摘要:

Metabolic scope and its utilization in relation to feeding and activity were measured in individual and grouped zebrafish (weight range, 430–551 mg) at 24° C by respirometry. Mean maximum metabolic rate, induced by swimming to exhaustion,Rmax(i), was 1223 (s.d., 157) mg O2, kg−1h−1for individuals. Standard metabolic rate, Rs. was 364 mg O2kg−1h−1, as estimated by extrapolating to zero activity from measurements of unfed, spontaneously active individuals. Mean routine metabolic rate,Rrout, of individuals was 421 (s.d., 58) mg O2, kg‐1h‐1. The mean voluntary maximum metabolic rate, Rmax(v), following transfer of minimally exercised fish to the respirometer, was 1110 (s.d., 83) mg O2kg−1h−1for groups of six fish, and was not significantly different from the value measured for individuals, 1066 (s.d., 122) mg O2, kg−1h−1. Grouped fish acclimated to the respirometer more slowly than individual fish and exhibited significantly higherRrout, apparently a result of greater social interaction and activity in groups. MeanRroutfor groups was 560 (s.d., 78) mg O2, kg−1h−1. While groups of zebrafish fed a ration of 5% wet body weight day−1exhibited consistently higher metabolic rates than fish fed rations of 2.5% wet body weight day−1the high ration group still used only a maximum of 77% of the metabolic scope. Zebrafish of the size studied do not appear to demonstrate a high degree of conflict in utilization of metabolic scope by different respiratory components. The metabolic rates measured for zebrafish are among the highest yet measured for fish of similar si

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02648.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Hatchery‐reared mature male Atlantic salmon parr were shorter than immature parr of the same age through the winter period and this difference increased prior to smolting in spring. Stripping had no effect on growth. In autumn mature male parr had a higher condition factor (CF) than immature parr, but from early January no difference was observed between unstripped mature males and immature parr. Stripping reduced the CF of male parr but the difference had disappeared by the time of smolting when the CFs of both mature groups were lower than that of immature fish. The quantity of expressible milt in stripped males decreased fromc. 3% body weight in November and December to<0.05% by 2 March, after which no further milt expression was recorded. Milt expression in previously unstripped males was about 1% of body weight on 2 March, similar to that of stripped males 1 month earlie

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02649.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Back‐calculation usually requires measurements of growth marks revealed on otoliths by specific preparations. The standardization of the grinding (or sectioning) plane is necessary, but difficult, especially along the antero‐posterior axis. In order to show the importance of the grinding plane, tetracycline labelling of eel otoliths (Anguilla anguillaL.) has been used. This marking has a calcio‐traumatic effect on otoliths, which can be revealed with staining techniques. Unless the grinding plane is incorrect, the tetracycline labelling and the staining of the ground surface are then super

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02650.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Juvenile plaice (Pleuronectes platessa) were studied in Port Erin Bay, Isle of Man, U.K. between September and March 1989/1990 and 1990/1991. Plaice (>90 mm) were tagged and individual growth rates calculated for the autumn, winter and over‐winter time periods. During the study the population of fish>90 mm remained fairly stable both within a study season and between years. Autumn growth rates ranged from 0 to 0.39 mm day−1(mean1989=0.13 mm day−1, mean1990=0.10 mm day−1) and winter 0 to 0.5 mm day−1(mean1990=0.11 mm day−1and mean1991=0.17 mm day−1). In general, growth rates were higher at higher mean seasonal temperatures. However, relative growth rate was significantly higher in the colder winter period of 1

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02651.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A bioenergetics model was developed for Eurasian perch (Perca fluviatilisL.) by revising an existing model for yellow perch and walleye. Data were gathered from field studies and the literature. Besides adjusting the original parameters of the model, effects of season on consumption and metabolic rates were added. The predictive capability of the revised model was high both concerning the levels of growth and its seasonal development in the Baltic coastal waters to which the model was applied. Perch young‐of‐the‐year attained almost maximum consumption and growth except in the highest temperatures experienced. In larger fish, the model estimated consumption to be about 50 per cent of the maximum possible

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02652.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Young grass carp held under laboratory conditions were fed either duckweed or tubificid worms. Food consumption (C), faecal production (F), excretion (U), metabolism (R) and growth (G) were estimated for fish fed both diets. Fish fed tubificid worms had higher growth rates than those fed duckweed, in terms of wet weight, dry matter, protein, lipid and energy. Fish fed duckweed consumed more wet and dry matter than did the fish fed tubificids, but rates of protein and lipid consumption were lower. The energy budget was estimated to be 100C = 9F+ 8U+ 61R+ 22Gfor fish fed tubificids, and 100C = 35F+ 5U+ 51R+ 9Gfor fish fed duckweed. Linear relationships existed between specific growth rate in wet weight and rate of food absorption (consumption minus faecal production) in dry matter, protein or energy. Food type did not have a significant effect on these relationships. It was concluded that differences in growth rate between grass carp fed different diets were mainly caused by differences in absorption rate.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02653.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

The recruitment dynamics and life history of migratory brown trout,Sulmo truttaL., were investigated in a small Baltic coast stream subject to recurring drought. Spawning males consisted of both mature male parr (101–206 mmt.l.) and migrant males (205–780 mmt.l.). Spawning females were all migrants which delayed maturity until reaching a significantly greater size on average (424–805 mmt.l.) than migrant males. Male: female ratios were very high in spawning aggregations (9–12 males: 1 female) with males representing up to five year‐classes or more. Gametes from several generations of males per spawning event may be important for maintaining the genetic viability of this population with few female spawners per year. The amount of spawning was dependent on precipitation just prior to and during the spawning period since migrants could not enter the stream under drought conditions. Migrants did not overwinter in the stream.Drought also caused variable fry mortality following emergence in early summer. Recruitment of 0+ parr in autumn varied fromc. 175 to 3000 during 3 years. Smolts were relatively young (ages 1–2) and small (≥8 cm), and were significantly longer on average than sibling parr. Yet emigration of 1‐year‐olds was not related to 0+ parr size the previous autumn because of overlapping growth rates.Persistence of the migratory brown trout in this unstable environment may be the consequence of (i) life history adaptation (e.g. short freshwater residence of both juveniles and spawners), and (ii) a complementary set of individual life histories where variation in age of migrant spawners and the occurrence of mature male parr result in a stable spawner population despite inconsistent recruitment of mi

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02654.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Three groups of rainbow trout,Oncorhynchus mykiss, (initial weight 40 g) were fed one of three rations (low, medium or high) for 73 days. Consumption by individual fish within the three ration groups was measured on four occasions (days 27, 55, 64 and 72) using radiography. Food intake by individual fish varied between days and this variability was expressed using the coefficient of variation (CV). Dominant fish within each ration group were defined as individuals with the greater share of the group meal and these fish had low CVs for food intake indicating relatively little variation in daily consumption. By contrast, the fish which had consumed a low mean proportion of the group meal displayed high CVs for food intake, indicating considerable variability in the sizes of individual meals consumed by these fish. As group ration increased, the range of meal sizes and individual CVs in daily feeding decreased, suggesting that the strength of the feeding hierarchy and the variability in individual consumption decreased as food availability increased. It is suggested that radiography can be used to assess social relationships within groups of fish allowing the assessment of feeding hierarchies in larger groups of fish than would be possible by observational techniques.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02655.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Size and structure of theLernaeocera branchialispopulation infecting 0+ whiting in the Oosterschelde were studied during 1989. Two periods of successful transmission were distinguished. The first transmission wave occurs in late spring when the post‐larval whiting enter the Oosterschelde. A second wave occurs in autumn. This pattern in the infection dynamics is possibly related to seasonal variations in spatial overlap of the intermediate (Platichthysflesus) and the final host (Merlangius merlangus). The dispersion pattern ofLernaeocera branchialiswithin the whiting population can be described by the Poisson distribution. Possible explanations for the observed dispersion pattern are given. Evidence is presented that the rejection of pennella larvae is a key mechanism determining the abundance ofL. branchialisin whiting. The potential impact of parasite‐induced host mortality on population size and dispersion pattern of the parasite is discus

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02656.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

The biology of the sixth population of A. boyeri Risso, 1810 to be recorded outside of the Mediterranean basin is described. The 2 year life cycle was similar to that of other populations of the species that have been investigated. A maximum standard length of 93 mm was recorded for 2‐year‐old fish. Sexual maturity was attained by females at a length of 39 mm. A temporal lag in ovarian development was noted between the two spawning age groups, with the older age group spawning first. Details are provided of batch spawning in A. boyeriand the difficulties of assessing fecundity in batch spawners is discussed. Discrepancies between direct and indirect methods of assessing batch size indicated that the eggs around the largest mode may not represent the next batch to be spawned. Evidence is presented to suggest that in A. boyeri these eggs represent a ‘ store’ from which batches of eggs are subsequently r

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1992.tb02657.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY