Size-Structured Morality in a Treespine Stickleback (Gastrosteus aculeatus) – Cutthroat Trout (Oncorhynchus clarki) Community

1990 ◽  
Vol 47 (6) ◽  
pp. 1194-1205 ◽  
Author(s):  
T. E. Reimchen
Keyword(s):  
Gasterosteus Aculeatus ◽  
Size Structure ◽  
Adult Population ◽  
Total Mortality ◽  
Cutthroat Trout ◽  
Oncorhynchus Clarki ◽  
Small Fish ◽  
Frequency Distributions ◽  
Queen Charlotte Islands ◽  
Young Of The Year

In a 112-ha bog lake on the Queen Charlotte Islands, British Columbia, small fish comprised the major element in the diet of cutthroat trout (Oncorhynchus clarki). Despite the presence of juvenile salmon and char in the lake, threespine stickleback (Gasterosteus aculeatus) was the most common fish in the diet (99.5%). Foraging activity appeared to be more frequent in littoral than in limnetic regions. Mark–recapture methods indicate an average population of 220 trout and 75 000 adult stickleback. Trout consumed an estimated 308 770 stickleback yearly (145 kg) of which 65% were taken during summer. Seventy-three percent of all fish consumed were young of the year and 2% were adults, the latter representing 4% of the adult population in the lake. There was a 75% reduction in total mortality between successive year classes of stickleback (0,1,2,3 +). This consumption curve, which resembles a typical survivorship curve of fish, is a function of the size-structure of the populations and includes interactions between size availability of stickleback, prey-size preferences of the trout, and length frequency distributions of trout. Total weight of stickleback consumed by trout comprised about 40% of that previously calculated for 16 species of avian piscivores in the lake.

Fitness consequences of habitat use for juvenile cutthroat trout: energetic costs and benefits in pools and riffles

2001 ◽  
Vol 58 (3) ◽  
pp. 585-593 ◽  
Author(s):  
Jordan S Rosenfeld ◽  
Shelly Boss
Keyword(s):  
Growth Rates ◽  
Habitat Preference ◽  
Cost Benefit Analysis ◽  
Cutthroat Trout ◽  
Cost Benefit ◽  
Invertebrate Drift ◽  
Oncorhynchus Clarki ◽  
Fitness Consequences ◽  
Young Of The Year ◽  
Bioenergetic Cost

To assess freshwater habitat requirements of juvenile anadromous cutthroat trout, Oncorhynchus clarki, we measured habitat preference and growth rates of young-of-the-year (YOY) and 1- to 2-year-old fish confined to either pools or riffles in Husdon Creek, British Columbia, during 1999. YOY preferred pools to riffles in habitat-preference experiments, despite normally occurring at lower densities in pools. YOY grew in both pools and riffles when experimentally confined to either habitat, but growth rates were higher in pools. Larger juvenile cutthroat trout, on average, grew in pools, but consistently lost weight in riffles, indicating that pools are a habitat preference for YOY but a requirement for larger fish. A bioenergetic cost–benefit analysis (based on swimming costs and energy intake from invertebrate drift) indicates that energetics alone are sufficient to account for avoidance of riffles by larger cutthroat trout, without having to invoke greater predation risk in shallow habitats. Energetics modeling demonstrates that the smaller size and energetic needs of YOY allow exploitation of habitats (e.g., pocket pools in riffles) that are unavailable to larger fish.

Evolutionary attributes of headfirst prey manipulation and swallowing in piscivores

1991 ◽  
Vol 69 (11) ◽  
pp. 2912-2916 ◽  
Author(s):  
T. E. Reimchen
Keyword(s):  
Experimental Data ◽  
Field Data ◽  
Gasterosteus Aculeatus ◽  
Cutthroat Trout ◽  
Escape Rate ◽  
Oncorhynchus Clarki ◽  
Large Prey ◽  
Fish Prey ◽  
Fold Reduction ◽  
Maximum Gape

Headfirst swallowing of fish prey is a common attribute of gape-limited predators, conferring the presumed advantage of reduced esophageal abrasion. I evaluate swallowing orientation using cutthroat trout (Oncorhynchus clarki) as predator and three-spine stickleback (Gasterosteus aculeatus) as prey. Field data indicate that orientation is random when prey diameter is less than one-half the gape of the predator, but this increases to 90% headfirst orientation as prey diameter approaches and exceeds the maximum gape, consistent with the suspected reduction in abrasion. Experimental data show two additional advantages to headfirst orientation. Following capture, there is a 2- to 5-fold reduction in escape rate of the prey, and among prey that were swallowed, the manipulation period is substantially reduced (mean 29 vs. 81 s for headfirst and tailfirst orientation, respectively), the differences being most accentuated at large prey sizes.

Population dynamics of the shore crab Pachygrapsus marmoratus (Brachyura: Grapsidae) in the central Portuguese coast

2002 ◽  
Vol 82 (2) ◽  
pp. 229-241 ◽  
Author(s):  
Augusto A.V. Flores ◽  
José Paula
Keyword(s):  
Population Dynamics ◽  
Size Structure ◽  
Shore Crab ◽  
Late Winter ◽  
Rocky Shores ◽  
Study Region ◽  
Frequency Distributions ◽  
Portuguese Coast ◽  
Pachygrapsus Marmoratus ◽  
Young Of The Year

The population dynamics of the shore crab Pachygrapsus marmoratus was studied at two different rocky shores, Cabo Raso and Avencas, within the central Portuguese coast. The population structure at these shores, obtained by pooling monthly samples, revealed marked discrepancies. Unimodal, right-skewed size–frequency distributions at Avencas contrasts with the bimodal distributions obtained at Cabo Raso, corresponding to early recruits and larger adults. Recruitment timing and intensity together with habitat complexity are probable causes of the differences observed. At Cabo Raso an intense recruitment season was recorded from September to November, but very small juveniles were always present in samples. Monthly polymodal distributions are apparent but the size structure too complex to identify age groups through the sampling period. At Avencas, the influx of new juveniles is temporally restricted and year groups recognizable from main recruitment events taking place around October. Young-of-the-year crabs grow quickly to mature size and join the reproductive stock in the next breeding season from late March to early September in the study region. The growth pattern in both sexes follows a seasonal trend with minimum growth during the breeding months and maximum growth rates from late winter to early spring. Life span may reach four years, probably more in males. At Avencas, population maintenance seems to be highly dependent on favourable conditions promoting adequate settlement intensity and timing. Early recruitment is presumed to enhance the reproductive output of young-of-the-year individuals which comprise the bulk of breeding crabs. At Cabo Raso settlement rates are much higher and recruitment timing may be less critical since most breeding crabs belong to the 1-y+ class.

Conservation, Ecology, and Management of Catfish: The Second International Symposium

2011 ◽  
Keyword(s):  
Native Species ◽  
Size Structure ◽  
Total Mortality ◽  
Small Fish ◽  
Total Biomass ◽  
Flathead Catfish ◽  
History Of ◽  
Native Fishes ◽  
Negative Impacts ◽  
Annual Mortality

<em>Abstract</em>.—Recent modeling indicates that increased exploitation on nonnative flathead catfish <em>Pylodictis olivaris</em> may be an avenue for native species recovery. Flathead catfish were illegally introduced into the Satilla River, Georgia, and negative impacts have occurred on native fishes. In an effort to aid in the restoration of native fish on the Satilla River, the Georgia Department of Natural Resources initiated an intensive electrofishing removal effort. In this study, we evaluated the changes in flathead catfish total mortality, condition, and size structure from those efforts. From 2007 to 2009, 13,472 flathead catfish totaling 19,337 kg were removed along a 129-km stretch of the Satilla River. The population size structure changed substantially from containing many large individuals (59% 510 mm total length [TL]) in 2007 to mainly small fish (79% 356 mm TL) by 2009. Total biomass per effort declined from 57.05 kg/h in 2007 to 19.96 kg/h in 2009. Mean individual weight of fish removed decreased from 2.64 kg in 2007 to 1.32 kg in 2008 to 0.61 kg in 2009. Population age structure was also truncated, but there was evidence for higher recruitment and earlier maturation, which would require that intensive harvest be maintained to prevent the population from rebuilding within 2–5 years. Catch-curves revealed increasing total annual mortality rates of 37, 48 and 52%, for 2007–2009, respectively. Considering the life history of the flathead catfish, being a long-lived species that presumably cannot withstand excessive rates of exploitation (i.e., greater than 25% exploitation), our results indicated that an electrofishing removal program is a reasonable management option for areas where this apex predator has been introduced, but continual removal may be required to maintain low biomass.

Size-Dependent Overwinter Mortality of Young-of-the-Year Yellow Perch (Perca flavescens): Laboratory, In Situ Enclosure, and Field Experiments

1989 ◽  
Vol 46 (11) ◽  
pp. 1958-1968 ◽  
Author(s):  
John R. Post ◽  
David O. Evans
Keyword(s):  
Yellow Perch ◽  
Field Experiments ◽  
Perca Flavescens ◽  
Total Mortality ◽  
Small Fish ◽  
Selective Mortality ◽  
Size Dependent ◽  
Young Of The Year ◽  
Overwinter Mortality

In laboratory experiments, fed and starved young-of-the-year yellow perch (Perca flavescens) lost weight when kept under simulated overwinter temperature and photoperiod regimes, small fish losing a greater proportion of their mass than larger ones. Perch in fed and starved treatments suffered 1 and 46% mortality, respectively, mortality being higher among the smaller individuals. Winter duration was an important determinant of both total mortality and the intensity of size-selective mortality. Size-selective mortality also occurred in yellow perch from the same stock kept overwinter in an in situ lake enclosure with natural food. Fall and spring population estimates for two cohorts of young-of-the-year yellow perch from Lake St. George also indicated the occurence of size-selective overwinter mortality. We present a quantitative technique for identification of size-dependent mortality and size-dependent growth from sequential length frequency distributions. This technique allowed identification of overwinter size-selective mortality for five natural cohorts sampled in the field. Results from a stochastic simulation model, incorporating observed variability in both first year growth and winter duration suggest that overwinter starvation mortality can cause substantial variability in year-class strength that is independent of adult stock size.

scholarly journals Linking population size structure, heat stress and bleaching responses in a subtropical endemic coral

Coral Reefs ◽  
2021 ◽  
Author(s):  
Liam Lachs ◽  
Brigitte Sommer ◽  
James Cant ◽  
Jessica M. Hodge ◽  
Hamish A. Malcolm ◽  
...  
Keyword(s):  
Heat Stress ◽  
Size Structure ◽  
Temporal Trends ◽  
Early Recovery ◽  
Size Frequency Distribution ◽  
Frequency Distributions ◽  
Community Organisation ◽  
Size Frequency ◽  
Eastern Australia

AbstractAnthropocene coral reefs are faced with increasingly severe marine heatwaves and mass coral bleaching mortality events. The ensuing demographic changes to coral assemblages can have long-term impacts on reef community organisation. Thus, understanding the dynamics of subtropical scleractinian coral populations is essential to predict their recovery or extinction post-disturbance. Here we present a 10-yr demographic assessment of a subtropical endemic coral, Pocillopora aliciae (Schmidt-Roach et al. in Zootaxa 3626:576–582, 2013) from the Solitary Islands Marine Park, eastern Australia, paired with long-term temperature records. These coral populations are regularly affected by storms, undergo seasonal thermal variability, and are increasingly impacted by severe marine heatwaves. We examined the demographic processes governing the persistence of these populations using inference from size-frequency distributions based on log-transformed planar area measurements of 7196 coral colonies. Specifically, the size-frequency distribution mean, coefficient of variation, skewness, kurtosis, and coral density were applied to describe population dynamics. Generalised Linear Mixed Effects Models were used to determine temporal trends and test demographic responses to heat stress. Temporal variation in size-frequency distributions revealed various population processes, from recruitment pulses and cohort growth, to bleaching impacts and temperature dependencies. Sporadic recruitment pulses likely support population persistence, illustrated in 2010 by strong positively skewed size-frequency distributions and the highest density of juvenile corals measured during the study. Increasing mean colony size over the following 6 yr indicates further cohort growth of these recruits. Severe heat stress in 2016 resulted in mass bleaching mortality and a 51% decline in coral density. Moderate heat stress in the following years was associated with suppressed P. aliciae recruitment and a lack of early recovery, marked by an exponential decrease of juvenile density (i.e. recruitment) with increasing heat stress. Here, population reliance on sporadic recruitment and susceptibility to heat stress underpin the vulnerability of subtropical coral assemblages to climate change.

scholarly journals Site fidelity and localised homing behaviour in three-spined sticklebacks (Gasterosteus aculeatus)

Behaviour ◽  
2013 ◽  
Vol 150 (14) ◽  
pp. 1689-1708 ◽  
Author(s):  
A.J.W. Ward ◽  
R. James ◽  
A.D.M. Wilson ◽  
M.M. Webster
Keyword(s):  
Social Facilitation ◽  
Site Fidelity ◽  
Gasterosteus Aculeatus ◽  
Home Ranges ◽  
Small Fish ◽  
Behavioural Ecology ◽  
Model Species ◽  
Homing Behaviour ◽  
Capture Site

The ability of animals to disperse towards their original home range following displacement has been demonstrated in a number of species. However, little is known about the homing ability of three-spine sticklebacks (Gasterosteus aculeatus), an important model species in behavioural ecology. In addition, few studies have examined the role of social facilitation in relation to homing behaviour in fishes. We examined homing behaviour of sticklebacks displaced over distances of between 80 m and 160 m in land-drains with directional water flow. Fish were translocated from their original capture site, tagged and then released either in groups or solitarily. We performed recapture transects either one or two days later. Data provided by recaptured sticklebacks show that the fish dispersed in the direction of their original capture site. Although fish translocated downstream typically moved further than those translocated upstream, both dispersed towards their original capture site. There was no difference between fish released solitarily or in groups in their homing ability and indeed there was little evidence that fish translocated in groups remained together following their release. The homing ability of the fish was demonstrated by the finding that up to 80% of fish returned to their home ranges within two days of release over a distance equivalent to approximately 5000 body lengths of these small fish.

scholarly journals Hybridization of Snake River Cutthroat in the Lower Gros Ventre River

2006 ◽  
Vol 30 ◽  
pp. 110-113
Author(s):  
Ryan Kovach ◽  
Lisa Eby
Keyword(s):  
Exotic Species ◽  
National Park ◽  
Cutthroat Trout ◽  
Snake River ◽  
Oncorhynchus Clarki ◽  
Oncorhynchus Clarkii ◽  
Grand Teton National Park ◽  
Water Diversions ◽  
Yellowstone Cutthroat Trout ◽  
Special Concern

The cutthroat trout Oncorhynchus clarki is Wyoming's only native trout. The Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) is designated as a "species of special concern" by a number of agencies and conservation groups. Although the Yellowstone cutthroat trout has recently avoided federal listing because of robust headwater populations (USFWS 2006), they face continued threats across their range. The fine-spotted Snake River native trout is a morphologically divergent ecotype of the Yellowstone subspecies, although it is not genetically distinguishable (Allendorf and Leary 1988, Novak et al. 2005). The Gros Ventre, an important tributary of the Snake River located partially in Grand Teton National Park, historically supported robust populations of fine­ spotted Snake River cutthroat trout. Principal threats to Gros Ventre native trout, especially in the lower end of the drainage within the park boundaries, include both water diversions (loss of water and fish into irrigation ditches) and presence of exotic species.

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