Northwest Science - Accepted Articles and Notes
Northwest Science 98(3)
Late-summer consumption of Chinese basket clam (Corbicula fluminea) carrion by adult yellow perch in Lake Washington - Roger A. Tabor, Lisa M. Crosson, Joseph Short, Lauren Mason-Sarantopulos
Large die-offs of invasive Chinese basket clam (Corbicula fluminea), which often occur in the late summer, can provide a resource subsidy to aquatic and terrestrial ecosystems. We documented an example of this with invasive yellow perch (Perca flavescens) in Lake Washington in western Washington State. Yellow perch were collected by angling in August 2023 and 2024 over a broad area of the lake. Identification of ingested Chinese basket clams was confirmed with genetic analysis. Chinese basket clams made up a substantial portion of their diet in the north part of the lake but not in the south part. Consumption of Chinese basket clam carrion was particularly notable in yellow perch ≥ 225 mm total length, representing 66% of the diet by weight for those collected in the north part of the lake. Virtually all ingested clams were comprised of soft tissue without shells, suggesting consumption was after a recent clam die-off. Consumption of Chinese basket clam carrion is an underappreciated process that may benefit the yellow perch population in Lake Washington and perhaps other fish populations in the Pacific Northwest.
The complete pre-print version of this article is available here.
Correction to note: biomass regressions for understory species in young-growth Sitka spruce–western hemlock forests of southeast Alaska - Annelise Z. Rue-Johns, Justin S. Crotteau, David V. D’Amore, Jeffrey C. Barnard
This notice describes the corrections made to “Rue-Johns AZ, Crotteau JS, D’Amore DV, Barnard JC. 2021. Biomass regressions for understory species in young-growth Sitka spruce–western hemlock forests of Southeast Alaska (corrected). Northwest Science 95:114–124. https://doi.org/10.3955/046.095.0108.” The original publication is available upon request. The authors have identified errors in the calculated and published results that likely stemmed from collating and rearranging tables for publication. Some of these errors were propagated through subsequent calculations. The authors have made corrections to the tables and the manuscript text. These changes do not substantively alter the conclusions of the original research note but provide necessary updates to the model parameters that can be used for future studies.
The complete pre-print version of this article is available here.
Evaluating conservation detection dogs during surveys of black-footed ferrets in Colorado - Tim L. Hiller, Julia Nawrocki, Tina Jackson, Florent Bled, Aimee Hurt, Melissa Steen, Paige G. Smith, Jesse T. Boulerice, Aran Meyer, Rickey L. Jones
Effectively monitoring populations of endangered black-footed ferrets (Mustela nigripes) is difficult due to their nocturnal and semi-fossorial behaviors and very low densities. We evaluated use of conservation detection dogs during surveys of ferrets on 5 study sites in Colorado during 2022–2023. We recorded strength of response at each point of interest (POI; n = 611) where a trained dog (n = 3) exhibited a response. For comparison, we conducted spotlighting surveys that included areas ≤ 100 m of 39 % of POI, and we installed motion-sensing cameras at 37 % of POI. Based on modeling, true-positive rates (i.e., presence of ferret) were related to season (higher during fall than spring), day of year, and wind speed (weak positive relationship) and direction, whereas false-positive rates were most influenced by survey duration (strong positive relationship), relative humidity (weak negative relationship), and time since sunrise associated with identification of a POI (weak positive relationship). Stronger response levels were associated with presence of a ferret, increasing survey duration, and surveys conducted during spring. Presence of burrowing owls (Athene cunicularia) was associated with an increase in strength of response level, whereas the presence of swift foxes (Vulpes velox) was associated with a decrease in strength of response level. Overall, the estimated occupancy probability of a ferret at a POI was 0.72. The performance of conservation detection dogs for detecting black-footed ferrets supports their use during properly designed surveys, particularly when spotlighting is intractable. However, spotlighting is likely a necessary survey method for black-footed ferrets, including for population demographics.
Northwest Science 98(2)
Environmental variability in freshwater drives spawn timing and spawner abundance for anadromous Coastal Cutthroat Trout - James P. Losee, Riley Freeman, Gabe Madel
Coastal Cutthroat Trout exhibit high variability in spawn timing across their range but also locally. However, little is known about the factors driving annual variation in spawn timing within a river system. In this study, we examined how specific abiotic factors influence spawn timing of Coastal Cutthroat Trout from Skookum, Totten, and Eld inlets in South Puget Sound. Weekly counts of Coastal Cutthroat Trout redds in Skookum Creek across nine years (2009 to 2017) and Kennedy and McLane Creek in 2015 were compared to measurements of streamflow, water temperature, air temperature, atmospheric pressure, precipitation, tidal coefficient, and photoperiod to identify determinants of spawn timing. Spawn timing (i.e., redd counts) varied across study years with streamflow representing the most important predictor of redd counts. Across study years the date of peak redd counts varied by more than two months (15 February 2013 versus 21 April 2011). Annual redd abundance negatively correlated with mean streamflow during the spawning period and the highest redd abundances occurred during periods when streamflow was between 0.25 and 0.5 m3 s-1. These results are cause for concern when considering the expectation for increased storm intensity, flooding, and periods of low summertime streamflow conditions associated with climate change. This work builds a foundation for future projects aimed at understanding how climate change may influence the spawn timing and abundance of Coastal Cutthroat Trout.
Gas bubble trauma progression and mortality in sculpin, threespine stickleback, and northern pikeminnow - Kenneth F. Tiffan, Brad D. Liedtke
We examined the progression of gas bubble trauma (GBT) and associated mortality in sculpin (Cottus spp.), threespine stickleback (Gasterosteus aculeatus), and northern pikeminnow (Ptychocheilus oregonensis) exposed to three levels of total dissolved gas (TDG; 120, 125, and 130 % saturation) in laboratory experiments. Sculpin were most sensitive to elevated TDG followed by stickleback and then pikeminnow, which were least sensitive. This was evidenced by GBT and associated mortality progressing fastest in sculpin and slowest in pikeminnow. GBT incidence and severity increased through time at all TDG levels tested, but relationships between severity and exposure time were statistically weak or nonexistent. GBT mortality progressed more rapidly as TDG increased in all species. Regional criteria developed to rank GBT in salmonids did not fully capture the incidence and severity of GBT in the three nonsalmonids we examined. Rather, using criteria that considered all areas of the fish provided more accurate data. The lateral line, body, dorsal fin, and pectoral fins were common locations of GBT in sculpin whereas in stickleback and pikeminnow, GBT was most common on the head and body. The proximate cause of GBT-related death was bubbles in the gills and heart, but unlike in other species, bubbles in these organs appeared rapidly just before the point of death. Our findings provide some of the first information on TDG effects on these little-studied species.