Life history and population dynamics of the finetooth shark (Carcharhinus isodon) in the northeastern Gulf of Mexico

The life history and population dynamics of the finetooth shark (Carcharhinus isodon) in the north-eastern Gulf of Mexico were studied by determining age, growth, size-at-maturity, natural mortality, productivity, and elasticity of vital rates of the population. The von Bertalanffy growth model was estimated as Lt=1559 mm TL (1–e–0.24 (t+2.07)) for females and Lt = 1337 mm TL (1–e–0.41 (t+1.39)) for males. For comparison, the Fabens growth equation was also fitted separately to observed size-at-age data, and the fits to the data were found to be similar. The oldest aged specimens were 8.0 and 8.1 yr, and theoretical longevity estimates were 14.4 and 8.5 yr for females and males, respectively. Median length at maturity was 1187 and 1230 mm TL, equivalent to 3.9 and 4.3 yr for males and females, respectively. Two scenarios, based on the results of the two equations used to describe growth, were considered for population modeling and the results were similar. Annual rates of survivorship estimated through five methods ranged from 0.850/yr to 0.607/yr for scenario 1 and from 0.840/yr to 0.590/yr for scenario 2. Productivities were 0.041/yr for scenario 1 and 0.038/yr for scenario 2 when the population level that produces maximum sustain-able yield is assumed to occur at an instantaneous total mortality rate (Z) equaling 1.5 M, and were 0.071/yr and 0.067/yr, when Z=2 M for scenario 1 and 2, respectively. Mean generation time was 6.96 yr and 6.34 yr for scenarios 1 and 2, respectively. Elasticities calculated through simulation of Leslie matrices averaged 12.6% (12.1% for scenario 2) for fertility, 47.7% (46.2% for scenario 2) for juvenile survival, and 39.7% (41.6% for scenario 2) for adult survival. In all, the finetooth shark exhibits life-history and population characteristics intermediate to those of sharks in the small coastal complex and those from some large coastal species, such as the blacktip shark (Carcharhinus limbatus).

Chronic and catastrophic influences of the environment on the population dynamics of the common fishes [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Seasonal, interannual, decadal and centennial influences on population dynamics have been described for several species. It now seems possible to interpret environmental changes that initiate population change ...

Morphometry and population dynamics of Sepia aculeata, (Orbigny - 1848) along the Bombay coast

Cephalopods gained importance in the fishing industry when they emerged as one of the leading sea food products exclusively for international market in the mid seventies. Cephalopods fishery in India is still in an infant stage with vast scope for exploitation. The present work on the cephalopods fishery along the Bombay coast is an effort to quantify the resource potential of Sepia acculeata. The morphometry, growth parameters, mortality (total, natural and fishing) rates, the yield per recruit and standing stock were studied.

Population dynamics and stock assessment of Koth (Otolithoides biauritus Cantor, 1850) along the north-west coast of India

MSY, growth, selection and mortality parameters of Otolithoides biauritus have been worked out from data collected by MFV Saraswati of CIFE, and length frequency data from Ferry Wharf, Sasson dock, and Versova fish landing centres of Bombay. Values of L infinity, K, and t omicron obtained from length frequency study are 1572 mm, 0.2633/yr and 0.0289 yr respectively, and of weight growth parameters are W infinity = 10067 g, K = 0.03904/yr and t omicron = 0.0137 yr. Selection parameters are L + 150 mm, t sub(r) + 0.4167 yr lc + 240 mm and t omicron = 0.6367 yr. Selection factor (K) for codent worked out to be 12. Based on Z = 0.6486, the MSY of O. biauritus off northwest coast of India is assessed as 1,802 tons which is slightly higher than the current catch level of 1,634 tons.

Population dynamics and stock assessment of the spider prawn, Nematopalaemon tenuipes Henderson along the Maharashtra coast

Nematopalaemon tenuipes is an important component of non-penaeid prawn resources of the northwest coast of India. During 1979-82 period, it contributed 29.9% to the non-penaeid prawn and 5.6% to the total fish landings of Maharashtra. The von Bertalanffy growth parameter L∞, K and t(sub)0 were 77.38 mm, 1.31 and -0.02 year for the males while for the females these parameters were respectively 87.23 mm, 1.30 and -0.01 year. The natural mortality coefficient (M) was 3.54 and 3.52 and the average total mortality coefficient (Z) during the period was 9.09 and 7.79 for the males and females respectively. With the exploitation rates of 0.61 and 0.55 for the males and females during the period, the total stock of the species was 26,270 tonnes and the standing stock was 3,418 tonnes. The maximum sustainable yield (MSY) of the species under the prevailing fishing conditions was 15,744 tonnes which is close to the average yield of 14,726 tonnes from the nets. Hence further increase in effort is not suggested.

Population dynamics of penaeid prawn Penaeus merguiensis off Mumbai coast

Stock dynamics of Penaeus merguiensis was studied using length composition data collected separately for males and females during the period 1995-1998, at New Ferry Warf landing, centre in Greater Mumbai. Food and feeding, sex ratio, fecundity and length-weight relationships were worked out on a representative sub-sample. Asymptotic length (Loo) and growth coefficient (K) were estimated to be 220 mm and 1.80 per annum respectively for males. These parameters were respectively 281 mm and 1. 72 per annum in the case of females. The instantaneous rate of total mortality coefficient (Z) was found to be 9.79 and 7.44 per annum for males and females respectively. The annual natural mortality coefficient (M) was estimated to be 2.80 for males and 2.60 for females. As the exploitation ratio exceeded 0.5 in the case of both the males and females, the study suggests the necessity for reduction in fishing pressure in order to achieve Maximum Sustainable Yield (MSY).

Population dynamics of Penaeus indicus at Sofala Bank, Mozambique: a preliminary study

Length-based methods are used to estimate growth and mortalities of Penaeus indicus at Sofala Bank in Mozambique. This Penaeid shrimp is one of the most important species in the fishery as it constitutes 45% of the catches and has a great influence in their trend. First estimates of growth parameters for this species in Mozambique are presented and a comparison of the derived mortalities with the previous estimates is made.

Preliminary investigations on the population dynamics of Otolithes ruber (Sciaenidae) on Sofala Bank, Mozambique

Catch length-frequency data of Otolithes ruber (Schneider, 1801) obtained from the "Projecto de Pesca Experimental da RDA" on Sofala Bank, Mozambique, in 1987 were used to estimate growth parameters, mortalities and exploitation rates. The yield-and biomass-per-recruit analyses based thereon suggest that the stock is overfished.

Population dynamics of two jewfishes Jhonius argentatus and Johnieops vogleri) in the coastal waters of Bay of Bengal, Bangladesh

Population parameters of Jhonius argentatus and Johnieops vogleri in coastal waters of Bay of Bengal, Bangladesh were estimated by using FiSAT programme. The von Bertalanffy growth parameters, extreme length (cm) and growth constant K (year ·1) were found to be 46.50 and 0.59 for J. argentatus, and 33.50 and 0.85 for J.vogleri The Loc(cm) and Z/K estimates provided by Wetherall plot were 46.694 and 1.791 for J. argentatus, and 31.25 and 2.623 for J. vogleri. The annual rate of natural (M) and fishing mortality (F) were estimated as 1.12 and 0.78 for J. argentatus, and 1.56 and 1.28 for J. vogleri. Rate of exploitation (E) was estimated as 0.41 for J. argentatus and 0.45 for J. vogleri. About 80.04% of J. argentatus were found to be recruited during peak pulses (April-May) and 19.96% during lean pulses (October-November) and 85.75% J. vogleri during peak pulses (May-July) and 14.25% during lean pulses (September-October). The growth performance index(') was 3.11 for J. argentatus and 1.93 for J. vogleri. The total length and body weight relationship was found to be W = 0.0403 TL25723 for J. argentatus and W = 0.0907 TV3482 for J. vogleri.

Population dynamics of killifish Aphanius dispar (Ruppel) in Sandspit area off Karachi

Growth and mortality parameters of Aphanius dispar a cyprinoides generally observed in the catches of near shore area were estimated from the length frequency data collected from Sandspit area of Karachi, using LFSA. The von Bertalanffy growth parameters were estimated as Loo=71.73 mm & K=L35/yr for Male Aphanius dispar and Loo=70.66 & K=l.41 for female. Total Mortality coefficient (Z) was estimated using Length converted catch curve which is equal to 2.12/yr, for male and for female 2.19/yr. Natural mortality (M) was estimated by Pauly's empirical formula: M=l.64/yr (male) and 1.70/yr (female). The species also displayed two cohorts a year.

Population dynamics of a cladoceran zooplankter, Daphnia magna, in two poultry-cum-fish (duck-fish and chicken-fish) integrated ponds

The population dynamics of Daphnia magna was studied in two integrated fish-cum-poultry ponds (duck-fish and chicken-fish). The seasonal changes in the population of D. magna were recorded. Peak population of the zooplankter was recorded in the month of January in both ponds. The birth rate (b), growth rate (r) and death rate {d) of D. magna were studied in field as well as in the laboratory. Three temperatures and three different food concentrations were selected for laboratory study. The maximum values of (b) and (r) were recorded during December-January in field. Under laboratory conditions, highest birth and death rate occurred at lowest temperature (15 °C). Both food and temperature were found to affect the population dynamics of the species; longest life span and maximum population were recorded at lowest temperature and maximum food concentration.

Cadmium leachability and microbial population dynamics in a stabilized and bioaugmented model contaminated soil

This article presents a laboratory study on the consequences of the application of combined soil stabilization and bioaugmentation in the remediation of a model contaminated soil. Stabilization and bioaugmentation are two techniques commonly applied independently for the remediation of heavy metal and organic contamination respectively. However, for a cocktail of contaminants combined treatments are currently being considered. The model soil was contaminated with a cocktail of organics and heavy metals based on the soil and contaminant conditions in a real contaminated site. The soil stabilization treatment was applied using either zeolite or green waste compost as additives and a commercially available hydrocarbon degrading microbial consortium was used for the bioaugmentation treatment. The effects of stabilization with or without bioaugmentation on the leachability of cadmium and copper was observed using an EU batch leaching test procedure and a flow-through column leaching test, both using deionized water at a pH of 5.6. In addition, the population of hydrocarbon degrading microorganisms was monitored using a modified plate count procedure in cases where bioaugmentation was applied. It was found that while the stabilization treatment reduced the metal leachability by up to 60%, the bioaugmentation treatment increased it by up to 100% Microbial survival was also higher in the stabilized soil samples.

Biological characteristics and determination of population dynamics parameters of Nemipterus japonicus in the coastal waters of Province Bushehr, Persian Gulf

This study was conducted to determine biological characteristics and population dynamics parameters of threadfin bream (Nemipterus japonicus) in Persian Gulf (Bushehr Province), during November 2006 and October 2007. The minimum and maximum specimens were 75-273 mm FL and their weight was 7.6 - 351.9 g. Based on the exponential relationship between fork length and weight, slope (b) for individuals, males and females was 2.987321, 2.992546 and 3.007314, respectively. The emptiness value (V) was 45.6% and it shows that N. japonicus is a moderate feeder. The results of Fp indicates that crustacean with 78.2% are main foods, mollusca (27.7%), fishes (20.7%), polychaeta (19.2%) and Foraminifera (11.7%) were identified as minor foods and phytoplanktons (9.9%), nematoda(8.0%), echinodermata (2.3%) and sea weeds (0.3%) were random foods. The reproduction studies showed the spawning season extended within 2 peaks, from April- May and September and main spawning occurs in spring season.The mean absolute and relative fecundities were 472388±42633 and 3817±293 (X±SE), respectively. The maximum, minimum and mean of oocyte diameter were 0.448, 0.022 and 0.221mm (SE=0.071), respectively.The fork length at 50% maturity estimated to be 20.25 cm for females. The growth coefficient (K) , length infinity (L∞ ) and ɸ' was estimated 0.42/yr , 34.17 cm and 2.69, respectively. The coefficient of total mortality, fishing mortality, natural mortality and E was 1.37, 0.43, 0.94 and 0.31, respectively.

Population dynamics and stock assessment of the common carp (Cyprinus carpio) in Iranian waters of the Caspian Sea

In order to come up with the responsible fishing pattern of common carp, there was a need to identify some of the biological characteristics and stock assessment of carp in Iranian waters of the Caspian Sea .The fork length ,weight ,age ,growth parameters of von bertalanffy and mortality rates of common carp were estimated from oct 2006 to sept 2007.Based on the exponential relationship between length and weight in the size range 6.3-65.6 cm ,b was calculated 2.895, 2.843 and 2.925 respectively for combined sexes ,males and females. The mean condition factor was 1.9 which is close to the ideal condition.The results from measuring 3170 specimens ,were showed the first fork length of maturity was 30 cm for males and 32 cm for females. The results indicated that females were predominate and sex ratio was 0.66:1 (M:F) and chi-squares analysis showeda significant difference between males and females.(p<0.05).Length infinity and growth coefficient were calculated by three different methods as below: Length frequency analysis : k=0.17 L∞ =68.04 Age-Length Key k=0.15 L∞ =74.25 Back calculation : k=0.14 L∞ =68.4 The mortality parameters and exploitation rate were estimated as below : Z=0.73 per year M=0.31 per year F=0.42 per year E=0.56 Refer to amount of common carp catch in 2007 -08 ,biomass was calculated 9640.2 tones by jone's cohort analysis and MSY 2374.5 tones.According to analysis ,the number of common carp in the distribution area (Iranian part of the Caspian Sea ) was estimated 24 millions in the 2006-07.

Kilka population dynamics in the south of the Caspian Sea

Populations of kilka in the Caspian Sea have important role in the food chain. This study was conducted to determine population parameters of three species of kilka in the south of the Caspian Sea, during 2006-2007. Mean length was 102.4±9.7 mm for common kilka, 117.8±6.9 mm for anchovy and 119.5±10.9 mm for bigeye. The relationship between length and weight indicated the negative allometric growth in the all three species. Mean age for common kilka, anchovy and bigeye were 3.6, 4.6 and 4.6 years, respectively. Sex ratio (M:F) were 0.52:1 for anchovy, 0.60:1 for common kilka and 1.60:1 for bigeye. The value of growth coefficient (K) was the highest (0.321) for the common kilka, (0.267) for the bigeye, and the lowest for the anchovy kilka (0.245). Total mortality estimated from the descending of the catch curve using the age structure, Z=1.280 yr-1 for common kilka, Z=1.067 yr-1 for anchovy, and Z=1.015 yr-1 for bigeye. Natural mortality (M) were estimated using Pauly formula as M=0.622, M=0.537 and M=0.503 per year for common kilka, bigeye and anchovy, respectively. Value of fishing mortality (F) were estimated from Z and M, as F=0.658 for common kilka, F=0.564 for anchovy and F=0.478 for bigeye. The exploitation rate (E) were estimated E=0.514 for common kilka, E=0.528 for anchovy and E= 0.471 for bigeye. The estimate of MCY (Maximum Constant Yield) was calculated using the more reliable time series of commercial catch data from 2001-2007, which resulted in an estimate of MCY for the kilka fishery of 14100 tonnes.