摘要:

A new type of miniature ultrasonic telemetry transmitter weighing less than 4 g underwater and usable on fish of less than 0.5 kg weight is described. The signal consisting of a sound pulse triggered by the QRS spike of the electrocardiogram is detectable at ranges to 400 m. Continuous records lasting 7 days were made of cardiac rhythms of brown trout. Mean heart rates were low indicating a metabolic rate of not more than 1.55 times the basal metabolic rate. Maximum heart rates were rare, occupying less than 0.5% of the time; there was no evidence of build up of oxygen debt due to periods of high activity. Following a settling down period after the attachment of the transmitter, the fish exhibited a diurnal rhythm with higher heart rates during the day. The transition from day to night heart rates and vice versa in one fish was shown to anticipate solar altitude change by half‐hour. Missing heart beats (cardiac inhibitory reflexes) are discussed as indicators of a sensory input, but they are not reliable indicators of feeding activity. It is concluded that stamina is not important for normal day to day survival of adult trout and the influence of various ecological factors is discusse

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb04064.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Four estuarine pond‐ecosystems equipped with tidal simulation were established and stocked with mullet, shrimp, and oysters. A 6 month pre‐spill sampling period established a consistently low incidence of disease in the mullet,Mugil cephalus, from all ponds. Following the preliminary study period, Empire Mix crude oil (4.0‐5.0 p.p.m.) was spilled on each of two of the ponds in mid‐July, 1974. Six to eight days following the oil spill all the mullet examined from the treated ponds had varying degrees of fin rot on one or more of their fins. The fin erosion involved primarily the caudal, pectoral, and pelvic fins with the caudal fin the most severely damaged. The degree of damage to the fins varied from a slight discoloration with no visible fraying to complete erosion of all of the fin elements. A gram negative rod tentatively identified asVibriosp. is considered the primary pathogen responsible for the fin erosion. Although the condition of the infected fish indicated the possibility of a systemic infection, only a low percentage of the kidney cultures taken from the diseased fish were positive indicating the infection was mostly external. The course of the infection was documented over a 56‐day period following the oil spill. Significantly, 96% of the mullet observed from the treated ponds had some degree of fin damage while only 6 % of those observed from the control ponds had eroded fins. The high incidence of fin rot which occurred in the estuarine‐pond ecosystems did not occur during numerous acute exposures of mullet to crude oil in the

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb04065.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A scanning electron microscopical examination of the gills ofH. fossilisis described. The surface architecture of gill filaments and secondary gill lamellae showed the presence of various features such as indentations, micropits and crevices. The possible functions of these morphological adaptations are discussed in relation to physiology of the gill.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb04066.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The specific status of the damsel fishChromis chromis(L) is discussed and it is suggested thatChromis chromisis retained for Mediterranean specimens and thatChromis lirnbatusis re‐introduced for the East Atlantic form. Behavioural and morphological differences which distinguish these two species are given. A key to these and other East AtlanticChromisis provided, the species are described and their geographical range discusse

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb04067.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A total of 531 references on the parasites and diseases of marine and freshwater fishes of India which appeared in 90 scientific journals have been documented.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb04068.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Diurnal variations in pituitary gonadotropin content were determined in the golden shiner,Notemigonus crysoleucas.In fish maintained on a 15‐5L/8‐5D–15°C regime, a pronounced circadian variation in pituitary gonadotropin potency was observed, the gonadotropin content being minimal early and maximal late during the light phase. Little temporal variation was seen in fish exposed to a 9L/15D–15°C regime. The effects of gonadotropin and prolactin treatment on gonadal activity inN. crysoleucaswere also investigated. Salmon gonadotropin was effective in stimulating an increased rate of gonadal development when given early during the light phase in fish maintained on a 15.5L/8‐5D–15°C regime; injections of gonadotropin given late in the light phase failed to accelerate gonadal growth. Regardless of time of injection, ovine luteinizing hormone accelerated gonadal growth in fish maintained on a 9L/15D–15°C regime. Ovine prolactin retarded gonadal development in fish exposed to a 15.5L/8‐5D–24°C regime, independent of injection time. In fish maintained on a 15.5L/8‐5D–15°C regime, injections of prolactin given early, but not late, during the light phase repressed gonadal maturation. These data show that under certain photoperiod‐temperature conditions there is a temporal aspect to responsiveness t

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb04069.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The growth rates, lengths at maturity, fecundity and natural mortality of several cichlids of importance in trawl catches in Lake Malawi are described. Growth rates were determined by analysis of length frequency data from trawl catches. The breeding season for each species was determined by monthly examination of the gonads, and fecundity determined by egg counts from ripe ovaries. Lengths at maturity were calculated from the proportion of mature fish during breeding seasons. Natural mortality rates were determined from length frequency data from an unfished area of the lake. Values of the growth constantKranged from 0.487 to 0.671. The ratio of length at maturity to asymptotic length varied from 0.56 to 0.82. Growth parameters are compared with those of other cichlids. Most species mature in their third year. Fecundity was proportional to the square of the length in four of the five species. The species studied appeared to produce only one batch of eggs per breeding season. Instantaneous natural mortality rates ranged from 0.92 to 1.69.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb04070.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Uptake and loss by sticklebacks of both stable zinc and65Zn in hard and soft water have been studied for periods of upto400 h. In calcium‐free water, the65Zn uptake curve is approximately asymptotic over a period of 24 h, while in hard water internal65Zn levels are dropping at 24 h. Over 5 h, however, fish in hard tapwater absorb about 3.5 times more65Zn than those in calcium‐free water. There is a positive linear relationship between log65Zn uptake and log wet weight of fish. Whole‐body concentration factors (c.f.) at 16 h reach a maximum of 12.2 (mean=2.9), highest concentrations of65Zn being found in the gills (mean c.f.=5.l) and lowest concentrations in the gonads (mean c.f.=0.8). Over longer periods (400 h), internal stable zinc levels offish exposed to 1 and 4 p.p.m. Zn2+remain little higher (max 28 %) than controls.65Zn efflux into zinc‐free water falls to zero after 5 h, more zinc (78 %) being lost after uptake in tapwater than in calcium‐free wat

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb04071.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The histology of the pectoral fin of the flounder,Platichthys flesus.(L.), is described and the presence of eosinophilic granule cells in the epidermis was noted. The histopathological effects of infection byL. pectoralisresult from the attachment and feeding activity of the parasite. Although the damage inflicted byL. pectoralisis usually confined to the epidermis the lesions caused by sessile life cycle stages, adult females and chalimus larvae, often extend into the dermis. In the dermis the inflammatory response comprised fibroplasia and cellular infiltration which resulted in the formation of a dense fibrous granulation tissue.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1977.tb04072.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY