Growth Of Whitefish Research Articles

The effect of water level changes on the density of newly hatched European whitefish (Coregonus lavaretus (L.)) larvae in unregulated and regulated lakes

The effect of the water levels during the period from spawning to hatching of whitefish (Coregonus lavaretus (L.)) on the density of newly hatched larvae was examined from a 23-year time series. The density of larvae was estimated in four lakes with contrasting water level regulation regimes in Central Finland using depth zone stratified bongo and tube net sampling in 2000–2022 and 2008–2022. In the regulated Tehinselkä, larval density was also modeled as a function of the whitefish spawning stock, vendace stock indices, and water levels. Larger water level maximum drops during winter were observed in three regulated lakes (41–68 cm) than in the unregulated lake (35 cm). The average larval densities were highest in the unregulated Lake Southern Konnevesi and regulated Tehinselkä, with densities >20 individuals ha−1. The regulated lakes Ruotsalainen and Puula had lower average densities, <10 individuals ha−1. Significant synchrony in the inter-annual variation in the density time series was observed between Tehinselkä and S. Konnevesi as well as Tehinselkä and Ruotsalainen. None of studied water level variables were associated with larval density in any lake. Thus, the small-scale regulation in these Finnish lakes did not show any direct effects on the production of whitefish larvae. Our analysis did not provide information on the potential effects of water level regulation on later life. For example, it did not cover the impact on whitefish food resources or the abundance of competitors and predators regulating whitefish growth and mortality in the juvenile stage.

Opposing growth trends in juvenile and mature Humpback Whitefish within the upper Tanana River drainage, Alaska, revealed using otolith biochronology

AbstractObjectiveWithin areas of Alaska, Humpback Whitefish Coregonus pidschian are an important subsistence resource for many Alaska Native communities. Recently, Humpback Whitefish in the upper Tanana River drainage were reported to be smaller at a given age and reach smaller maximum sizes than fish sampled 20 years ago. The objective of this study was to identify the factors that influence annual growth of Humpback Whitefish within the upper Tanana River drainage based on an analysis of otolith increments.MethodsA series of mixed‐effects models were used to determine the relative importance of biotic (i.e., age, age at capture) and abiotic (i.e., year, sampling time period) factors on the growth of Humpback Whitefish. Juvenile (<5 years of age) and mature (≥5 years of age) growth periods were examined separately due to the unique habitats occupied by each life stage. Climate variables were correlated with the mature Humpback Whitefish biochronology to assess environmental drivers of adult growth.ResultBiochronologies spanning over three decades (1982–2018) revealed patterns of variation in Humpback Whitefish otolith growth across years. A negative temporal trend spanning the entire study period was evident for juvenile growth, while a mostly positive trend was observed for mature growth. Between time periods, otolith growth was significantly different from zero for juvenile (estimate: −0.087; 95% CI = −0.151 to −0.023) but not mature (estimate: −0.030; 95% CI: −0.092 to 0.032) growth periods. Several environmental factors were positively (i.e., mean monthly temperature, growth degree days) and negatively (e.g., snow depth) correlated with the mature Humpback Whitefish biochronology. However, the model with mean April snow depth was the best‐performing environmental model.ConclusionThese results suggest years with elevated snow depths negatively impact mature Humpback Whitefish growth. Cumulatively, these results illustrate the importance of juvenile growth periods and how early‐in‐life declines in growth may not be offset by above average growth as adults and help further our understanding of how environmental conditions influence growth.

Growth of the Whitefish Coregonus lavaretus (Salmonidae: Coregoninae) in the Ural Tributaries of the Pechora River

For the first time, we represent a comparative characteristic of the growth of, presumably, the freshwater form of the whitefish Coregonus lavaretus in the Ural tributaries of the Pechora River. The growth rate of the whitefish in the studied rivers varies significantly, which testifies the assumption of existence of several local groups in the Pechora river system, confined to different parts of the river basin. In the Ilych and Kosyu rivers as well as in the upper reaches of the Pechora River (Northern Urals), the calculated body lengths and linear growth rates do not differ significantly. Similar growth rates have been observed for the whitefish from the plain tributaries of the Pechora (lower reaches of the Kosyu and Usa rivers). In the rivers of the Subpolar Urals, the variability of whitefish growth rates is significantly higher. The specific growth rate of the subadult whitefish positively correlates with the benthos biomass in the watercourse (ρs = 0.57 according to Spearman, p = 0.04), while the dependence on climatic conditions is less significant.

Turning summer into winter: nutrient dynamics, temperature, density dependence and invasive species drive bioenergetic processes and growth of a keystone coldwater fish

A combination of global changes such as species invasions, climate change and nutrient pollution have altered ecosystems, food webs and the bioenergetic processes that control growth. These changes are especially pronounced in freshwater ecosystems and often lead to rapid variation in fish growth and dependent ecosystems services such as fishery yield. Understanding the mechanisms driving growth responses to environmental change is important for interpreting past dynamics and sustainably managing ecosystems. This study uses integrated bioenergetics and growth modeling to understand how nutrient dynamics, species invasions and changing temperatures have altered growth of the keystone pelagic whitefish Coregonus wartmanni in Lake Constance, Germany from 1925 to 2020. Growth variation was modeled by allowing covariates to alter temperature‐dependent consumption, while size‐specific metabolism varied only with temperature. Consumption and growth increased strongly to a maximum with phosphorous, and this effect was stronger when intraspecific competition (measured as whitefish biomass) was low. Increasing whitefish biomass reduced growth under mesotrophic conditions, but had no effect under oligotrophic conditions. In contrast, increasing competition with invasive three‐spined stickleback Gasteosteus aculeauts was predicted to reduce growth even under oligotrophic conditions. The invasion has effectively turned summer into winter for whitefish, with older fish ceasing to grow and younger fish losing up to 10% of their body weight during the normal growing season in subsequent years. Warming is predicted to further reduce whitefish growth due to competition with invasive stickleback, which would further alter zooplankton food availability and reduce already low fishery yields. These results demonstrate the importance of considering biotic interactions and synergistic effects in global change studies, as well as the value of mechanistic based models for understanding effects. Similar growth responses to ecosystem change are likely within and across ecosystems, and bioenergetic models can help understand effects to support informed ecosystem management.

Contemporary and Historic Dynamics of Lake Whitefish (Coregonus clupeaformis) Eggs, Larvae, and Juveniles Suggest Recruitment Bottleneck during First Growing Season

To determine if a survival bottleneck occurs in Lake Erie's lake whitefish (Coregonus clupeaformis) population and explore possible mechanisms responsible, we examined contemporary and historical dynamics of lake whitefish eggs, larvae and juveniles. Widespread spawning and low overwinter egg retention were observed in 2016–2018, however subsequent larval CPUE remained consistent with historical observations when regular recruitment occurred. Highest larval CPUE was consistently observed in nearshore areas 3–11 km from mid-lake spawning locations. Fall age-1 juvenile presence was predicted by fall age-0 catches, indicating the bottleneck occurs during the first growing season. Our results suggest the following: (1) factors limiting recruitment affect survival during or after the pelagic larval stage to fall age-0, and (2) physical and biological processes underlying connectivity between spawning and nearshore nursery habitats may be limiting recruitment. Future research focusing on larval nursery habitat characterization and lake whitefish growth and survival may reveal mechanisms affecting recruitment.

The Size-Age Structure and Growth of Whitefish (Coregonidae) in Arctic Lake Ioni, Eastern Chukotka

The Size-Age Structure and Growth of Whitefish (Coregonidae) in Arctic Lake Ioni, Eastern Chukotka

Collapse of Lake WhitefishCoregonus clupeaformis(Mitchill, 1818) species pair in Como Lake, Ontario

Lake Whitefish (Coregonus clupeaformis) species pairs exist in a small number of northern temperate lakes in North America. Sympatric populations of dwarf and normal-sized whitefish represent a continuum of morphological and genetic divergence among these lakes. In this study, we used morphological and age data to assess the status of the Lake Whitefish species pair in Como Lake, Ontario (Canada). Whitefish were collected with gill-nets from spawning shoals during the fall of 2012 and 2014 and compared with archived (circa 1989) dwarf and normal-sized specimens. Our study indicates that the two previously collected forms have been replaced by a single form with a different morphology and age structure. In comparison to archived specimens, contemporary Lake Whitefish were larger, deeper-bodied and older; with more gill rakers, lateral line scales, smaller eyes and a wider interorbital width. We hypothesize that the recent invasion of Como Lake by Spiny Waterflea (Bythotrephes longimanus) has affected whitefish growth rates and changed the ecosystem conditions that previously maintained the species pair.

Linear growth of sparsely rakered whitefish Coregonus lavaretus (Coregonidae) of the Imandra Lake (Murmansk oblast)

This paper studies the properties of linear growth in sparsely rakered whitefish Coregonus lavaretus in the stretches of the large subarctic Imandra Lake, which are characterized by the diversity of habitat conditions and anthropogenic stress levels. The groups of sparsely rakered whitefish that are confined to different areas of the lake are marked out based on the properties of growth, trophic status, and anthropogenic stress intensity. A direct relationship of the linear growth in whitefish with the age of sexual development and trophic level of its habitats is found.

Cross-basin analysis of long-term trends in the growth of lake whitefish in the Laurentian Great Lakes

Abstract We conducted a basin-wide analysis of trends in the growth rate of lake whitefish ( Coregonus clupeaformis ), a commercially harvested species in the Laurentian Great Lakes. Juvenile growth (measured as the growth between ages 1 and 2 years) was back-calculated from agency archived scale collections going back as far as the 1950s. We examined trends for 11 locations within the Great Lakes, and investigated the role of multiple explanatory factors (dreissenid mussel establishment; lake whitefish relative abundance; growing degree days) in contributing to the variation observed. Juvenile growth rates declined in all but one location where dreissenid mussels have had widespread establishment. Growth of juvenile lake whitefish from Lake Ontario showed the largest decline following dreissenid establishment, decreasing by 32%. In several locations, lake whitefish growth rates declined or had breakpoints prior to dreissenid establishment and have stabilized or increased in recent years, thus indicating the contribution of other factors. One location in Lake Superior (Apostle Islands) also showed a marked decline and subsequent increase in growth, whereas the other two Lake Superior locations showed no obvious trends. Changes in relative abundance of lake whitefish and growing degree days contributed to growth patterns among locations, but the effect was inconsistent and in most cases weaker than that from the timing of dreissenid establishment. Although our study cannot identify a specific mechanism involved, the suite of changes at the base of the food web that coincided with the timeline of dreissenid establishment appear to have had a broad-scale impact on lake whitefish.

Seasonal depletion of resources intensifies trophic interactions in subarctic freshwater fish communities

Summary Climate change in recent decades has resulted in an increase in both the density and diversity of consumers in subarctic freshwater ecosystems. Despite this, harsh winter conditions in the region limit productivity and may serve as a bottleneck driving trophic interactions within the fish community, potentially determining the outcome of climate change for resident biota. However, due to the difficulties in sampling during winter months, few studies have assessed seasonal variation in the ecological interactions between native and range‐expanding species in subarctic regions. We examined seasonal variation in activity, diet (stomach content) and resource use (δ13C and δ15N stable isotope ratios) of two fishes: the resident cold‐water‐adapted European whitefish (Coregonus lavaretus L.) and the range‐expanding cool‐water‐adapted ruffe (Gymnocephalus cernua L.) in lakes with low and high consumer density. Results were contrasted with seasonal availability of benthic and pelagic resources and indirect measures of individual fitness, that is condition, growth and estimated lipid content (muscle elemental C : N ratio) of both species. The effects of fish density were apparent in both the diet and resource use of whitefish, which altered their diet and displayed reduced stomach fullness during winter in high‐density lakes. This was associated with an overall reduction in whitefish growth, condition and estimated lipid content in high‐density lakes, which was especially pronounced during winter. Ruffe utilised a greater proportion of profundal resources than whitefish in both summer and winter, potentially exploiting a vacant niche. Ruffe maintained condition and lipid reserves throughout the winter, highlighting the potential for further northward range expansion of the species. Winter acts as a seasonal bottleneck in subarctic lakes, but assumptions that this bottleneck primarily selects against warmer‐water‐adapted invasive species such as ruffe may be too restrictive. The effects of seasonal resource depletion on fish condition and invertebrate density were most severe in lakes with a high density of fish, and in these conditions, the cold‐water‐adapted resident whitefish was most adversely affected.

Effects of temperature and food supply on the growth of whitefish Coregonus lavaretus larvae in an oligotrophic peri‐alpine lake

The relative roles of temperature and food availability on the seasonal and daily growth of whitefish Coregonus lavaretus larvae were investigated in the oligotrophic peri-alpine Lake Annecy, France. During the spring from 2004 to 2007, surface water temperature and density of potential zooplankton prey were monitored, and 2688 larvae were caught and measured. In addition, the daily growth of 130 larvae was estimated retrospectively by investigating the microstructure of their otoliths. Temperature played the predominant role in controlling both seasonal and daily growth of early larvae. In contrast, the abundance of Mesocyclops leuckarti and larval density was only slightly correlated to larval growth, suggesting no food limitation nor strong interindividual competition over the study period. Overall, these findings run counter to concerns about potential food limitation, but sound a warning about the potential impact of climate change on fish ecology and fisheries management.

Energy acquisition and allocation patterns of lake whitefish (Coregonus clupeaformis) are modified when dreissenids are present

We evaluated the effects of dreissenid-induced food web changes on rates of lake whitefish ( Coregonus clupeaformis ) energy acquisition and allocation in North American populations. We used mass-balance models of lake whitefish growth and methylmercury accumulation in 17 populations with and without dreissenids present to estimate and contrast rates of activity (ACT), consumption (C) and conversion efficiency (V). Historical estimates were also generated for a single lake whitefish population during dreissenid establishment. Bioenergetic estimates from both scenarios were compared with densities of Diporeia , a historically important diet component of lake whitefish. Mean lake whitefish ACT and C estimates in populations with dreissenids were significantly greater: 1.3–2 times those of populations without dreissenids. Conversion efficiencies scaled positively and significantly, while C and ACT varied negatively and significantly with Diporeia abundance. Our results suggest that changes in lake whitefish activity may affect density estimates — and ultimately sustainable management quotas — for this species. Our results also show that reported declines in lake whitefish individual growth rates in South Bay, Lake Huron, can be explained by increased activity rates due to increased foraging activity in an energetically depleted prey community.

Spatio-temporal trends in the food habits of age-0 lake whitefish

We compared diets of juvenile lake whitefish among six sites in Lake Michigan and one in Lake Superior during 2005 and 2006 to assess spatial and temporal patterns in food habits and evaluate if ontogenetic diet shifts occur that may influence growth and survival. A total of 262 and 496 juveniles were captured in 2005 and 2006, the majority of which were captured during June and July. Sites in southern Lake Michigan tended to have larger juveniles, and the smallest juveniles were observed at Naubinway, northern Lake Michigan, and Whitefish Point, Lake Superior. The mean number of prey items per stomach differed among sampling sites and years. Copepods were the most prevalent prey item, and were present in greater than 70% of juvenile stomachs from most sites. However, the percent by number of copepods decreased during July as chironomids and other benthic macroinvertebrates increased in number. There was a significant positive relationship between percent of benthic prey items and mean length of juvenile lake whitefish. A substantial increase in the percent of benthic prey consumed after 40 mm (total length) was observed and likely resulted from juvenile lake whitefish crossing a size threshold for benthic feeding relating to morphological changes (i.e., transition of mouth opening from terminal to sub-terminal) in addition to a potential increase in the availability of emergent macroinvertebrates. Timing of the transition to benthic feeding is likely regulated by the number of prey per juvenile and the overlap with peak emergence of important benthic aquatic invertebrates such as chironomids. A better understanding of these factors will increase our understanding of juvenile lake whitefish growth and survival, which are necessary for improving year-class strength predictions.

Factors affecting the growth and condition of lake whitefish (Coregonus clupeaformis)

Though declines in the growth and condition of Great Lakes lake whitefish ( Coregonus clupeaformis ) have been largely attributed to food web disruptions caused by invasive dreissenid mussels, a comprehensive evaluation of alternative hypotheses is currently lacking. Using various statistical approaches, we evaluated 69 years of data from the inner basin of South Bay, Lake Huron, considering the role of biological variables (food availability as Diporeia abundance and lake whitefish relative abundance as catch per unit effort, CPUE) versus environmental variables (climate change as growing degree days >5 °C and productive habitat capacity as percent epilimnetic volume, EV) on the condition and early growth rates of resident lake whitefish. Consistently, biological variables (Diporeia abundance, CPUE) best explained changes in lake whitefish growth and condition, respectively, in years when Diporeia data were available. In their absence, environmental variables (EV) best explained early growth rates of lake whitefish, whereas CPUE again best explained lake whitefish condition. Our analysis revealed that environmental change contributed significantly but alone was not sufficient to explain declines in lake whitefish growth after dreissenid establishment, whereas biological variables considered here could account for the majority of growth and condition changes observed in this population.

Origins of carbon sustaining the growth of whitefish Coregonus lavaretus early larval stages in Lake Annecy: insights from fatty‐acid biomarkers

The hypothesis that diatom carbon (C) produced during the spring peak supported spring zooplankton production and, ultimately, the growth of Coregonus lavaretus early larval stages from March to May 2006 in Lake Annecy, France, was tested using gut content analyses and fatty acid biomarkers. Gut content results showed that C. lavaretus larvae from stages 1 to 4 preferentially fed on copepods with Daphnia sp. only a minor proportion of larval diet. The levels of diatom-marker fatty acids (C16:1n-7 and C20:5n-3) were high in Daphnia sp., but lower in both copepods and C. lavaretus larvae from stages 0 to 4. These results indicated that the spring diatom biomass was actually grazed by Daphnia sp., but, contrary to what was expected, the spring bloom was not the only C source supporting copepods secondary production and, consequently, the growth of C. lavaretus early larval stages. In contrast, levels of terrestrial fatty acid marker (C24:0) were low in Daphnia sp. but high in copepods and C. lavaretus larvae, indicating a significant contribution of terrestrial carbon to copepods and, ultimately, to the growth of C. lavaretus early larval stages.

Effect of eye fluke infection on the growth of whitefish ( Coregonus lavaretus) —An experimental approach

Effect of the eye fluke Diplostomum spathaceum on fish growth has remained somewhat unclear because 1) the question has not been subjected to experimental examination with treatment-control setup and 2) growth has not been related to the coverage of parasite-induced cataracts in a quantitative manner. We examined effects of the parasite on growth and competitive ability of whitefish ( Coregonus lavaretus) in experimental conditions resembling those at fish farms by maintaining groups of exposed and control fish, as well as mixed groups from both treatments, under optimal conditions for 8 weeks. Contrary to our expectations, we did not observe differences in fish growth between the treatments. However, at the level of individual fish, parasite-induced cataracts had a negative effect on weight of the exposed fish but this took place only when the cataract coverage reached 100% in both eyes. No effect of the infection on competitive ability of fish was observed in mixed treatments which may be related to patterns of food distribution in the tanks or cues received by the fish from less infected conspecifics. Overall, the results suggest that effects of D. spathaceum on fish growth become apparent only in cases of very high cataract coverage, and that feeding regimes and the shape of the cataract coverage distribution in a fish group are important determinants of the magnitude of these effects.

Changes in Fecundity and Egg Lipid Content of Lake Whitefish ( Coregonus clupeaformis) in the Upper Laurentian Great Lakes between 1986–87 and 2003–05

Lake whitefish ( Coregonus clupeaformis Mitchill), an important commercial species in the Laurentian Great Lakes, have experienced decreased growth and condition in regions of the upper Great Lakes over the past 20 years. Increases in lake whitefish density and decreases in the density of Diporeia spp., an energy rich and historically important part of the lake whitefish diet, have been implicated in the recent declines in lake whitefish growth and condition. The goal of this study was to describe lake whitefish fecundity, egg lipid content, and total ovary lipid content in selected regions of Lakes Huron, Michigan, and Superior in 1986–87 and 2003–05, two time periods with different lake whitefish and Diporeia densities. Under conditions of high lake whitefish density and low Diporeia density, female lake whitefish in the upper Laurentian Great Lakes generally produced fewer eggs. Egg lipid content was higher in 2003–05 than in 1986–87 at all sites, regardless of changes in lake whitefish or Diporeia densities. Total ovary lipid content and lake whitefish abundance were inversely related, while there was no significant relationship between total ovary lipid content and Diporeia density. The amount of energy that lake whitefish invested in egg production was more closely associated with lake whitefish abundance than with Diporeia density. This study provides evidence that recent changes in production dynamics of Great Lakes lake whitefish have not been driven solely by declines in Diporeia but have been significantly influenced by lake whitefish abundance.

The influence of eutrophication and population biomass on common whitefish (Coregonus lavaretus) growth — the Lake Constance example revisited

Accelerated growth of freshwater fish during anthropogenic eutrophication has been attributed almost exclusively to the increased nutrient content, while density-dependent effects have been largely neglected. We evaluated the relative importance of these factors by studying the growth of 43 consecutive year classes of common whitefish (Coregonus lavaretus) from Upper Lake Constance. This prealpine lake underwent eutrophication from the 1950s to 1970s, followed by reoligotrophication. Because whitefish are harvested with gill nets in a strongly size-selective way, we used back-calculated lengths of average fast-growing fish to compare growth among cohorts. Standing stock biomass was estimated based upon virtual year-class strengths. Multiple linear regression analysis revealed that growth of whitefish during their second year was most strongly related to standing stock biomass followed by PO4-P content during spring turnover and by calendar year, which was incorporated as a third independent variable (adjusted R2 = 0.84). The negative correlation between whitefish growth rate and calendar year is interpreted as evidence of an evolutionary response to the highly size-selective fishery during at least four decades. We conclude that density-dependent effects on whitefish growth are more important than had been realized previously and that the impact of eutrophication on growth of whitefish needs to be reconsidered.

Changes in Benthic Invertebrate Communities of South Bay, Lake Huron Following Invasion by Zebra Mussels ( Dreissena polymorpha), and Potential Effects on Lake Whitefish ( Coregonus clupeaformis) Diet and Growth

In this study we evaluated changes in benthic invertebrate communities of South Bay, Lake Huron following the invasion of zebra mussels ( Dreissena polymorpha) and considered the implications for diets and growth of whitefish ( Coregonus clupeaformis), a commercially important fish in the Great Lakes. Of the ten benthic invertebrate groups identified prior to invasion (1980–81), only densities of Diporeia and Oligochaeta have changed since the appearance of the zebra mussel, and only Diporeia and Chironomidae changed in relative abundance. These changes are similar to those observed in other areas of the Great Lakes, with the exception of an increase in Oligochaeta density. Post-invasion (2002–03) shallow-water communities appear to be more homogeneous, dominated by zebra mussels and Isopoda, whereas deep-water sites are more heterogeneous due to the loss of Diporeia. Additional data on Diporeia density for several years between 1959 and 2004 indicated that current low densities are not typical of South Bay. Based on changes in the benthic communities and published literature on whitefish diets, we predict that unless whitefish are able to switch to Mysis as an alternative to Diporeia, post-invasion whitefish diets will only contain a maximum of 57 to 84% of their former energy content. These predictions are likely underestimates, as they do not take into account increased energy costs associated with reductions in total invertebrate density at historical foraging depths.

Acute effects on perch (Perca fluviatilis) and long-term effects on whitefish (Coregonus lavaretus pallasi) of liming of an acidified lake

Summary The acute effects on perch and long-term effects on whitefish were studied after liming one side of a lake [initial pH: 4.6–5.5; aluminium (Al): 29–54 μg L−1; Ca2+: 0.02–0.07 mmol L−1] that was divided into two parts with a plastic curtain. Some Al precipitation was observed on the gill surface of perch 1 day after liming; the concentration of plasma sodium of perch females in the limed side was also higher than in the acidic side. Nearly 6 months after liming, at the spawning time of whitefish, the plasma chloride concentration of whitefish in the limed side was higher and blood glucose concentration lower than in the acidic side. Four of five whitefish males from the limed side, but only one of five males and none of the five females from the acidic side, were ready to spawn. The growth of whitefish in the limed side was also more rapid. These changes illustrate that liming had no acute harmful effects on perch, and allowed whitefish to recover from acidity-related physiological stress.