Showing papers in "Fisheries Research in 1993"

TL;DR: Reviewing studies on the patterns of straying of adult salmonids from their river or hatchery of origin, with emphasis on Pacific salmon finds fundamental gaps in understanding of the genetic and environmental factors that influence straying hinder accurate prediction of the levels and consequences of strays.

TL;DR: The proportion of cultured salmon in these populations has increased together with the rapid growth of the Norwegian salmon farming industry, and fish of cultured origin now exceed the number of wild fish in several spawning populations.

TL;DR: Although the production of nauplii remained relatively constant between March and July, transmission to sea trout was apparently restricted in time to late April and May, suggesting temporarily varying susceptibility to infestation may have a role in determining the level of infestation that develops.

TL;DR: Methodical approaches of efficient determination of squid age, growth and stock structure by means of investigation of squid biological features and statolith microstructure in each distinguished wave of abundance were elaborated.

TL;DR: Routine pastruerization of fish products in the diests has reduced, but not eliminated, BKD in these stocks of fish, and important advances allow rapid and sensitive detection of R. salmoninarum, which continues to be serius problem for both wikld and cultured salmonids.

TL;DR: It is concluded that chronic elevation of plasma cortisol levels in response to environmental stress can be an important factor responsible for increased mortality rates and reduced recruitment with salmonid popultions.

TL;DR: In this paper, the authors reported an increasing ability to tolerate Gyrodactylus salaris infection with increasing size on the part of the salmon parr in three hatchery-reared stocks from the Rivers Shin and Conon in northeast Scotland, and from the River Lierelva in southeast Norway.

TL;DR: The predictive power of the empirical models most commonly used is evaluated and it is suggested that the prediction errors of the mortality estimates are substantial and should be taken into account when considering whether to employ alternative and more expensive methods leading to direct estimates of natural mortality.

TL;DR: It is indicated that 4 days is an adequate length of time for experiments to measure survival of animals discarded from trawl catches, indicating that temperate fish captured in trawls may continue to die over a longer period but this cannot be determined in tanks.

TL;DR: This paper starts with a brief review of previous attempts to set up a general model of trawl herding and capture, and goes on to show how work already published can be extended to estimate the absolute efficiency of the trawl net with bobbin groundrope.

TL;DR: Correlation analyses reveal a strong correlation between HbI 2 frequency and Arctic cod otolith characteristics, offering haemoglobin analyses at early cod stages as reliable classification of offspring from Arctic cod spawning.

TL;DR: In this paper, the authors found that the growth of Bristol Bay sockeye salmon in freshwater and in the last few months at sea is dependent on their abundance (a negative correlate) and the prevailing water temperature (a positive correlate).

TL;DR: The paper focuses on identifying the smallest detectable population with unique sets of characters, i.e. a ‘species’ under the phylogenetic species concept, which requires identification before any subsequent groupings under which individual populations may ultimately be managed.

TL;DR: In this article, acoustic surveys were carried out in the Yellow Sea and East China Sea by the Chinese research vessel "Bei Dou" during the winter seasons (November-April 1985-1990).

TL;DR: The positive relationship between female density and smolt density indicates a trend towards constant proportional survival at sea and the similarity of sea mortality rates in many year-classes supports this trend.

TL;DR: The results of this analysis suggest that present levels of salmon feeding have a minimal impact on zooplankton stocks in Prince William Sound, however, several key questions remain to be answered regarding the use of forage resources by wild and hatchery fry populations.

TL;DR: In natural waters as well as in fish farms, G. salaris and G. derjavini seem to have an uneven distribution, which may be due to geographic distribution of the species, anthropochoric spreading, macroenvironment, seasonal variations, or life cycle dependent variations of infestation intensity.

TL;DR: Ulcerative dermal necrosis is predominantly a condition of the head skin of salmonid fish native to the waters of the British Isles and currently the disease is in a period of remission and no outbreaks have been reported for some years.

TL;DR: There was a negative relationship between parasite intensity and host size in the 1 + and older salmon parr, demonstrating heterogeneity in susceptibility and/or resistance to G. salaris among host individuals.

TL;DR: The evolution of catches and population structure is closely related to the population biology of the Squilla mantis: recruitment, growth and adult disappearance.

TL;DR: In this article, the authors proposed a biologically sound management program for the Baltic salmon, which would have to include regulations prohibiting or severely restricting the offshore fishery on mixed stocks, by a more terminal fishery at the coast or in rivers.

TL;DR: In this paper, the authors used published data to test a theoretical model of trawl gear efficiency and found if the results from four separate experiments can be fitted to it coherently and without contradiction.

TL;DR: Brook trout exposed to waters enzootic for PKD showed no evidence of the disease or of infection with the PKX parasite, but laboratory experiments demonstrated that brook trout can be infected with rainbow trout PKX cells and that, although clinical signs of PKD did not develop and PKZ cells were not observed, the parasite was able to reach the renal tubule lumens and commence sporogony.

TL;DR: Although appropriate technology is the key in producing healthy hatchery fish, the critical component for success of the hatchery concept is the seed stock used for propagation, and every effort must be made to work with the negative gene pool and avoid contamination from other brood sources to maintain stock synchrony with the environment.

TL;DR: Catches of lumpsucker (Cyclopterus lumpus, L.) taken in late summer 1991 indicate that this species is widely distributed throughout the Norwegian Sea, with the largest concentrations occurring in the areas close to the polar front as discussed by the authors.

TL;DR: It is believed that the adaptedness and productivity of salmon stocks are dependent on genetic infrastructure; fisheries management practices, including enhancement of harvests by hatcheries and ocean ranching, potentially reduce genetic infrastructure as they may reduce other levels of genetic diversity.

TL;DR: In this paper, the avoidance behavior of herring and mackerel was quantified by means of a true motion sonar in purse seine capture situations, and a relation between the avoidance and the sound emission pattern of the vessel was indicated.

TL;DR: Analysis of the relationships between three successive removals with electrofishing and the subsequent estimated numbers for two and three catches (Zippin method) in four contrasting trout streams found that catchability is rather unpredictable.

TL;DR: In this article, the effects of trawlable species due to the duration of tows and temporal and spatial heterogeneity were examined using demersal trawling in the prawn grounds off the east coast of New South Wales, Australia.

TL;DR: In summer and autumn both increasing and decreasing infrapopulations were observed in all groups, revealing an increasing heterogeneity in resistance among the salmon parr, and consequently a negative impact of host resistance on the parasite population as the summer proceeded.