The food consumption to biomass ratio (C) is one of the most important population parameters in ecosystem modelling because its quantifies the interactions between predator and prey. Existing models for estimating C in fish populations are per-recruit cohort models or empirical models, valid only for stationary populations. Moreover, empirical models lack theoretical support. Here we develop a ...

The growth and mortality coefficient of Rutilus frisii kutum, were estimated using length frequency data collected in southern waters of the Caspian Sea during October 2008 to April 2009. The following population parameters were evaluated: length-weight relationship, W = 0.004L 3.258, (r= 0.976) Von Bertalanffy growth constants, W∞ (g) = 4192.3, L∞ (cm) = 70.45, K = 0.2, per year t0 = −0.75 tot...

Maternal effects on offspring viability significantly contribute to the productivity and resilience of exploited marine fish populations. The temporal trend biomass chub mackerel ( Scomber japonicus ) in western North Pacific showed cyclic fluctuation patterns, but it has been rapidly increasing since 2011. Although there are several assumptions regarding mechanisms population dynamics this spe...

Background: Fluoxetine (ProzacTM) is one of the most popular antidepressant that can be released to aquatic systems via sewage-treatment effluents. It is suspected to provoke substantial effects in the aquatic environment. Methods: In spawning tanks, specimens were exposed to concentrations of 0 and 0.54 µgl-1 fluoxetine from male introduction until the larvae had hatched. Prior to spawning, n...

The early life history 7 Abstract The relationship between the biomass of reproductively mature individuals (spawning stock) and the resulting offspring added to the population (recruitment), the stock–recruitment relationship, is a fundamental and challenging problem in all of population biology. The steepness of this relationship is commonly defined as the fraction of recruitment from an unfi...

Pacific salmon (Oncorhynchus spp.) returning to streams around the North Pacific Rim provide a nutrient subsidy to these ecosystems. While many species of animals feed directly on salmon carcasses each autumn, salmon-derived nutrients can also be stored in coastal habitats throughout the year. The effects of this storage legacy on vertebrates in other seasons are not well understood, especially...

Recruitment overfishing (the reduction of a spawning stock past a point at which the stock can no longer replenish itself) is a common problem which can lead to a rapid and irreversible fishery collapse. Averting this disaster requires maintaining a sufficient spawning population to buffer stochastic fluctuations in recruitment of heavily harvested stocks. Optimal strategies for managing spawne...

background: fluoxetine (prozactm) is one of the most popular antidepressant that can be released to aquatic systems via sewage-treatment effluents. it is suspected to provoke substantial effects in the aquatic environment. methods: in spawning tanks, specimens were exposed to concentrations of 0 and 0.54 µgl-1 fluoxetine from male introduction until the larvae had hatched. prior to spawning, ne...