Dynamics of lake trout production in the main basin of Lake Huron

2020 ◽  
Vol 77 (3) ◽  
pp. 975-987
Author(s):  
Ji X He ◽  
James R Bence ◽  
Charles P Madenjian ◽  
Randall M Claramunt
Keyword(s):  
Fishery Management ◽  
Lake Trout ◽  
Stock Assessment ◽  
Round Goby ◽  
Lake Huron ◽  
Prey Fish ◽  
Total Consumption ◽  
Age Structured ◽  
Population Mortality ◽  
Ecosystem Changes

Abstract To inform lake trout (Salvelinus namaycush) fishery management in Lake Huron that has undergone rapid ecosystem changes, we quantified lake trout production dynamics by coupling age-structured stock assessment and fish bioenergetics models. Our approach revealed the connection between piscivore production and prey consumption, included growth compensation to reproduction losses, and allowed comparisons between long-term dynamics of fishery harvests and fish production. We found that, despite the collapse of alewives, a major non-native pelagic prey fish, lake trout production appeared to be sustainable. To a certain degree, the effect of recent recruitment declines on lake trout production was offset by the release of harvest pressure from subadult lake trout and reduction in fishing and sea lamprey-induced mortality on adult lake trout. Evidence for sustainability also included the finding that no changes in average ratios of annual production to beginning-of-the-year biomass. Juvenile P:B ratio remained as high as 2.1. The effect of growth declines on adult and subadult production was offset by reduction in population mortality. Body growth and condition did not continue to decline when lake trout became more and more reliant on round goby as food, and the dynamics of total consumption of prey fish continued to be recipient controlled.

From Catastrophe to Recovery: Stories of Fishery Management Success

2019 ◽  
Keyword(s):  
Water Quality ◽  
Fishery Management ◽  
Stock Assessment ◽  
Lessons Learned ◽  
Lake Huron ◽  
Data Sets ◽  
Alosa Pseudoharengus ◽  
Commercial Fishery ◽  
Natural Reproduction ◽  
Water Legislation

<i>Abstract</i>.—Saginaw Bay is a large coolwater region of Lake Huron and Walleye <i>Sander vitreus</i> is the apex predator. From the time of first settlement to the mid-1940s, the bay’s Walleye population was the target of a loosely regulated commercial fishery characterized by periods of overharvest and recovery but was sustained for more than half a century at an average annual yield of about 495 metric tons. The fishery collapsed due to a series of year-class failures attributed to declining water quality, habitat degradation, and effects of invasive species. The degraded and collapsed condition lasted until the early 1980s. With improving water quality stemming from clean water legislation and the closure of the commercial fishery, a new period of improvement was achieved. Walleye fingerling stocking was implemented and a recreational fishery soon emerged. Research and assessment sought to monitor stock mortality, growth, and exploitation rates as well as contribution of stocked fish to the fishery. Recovery plans were drafted that sought to improve spawning habitat and improve survival of Walleye fry by creating a predation barrier to the predatory effects of the invasive Alewife <i>Alosa pseudoharengus</i> through increased Walleye stocking. A series of cascading food-web changes took place in Lake Huron, resulting in the sudden collapse of Alewives, and Walleye natural reproduction surged beginning in 2003. Walleye stocking was discontinued in 2006 and recovery targets were first achieved in 2009. Management and research shifted from recovery efforts to enhanced stock assessment efforts and modeling, a clear sign of success! Key lessons learned include (1) eliminating or at least reducing obstacles to reproduction (such as habitat and water quality) are essential first steps to laying the foundation for recovery, (2) maintaining populations (via of stocking in this instance) will help ensure that broodfish are available for spawning when conditions improve, (3) ecosystems are resilient and when released from stressors (Alewives in this instance) natural processes can resume, (4) great value exists in survey/assessment investment and long-term data sets for guiding restoration, and (5) resolve and commitment by natural resource professionals, administrators, and stakeholders is critical for sustaining restoration efforts and the investment they require.

scholarly journals Ecology of the Lake Huron fish community, 1970-1999

2005 ◽  
Vol 62 (6) ◽  
pp. 1432-1451 ◽  
Author(s):  
Norine E Dobiesz ◽  
David A McLeish ◽  
Randy L Eshenroder ◽  
James R Bence ◽  
Lloyd C Mohr ◽  
...  
Keyword(s):  
Fish Community ◽  
Lake Trout ◽  
Pacific Salmon ◽  
Lake Huron ◽  
Prey Fish ◽  
Saginaw Bay ◽  
Top Predators ◽  
Sea Lampreys ◽  
The Status ◽  
And Control

We review the status of the Lake Huron fish community between 1970 and 1999 and explore the effects of key stressors. Offshore waters changed little in terms of nutrient enrichment, while phosphorus levels declined in inner Saginaw Bay. Introduced mussels (Dreissena spp.) proliferated and may have caused a decline in Diporeia spp. This introduction could have caused a decline in lake whitefish (Coregonus clupeaformis) growth and condition, with serious repercussions for commercial fisheries. Bythotrephes, an exotic predatory cladoceran, and other new exotics may be influencing the fish community. Sea lampreys (Petromyzon marinus) remained prevalent, but intensive control efforts on the St. Mary's River may reduce their predation on salmonines. Overfishing was less of a problem than in the past, although fishing continued to reduce the amount of lake trout (Salvelinus namaycush) spawning biomass resulting from hatchery-reared fish planted to rehabilitate this species. Massive stocking programs have increased the abundance of top predators, but lake trout were rehabilitated in only one area. Successful lake trout rehabilitation may require lower densities of introduced pelagic prey fish than were seen in the 1990s, along with continued stocking of hatchery-reared lake trout and control of sea lamprey. Such reductions in prey fish could limit Pacific salmon (Oncorhynchus spp.) fisheries.

Coupling age-structured stock assessment and fish bioenergetics models: a system of time-varying models for quantifying piscivory patterns during the rapid trophic shift in the main basin of Lake Huron

2015 ◽  
Vol 72 (1) ◽  
pp. 7-23 ◽  
Author(s):  
Ji X. He ◽  
James R. Bence ◽  
Charles P. Madenjian ◽  
Steven A. Pothoven ◽  
Norine E. Dobiesz ◽  
...  
Keyword(s):  
Alternative Energy ◽  
Lake Trout ◽  
Stock Assessment ◽  
Time Varying ◽  
Rainbow Smelt ◽  
Trophic Shift ◽  
Fish Bioenergetics ◽  
Age Structured ◽  
Time Varying Models ◽  
Energy Pathways

We quantified piscivory patterns in the main basin of Lake Huron during 1984–2010 and found that the biomass transfer from prey fish to piscivores remained consistently high despite the rapid major trophic shift in the food webs. We coupled age-structured stock assessment models and fish bioenergetics models for lake trout (Salvelinus namaycush), Chinook salmon (Oncorhynchus tshawytscha), walleye (Sander vitreus), and lake whitefish (Coregonus clupeaformis). The model system also included time-varying parameters or variables of growth, length–mass relations, maturity schedules, energy density, and diets. These time-varying models reflected the dynamic connections that a fish cohort responded to year-to-year ecosystem changes at different ages and body sizes. We found that the ratio of annual predation by lake trout, Chinook salmon, and walleye combined with the biomass indices of age-1 and older alewives (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) increased more than tenfold during 1987–2010, and such increases in predation pressure were structured by relatively stable biomass of the three piscivores and stepwise declines in the biomass of alewives and rainbow smelt. The piscivore stability was supported by the use of alternative energy pathways and changes in relative composition of the three piscivores. In addition, lake whitefish became a new piscivore by feeding on round goby (Neogobius melanostomus). Their total fish consumption rivaled that of the other piscivores combined, although fish were still a modest proportion of their diet. Overall, the use of alternative energy pathways by piscivores allowed the increases in predation pressure on dominant diet species.

A perspective on steepness, reference points, and stock assessment

2013 ◽  
Vol 70 (6) ◽  
pp. 930-940 ◽  
Author(s):  
Marc Mangel ◽  
Alec D. MacCall ◽  
Jon Brodziak ◽  
E.J. Dick ◽  
Robyn E. Forrest ◽  
...  
Keyword(s):  
Life History ◽  
Fishery Management ◽  
Stock Assessment ◽  
Reference Points ◽  
Production Model ◽  
Published Data ◽  
Difficult Situation ◽  
Life History Parameters ◽  
Stock Recruitment ◽  
Age Structured

We provide a perspective on steepness, reference points for fishery management, and stock assessment. We first review published data and give new results showing that key reference points are fixed when steepness and other life history parameters are fixed in stock assessments using a Beverton–Holt stock–recruitment relationship. We use both production and age-structured models to explore these patterns. For the production model, we derive explicit relationships for steepness and life history parameters and then for steepness and major reference points. For the age-structured model, we are required to generally use numerical computation, and so we provide an example that complements the analytical results of the production model. We discuss what it means to set steepness equal to 1 and how to construct a prior for steepness. Ways out of the difficult situation raised by fixing steepness and life history parameters include not fixing them, using a more complicated stock–recruitment relationship, and being more explicit about the information content of the data and what that means for policy makers. We discuss the strengths and limitations of each approach.

scholarly journals Stock assessment and projections incorporating discard estimates in some years: an application to the hake stock in ICES Divisions VIIIc and IXa

2010 ◽  
Vol 67 (6) ◽  
pp. 1185-1197 ◽  
Author(s):  
C. Fernández ◽  
S. Cerviño ◽  
N. Pérez ◽  
E. Jardim
Keyword(s):  
Time Series ◽  
Stock Assessment ◽  
Reference Points ◽  
Assessment Model ◽  
Marine Science ◽  
Fishing Mortality ◽  
Change Over Time ◽  
Age Structured ◽  
Available Information ◽  
Over Time

Abstract Fernández, C., Cerviño, S., Pérez, N., and Jardim, E. 2010. Stock assessment and projections incorporating discard estimates in some years: an application to the hake stock in ICES Divisions VIIIc and IXa. – ICES Journal of Marine Science, 67: 1185–1197. A Bayesian age-structured stock assessment model is developed to take into account available information on discards and to handle gaps in the time-series of discard estimates. The model incorporates mortality attributable to discarding, and appropriate assumptions about how this mortality may change over time are made. The result is a stock assessment that accounts for information on discards while, at the same time, producing a complete time-series of discard estimates. The method is applied to the hake stock in ICES Divisions VIIIc and IXa, for which the available data indicate that some 60% of the individuals caught are discarded. The stock is fished by Spain and Portugal, and for each country, there are discard estimates for recent years only. Moreover, the years for which Portuguese estimates are available are only a subset of those with Spanish estimates. Two runs of the model are performed; one assuming zero discards and another incorporating discards. When discards are incorporated, estimated recruitment and fishing mortality for young (discarded) ages increase, resulting in lower values of the biological reference points Fmax and F0.1 and, generally, more optimistic future stock trajectories under F-reduction scenarios.

A Synthesis of Knowns, Unknowns, and Policy Recommendations from the Sea Lamprey International Symposium

1980 ◽  
Vol 37 (11) ◽  
pp. 2202-2208 ◽  
Author(s):  
Carl J. Walters ◽  
George Spangler ◽  
W. J. Christie ◽  
Patrick J. Manion ◽  
James F. Kitchell
Keyword(s):  
International Symposium ◽  
Large Scale ◽  
Fishery Management ◽  
Field Experiments ◽  
Lake Trout ◽  
Sea Lamprey ◽  
Future Research ◽  
Fish Stock ◽  
Total Production ◽  
Pilot Studies

The Sea Lamprey International Symposium (SLIS) has provided a broad spectrum of facts and speculations for consideration in future research and management programs. Many aspects of the laboratory biology and field life history of the sea lamprey (Petromyzon marinus) are now well understood. There is little question that it can now be controlled by chemical larvicides, and perhaps in the future by more efficient integrated control programs. There is correlative evidence (wounds, scars, catch curves) that lamprey caused major mortalities in some fish species, and that control in conjunction with stocking has lead to remarkable recoveries of salmonid stocks in the Great Lakes. However, there are great gaps in understanding about just what the lamprey does under field conditions, and it is not yet possible to reject several hypotheses that assign lamprey a minimum or transient role in fish stock changes. Further studies on details of lamprey biology are, in themselves, unlikely to fill the gaps; one alternative is to conduct a large-scale field experiment involving cessation of lamprey control while holding other factors (fishing, stocking) as steady as possible. If it is decided to proceed with management on the assumption that lamprey are important, without the major field experiments to confirm it, then at least the following steps should be taken: (1) the chemical treatment program should be reviewed in detail, with a view to finding treatment schedules that will minimize frequency and dose rates for lampricide applications; (2) pilot studies on alternative control schemes (sterile male, attractants, barriers) should only be funded if they are statistically well designed (several replicate and control streams), and involve quantitative monitoring of lamprey spawning success and subsequent total production of transforming larvae; (3) the lake trout (Salvelinus namaycush) stocking program should be maintained at its present level, and should involve diverse genotypes rather than a few hatchery strains; (4) growth in the sport fisheries for lake trout should be curtailed, and commercial fisheries should not yet be permitted; (5) a multispecies harvesting policy should be designed that takes into account the buffering effect of each species on lamprey mortality suffered by others (i.e. should some species not be harvested at all, and viewed instead as buffers for more valuable species?); and (6) a program should be developed for restoring, by culture if necessary, native forage species in case the introduced smelt and alewife should collapse under pressure from fishing and prédation by the growing salmonid community.Key words: sea lamprey, proposed research, fishery management, mathematical models, population dynamics

Cross-basin comparison of mercury bioaccumulation in Lake Huron lake trout emphasizes ecological characteristics

2014 ◽  
Vol 34 (2) ◽  
pp. 355-359 ◽  
Author(s):  
Rachel A. Abma ◽  
Gordon Paterson ◽  
Anne McLeod ◽  
G. Doug Haffner
Keyword(s):  
Lake Trout ◽  
Lake Huron ◽  
Ecological Characteristics ◽  
Mercury Bioaccumulation

The Thermal Regime of South Bay, Manitoulin Island

1967 ◽  
Vol 24 (1) ◽  
pp. 101-125 ◽  
Author(s):  
A. M. McCombie
Keyword(s):  
Thermal Regime ◽  
Thermal Stratification ◽  
Yellow Perch ◽  
Lake Trout ◽  
Smallmouth Bass ◽  
Lake Huron ◽  
Vertical Temperature ◽  
Class Strength ◽  
Influence Of Temperature On ◽  
History Of

The thermal regime of South Bay is described from records collected from 1953 to 1962 with thermometers, thermographs, and bathythermographs, the last being cast at 11 stations along the bay and one in Lake Huron. Warming begins in April and thermal stratification is established in June. Shallow areas warm more rapidly than deep in the spring and cool more quickly in autumn. The boundary between the epilimnion and the thermocline becomes sharper as summer advances but the transition from thermocline to hypolimnion remains gradual. The average seasonal trend of surface temperatures is a sine function with a maximum of 66 F in mid August and a minimum of 34 F in late March, though values outside this range occur frequently. At 180 ft the maximum of 47 F is attained in November. At the lake and outermost bay stations there is a temperature slump in June and July which may be due to an upwelling in the lake. Evidence of an exchange of water between the lake and bay is seen in vertical temperature sections and water movements Variations in epilimnial temperatures are correlated with those of the air temperature, but variations in epilimnial and hypolimnial temperatures appear to be unrelated. Finally, literature describing the influence of temperature on the year class strength of smallmouth bass, the distribution of lake trout, the growth of yellow perch, and the life history of Pontoporeia in South Bay is reviewed.

Fecundity and Egg Size of a Brood Stock of Salvelinus fontinalis × S. namaycush Hybrids (Splake)

1974 ◽  
Vol 31 (2) ◽  
pp. 217-220 ◽  
Author(s):  
G. B. Ayles
Keyword(s):  
Egg Size ◽  
Lake Trout ◽  
Salvelinus Fontinalis ◽  
Lake Huron ◽  
Female Size ◽  
Brood Stock ◽  
Trout Population ◽  
Egg Diameter

Estimates of average egg diameter and average number of eggs per female from a brood stock of Salvelinus fontinalis × S. namaycush (splake) hybrids were 0.468 cm and 1169 eggs, respectively. Variation in egg size between females was attributable to variation in both size and age of the fish, whereas differences in fecundity were attributed only to differences in female size. At a given size a splake had more and larger eggs than have been reported for lake trout. The significance of the findings is discussed in relation to the reestablishment of a viable trout population in Lake Huron.

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