摘要:

The present communication deals with a histological study of the pituitary gland of the teleost fishMugil cephalus, found in the estuarine waters of Cochin area. Six different cell types were identified in the pituitary gland on the basis of their grouping, distribution and staining properties. The prolactin and the TSH cells (thyroid stimulating hormone producing cells or thyrotrops) were identified in the rostral pars distalis and the ACTH cells (adrenocorticotropic hormone producing cells or corticotrops) in the interphase between the neurohypophysis and the rostral pars distalis. The STH cells (somatotropic hormone producing cells or somatotrops) and the gonadotropic cells were distinguished in the proximal pars distalis and the MSH cells (melanin stimulating hormone producing cells or melanotrops) in the pars intermedia.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04278.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The results of three investigations, two with wild smolt and one with hatchery‐reared smolt of altic salmon, were analysed with regard to mortality due to predation during river and estuarine migration. This mortality was found to be high, at least 50% of the initial number of smolt was estimated not to reach marine waters. Smolt mortality may be important in population regulation, analoguous to other animal species having the same life strategy with two life stages and a transfer to a new habitat connected to the shift in life stag

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04279.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Aplocheilichthys normaniis a small Cyprinodontidae endemic in tropical Africa from Senegal to central Sudan. Analysis of the gut content of two populations from Guinea reveals that it feeds mainly on small crustaceans and chironomid larvae. Experimental investigations into its predatory capacity vis‐á‐vis the larvae ofAedes aegyptishow that there is a significant difference between the daily feeding rates in adult versus subadult specimens. Moreover, significant 24 h variations were also observed. The feeding rate is also related to the stage of the larvae, i.e. the predatory capacity is greater for smaller prey. The 24h feeding rate variations show thatA. normanifeeds both during the daylight hours and at night, with a slightly higher predatory activity during the daylight hours. The peak in feeding activity occurs during the two hours before dark. Tests on feeding preferences show that the fish prefers, in descending order,Aedes, AnophelesandCulexlarvae. Its larvivorous activity against mosquito larvae was corroborated by small‐scale field studies. We propose that this species be considered for possible use in the biological control of mosquito larvae in West

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04280.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The diet, feeding habits and feeding structures of 519Sillago sihamaand 493S. analisspecimens collected from beaches and estuaries in the Townsville region are described. The species are carnivores on a wide range of benthic, epibenthic and planktonic prey. Both undergo size related dietary shifts;S. sihamafrom predominantly planktonic crustaceans in fish of less than 80 mmt.l. to polychaetes, penaeid and brachyuran crustaceans and molluscs at larger sizes;S. analisfrom a mixture of smallMesodesma eltanaeand amphipods at sizes of less than 80 mmt.l. to predominantlyM. eltanaeand small quantities of penaeids and brachyuran crabs in larger fish. The dietary shift was not associated with migration from a nursery area.While the species showed considerable overlap in the types of prey utilized, there were significant differences in the relative importance of shared components in their diets. The major difference was in the relative importance of the bivalve mollusc,M. eltanae.This was the dominant food ofS. analisbut of secondary importance inS. sihama.Associated with this basic difference in diet was a specialization of the pharyngeal dentition inS. analisto molariform crushing plates and a reduction of the gill rakers to vestigial knobs. InS. sihama, the pharyngeal teeth are sharp and pointed and the gill rakers normal.The feeding activity ofS. analis, but notS. sihama, is limited by the tidal cycle, a factor which may be a form of temporal partitioning.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04281.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Cyprinus carpioimmunized at 9 weeks after hatching with either human gamma globulin or trinitrophenylated sheep red blood cells either fail to respond or respond poorly on secondary exposure at 17 weeks of age. Injection of cortisol either simultaneously with the antigen, or 3 days prior to, or 3 days after antigen, permits the antibody response to proceed upon subsequent challenge. The implication of these results for the ontogeny of the fish immune response is discussed.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04282.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Plasma levels of catecholamines, cortisol, and glucose were monitored in rainbow trout during a 6‐week forced swimming exercise programme. Compared to resting non‐exercised controls, resting trained fish had lower levels of epinephrine, norephinephrine, cortisol, and glucose during the last 3 weeks of training. Initially, trained fish that were swimming had higher levels of epinephrine than resting trained fish. After 2 weeks of exercise, swimming did not significantly elevate epinephrine levels in trained fish. Glucose levels were consistently greater in swimming fish than in resting fish. At the end of the training period, exercised trout had lower (15–20%) oxygen consumption rates while resting or swimming than unexercised fish.After a 5‐month forced swimming exercise programme plasma levels of catecholamines and glucose were monitored in trained and untrained cannulated rainbow trout after 2 min of mild agitation. Trained fish showed an immediate (within 1 min) increase in the levels of epinephrine, but not norepinephrine and a delayed (within 15 min) increase in the levels of plasma glucose. Epinephrine levels returned to pre‐stress levels within 15 min. Untrained fish had no significant increase in the plasma levels of norepinephrine, epinephrine, o

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04283.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Five hypotheses explaining variations in growth and recruitment were tested statistically with data from a study of yellow perch,Perca flavescens, 1950–83. Recruitment was not a function of water temperature during spawning, hatching or the first year, but was a function of lake water levels. Growth was not related to average water temperatures or degree‐days, but was inversely correlated with the abundance of year‐cl

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04284.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Experiments were conducted in earth ponds (242–1260m2) to evaluate the Nile perch(Lates niloticusL.) as a predator for recruitment control and the production of marketableOreochromis niloticusL. in the Sudan. Supply of the predatory fish was maintained by induced spawning ofL. niloticusbrooders by raising the water level in a 1–0 ha earth pond.Lates niloticusfingerlings (7–5 cm total length) were then stocked with same sizeO. niloticusat the ratios 1:5, 1:10 and 1:15,Lates:Oreochromis, respectively. Over a period of 7 monthsLates niloticusreduced young 50g)Oreochromispopulation and enhanced the production of preferred‐size ( 200 g)Oreochromis.The ratio 1:5Lates:Oreochromiswas established to be the most desirable forLates‐with a total production of 0.2428 kg/m2ofO. niloticuswith 55.7% (by weight) at the target size averaging 287.5g. The ratios 1:10 and 1:15 produced 0.2106 and 0.2153 kg m2ofO. niloticus, with 49.4% and 16.9% averaging 235.0 and 210.0 g, res

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04285.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Environmental variables besides temperature such as length, weight, sex, and photoperiod were shown to affect the metabolic rate in gill and white muscle tissue. This required statistical adjustment to account for these factors. Oxygen consumption rates for gill tissue were greater following cold acclimation at all determination temperatures. This suggests thermal compensation had occurred. Metabolic rates for white muscle tissue showed inverse compensation between 7 °C and 15 °C, but little compensation was evident between 15 °C and 23 °C. Both gill and white muscle tissue had Q10values ranging between 1–00 and 2–00. These are lower than values previously recorded for fathead

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04286.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Significant leucopenia, predominantly the result of a large reduction in lymphocyte concentration, was observed in rainbow trout exposed to 301 μg1−1copper for 24h. A strong trend (P =0–085) toward reduced erythrocyte concentration was also apparent. The pattern of haematological change after chronic exposure (118 μg 1−1copper for 16 weeks) was substantially different. With the exception of a significant increase in neutrophil concentration (neutrophilia), all blood cell concentrations had returned to control

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1985.tb04287.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY