摘要:

Between 1974–1977 the gonads of a number of commercial reef fishes were examined during a study of gear improvement and stock assessment along the East African Coastal waters. Different methods of fishing ranging from modern methods of trawling to local methods of traps were used. Twenty‐one families with a total of 73 species were examined. The spawning of these species occurred throughout the year with two peaks in January to March and September to November. The highest peak of breeding was in October, corresponding to the time of the South East Monsoons, and to the highest water temperat

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03528.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Apparent SDA was defined as the energy expenditure associated with the ingestion of a meal. In the present study apparent SDA was equated to an increase in oxygen consumption above the postabsorptive level subsequent to the ingestion of a meal. The energy cost for physically processing a meal, mechanical SDA, was equated to the oxygen uptake associated with the ingestion of non‐digestible cellulose. The energy utilized by anabolic and catabolic processes associated with the ingestion of a standard diet was identified as biochemical SDA. Apparent, mechanical and biochemical SDA were each positively related to the energy intake of the standard diet. Apparent SDA expressed relatively to energy ingested equalled 10·5% and was independent of the caloric content of the meal. Mechanical SDA increased asymptotically with ingested meal size and energy content. Relative to apparent SDA, mechanical SDA decreased with meal size, suggestive of an enhancement in efficiency. Biochemical SDA rose exponentially with increase in ingested energy, reflective of the cost for growth and cataboli

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03529.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The effect of particle size of a commercial pelleted feed on the growth of Atlantic salmon from first feeding alevins to first and second year smolts was investigated using 20‐day feeding experiments. Ten experiments were performed over a two year period, each comprising six groups of fish separately selected from stock populations. Each group was presented with one of six sizes of food particle ranging from larger than the respective mean mouth breadth (100% feed size), through 50%, 25%, 12·5%, 6·25% to 3·125%. Experiments were performed in six radial flow/circumferential drain tanks under ambient photoperiod and water temperature. Growth rate was found to be closely related to feed size. Maximum growth in each case was shown only on one size of particle; larger and smaller sizes resulted in reduced growth. The particle size for maximum growth increased in direct proportion to fish length. Fish from 4·2 to 20·3 cm in length showed maximum growth on particle diameters 0·022 to 0·026 × fish fork length (PFR). First feeding alevins were found to show comparable growth rate on particle diameters 0·0115 to 0·090 PFR. Some seasonal variation in growth response was indicated. The results are discussed in relation to developmental and seasonal effects. Possible factors affecting the energetics of prey size related differential growth ar

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03530.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Seasonal changes in the levels of copepod ectoparasitic infections fromMerlangius merlangusandPlatichthys flesuswere examined and related to the annual migrations of young fish into an estuary.Lernaeocera branchialis(L.) was the only parasite common to both fish species; its life‐cycle stages infected the branchial chambers of 96·7% flounders (P. flesus) and 40·4% whiting (M. merlangus). Infection in the two fish species exhibited similar seasonal fluctuations and a temporal relationship between the parasite's occurrence on its two hosts was apparent. Whiting were also parasitized byClavella uncinata(Milller); 26·9 % fish were affected. The copepods' distribution was highly localized with the majority restricted to the long gill rakers of the first gill arch. Infection was related to size of whiting up to 12·5 cm; there was little increase beyond this length. In addition toL. branchialis, flounder was also host toAcanthochondria depressa(T. Scott) andLepeophtheirus pectoralis(Müller).A. depressashowed a preference for the ocular side of the body with its developing stages attached mainly to the second gill arch and the adults located in the posterior pocket of the branchial chamber.L. pectoraliswas associated with the paired fins. Factors which could result in such localized distributions are dis

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03531.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The present paper describes the morphology, histology, and annual cyclical changes in the ovaries ofBarbus luteus(Heckel). The ovaries are paired structures, joined by short oviducts. The ovarian structure consists of a number of lamellae, which contain the germ cells in various phases of maturation—immature, maturing and mature. Two types of yolk have been reported in the oocyte. The endocrine function of the gonads has been attributed to the follicular cells forming the ‘pre‐ovulatory corpus luteum’ and ‘postovulatory corpus luteum’. The ovaries undergo a regular annual cycle which has been divided into five stages, based on various criteria, viz, ovarian size, colour, gonosomatic index, average ova‐diameter, histological composition, and the spaw

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03532.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

An attempt has been made to assess blood flow in the oval region ofP. virensusing radiolabelled microspheres. The results suggest a low flow rate and they are similar to those calculated using the Poiseuille equation in a previous paper. A substantial increase in flow rate was obtained on inflation of the bladder, showing that the deflating reflex was elicited.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03533.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Fish populations in the Medway Estuary become infected withCryptocotyle lingua(Creplin) shortly after their inshore migrations. The present study examines infection levels between 1973 and 1975 in four fish species; whiting,Merlangius merlangus(L.), pouting,Trisopterus luscus(L.), plaice,Pleuronectes platessaL. and flounder,Platichthys flesus(L.). Frequency of infection was highest in flounder, followed by pouting, plaice and whiting. Unusually, parasite density was lowest in plaice even though gastropod molluscs (the parasite's first intermediate host) were most common in their diet. Seasonal levels of infection are discussed and prove useful indicators to the migratory movements of individual fish populations. In whiting and pouting, incidence of infection increased with length of host while no relationship between infection and age of host was observed in either flatfish. Metacercariae were not distributed randomly over the body surface; in gadoids they were concentrated above the lateral line while in pleuronectids they were most intense in the fins and gills.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03534.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

An electromyographical study has been made of carp swimming muscles at various points along the body length during sustained and burst locomotion. During sustained swimming, red muscles show a constant time lag between activation of anterior and posterior segments which is practically independent of the speed of locomotion. In contrast, anterior and posterior homolateral segments are activated simultaneously during bursts of rapid movement. This pattern of co‐ordination between body segments differs from that reported for other specie

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03535.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The levels of lactate dehydrogenase, hydroxy butyric dehydrogenase, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, glutamate dehydrogenase, alkaline phosphatase and leucine amino peptidase were determined in the plasma of rainbow trout. The protein concentration and the amount of alkaline phosphatase were reduced in starving trout. Fed trout showed reduced lactate dehydrogenase activity. There was a significant correlation between the condition factor, most of the enzyme activities and the protein concentration. At 10 parts per thousand salinity the activities of alkaline phosphatase and leucine amino peptidase were significantly elevated, while lactate dehydrogenase activity was significantly decreased.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03536.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

A year long study based on monthly observations on the haematology of femaleChanna punctatuswith respect to haemoglobin, haematocrit values, total erythrocyte and leucocyte numbers together with a differential enumeration of various leucocytesviz.thrombocytes small and large lymphocytes, monocytes, neutrophils, eosinophils and basophils is recorded. The study showed that the total erythrocytic number, haemoglobin and haematocrit values decrease during the breeding time i.e. July to September. The thrombocyte number significantly increased while the neutrophilic number showed a decrease. The physiological significance of these changes is discussed with reference to the available literature.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1979.tb03537.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY