摘要:

This study was designed to determine whether orange roughy reproduce throughout their distribution in Australian waters, and if so, whether commencement of spawning and length at maturity vary within the region. We found that females from four widely separated sampling areas reproduced in 1988, but that the onset of spawning and length at maturity were not the same in all the areas. In New South Wales, ovulation was finished by mid‐June, and 50% of females were mature at 28 cm standard length (S.L.). On the other hand, females from eastern and western Tasmania and South Australia did not spawn until mid‐July, and 50% of females from Tasmania were not mature until 32 cm S.L. Females from all areas had oocytes with yolk granules at least 5 months before ovulation. However, in the few months before spawning, some adult females from all areas had not undergone vitellogenesis or were resorbing all yolky oocytes. The best estimates of the proportion of these non‐reproductive females were made in March and April, when the single batch of eggs to be spawned was clearly distinguishable, and before spawning aggregations had formed. In 1990 in eastern Tasmania, at the site of a major spawning aggregation, the best estimate of the proportion of non‐reproductive fish was 45%. We suggest that scarcity of food, coupled with the cost of joining a spawning aggregation, may result in intermittent spawning in this long‐live

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02558.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Patterns of food resource utilization byBarbus bocageiin a lowland river in the central part of the Iberian Peninsula are presented and discussed. Focal points include feeding activity, diet composition and seasonal and ontogenetic diet shifts. Striking features of overall feeding pattern of barbel are its continuous feeding activity, bottom habits, high consumption of detritus and dipteran larvae and narrow diet breadth. Seasonal changes in food resource availability elicited changes in food utilization patterns, revealing a trend to more generalist feeding during spring. Barbel increase consumption of plant material and large prey during ontogeny, but overlap in prey resource utilization between size classes is high. The versatility of barbel foraging behaviour may be an important feature in its exploitation of Iberian lotic systems.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02559.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Squid‐encapsulated acoustic transmitters were ingested by Atlantic cod,Gadus morhua, (3128–10 221 g) held in captivity at 12° C. Retention times ranged from 5 to>21 days. There was no significant change in feeding rate after transmitter inges

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02560.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Two Red Sea species, the sparidRhabdosargus haffaraand the sphyraenidSphyraena flavicauda, previously unrecorded in the Mediterranean, have been recently found in the vicinity of Tel‐Aviv, coast of Israe

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02561.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY