Length frequency and growth studies on Cynoglossus macrolepidotus (Bleeker) off Bombay coast

Specimens randomly collected from Sassoon Docks, Bombay, India, at monthly intervals during 1979 to 1981 were considered for age/growth studies. Cynoglossus macrolepidotus, the fish, attained a length of 202 mm at 1 year, 250 mm at 1 1/2 year and 272 mm at 21 months respectively; the maximum length of the fish could be 353 mm and the life span could be 7 years. The scale ring studies showed presence of only 0 to 3+ rings. Majority of the fishes were of 1 and 1+ year class.

Wadge Bank trawl fishery studies. Pt. 4. An analysis of the length frequency measurements of the sea bream (Lethrinus nebulosus) made in 1949 and 1953 to 1958

Length frequency distributions of the sea bream collected during the period 1953 to 1958 have been analysed. The increase in average sizes of the sea bream with depth suggests a movement to deeper waters with increase in size. By numbers, the sea bream is more abundant between 21 and 30 fathoms than in deeper areas. The recruitment was continuous and regular. There is no sign of entry or progression of a dominant brood throughout the period under study. Length frequency distribution shows three distinct modes. The first mode occurs regularly but does not progress beyond 40cm, recruitment being balanced by natural and fishing mortality. The other two which are not regular are probably the result of fishing outside regular areas. Short sections of “growth” lines which fit into one another when extrapolated, are evident. The larger lines obtained by extrapolation are parallel to one another. These tentative "growth lines" indicate that this species which enters the fishing grounds, when 15 cm or larger in length are exploited by the trawl fishery for a period of three to four years. This species appears to be six months old when it enters the fishing grounds and increases in length by about 37.5 cm in the next 30 months. Later growth slows down. The average size of the specimens sampled continued to get smaller from 1953 till 1957. It is shown that this reduction in size is due to increased fishing effort.

Effect of feeding frequency on the growth of common carp (Cyprinus carpio L.) fry

A laboratory-feeding trail was conducted for 45 days with fry of common carp Cyprinus carpio L. (0.45±0.03g) in aquaria in a static indoor fish rearing system. The fry were fed on a pelleted diet containing 33% crude protein having fishmeal as major protein source. The fish fry in five treatments A, B, C, D, and E, each with two replicates were fed on 5% daily ration divided into different feeding frequencies of 2, 3, 4, 5 and 6 times a day respectively in order to observe the growth performance. Each replicate contained 15 fry having total initial weight of 6.87±0.31g. At the end of the feeding trial, significantly different and higher (p<0.05) growth response was observed in treatment C having a feeding frequencies of 4 times a day. Significantly the highest and the lowest percent growth of 334.30 and 218.91% were observed in fish fed on the diet (Treatment C) with 4 times and (Treatment A) 2 times feeding frequencies per day, respectively. Food conversion ratio (FCR) of 1.78 was significantly higher (p

Size frequency distribution and carapace length-total length relationship of Acetes chinensis in the Kutubdia channel of Bangladesh coast

The seasonal mean size distribution of A. chinensis were estimated as 29.229mm ±4.77, 25.125mm ±2.55, 25.165mm ±2.29 and 32.44mm ±3.63 for annual, monsoon, postmonsoon and pre-monsoon period, respectively. Seasonal mean carapace length distribution were estimated as 9.37mm ±1.457, 8.063mm ±0.63,8.258mm ±0.59 and 10.37mm ±l.ll3 for annual, monsoon, post-monsoon and the pre-monsoon season. The carapace length and total length relationships was found to be TL= - 1.39±3.23 CL. Linear relation was found in arithmetic and as well as logarithmic scale.

Effect of sublethal concentration of artificial seawater on oxygen uptake and opercular frequency in an Indian major carp, Labeo rohita (Ham.)

The present study reports the effect of artificial seawater on oxygen uptake and opercular frequency in an Indian major carp, Labeo rohita. Whereas a control fish of 7.34 g average body weight consumed 1.538 ml O sub(2.) hˉ¹, the 24h and 96h exposed fish of the same body weight consumed 1.07 4 and 0.897 ml O sub(2.) hˉ¹, respectively. The oxygen uptake per unit body weight under controlled condition was 0.219 ml. gˉ¹. hˉ¹, whereas in 24h and 96h exposed fish, it was 0.152 and 0.124 ml. gˉ¹, hˉ¹, respectively. The change in opercular movement in 24h exposed fish was 7.67% higher, whereas in 96h exposed fish, it was 22.43% higher as compared to the control one. All changes are highly significant (p<0.001).

Effect of varying crude protein levels on spawning frequency and growth of Sarotherodon niloticus breeders

Four-month-old S. niloticus breeders were fed with dry pellets containing 20-50% crude protein and the frequency of spawning involving removal of egg from the mouthbrooding females and growth were determined. When the diets contain high quality proteins from fish meal and soybean oil meal and the amounts of daily food allowance are at satiation level, the influence of increasing dietary crude protein on spawning frequency involving egg removal from the brooder and growth may not be significant.

Relationship between El Nino and summer monsoon rainfall over Pakistan

The present paper deals with the influence of El Nino event on the summer monsoon rainfall over Pakistan. The correlation between monthly rainfall of summer monsoon season and bi-Monthly Multivariate ENSO Index (MEI) has been calculated to see the influence of El Nino on the summer monsoon rainfall. MEI is bimonthly ENSO Index pertaining to the period from first week of previous month to first week of the month under consideration. While study the correlation's with the ENSO events out side the Pacific Ocean MEI is more appropriate than other indices like Southern Oscillation Index (SOI) as MEI integrates complete information on ENSO viz. six oceanic and meteorological variables over the tropical Pacific. The results of the study show that there is a tendency of reduction in summer monsoon rainfall over Pakistan during El Nino years. The deficiency in % rainfall is statistically significant up to 90% level during July and September months. It is interesting to note that Pakistan receives more than normal rainfall during summer monsoon season in the immediate following year after the El Nino event. The correlation analysis is also performed on the summer monsoon months for individual provinces of Pakistan. All provinces receive deficient rainfall during monsoon months. The deficiency in rainfall over Punjab during all monsoon months is significant, whereas the deficiency in rainfall is significant during July and August over NWFP and Sindh respectively. No significant impact of El Nino on the summer monsoon rainfall over Baluchistan is observed.

Reproductive physiology of ribbon fish (Trichiurus lepturus)

The ribbon fishes ‘of the family Trichiuridac are represented as one of the most important food resources in Indian ocean. High density of the dominant species of ribbon fish (Trichiurus lepturus) in Oman sea and the 'Tillable catch in last yeas (more than 7000 tones per year) makes a trust area for studing their population biolog and stock assessment. As our knowledge on reproductive biology of this species has an important role on their fisheries management, as well as conservation of this stock from decline or over fishing, this research was held to determine some aspects of reproductive physiology of ribbon fish and the effects of environmental factors in gonadal cycle. The goals of the present thesis is to determine some aspects of reproductive physiology such as gonadosomatic index (GSI) , hepatosomatic index (HSI), condition factor (Ko, fecundity, sex ratio, size at first maturity, size at maturity (LM5O) and their relative hormonal & biochemical fluctuations. In this regards annual variation of sex hormones ic. estradiol 17-B, progestron, cortisol, testostrone and gonadotropins FSH (GTH-I) , LH (GTH-ll)I were measured ; gonadal histological studies were done by light & electron micrography. The research was carried out from April 1995 to January 19% in Ras Nleidani in the north part of Oman sea, and the environmental factors such as temperature, salinity, oxygen, rainfall and pH were measured. The effects of these parameters on reproductive cycle and hormonal fluctuationswere discussed by using correlation and principle component analysis (PCA). Female Ribbon fish reproductive strategy shows the same paterns of nonguarder marine teleosts. T. lepturus has more than one spawning season (existance of egges in different size in each month) and therfore it must have asynchronous ovaries and belong to continious spawners. GSI and HSI are good evidences for this type of reproductive patern. The testis of the lobular type , which is typical of most teleosts , is composed of numerous lobules which are separated from each other by a thin layer of fibrous connective tissue. GSI fluctuations revealed prolong- spawning time in males. There is significant increase in 17-13 estradiol. progestrone , cortisol and gonadotropins with maturity and prespawning period of female T lepturus. Plasma concentration of E2 and GTH II incresaed along with water temperature increasing (3300).. Spawning was observed from Nov. 1995 to Apr. 1996 in this species. Progestrone increased significantly with increasing rainfall in this season (P<0.01). Plasma cortisol levels increased with maturation and vitelpgenesis and also with the peak of spawning. From lenght-weight frequency and size distribution in each age groups and also minimum size at first maturity (52a cm) it would he concluded that T. lepturus must be matured at 2 years of age. Serum cholestrol and triglicerides significantly increased when maturation occured in this species. The relationship between alkaline phosphatase activity and hormonal fluctuations with maturity and vitelogenesis were discussed. Proximate compostion (muscle) shows significant variation with spawning period and maturity. Absolute individual fecundity (17420-159150) increased with body length and weight. Ultrastructural observations show dramatic variation in cell membrane (0ocyte membrane), yolk vesicles and, nucleolus dispersal in relation to maturity stages. fluctuations of gonadal hormones were discused in relation with vitelogenesis. Testosterone increased in males from Nov: to Mar. due to environmental impacts and spawning time. Sex ratio in different depth (10-40 m ,80-110 m) shows significnt differences in this ratio for two depths. In 10-40 m depth female shows dominant abundance to male in each months that may be due to their reproductive migration behaviour. The effects of temperature photoperiod and rainfall to maturity and spawning were discussed. According to -pawning period of T. leptunts in our sampling area it could be suggested that ribbon fish fi,theries must be restricted in the peak of spawning seasons (Feb. to Mar.) and in the spawning grounds (under 40 m depths). Other suggestions for population conservation have been mentioned.

Marine Vertebrates and Low Frequency Sound: Technical Report for LFA EIS

Over the past 50 years, economic and technological developments have dramatically increased the human contribution to ambient noise in the ocean. The dominant frequencies of most human-made noise in the ocean is in the low-frequency range (defined as sound energy below 1000Hz), and low-frequency sound (LFS) may travel great distances in the ocean due to the unique propagation characteristics of the deep ocean (Munk et al. 1989). For example, in the Northern Hemisphere oceans low-frequency ambient noise levels have increased by as much as 10 dB during the period from 1950 to 1975 (Urick 1986; review by NRC 1994). Shipping is the overwhelmingly dominant source of low-frequency manmade noise in the ocean, but other sources of manmade LFS including sounds from oil and gas industrial development and production activities (seismic exploration, construction work, drilling, production platforms), and scientific research (e.g., acoustic tomography and thermography, underwater communication). The SURTASS LFA system is an additional source of human-produced LFS in the ocean, contributing sound energy in the 100-500 Hz band. When considering a document that addresses the potential effects of a low-frequency sound source on the marine environment, it is important to focus upon those species that are the most likely to be affected. Important criteria are: 1) the physics of sound as it relates to biological organisms; 2) the nature of the exposure (i.e. duration, frequency, and intensity); and 3) the geographic region in which the sound source will be operated (which, when considered with the distribution of the organisms will determine which species will be exposed). The goal in this section of the LFA/EIS is to examine the status, distribution, abundance, reproduction, foraging behavior, vocal behavior, and known impacts of human activity of those species may be impacted by LFA operations. To focus our efforts, we have examined species that may be physically affected and are found in the region where the LFA source will be operated. The large-scale geographic location of species in relation to the sound source can be determined from the distribution of each species. However, the physical ability for the organism to be impacted depends upon the nature of the sound source (i.e. explosive, impulsive, or non-impulsive); and the acoustic properties of the medium (i.e. seawater) and the organism. Non-impulsive sound is comprised of the movement of particles in a medium. Motion is imparted by a vibrating object (diaphragm of a speaker, vocal chords, etc.). Due to the proximity of the particles in the medium, this motion is transmitted from particle to particle in waves away from the sound source. Because the particle motion is along the same axis as the propagating wave, the waves are longitudinal. Particles move away from then back towards the vibrating source, creating areas of compression (high pressure) and areas of rarefaction (low pressure). As the motion is transferred from one particle to the next, the sound propagates away from the sound source. Wavelength is the distance from one pressure peak to the next. Frequency is the number of waves passing per unit time (Hz). Sound velocity (not to be confused with particle velocity) is the impedance is loosely equivalent to the resistance of a medium to the passage of sound waves (technically it is the ratio of acoustic pressure to particle velocity). A high impedance means that acoustic particle velocity is small for a given pressure (low impedance the opposite). When a sound strikes a boundary between media of different impedances, both reflection and refraction, and a transfer of energy can occur. The intensity of the reflection is a function of the intensity of the sound wave and the impedances of the two media. Two key factors in determining the potential for damage due to a sound source are the intensity of the sound wave and the impedance difference between the two media (impedance mis-match). The bodies of the vast majority of organisms in the ocean (particularly phytoplankton and zooplankton) have similar sound impedence values to that of seawater. As a result, the potential for sound damage is low; organisms are effectively transparent to the sound – it passes through them without transferring damage-causing energy. Due to the considerations above, we have undertaken a detailed analysis of species which met the following criteria: 1) Is the species capable of being physically affected by LFS? Are acoustic impedence mis-matches large enough to enable LFS to have a physical affect or allow the species to sense LFS? 2) Does the proposed SURTASS LFA geographical sphere of acoustic influence overlap the distribution of the species? Species that did not meet the above criteria were excluded from consideration. For example, phytoplankton and zooplankton species lack acoustic impedance mis-matches at low frequencies to expect them to be physically affected SURTASS LFA. Vertebrates are the organisms that fit these criteria and we have accordingly focused our analysis of the affected environment on these vertebrate groups in the world’s oceans: fishes, reptiles, seabirds, pinnipeds, cetaceans, pinnipeds, mustelids, sirenians (Table 1).