Density-Dependent Maturation, Growth, and Female Dominance in Lake Superior Lake Herring (Coregonus artedii)

1991 ◽  
Vol 48 (4) ◽  
pp. 569-576 ◽  
Author(s):  
Stephen H. Bowen ◽  
Donna J. D'angelo ◽  
Stephen H. Arnold ◽  
Michael J. Keniry ◽  
Ronald J. Albrecht
Keyword(s):  
Sex Ratio ◽  
Egg Production ◽  
Lake Superior ◽  
Adult Mortality ◽  
Female Dominance ◽  
Low Density ◽  
Young Males ◽  
Recruitment Failure ◽  
Coregonus Artedii ◽  
Lake Herring

Density-related changes in age at maturation, sex ratio of recruits, growth, and fecundity at very low density result in spawning populations which comprise many older females and few young males and in which egg production per lake herring (Coregonus artedii) is increased by a factor of five. Age of maturation is delayed at low density for females, but not for males. Thus, males dominate the youngest age classes but females become increasingly more abundant from age 2 + through age 6 +. A model of lake herring population structure showed that although delayed maturation accounts for many characteristics of depressed populations, it does not explain overall population femaleness. The model was used to evaluate effects of differential adult mortality, recruitment failure, and changes in the sex ratio of recruits, and only the latter provided an adequate explanation for overall femaleness. Despite the apparently compensatory nature of these responses, the slow and unsteady recovery of depressed Lake Superior populations during the last two decades indicates that one or more additional factors play important roles in determination of year class strength.

Decline of Lake Herring (Coregonus artedii) In Lake Superior: An Analysis of the Wisconsin Herring Fishery, 1936–78

1982 ◽  
Vol 39 (4) ◽  
pp. 554-563 ◽  
Author(s):  
James H. Selgeby
Keyword(s):  
Lake Superior ◽  
Commercial Fishing ◽  
Productive Capacity ◽  
Spawning Areas ◽  
Spawning Stock ◽  
Coregonus Artedii ◽  
The 1960S ◽  
Lake Herring

Annual harvests of lake herring (Coregonus artedii) in American waters of Lake Superior declined from an average of 2 million kg in 1936–62 to less than 25 000 kg in 1978. Analysis of commercial fishing records revealed that the sequential overexploitation of discrete unit stocks caused the collapse of the herring population in Wisconsin waters. In each of six major spawning areas, catch exceeded the productive capacity of the stock and the stock failed. Because stocks in the six areas were exploited sequentially, mostly in groups of two or three simultaneously, the demise of the stocks was not readily apparent until the last two failed in the early 1960s. After the collapse of the last major spawning stock, the fishery dwindled but may have continued to overexploit the remaining small stocks. The residual populations were apparently able only to replace themselves. Some form of density-independent mortality was apparently operating to prevent their recovery during the 1960s and 1970s.Key words: lake herring, overfishing, Lake Superior

Biomass Dynamics of Lake Superior Lake Herring (Coregonus artedii): Application of Schnute's Difference Model

1987 ◽  
Vol 44 (S2) ◽  
pp. s275-s288 ◽  
Author(s):  
Lawrence D. Jacobson ◽  
Wayne R. MacCallum ◽  
George R. Spangler
Keyword(s):  
General Trend ◽  
Lake Superior ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Difference Model ◽  
Gill Nets ◽  
Thunder Bay ◽  
Biomass Dynamics ◽  
Coregonus Artedii ◽  
Lake Herring

Schnute's (1985. Can. J. Fish. Aquat. Sci. 42: 414–429) difference model was used to study the biomass dynamics of lake herring (Coregonus artedii) in Thunder Bay and Black Bay, Lake Superior, during 1948–79. Recruitment to both fisheries appeared to be independent of escapement during previous years. Abundance of lake herring in Black Bay varied without trend during the study period despite a strong peak in effective fishing effort during 1968–70 and a general trend of increasing effort throughout the study period. Abundance of Thunder Bay lake herring declined during 1948–50 and 1959–67 and increased when fishing effort declined. The estimated catchability coefficient for small-mesh gill nets (54–83 mm stretched measure) set in Black Bay for lake herring during November was 0.467/102 km net. The estimated catchability coefficient for small mesh gill nets set in Thunder Bay for lake herring during December was 0.132/102 km net. Estimates of natural mortality rates and recruitment levels for both fisheries were confounded and unreliable. This analysis demonstrates the utility of Schnute's model for management of Great Lakes herring stocks and some difficulties with its application.

Antennoseius (Vitzthumia) janus n.sp. (Acari: Ascidae), a mesostigmatic mite exhibiting adult female dimorphism

1989 ◽  
Vol 67 (5) ◽  
pp. 1291-1310 ◽  
Author(s):  
Evert E. Lindquist ◽  
David Evans Walter
Keyword(s):  
Sex Ratio ◽  
Adult Female ◽  
Generation Time ◽  
Egg Production ◽  
Low Density ◽  
Adult Males ◽  
Adult Females ◽  
As Species ◽  
Single Animal ◽  
The Impact

All instars of Antennoseius janus n.sp are described. Adult females occur as two distinct morphs, a nondispersing female with granular soft integument, barbed dorsal setae, emarginated opisthonotal shield, and fully developed sternal shield, and a dispersing female with smooth soft integument, nearly smooth dorsal setae, entire opisthonotal shield, and reduced sternal shield. Granular morph females begin egg production within 3 days of mating; however, smooth morph females delay reproduction for many weeks, apparently to disperse. Adult males and immatures have a granular soft integument and barbed setae similar to the granular morph females. Females produced in single animal or low density cultures (less than six individuals per culture) with excess food are granular morphs, whereas in more crowded cultures 5–100% of the maturing females are smooth morphs. This is the first example of adult female dimorphism confirmed experimentally for any family of mites in the entire order Mesostigmata of the Acari. The impact of this phenomenon on taxonomic concepts in the genus Antennoseius is discussed. A key is included, which distinguishes between the genera Anystipalpus Berlese, 1911 and Antennoseius Berlese, 1916, between the subgenera Antennoseius s.str. and Vitzthumia Thor, 1930, and between the seven forms of Vitzthumia currently regarded as species. All instars of A. janus are voracious predators of nematodes and small arthropods. Development from egg to adult takes 9–11 days on a diet of rhabditid nematodes at 23 °C. Generation time for granular morph females is about 14 days. Females require insemination before eggs can be laid, and the sex ratio is about 1 male: 1.3 females.

Predation by Rainbow Smelt (Osmerus mordax) on Lake Herring (Coregonus artedii) in Western Lake Superior

1978 ◽  
Vol 35 (11) ◽  
pp. 1457-1463 ◽  
Author(s):  
James H. Selgeby ◽  
Wayne R. MacCallum ◽  
Donald V. Swedberg
Keyword(s):  
Lake Superior ◽  
Commercial Production ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Predator Prey ◽  
Western Lake ◽  
Large Numbers ◽  
Coregonus Artedii ◽  
Historical Levels ◽  
Lake Herring

The stock of lake herring (Coregonus artedii) in the Apostle Islands (Wisconsin) region of western Lake Superior has diminished severely during the past 30 yr, and predation by rainbow smelt (Osmerus mordax) on herring larvae has been considered a possible cause of this decline. In contrast, the herring stock in Black Bay, 160 km to the northeast, has remained nearly stable despite the presence of large numbers of smelt and high commercial production of herring. Predator–prey interactions were studied in both areas during 1974. Herring larvae and smelt were about 120 and 3 times as dense, respectively, in Black Bay as in the Apostle Islands region. Substantial predation by smelt on young herring was evident in Black Bay, where 17% of 1195 smelt stomachs examined contained herring larvae. From calculations of the relative densities of the two species, and of the daily ration of the predators, we estimated that smelt consumed 3.3–11% of the herring larvae. Nevertheless, the herring stocks have sustained average historical levels of commercial production. In contrast, no herring larvae were found in the stomachs of 1711 smelt collected in the Apostle Islands region. We conclude that predation by smelt on herring larvae is not the major factor controlling or suppressing herring stocks in either region. Key words: lake herring, rainbow smelt, predation, Lake Superior

The Life-History of Badumna-Candida (Araneae, Amaurobioidea)

1993 ◽  
Vol 41 (5) ◽  
pp. 441 ◽  
Author(s):  
MF Downes
Keyword(s):  
Sex Ratio ◽  
Egg Production ◽  
Production Cycle ◽  
Social Spider ◽  
Social Spiders ◽  
Primary Sex Ratio ◽  
The Social ◽  
The Status ◽  
History Of ◽  
Changes Over Time

A two-year study of the social spider Badumna candida at Townsville, Queensland, provided information on colony size and changes over time, maturation synchrony, temperature effects on development, sex ratio, dispersal, colony foundation, fecundity and oviposition. Key findings were that B. candida outbred, had an iteroparous egg-production cycle between March and October, had an even primary sex ratio and achieved maturation synchrony by retarding the development of males, which matured faster than females at constant temperature. There was no overlap of generations, the cohort of young from a nest founded by a solitary female in summer dispersing the following summer as subadults (females) or subadults and adults (males). These findings confirm the status of B. candida as a periodic-social spider (an annual outbreeder), in contrast to the few known permanent-social spider species whose generations overlap. Cannibalism, normally rare in social spiders, rose to 48% when spiders were reared at a high temperature. This may be evidence that volatile recognition pheromones suppress predatory instincts in social spiders.

Influence of Freshwater Migration on the Reproductive Patterns of Anadromous Populations of Cisco (Coregonus artedii) and Lake Whitefish (C. clupeaformis)

1990 ◽  
Vol 47 (2) ◽  
pp. 335-345 ◽  
Author(s):  
Yvan Lambert ◽  
Julian J. Dodson
Keyword(s):  
Adult Mortality ◽  
Lake Whitefish ◽  
Age At Maturity ◽  
Predominant Role ◽  
Reproductive Patterns ◽  
Interspecific Differences ◽  
Survival And Reproduction ◽  
Coregonus Artedii ◽  
The Difference ◽  
Species Specific

We tested the hypothesis that differences in the cost of freshwater migration are responsible for the different reproductive patterns exhibited by the Eastmain River (James Bay) populations of anadromous cisco and lake whitefish, as predicted by species-specific migration costs that result in interspecific differences in energy allocation to growth, survival, and reproduction. In the Eastmain River, cisco spawn at a younger age and a smaller size, have a shorter life span and show a higher fecundity and a higher mortality than lake whitefish. Assuming that the two populations are stable (being only lightly exploited), the two species spawn at an age that maximizes their lifetime fecundity. Either juvenile (between three and age at maturity) and/or adult mortality is of major importance in moulding the observed age at maturity but adult mortality may play a predominant role. Adult mortality is associated with migration, an obligatory cost representing a major proportion of the energy loss experienced by reproductive individuals. The difference in the energy cost of migration between the two species suggests that migration may play a predominant role in producing the different reproductive patterns of cisco and lake whitefish in the Eastmain River and that within the physiological and size constraints of each species, these patterns represent optimal adaptations maximizing fitness.

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