Migration costs drive convergence of threshold traits for migratory tactics

Partial migration of some, but not all, members of a population is a common form of migration. We evaluated how migration costs influence which members migrate in 10 populations of two salmonid species. The migratory patterns of both species were evaluated based on the size at maturity for resident males, which is the threshold trait that determines the migratory tactics used within a population. In both species, this size was smaller in males located further from the sea, where migration costs are presumably higher. Moreover, the threshold sizes at maturity in males were correlated between both species. Our results suggest that migration costs are a significant convergent selective force on migratory tactics and life-history traits in nature.     

Timing of Development During Epiboly in Embryos of Second-Generation Crosses and Backcrosses between Odd- and Even-Broodyear Pink Salmon, Oncorhynchus gorbuscha

Synopsis Odd- and even-year-spawning pink salmon (Oncorhynchus gorbuscha) are genetically isolated; their broodlines differ even in the same natal stream. Hybrids between broodlines exhibit outbreeding depression in survival. Variation in the time to completion of epiboly in embryos appears to be adaptive in both broodlines. We compared stage of development at a time near the completion of epiboly in families of second-generation offspring from crosses between odd- and even-year broodlines with development stages of within-broodyear controls and of backcrossed families. We observed embryos derived from matings of mature fish that were the results of fertilizations made 2 years earlier of eggs from females from the even brood year with semen from males from the even broodyear and with cryopreserved semen from males of the odd broodyear. The resulting fry had been released to the Pacific Ocean and recovered at maturity. Second generation embryos were produced by factorial matings of these mature fish involving (1) female and male controls, (2) female and male hybrids, and (3) both backcrosses. Analysis of variation of development time detected no effect of outbreeding, i.e., differences between controls and second generation hybrids (p > 0.05), but did detect variation between individual female parents (p < 0.03). Neither epistatic nor additive outbreeding depression could be detected in the rate of early embryonic development of pink salmon. However, effects on development rate attributable to female parents indicate that either a maternal effect or early additive genetic effects occurred before the expression of the paternal genome in embryos.     

Temperature effects on juvenile anadromous salmonids in California’s central valley: what don’t we know?

The anadromous Chinook salmon (Oncorhynchus tshawytscha) (4 runs) and steelhead (rainbow trout, O. mykiss), are both native to Californias Sacramento-San Joaquin River (SSJR) system, whose watershed encompasses the central valley of California. The SSJR system holds the southernmost extant Chinook salmon populations in the Eastern Pacific Ocean, whereas coastal anadromous steelhead populations are found at more southerly latitudes. Populations of both species of anadromous salmonid have experienced dramatic declines during the past 100 years, at least partly from water impoundments and diversions on most central valley rivers and their tributaries. These changes restricted the longitudinal distribution of these salmonids, often forcing the superimposition of steelhead populations and Chinook salmon populations in the same reaches. This superimposition is problematic in part because the alterations to the river systems have not only changed the historic flow regimes, but have also changed the thermal regimes, resulting in thermally-coupled changes in fish development, growth, health, distribution, and survival. Given the highly regulated nature of the system, resource managers are constantly trying to strike a balance between maintaining or increasing the population size of anadromous fish runs and with other demands for the water, such as irrigation and water quality. To do so, in this review, we summarize the published information on the temperature tolerance and growth of the stream-associated life stages of these two valuable species, which are so central to the natural heritage of the State and its cultures. We show that many of these limits and growth-related effects are specific regarding life stage and that some may be specific to distinct strains or races of Chinook salmon and steelhead within the system. Because the number of published studies on the physiology of central valley salmonids was surprisingly low, we also use this review to highlight critical areas where further research is needed. Overall, this review should assist biologists and resource decision-makers with improved understanding for the protection and enhancement of these native fishes.     

环渤海湾地区棉铃虫成虫的卵巢发育特点及与迁飞行为的关系

1996－2000年期间先后在河北省廊坊市、北京市西郊和辽宁省辽阳市系统研究了不同代别棉铃虫成虫的卵巢发育特点及与季节性迁飞行为的关系,研究结果表明环渤海湾南部的河北省廊坊市和北部的辽宁省辽阳市第1代棉铃虫成虫种群主要由外地迁人,第2－3代种群多数年份主要来源于当地,但部分年份亦有外地种群大量迁入,北京市西郊空中诱捕的棉铃虫1－3代成虫多为产卵前期个体,具迁飞昆虫的生殖生理特征,表明棉铃虫成虫迁飞活动存在于各个代别。     

Effects of thermal regime on energy and nitrogen budgets of an early juvenile Arctic charr, Salvelinus alpinus, from Lake Inari

The feed intake, growth, oxygen consumption and ammonia excretion of juvenile Arctic charr were measured over period of four weeks at different temperatures which were either constant (11.0, 14.4, 17.7 °C) or fluctuated daily (14.3 ± 1 °C). Maximum feed intake was estimated to occur at 14.3 °C, while oxygen consumption and nitrogen excretion were highest at the highest temperature, and growth rate was estimated to be highest at 13.9 °C. Feed conversion efficiency was estimated to be highest at 13.2 °C, where over 62.7% of ingested energy was allocated to growth. Metabolic rate accounted for 16–30% of ingested energy and nitrogen excretion was under 3% of ingested energy. The nitrogen budget was under similar thermal influences to the energy budget. Thermal fluctuation increased metabolic rate, but not feed intake, leading to a reduction in feed conversion efficiency under fluctuating temperature conditions.     

Fish cell lines: Establishment and characterization of nine cell lines from salmonids

Summary Nine permanent cell lines have been established from five species of salmonids native to America's Pacific Northwest. With the exception of a hepatoma from an adult trout, the lines were derived from normal tissues of embryonic or juvenile fish. Cells were routinely grown in Eagle's minimum essential medium with 10% fetal bovine serum. Optimum growth temperatures for these lines ranged from 21 to 24°C. All survived storage for at least 1 yr at −65°C and at least 5 yr in liquid nitrogen. Six of the lines were demonstrably free of any microbial contamination but mycoplasmas were found in three. Eight of the lines were heteroploid. The morphology of only one was fibroblastic. All the lines effectively replicated one or more of the common salmonid viruses. Isozyme patterns were consistent with those of the species of origin. These cell lines have significant application in fish virology. This work is a result of research sponsored in part by the Oregon State University Sea Grant College Program supported by NOAA Office of Sea Grant, U.S. Department of Commerce, under Grant NA79AA-D-0016 and by the Oregon Department of Fish and Wildlife under PL-89304 Anadromous Fish Act and is Oregon Agricultural Experiment Station Technical Paper 6857.     

The study of familial migratory network: An inquiry whithin the help center A. Chiara (Palermo)

The present paper proposes a synthetic methodology in order to give a more exhaustive picture of the migratory phenomenon by the use of different instructive sources. In particular we suggest a socio-demographic analysis of the procreative behaviour and familiar strategies. For this purpose a socio-sanitarian centre in Palermo, as a place of observation of the migratory realities, offers the possibility to investigate the process under different facets. The use of a non-institutional centre allows a direct contact with the “less visible” migrants which enables the researcher to get more complete information. This survey has adopted the questionnaire as main tool of investigation, in order to recognise the influences of kinship and cultural constraints. Two different but complementary typologies of questionnaires have been adopted: a familial background questionnaire and a gynaecological questionnaire.     

Synchronous Crepuscular Flight of Female Asian Gypsy Moths: Relationships of Light Intensity and Ambient and Body Temperatures

Female gypsy moths (Lymantria dispar) of Asian heritage studied in central Siberia and Germany exhibit a highly synchronous flight at dusk, after light intensity falls to about 2 lux. This critical light intensity sets the timing of flight behaviors independent of ambient temperature. Flight follows several minutes of preflight wing fanning during which females in Germany and those from a laboratory colony (derived from Siberian stock) raised their thoracic temperatures to 32–33°C at ambient temperatures of 19–22°C. Thoracic temperature of females in free flight exceeded the air temperature (19–22°C) by approximately 11–13°C. The duration of wing fanning was strongly dependent on ambient temperature. In Germany, where ambient temperatures at dusk ranged between 21 and 25°C, females wing fanned for only 2.1 ± 0.2 (SE) min; in the much colder temperatures prevalent at dusk in Bellyk, central Siberia (11–13°C), females spent 11.2 ± 0.6 min in preflight wing fanning. The majority (80%) of mated and even virgin females initiated flight during the evening of the day they eclosed. However, in Bellyk, a small proportion (12%) of females wing fanned for an extended time but then stopped, whereas others (8%) never wing fanned and, therefore, did not take flight. Females also were capable of flight when disturbed during the daylight hours in Germany where the maximal temperature was high (27–30°C), but not in Siberia, where temperatures peaked at only 17–19°C. However, Siberian females were able to propel themselves off the tree on which they were perched by executing several vigorous wing flicks when approached by the predaceous tettigoniid, Tettigonia caudata.     

Environmental requirements of common riverine European salmonid fish species in fresh water with particular reference to physical and chemical aspects

This review attempts to assess, as quantitatively as possible, the habitat requirements in fresh water of three common and widespread European salmonid species. Namely: the trout (Salmo trutta L.), the salmon (S. salar L.) and the grayling (Thymallus thymallus L.). Requirements are considered for spawning, incubation and emergence, juveniles and smolts and for adults and spawning movements.