Feeding and reproductive biology of Saurida undosquamis (Richardson, 1848) from Parangipettai coast, Southeast coast of India.
The feeding biology, spawning season, size at first maturity, sex ratio and fecundity of the commercially important lizardfish (Saurida undosquamis) were studied in Parangipettai waters of the southeast coast of India. Fishes formed the predominant food item. Diversity of the prey items showed maximum value (H'log 2-3.61 +/- 0.11) during the postmonsoon season and minimum during the monsoon season (2.89 +/- 0.17). The richness (1-lambda') also showed a similar trend and varied from 0.81 +/- 0.13 (monsoon) to 0.91 +/- 0.01 (postmonsoon). The size at first maturity (50% incidence of mature fish) was 195 mm. But when the size at first maturity was calculated by adjusting the proportion of maturity percentages, the maturity size was found to be 140 mm. This method is advantageous from the point of view of fisheries management as this species can be exploited above 140 mm rather than above 195 mm. The gastrosomatic index was found maximum during postmonsoon and minimum during the monsoon season showing the inverse relationship between feeding and spawning. This species was found to spawn from August to January with a peak in November. The fecundity ranged from 19, 856 in a fish measuring from 20.1 cm in length (97 g) to 79,282 in a fish of 29 cm (290 g). The overall sex ratio (1:1.19) was found to deviate significantly from the expected 1:1 ratio. (chi2 = 19.1, p < 0.005). Month- wise, it conformed to the expected 1:1 ratio during most of the months except January, June, September, November and December. Higher gonado-somatic index values observed during October-December suggested spawning activity during this period. This species is found to a total spawner in the Parangipettai waters.
Growth and mortality of brushtooth lizardfish, Saurida undosquamis, from Pakistani waters.
Growth and mortality parameters of brushtooth lizardfish Saurida undosquamis (Richardson, 1848) were investigated using the length frequency data from five research trawl surveys from Pakistani waters during 2009 - 2010. The analysis was based on FiSAT computer software package. The pooled data of S. undosquamis consist of n = 870 pair of length weight data and n = 3607 length frequency data of both sexes combined with maximum length and weight of 38 cm (FL) and 492 g respectively. The length-weight relationship parameters from pooled data were a = 0.008, b = 3.000 and R 2 = 0.965. The von Bertalanffy growth function parameters were L = 39.90 cm, K = 0.270 year-1 (using ELEFAN method) and age at zero length t0 = - 0.572. Based on those growth parameters, the total mortality rate was calculated using length-converted catch curve analysis as 1.15 year-1. The natural mortality (M) was 0.687 using Pauly's equation (the annual average sea surface temperature was 27°C) hence the fishing mortality (F) was estimated by F = Z - M = 0.463 year-1. The yield per recruitment analysis indicated when tc was assumed to be 2, Fmax was estimated at 1.1 and F10 at 1; when tc was assumed to be 1, Fmax was estimated at 0.85 and F10 at 0.7. Currently age at first capture is about 1 year and Fcurrent was 0.463, therefore Fcurrent was smaller than F10 and Fmax. This indicates that the current fishery is in a safe condition. Using Gulland (1971) biological reference point Fopt was equal 0.687. The current fishing mortality rate of 0.463 year -1 was lower than biological reference point.
Population and Settlement
Part 1 Population distribution: world population distribution variations in world population distribution population distribution in the Highlands and Islands population distribution in Japan population distribution in Brazil. Part 2 Population growth and movement: population structure the world population explosion variations in population growth migration why do people migrate types of migration in North and West Africa West German migration populating the USSR populating Australia attitudes to population control population and natural resources. Part 3 Settlements: location of settlement settlement types settlement functions settlement patterns South Wales valley settlements the changing village. Part 4 Urbanization: million cities world urbanization rural-urban migration in the developing world urban land use inner city problems urban transport the Tyneside metro spheres of influence changing shopping habits the Dutch Randstad Lagos - a city in the developing world new and expanding towns in the UK new settlements in developing countries green belts or red bricks? Part 5 Further studies: UK population migration Kenya's population problems Sheffield Washington New Town.