Biology of peron's threadfin bream, Nemipterus peronii (Valenciennes), from the north west shelf of Australia

1984 ◽  
Vol 35 (2) ◽  
pp. 167 ◽  
Author(s):  
KJ Sainsbury ◽  
AW Whitelaw
Keyword(s):  
Growth Curve ◽  
Sexual Maturity ◽  
Growth Parameters ◽  
Fork Length ◽  
Instantaneous Rate ◽  
Fish Size ◽  
North West ◽  
The North ◽  
Age Range ◽  
Annual Mortality

Samples of N. peronii collected at depths of less than about 100 m showed a slight positive correlation between fish size and depth, but no correlation between abundance and depth and no die1 change in catch rate. Feeding occurred during the day, with crustaceans (Brachyura, Natantia, Mysidacea and Stomatopoda in particular) occurring in 70% of feeding individuals and fish occurring in 17%. Individuals containing ripe eggs were found throughout the year, although the proportion of ripe fish was highest in November and December. Sexual maturity in 50% of females was attained at a fork length of about 15 cm and at an age of 1 year. Zonation on the otoliths was shown to be annual and estimates of the parameters of the von Bertalanfi growth curve were L∞ = 41.9 cm, K= 0.25, t0 = 0.74 years over the age range 0.5-5 years. The growth parameters for sexually differentiated animals differed significantly, but the age-length trajectory of each was very similar over the observed age range. The instantaneous rate of total annual mortality was 1.85 and did not differ between sexes.

Age and growth of the scalloped hammerhead shark, Sphyrna lewini, in the north-west Atlantic Ocean and Gulf of Mexico

2007 ◽  
Vol 58 (1) ◽  
pp. 34 ◽  
Author(s):  
Andrew N. Piercy ◽  
John K. Carlson ◽  
James A. Sulikowski ◽  
George H. Burgess
Keyword(s):  
Atlantic Ocean ◽  
Gulf Of Mexico ◽  
Growth Parameters ◽  
Fork Length ◽  
Age And Growth ◽  
North West ◽  
Scalloped Hammerhead ◽  
The North ◽  
The Usa ◽  
Cent Error

The scalloped hammerhead, Sphryna lewini (Griffith & Smith, 1834), is a globally exploited species of shark. In order to gain insight into the life history of this species in the USA waters, age and growth was examined from specimens (n = 307) captured from the north-west Atlantic Ocean and from the Gulf of Mexico. The von Bertalanffy growth model resulted in growth parameters of L∞ = 214.8 cm fork length (FL), k = 0.13 year–1, t0 = –1.62 year for males and L∞ = 233.1 cm FL, k = 0.09 year–1, t0 = –2.22 year for females. The oldest age estimates obtained for this population were 30.5 years for both males and females, which corresponded to FL of 234 cm and 241 cm respectively. Bowker’s test of symmetry and Index of Average Per Cent Error suggests that our ageing method represents a non-biased and precise approach to the age assessment. Marginal increments were significantly different between months (Kruskal–Wallis P = 0.017) with a distinct trend of increasing monthly increment growth beginning in January. When compared to previously published studies, our growth estimates suggest slower growth than populations in the Pacific Ocean but faster growth than previously reported in the Gulf of Mexico.

The Tasmanian Trout Fishery. II. The Fishery of the North-West Region

1958 ◽  
Vol 9 (1) ◽  
pp. 19 ◽  
Author(s):  
AG Nicholls
Keyword(s):  
Mortality Rate ◽  
Detailed Consideration ◽  
North West ◽  
Hatchery Fish ◽  
The North ◽  
West Region ◽  
Change In The Mean ◽  
The Mean ◽  
Trout Fishery ◽  
Annual Mortality

A brief account is given of the several rivers, and of the results derived from the study of the fishery in each. Anglers' returns of catches have been analysed with respect to the daily catch per angler for nine seasons, and the lengths of fish for five seasons, and the results are similar for each river. Detailed consideration of a summary of the data received from all sources in this region shows a definite downward trend in the daily catch which is statistically significant and more pronounced in the estuarine than in the inland fishery. There has been no change in the mean lengths of fish taken, and the size distribution of the catch has remained constant over five seasons. An 80 per cent. annual mortality rate has been found for fish from 1 to 6 years of age, after which it falls slightly. The total annual catch has risen with the increase in licensed anglers. Analysis of the diary of one angler over 27 years shows a decline in the catching rate, but the mean weight of fish has remained fairly constant. No direct consistent correlation was found between the estuarine trout fishery and the commercial whitebait fishery. It is concluded that the decline in catching rate is probably related to a change in the representation of anglers making returns during the nine seasons. A study of the contribution made by the release of hatchery fish shows a maximum possible return to anglers of 2 per cent., subject to a correction for the proportion of takable fish caught by anglers for which no data are available. Evidence is produced to show that the release of hatchery fish is unproductive and wasteful in a stream already stocked to capacity.

scholarly journals Tick-borne Relapsing Fever in Children in the North-west of Iran, Qazvin

2015 ◽  
Vol 116 (3) ◽  
pp. 193-202 ◽  
Author(s):  
Parviz Ayazi ◽  
Abolfazl Mahyar ◽  
Sonia Oveisi ◽  
Neda Esmailzadehha ◽  
Sadralnesa Nooroozi
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Febrile Illness ◽  
Control Measures ◽  
Relapsing Fever ◽  
Laboratory Findings ◽  
North West ◽  
The North ◽  
High Prevalence ◽  
Age Range

Relapsing fever is caused by theBorreliaspecies of spirochetes. Louse-borne epidemics of the disease may happen but the endemic disease is generally transmitted to humans by the bite of an infected tick (Ornithodorus). Clinical and laboratory findings of tick-borne relapsing fever in children in the north-west of Iran, Qazvin, were evaluated. This study was conducted from September 1992 to September 2012. Records from 53 cases of tick-borne relapsing fever (TBRF) were reviewed. In positive cases, febrile illness, and spirochetes were recognized in peripheral blood preparations. Of the 53 children younger than 12 years, fifty two percent were male and about one third (34%) of the patients were in the age range of 7–12 years. The disease is recorded through the whole year but its peak occurs during summer (52.8%) and autumn (32.1%). Sixty eight percent of patients were living in urban areas but had frequent travel to rural area. Thirty two percent of the cases were living in rural areas where their dwellings were close to animal shelters. All (100%) of the 53 subjects were febrile. Travellers to the rural areas with high prevalence of the disease should be attentive of the risk of tick-borne relapsing fever and use suitable control measures. Consequently relapsing fever should be considered when patients who live in or have vacationed in north-west of Iran show a recurring febrile illness.

Body size at sexual maturity in the eteline snappers Etelis carbunculus and Pristipomoides sieboldii: subregional comparisons between the main and north-western Hawaiian Islands

2017 ◽  
Vol 68 (6) ◽  
pp. 1178 ◽  
Author(s):  
Edward E. DeMartini
Keyword(s):  
Life Histories ◽  
Sexual Maturity ◽  
Hawaiian Islands ◽  
Fork Length ◽  
Geographic Variations ◽  
The North ◽  
General Importance ◽  
Body Sizes ◽  
History Of ◽  
North Western

New estimates of median body length at sexual maturity (L50) are presented for females of ehu (Etelis carbunculus) and kalekale (Pristipomoides sieboldii) in the main Hawaiian Islands (MHI); these are compared with published estimates for females of each species in the north-western Hawaiian Islands (NWHI). This case study illustrates the general importance of identifying regional and subregional variations in species’ life histories when estimating parameters for input to stock assessments. L50 values differed somewhat between the two species, but greatly between the MHI and NWHI for each species. Size-standardised ovary weights were greater in the NWHI v. MHI for all-sized fish of both species and nominally greater at larger body sizes among the mature females of both species in the MHI compared with the NWHI. L50 was smaller in the MHI compared with NWHI for females of both species. The mean (±s.e.m.) L50 for female ehu was 23.4±0.3- v. 27.2±1.0-cm fork length (FL) in the MHI v. NWHI respectively. For female kalekale, the respective estimates were 23.8±0.3 and 28.6±0.7cm FL. Possible determinants of these subregional geographic variations in L50, including latitude, productivity and history of extraction by Hawaiian bottomfish fisheries, are discussed.

scholarly journals Interannual dynamics of size, age composition and parameters of growth for japanese sardine Sardinops melanostictus in periods of its high abundance in the North-West Pacific

2021 ◽  
Vol 201 (3) ◽  
pp. 561-576
Author(s):  
V. A. Dudarev ◽  
A. I. Galeev
Keyword(s):  
Growth Parameters ◽  
Japan Sea ◽  
Size Composition ◽  
Reproduction Rate ◽  
Japanese Sardine ◽  
West Pacific ◽  
North West ◽  
The North ◽  
Sardine Population ◽  
Interannual Dynamics

Interannual dynamics of size composition, age structure, and growth parameters are considered for japanese sardine Sardinops melanostictus in context of its recent and previous blooms and mass migrations to the Pacific waters at Kuril Islands and to the northern Japan Sea. Before the post-bloom catastrophic decline in the 1990s, in conditions of the highest density of the sardine population, small-sized fish with relatively slow growth rate became dominant, distinguished by lowered reproductive potential because of low population fecundity and reproduction rate. In the new, modern bloom of sardine population, two modal groups are observed in the year-classes size composition, in particular in the Japan Sea, with different exterior and biological parameters. There is assumed that they correspond with two morphological types, which alter each other at different stages of the demographic cycle, that determines total abundance of sardine population in the North-West Pacific and its long-term dynamics.

Estimating Growth Parameters for Pacific Halibut from Mark–Recapture Data

1981 ◽  
Vol 38 (4) ◽  
pp. 394-398 ◽  
Author(s):  
Donald A. McCaughran
Keyword(s):  
Growth Curve ◽  
Growth Parameters ◽  
Fork Length ◽  
Minimum Variance ◽  
Population Parameters ◽  
Pacific Halibut ◽  
Unbiased Estimates ◽  
The Mean ◽  
The Individual ◽  
Growth Estimation

The parameters in the model L(t) = αtβ were estimated for each fish from mark and recapture lengths. The individual estimates of the parameters were combined to give minimum variance unbiased estimates for the population parameters lnα and β. The age-specific lengths of halibut were found to fit a lognormal distribution; hence, the model was fitted to the median of the lengths instead of the mean. The median of the estimator [Formula: see text] is equal to the population median fork length at time t. In this sense the estimator is "median unbiased." As an example of the method, a growth curve is fitted to a group of halibut born between 1961 and 1965 and recaptured in the Yakutat region.Key words: Pacific halibut, growth, estimation

SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

1990 ◽  
Vol 48 (3) ◽  
pp. 58-59
Author(s):  
Daryl A. Cornish ◽  
George L. Smit
Keyword(s):  
Morphological Characteristics ◽  
Oreochromis Mossambicus ◽  
Breeding Cycle ◽  
Limited Information ◽  
North West ◽  
The North ◽  
Sem And Tem ◽  
Sperm Development ◽  
Ultrastructural Characteristics ◽  
The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

The North West Passage

2014 ◽  
Author(s):  
Roald Amundsen ◽  
Godfred Hansen
Keyword(s):  
North West ◽  
The North
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