Dynamics of an Exploited Population of Lake Whitefish (Coregonus clupeaformis)

1977 ◽  
Vol 34 (7) ◽  
pp. 942-953 ◽  
Author(s):  
Graham Bell ◽  
Paul Handford ◽  
Carl Dietz
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Age Structure ◽  
Annual Rate ◽  
Multiple Regression Equation ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
History Of ◽  
Almost All ◽  
Key Words Population Dynamics

The life history of the exploited lake whitefish (Coregonus clupeaformis) population of Lesser Slave Lake, Alberta, is described. Mean age is high, having increased under continued exploitation during the last 30 yr. A method of estimating the population age structure is described. The apparent annual rate of survival of adult fish has fluctuated markedly, but on average seems to lie in the interval 0.40–0.50; the annual rate of natural survival is estimated to be 0.53. Juveniles survive better than adults. Rate of survival during the 1st yr of life was estimated to be about 0.0002. Maturity was late, the median age at first reproduction being 6–61/2 yr. The regressions of fecundity on age and length are described; length now contributes almost all the attributable variance to maturity and fecundity. The sex ratio fluctuates in time; this is caused by the fluctuations in age structure, since sex ratio varies with age. The relationship between sex ratio and age is used to calculate the relative rates of survival of male and female fish.These data are used to construct a life table and to compute population parameters. It is inferred that the ability of the population to respond to exploitation has been eroded during the last 30 yr. In some respects, the life history of the Lesser Slave Lake stock appears to be unusual.After about 30 yr of large-amplitude oscillation the whitefish population collapsed in 1965. This does not seem to have been caused by chronic overfishing. In the first place, the rate of fishing mortality is no more than moderate. Secondly, a multiple regression equation describing whitefish catch in 48 other Alberta lakes in which there has been no overall decline in catch successfully predicts the observed mean catch at Lesser Slave Lake. The oscillations in catch are claimed to reflect a limit cycle in the abundance of the whitefish, driven by a lagged relationship between a predator (the fishermen) and its prey (the whitefish). Whether or not this cycle was deterministically stable, such behavior will inevitably put the population in risk of extinction during troughs in the cycle. We suggest that current management policies may encourage the destabilization of whitefish populations, and we propose a remedy. Key words: population dynamics, population regulation, life history, exploitation, survival, fecundity, Coregonus clupeaformis

scholarly journals On the supposed first stage larva of Leptohylemyia coarctata, Fall.

1917 ◽  
Vol 8 (2) ◽  
pp. 121-123 ◽  
Author(s):  
D. Keilin
Keyword(s):  
Life History ◽  
Recent Work ◽  
European Countries ◽  
Stage Larva ◽  
History Of ◽  
Almost All

It has been well known since the studies of Taschenberg (1864–1872) that the larvae of Leptohylemyia coarctata, Fall., attack wheat and rye. The damage due to this fly has been observed many times in almost all European countries, and many papers have been devoted to its life-history. Of these papers the most important are those of E. Ormerod (1882–1895), S. Rostrup (1905–1911), T. Hedlund (1906- 1907), P. Marchal (1909) and finally the recent work of Kurdjumov (1914).

Population dynamics of Stenothoe valida Dana, 1852 (Amphipoda, Stenothoidae) at Cheongsapo beach of Busan, Republic of Korea

Crustaceana ◽  
2021 ◽  
Vol 94 (4) ◽  
pp. 413-429
Author(s):  
Ye Ji Lee ◽  
Won Gyu Park
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Sex Ratio ◽  
Brood Size ◽  
Ovigerous Female ◽  
Seasonal Pattern ◽  
Recruitment Rate ◽  
Republic Of Korea ◽  
Female Size ◽  
History Of

Abstract The population dynamics of Stenothoe valida Dana, 1852 were studied at Cheongsapo beach of Busan, Republic of Korea, from March 2019 to March 2020. Sampling was conducted once a month at low tide during spring tides. Specimens were grouped by the cephalic length at 0.025 mm intervals, and classified into four categories: females, ovigerous females, males and juveniles. The sex ratio, defined as females : total males + females, exceeded 0.5 during most of the study period. Brood size was significantly coupled with ovigerous female size. Two to four cohorts appeared at each study period. New cohorts occurred at almost every sampling except in the samples Jun-2, and Nov-2. Life span was estimated at 1-2 months. The juvenile ratio, the ratio of ovigerous females, and the recruitment rate estimated by FiSAT were commonly high in summer and winter. The life history of S. valida was not coupled with water temperature, but had a strong seasonal pattern.

scholarly journals Some aspects of the history and population ecology of the tsessebe damaliscus lunatus lunatus in the Kruger National Park

Koedoe ◽  
1977 ◽  
Vol 20 (1) ◽  
Author(s):  
S.C.J. Joubert ◽  
P.J.L. Bronkhorst
Keyword(s):  
Sex Ratio ◽  
Population Ecology ◽  
Age Structure ◽  
National Park ◽  
Kruger National Park ◽  
Population Trends ◽  
Social Organisation ◽  
Developmental History ◽  
The Social ◽  
History Of

The population trends and distribution of the tsessebe population of the Kruger National Park are evaluated in terms of the available data derived from records compiled in the developmental history of the Kruger National Park (KNP). The recent numerical status of the population is also given. A description of the habitats favoured by tsessebe in the KNP is presented as well as an analysis of the age structure and sex-ratio of the population. Aspects of the social organisation of tsessebe affecting the interpretation of the age structure and sex-ratio phenomena of the population, are also discussed.

Growth and Reproduction of the Lake Whitefish, Coregonus clupeaformis, in Lac la Ronge, Saskatchewan

1968 ◽  
Vol 25 (10) ◽  
pp. 2091-2100 ◽  
Author(s):  
S. U. Qadri
Keyword(s):  
North America ◽  
Sex Ratio ◽  
Life Span ◽  
Fork Length ◽  
Growing Season ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Young Fish ◽  
Large Lakes ◽  
Growth And Reproduction

In Lac la Ronge the lake whitefish (Coregonus clupeaformis (Mitchill)) spawned from late October until the middle of November at ages of 8 years and over. The growing season lasted from late May to early October and young fish grew faster than older ones and tended to have a longer growing season. Ages for 1604 fish taken during 4 years showed that they grew to a fork length of about 16 inches in 10 years, the rate being slower than for lake whitefish in other large lakes in North America. The length-weight relationships were linear: for the open lake, log W = 3.48 log L – 3.93, and for Hunter Bay, log W = 3.26 log L – 3.66. The males matured a little earlier than females and their life span was somewhat shorter. The sex ratio was approximately 1:1.

Relations Among Net Reproductive Rate and Life History Parameters for Lake Whitefish (Coregonus clupeaformis)

1985 ◽  
Vol 42 (1) ◽  
pp. 164-168 ◽  
Author(s):  
A. L. Jensen
Keyword(s):  
Life History ◽  
Growth Curve ◽  
Reproductive Rate ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Age At Maturity ◽  
Net Reproductive Rate ◽  
Growth Coefficient ◽  
Life History Parameters ◽  
Immature Fish

An equation is derived that relates net reproductive rate to six life history parameters; the equation is applied to determine changes in the net reproductive rate of lake whitefish (Coregonus clupeaformis) that result from variation in these life history parameters. Changes in age at maturity and survival of immature fish are the only parameters that have a large effect on the net reproductive rate. Age at maturity occurs near the inflection of the growth curve, and this implies a relationship between age at maturity, length at maturity, the growth coefficient, and asymptotic length.

Short sea migration and precocious maturation in reared Atlantic salmon post-smolts in the northern Baltic Sea

2017 ◽  
Vol 75 (3) ◽  
pp. 1063-1070 ◽  
Author(s):  
Panu Orell ◽  
Jaakko Erkinaro ◽  
Mikko Kiljunen ◽  
Jyrki Torniainen ◽  
Tapio Sutela ◽  
...  
Keyword(s):  
Life History ◽  
Atlantic Salmon ◽  
Baltic Sea ◽  
Isotope Analysis ◽  
History Of ◽  
The Baltic ◽  
Bothnian Bay ◽  
Almost All ◽  
Induced Changes ◽  
Sea Area

Abstract Atlantic salmon (Salmo salar L.) display significant variation in life history traits, including migration patterns and age at maturity. Hatchery rearing has been shown to affect the life history, and rearing-induced changes may include unfavourable consequences, e.g. shortened sea migration period and smaller size at maturity. We report on a new phenomenon of life history of reared Atlantic salmon in the Baltic Sea area: small-sized salmon returning to freshwater only a few months after release as smolts. These “one-sea-summer (1SS)” salmon were ca. 35 cm in length and weighed ca. 400 g, being clearly larger than smolts, but substantially smaller than one-sea-winter (1SW) salmon from the same cohorts. Almost all 1SS salmon were mature males and, at release, had been longer than the overall mean. Stable isotope analysis suggested that the 1SS salmon had been feeding in different sea areas than 1SW and multi-sea-winter salmon, likely in nearby Bothnian Bay, which is typically not a salmon feeding area. If an increasing proportion of the released salmon are not undertaking a normal marine migration (≥1SW) and are returning to estuaries and rivers as 1SS fish, the success and profitability of the reared salmon releases will decline even more than the reduced post-smolt survival is suggesting. We suggest that alternative rearing practices (e.g. enriched rearing environments and advanced diets) should be considered in hatchery production for shaping the reared smolts towards a closer resemblance to wild smolts.

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