Aspects of the population dynamics of the western rock lobster, Panulirus cygnus George. II. Seasonal changes in the catchability coefficient

1974 ◽  
Vol 25 (2) ◽  
pp. 249 ◽  
Author(s):  
GR Morgan
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Water Temperature ◽  
Linear Combination ◽  
Seasonal Changes ◽  
Stock Assessment ◽  
Water Salinity ◽  
Rock Lobster ◽  
Highly Correlated ◽  
Panulirus Cygnus

The catchability coefficient, q, of a population of the western rock lobster P. cygnus was calculated monthly from November 1969 to January 1973 using measurements of catch, effort, population density, and area of reef. The catchability coefficient varied significantly during this time and was positively correlated with water temperature and water salinity, and negatively correlated with the percentage of rock lobsters in a premoult condition. A linear combination of these three factors was highly correlated with the catchability coefficient (P < 0.001) and appears to offer a method of adjusting the catchability coefficient and so leading to an improved stock assessment for this species.

Aspects of the population dynamics of the western rock lobster, Panulirus cygnus George. I. Estimation of population density

1974 ◽  
Vol 25 (2) ◽  
pp. 235 ◽  
Author(s):  
GR Morgan
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Population Size ◽  
Equal Probability ◽  
Rock Lobster ◽  
Single Population ◽  
Baited Traps ◽  
Unbiased Estimates ◽  
Panulirus Cygnus ◽  
Probability Of Capture

Breakdowns in the assumptions made by the Jolly (1965) method of estimating population size were detected in mark-recapture experiments with the western rock lobster. Using information gathered from sampling by both baited traps and by diving it was shown that, in particular, the assumptions of (1) a single population and (2) equal probability of capture of marked and unmarked rock lobsters, were not valid at all times in the 'population' studied, and this resulted in underestimates of population density. However, it was found possible to make suitable corrections to the raw data to arrive at apparently unbiased estimates of population density. In the cases studied, the calculated unbiased estimates of population density agreed well with unbiased estimates calculated from information gathered by marking and recapturing by different methods. Single census and the De Lury (1958) methods also grossly underestimated population density.

Environmental effects on recruitment of the western rock lobster, Panulirus cygnus

2001 ◽  
Vol 52 (8) ◽  
pp. 1167 ◽  
Author(s):  
Nick Caputi ◽  
Chris Chubb ◽  
Alan Pearce
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Larval Survival ◽  
Current Strength ◽  
Sea Surface ◽  
Rock Lobster ◽  
Leeuwin Current ◽  
Westerly Winds ◽  
Highly Correlated ◽  
Panulirus Cygnus

The Leeuwin Current, which brings warm, nutrient-poor waters southward along the edge of the West Australian continental shelf, is positively correlated with western rock lobster (Panulirus cygnus) puerulus settlement along the coast. Westerly winds, also positively correlated with puerulus settlement, probably assist the transport of larvae to the coast during settlement. We examined relationships between (a) monthly sea-surface temperature where phyllosoma larvae occur – and annual levels of puerulus settlement at locations throughout the fishery and (b) monthly variation in Leeuwin Current strength (and westerly winds) and annual puerulus settlement later in the year (August–January). The Leeuwin Current, when it begins to strengthen during February–April, was highly correlated with puerulus settlement; sea-surface temperature during this period may have strongly influenced puerulus settlement at many locations. Its influence on puerulus settlement may have been due to improved larval survival and growth caused by higher water temperatures associated with a stronger Leeuwin Current in April or to increased retention of larvae close to the coast. In years when the southward-flowing Leeuwin Current was very strong, settlement in the southern locations was relatively higher than that farther north. In years of strong puerulus settlement, settlement also occurred earlier in the season.

Population dynamics of Pseudo-nitzschia pungens in Zhelin Bay, China

2008 ◽  
Vol 89 (4) ◽  
pp. 663-668 ◽  
Author(s):  
Changjiang Huang ◽  
Xiaoping Lin ◽  
Junda Lin ◽  
Hong Du ◽  
Qiaoxiang Dong
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Water Temperature ◽  
Ecosystem Health ◽  
Large Scale ◽  
Algal Bloom ◽  
Zooplankton Community ◽  
Essential Condition ◽  
Total Phytoplankton ◽  
Nitzschia Pungens

Population dynamics of the planktonic diatom Pseudo-nitzschia pungens was investigated at the Zhelin Bay, China, between May 2000 and December 2004. Monthly or seasonal plankton samples were collected from nine stations along the inner to outer bay gradient. Among the 1045 samples collected, P. pungens on average accounted for 2.9% of the total phytoplankton cells, with densities ranging from 0 to 50.94 × 104 cells l−1 and a grand mean of 1.43 × 104 cells l−1. Two hundred and fourteen samples (20.5%) had densities of P. pungens above 104 cells l−1 and 40 samples (3.8%) had densities that were above 105 cells l−1. Results of the grey incidence–regression analysis show that water temperature, zooplankton and salinity were the most important among the 13 environmental factors influencing population density of P. pungens. Water temperature has a highly significant linear relationship with the population density, with 23.8°C or higher being an essential condition for the algal bloom. Grazing by zooplankton was probably the most important factor controlling the algal bloom. With continued decreasing of richness and organism size of the zooplankton community at the Zhelin Bay, P. pungens blooms may become more frequent. The bay has a large-scale mariculture operation, therefore it is important to carefully examine and monitor the potential impacts of toxin-producing P. pungens on human health as well as ecosystem health of the bay.

The effect of climate change on the western rock lobster (Panulirus cygnus) fishery of Western Australia

2010 ◽  
Vol 67 (1) ◽  
pp. 85-96 ◽  
Author(s):  
Nick Caputi ◽  
Roy Melville-Smith ◽  
Simon de Lestang ◽  
Alan Pearce ◽  
Ming Feng
Keyword(s):  
Climate Change ◽  
Water Temperature ◽  
Deep Water ◽  
El Niño ◽  
El Nino ◽  
Rock Lobster ◽  
Westerly Winds ◽  
El Niño Events ◽  
Panulirus Cygnus ◽  
El Nino Events

Environmental factors such as the Leeuwin Current (influenced by the El Niño – Southern Oscillation cycle) and westerly winds in late winter – spring significantly affect puerulus settlement of the western rock lobster ( Panulirus cygnus ) fishery. Climate change is causing an increase in water temperature that is seasonally variable, a weakening of westerly winds in winter, and an increase in the frequency of El Niño events. Rising water temperatures over 35 years may have resulted in a decrease in size at maturity and size of migrating lobsters from shallow to deep water, increases in abundance of undersized and legal-sized lobsters in deep water relative to shallow water, and shifts in catch to deep water. The size of migrating lobsters is related to the water temperature about the time of puerulus settlement (four years previously). Climate change effects on puerulus settlement, catchability, females moulting from setose to non-setose, timing of moults, and peak catch rates are assessed. As climate change models project that the warming trend will continue, these biological trends are likely to continue. The changes may have negative (increasing frequency of El Niño events) or positive (increasing water temperature) implications for the fishery, which need to be taken into account in stock assessments and management.

Testing collector designs for commercial harvesting of western rock lobster (Panulirus cygnus) puerulus

2001 ◽  
Vol 52 (8) ◽  
pp. 1465 ◽  
Author(s):  
Bruce F. Phillips ◽  
Roy Melville-Smith ◽  
Yuk Wing Cheng ◽  
Mark Rossbach
Keyword(s):  
Published Data ◽  
Rock Lobster ◽  
Different Depths ◽  
New Moon ◽  
Catch Rates ◽  
Highly Correlated ◽  
Carry Over ◽  
Panulirus Cygnus ◽  
Do So ◽  
Commercial Harvesting

We have (i) tested modified western rock lobster sandwich collectors at different depths and distances offshore (ii) tested different collector designs (iii) examined the effect of collector size, and (iv) tested the effect of frequency of servicing the collectors. The only catches recorded in the onshore-offshore trials were on gear set at the inshore site (depths <5 m). Published data from the 1970s on the effect on catches of collector arrays and locations were reexamined with a general linear model. The analysis revealed marginally significant corner and layer effects, carry-over effects, and square-of-time effects. Five collector designs were therefore set in the shallows, two of which had replicates of three different sizes, and were checked over four lunar months during peak settlement. Sandwich collectors had significantly better catch rates than others (P <0.001), and settlement rates were highly correlated with collector dimensions (r = 0.72). Daily servicing for seven days around the time of new moon yielded catches 170% higher than those from a single monthly servicing (P <0.001). Results indicate that tests for collectors must take into account corner, carry-over, neighbour, and layer effects and that to do so they must be set out in an array and repositioned after each sampling.

scholarly journals Effect of water temperature and population density on the population dynamics of Schistosoma mansoni intermediate host snails

2014 ◽  
Vol 7 (1) ◽  
Author(s):  
Nicky McCreesh ◽  
Moses Arinaitwe ◽  
Wilber Arineitwe ◽  
Edridah M Tukahebwa ◽  
Mark Booth
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Schistosoma Mansoni ◽  
Water Temperature ◽  
Intermediate Host ◽  
Effect Of Water

Temperature and hunger mediate sablefish (Anoplopoma fimbria) feeding motivation: implications for stock assessment

2004 ◽  
Vol 61 (2) ◽  
pp. 238-246 ◽  
Author(s):  
Allan W Stoner ◽  
Erick A Sturm
Keyword(s):  
Water Temperature ◽  
Food Deprivation ◽  
Stock Assessment ◽  
Effective Area ◽  
Activity Level ◽  
Anoplopoma Fimbria ◽  
Feeding Motivation ◽  
Population Sizes ◽  
Increasing Temperature ◽  
Olfactory Cue

Laboratory experiments were conducted to test the hypothesis that temperature (2–8 °C) and recent feeding history (1–6 days of food deprivation) influence feeding motivation and attacks on baits by adult sablefish (Anoplo poma fimbria). Activity level after introduction of a bait-related olfactory cue increased with increasing water temperature and food deprivation. Fish at the lowest temperature (2 °C) attacked and consumed fewer squid baits (33–71%) than those at higher temperatures (100% at 8 °C). Baits were frequently inspected or handled multiple times before consumption in low temperatures, and time to attack (seconds to >40 min), time to consume, and time to handle baits (2–20 s) all decreased significantly with increasing temperature, with some temperature × feeding history interactions. The total ration consumed increased (<1–8% of body weight) with increasing water temperature. The observed variability in activity and feeding motivation in sablefish may have a large impact on the effective area of baited gear but is rarely considered in stock assessment models. In particular, population sizes based upon baited gear surveys may be underestimated in conditions where temperature is low, natural prey density is high, or where other environmental variables reduce feeding motivation.

scholarly journals Effects of Temperature and Salinity on Vibrio vulnificus Population Dynamics as Assessed by Quantitative PCR

2004 ◽  
Vol 70 (9) ◽  
pp. 5469-5476 ◽  
Author(s):  
Mark A. Randa ◽  
Martin F. Polz ◽  
Eelin Lim
Keyword(s):  
Population Dynamics ◽  
Water Temperature ◽  
Water Column ◽  
Quantitative Pcr ◽  
Vibrio Vulnificus ◽  
Most Probable Number ◽  
Salinity Regime ◽  
Optimal Salinity ◽  
Probable Number ◽  
Barnegat Bay

ABSTRACT The abundance of Vibrio vulnificus in coastal environments has been linked to water temperature, while its relationship to salinity is less clear. We have developed a culture-independent, most-probable-number quantitative PCR approach to examine V. vulnificus population dynamics in Barnegat Bay, N.J. Based on the combined analysis of our results from Barnegat Bay and from the literature, the present data show that (i) V. vulnificus population dynamics are strongly correlated to water temperature and (ii) although the general trend is for V. vulnificus abundance to be inversely correlated with salinity, this relationship depends on salinity levels. Irrespective of temperature, high abundances of V. vulnificus are observed at 5 to 10 ppt, which thus appears to be the optimal salinity regime for their survival. At 20 to 25 ppt, V. vulnificus abundances show a positive correlation to salinity. Unsuccessful attempts to resuscitate V. vulnificus, combined with our inability to detect cells during the winter despite an assay adapted to detect viable but nonculturable (VBNC) cells, suggest that the decline and eventual disappearance of V. vulnificus from the water column during the winter months is due primarily to a significant reduction in population size and is not only the consequence of cells entering the VBNC state. These findings are in line with the hypothesis that the sediment serves as a refuge for a subpopulation of V. vulnificus over the winter and weather-driven mixing events during the spring initiate a summer bloom in the water column.

Effects of crop sequence and rainfall on population dynamics of Fusarium solani f.sp. phaseoli in soil

1992 ◽  
Vol 70 (10) ◽  
pp. 2005-2008 ◽  
Author(s):  
Robert Hall ◽  
Lana Gay Phillips
Keyword(s):  
Population Dynamics ◽  
Phaseolus Vulgaris ◽  
Population Density ◽  
Fusarium Solani ◽  
Population Densities ◽  
Total Rainfall ◽  
Colony Forming Units ◽  
Bean Crop ◽  
Previous Summer ◽  
Crop Sequence

Evidence is presented that population dynamics of Fusarium solani f.sp. phaseoli in soil depend on the effects of crop sequence and rainfall on parasitic activities of the pathogen. In a rotation trial started in 1978 and conducted over 14 years, population densities (colony-forming units/g) of the fungus in soil remained below 50 in treatments (fallow, repeated corn, repeated soybean) where the preferred host plant (common bean, Phaseolus vulgaris) was not grown. Where bean was grown every 3rd year or every year, population densities reached 475 and 660, respectively, by 1984. Thereafter, population densities of the fungus fluctuated widely from year to year in both rotation and repeated bean treatments. In the rotation treatment, peaks in population density of the pathogen coincided with the years of bean production. In repeated bean plots between 1985 and 1991, population density of the fungus in June was significantly correlated (r = 0.77, p = 0.04) with total rainfall received during the previous summer (June–August). It is postulated that higher rainfall during the growing season of the bean crop stimulated root growth and root infection, leading to the accumulation of higher levels of potential inoculum in infected tissue and the release of higher levels of inoculum into the soil by the following June. Key words: Fusarium solani f.sp. phaseoli, bean, Phaseolus vulgaris, rainfall, crop rotation.

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