Research Technology Program (DSCRTP) began a 4-yr funding initiative for the U.S. West Coast in 2017. The goals of the West Coast Deep-Sea Coral Initiative (WCDSCI) were to: 1) gather baseline information on areas subject to fishing regulation changes prior to the implementation of Amendment 28; 2) improve our understanding of known DSCS bycatch “hot spots”; and 3) explore and assess DSCS resources within NOAA National Marine Sanctuaries with emphasis on areas of sanctuary resource protection and management concerns. As part of the WCDSCU, an 11-day expedition (3 Sep – 13 Sep 2022) was launched from the NOAA Ship Bell M. Shimada, beginning and ending in Newport, OR. The science team assembled for this cruise were members of the EXpanding Pacific Research and Exploration of Submerged Systems (EXPRESS) campaign, which brings together researchers from federal and nonfederal institutions to collaborate on scientific expeditions targeting the deepwater areas off California, Oregon, and Washington. EXPRESS supports researchers leveraging funding, resources, personnel, and expertise to accomplish more science than would have been possible by a single entity alone. The 2022 expedition included research partners from National Marine Fisheries Service (NMFS) Southwest Fisheries Science Center (SWFSC) and Northwest Fisheries Science Center (NWFSC), Bureau of Ocean Energy Management (BOEM), U.S. Geological Survey (USGS), Pacific Fisheries Management Council Habitat Committee, and Woods Hole Oceanographic Institution.

Report

As the prey thickens: Rainbow trout select prey based upon width not length

Drift-feeding fish are typically considered size-selective predators. Yet, few studies have explicitly tested which aspect of prey “size” best explains size selection by drift-foraging fish. Here, we develop a Bayesian discrete choice model to evaluate how attributes of both prey and predator simultaneously influence size-selective foraging. We apply the model to a large dataset of paired invertebrate drift ( n = 784) and rainbow trout ( Oncorhynchus mykiss ) diets ( n = 1028). We characterized prey “size” using six metrics (length, width, area, hemispherical area, volume, mass) and used pseudo- R 2 to determine which metric best explained observed prey selection across seven taxa. We found that rainbow trout are positively size-selective, they are selecting prey based upon differences in prey width, and size-selectivity increases with fish length. Rainbow trout demonstrated strong selection for the adult and pupae stages of aquatic insects relative to their larval stages. Our study provides strong empirical evidence for size-selective foraging in rainbow trout and demonstrates prey selection is based primarily upon width, not length or area as has been widely reported.

Arizona

Comparison of prehatch C-start responses in rainbow trout and lake trout embryos by means of a tactile stimulus test

The C-start in teleost fishes, a type of startle response, mediates the ability to respond to abrupt, unexpected stimuli and is characterized by a short-latency, C-type fast start acceleration. In prehatch fish embryos, the C-start appears necessary for mechanical breakdown of the egg chorion and successful hatching by way of increased embryo movement and distribution of the hatching enzymes. In later stages, the C-start plays an important role in predator avoidance. Using tactile stimulation, we evaluated the C-start response in rainbow trout Oncorhynchus mykiss at 170 degree-days, when 6.6% of embryos exhibited C-starts, and lake trout Salvelinus namaycush embryos at 320 degree-days, when 23% of embryos exhibited C-starts. Triplicate groups of embryos were later tested at three developmental stages: early (220 and 360 degree-days for rainbow trout and lake trout, respectively), middle (260 and 480 degree-days, respectively), and late (320 and 560 degree-days, respectively). The proportion of trout embryos exhibiting C-start increased through time, such that 100% had responded by the late stage, just prior to hatching. C-starts could be obtained by repeated stimulation, and the relative activity of the embryos (based on the number of flexures per stimulus) also increased over time. Rainbow trout and lake trout showed very similar C-start responses at parallel developmental stages, and these patterns of response were similar to those reported in other fish species.

Transactions of the American Fisheries Society