Duration of larval and spawning periods inPagrus auratus (Sparidae) determined from otolith daily increments

1994 ◽  
Vol 39 (2) ◽  
pp. 137-152 ◽  
Author(s):  
Malcolm P. Francis
Keyword(s):  
Daily Increments ◽  
Spawning Periods

Environmental influence on maturation and dominance relationships in the three-spined stickleback (Gasterosteus aculeatus L.): temperature competes with photoperiod for primacy

2009 ◽  
Vol 38 (4) ◽  
Author(s):  
Ewa Sokołowska ◽  
Ewa Kulczykowska
Keyword(s):  
High Temperature ◽  
Visual Information ◽  
Gasterosteus Aculeatus ◽  
Environmental Influence ◽  
Gonadal Development ◽  
Constant Darkness ◽  
Dominance Relationships ◽  
Final Maturation ◽  
Maturation Rate ◽  
Spawning Periods

Environmental influence on maturation and dominance relationships in the three-spined stickleback (In this study, the influence of a combination of different photoperiods and temperatures on the final maturation and social interactions in three-spined sticklebacks was investigated. Water temperature appears to be the principal signal affecting gonadal development and breeding activity of sticklebacks in pre-spawning and spawning periods. Males can mature independently of photoperiod and a stimulatory effect of high temperature is not diminished by light deprivation. On the other hand, low temperature can inhibit the development of secondary sexual characters in males exposed to long day or constant light. In females, lighting seems to be more decisive for complete maturation and the lack of light delays the maturation rate, even in high temperature. While kept under the same conditions, males mature quicker than females. The presence of light and visual information are crucial to establish the social position of individuals in the group. In light, a rigid social hierarchy with one dominant, sexually active male is observed. In constant darkness, however, several males in the group demonstrate every sign of sexual activity.

Validation of daily increments and a marine-entry check in the otoliths of sockeye salmon Oncorhynchus nerka post-smolts

2015 ◽  
Vol 87 (1) ◽  
pp. 169-178 ◽  
Author(s):  
C. Freshwater ◽  
M. Trudel ◽  
T. D. Beacham ◽  
C.-E. Neville ◽  
S. Tucker ◽  
...  
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Daily Increments

scholarly journals Oceanic and atmospheric patterns during spawning periods prior to extreme catches of the Brazilian sardine (Sardinella brasiliensis) in the southwest Atlantic

2011 ◽  
Vol 75 (4) ◽  
pp. 665-677 ◽  
Author(s):  
Helena Cachanhuk Soares ◽  
Luciano Ponzi Pezzi ◽  
Douglas Francisco Marcolino Gherardi ◽  
Eduardo Tavares Paes
Keyword(s):  
Southwest Atlantic ◽  
Spawning Periods

scholarly journals Age, growth and mortality of the anchovy Stolephorus commersonnii (Lacepède,1803) (Clupeiformes) caught off the coast of Tanga, Tanzania

2021 ◽  
pp. 95-104
Author(s):  
Albogast T. Kamukuru ◽  
Shigalla B. Mahongo ◽  
Baraka C. Sekadende ◽  
Joseph S. Sululu
Keyword(s):  
Software Tool ◽  
Growth Function ◽  
Fishing Effort ◽  
Northern Coast ◽  
Management Intervention ◽  
Von Bertalanffy Growth Function ◽  
Relationship Model ◽  
June July ◽  
Spawning Periods ◽  
Length Frequency Data

The population dynamics of Stolephorus commersonnii (Lacepède, 1803) from a ringnet fishery operating off the northern coast of Tanga Region were evaluated based on monthly length-frequency data collected from August 2016 to August 2017. The total length (TL) and total weight (TW) of 14,410 individuals ranged from 22 to 130 mm and from 0.39 to 14.64 g respectively. S. commersonnii exhibited a negative allometric growth pattern with the length-weight relationship model: W = 0.00001 x L2.886. The von Bertalanffy growth function was Lt = 86.03 x (1 – e–1.19(t – (–0.01))) using ELEFAN I from the FiSAT II software tool package. Growth performance index and longevity were estimated at (ɸ) = 3.9 and Tmax = 2.5 yrs, respectively. The total (Z), fishing (F) and natural (M) mortalities were determined at 1.39, 0.53 and 0.86 yr-1, respectively. The current exploitation rate (Ecur) was estimated at 0.38. S. commersonnii exhibited a year-round breeding pattern, with two recruitment peaks in March and June/July. Length-at-first-capture (Lc50) and length-at-first-sexual maturity (Lm50) were 40.51 and 57.35 mm TL, respectively, suggesting growth overfishing. The stock of anchovy indicates an overfishing scenario requiring management intervention such as reducing fishing effort levels, increasing mesh sizes and introducing seasonal closures during peak spawning periods.

Muskellunge Management: Fifty Years of Cooperation Among Anglers, Scientists, and Fisheries Biologists

2017 ◽  
Keyword(s):  
Growth Models ◽  
Adult Population ◽  
Open Water ◽  
Maximum Size ◽  
Population Characteristics ◽  
Residual Effects ◽  
Fish Length ◽  
Frequency Distributions ◽  
Minnesota Lakes ◽  
Spawning Periods

<em>Abstract</em>.—A population assessment of Muskellunge <em>Esox masquinongy </em>in two connected north-central Minnesota lakes allowed evaluation of angler data when assessing various population metrics, including the residual effects of historical stocking efforts, as a nonlocal strain had been introduced into the native population during the 1970s. In 2012, the Minnesota Department of Natural Resources sampled and marked Muskellunge using trap nets during the prespawn and spawning periods and electrofishing during the postspawn period, while anglers collected data from fish caught during the 2012 open-water season. Anglers released all fish after collecting a scale for genetic analysis. Microsatellite DNA genotypes were used to differentiate individuals, thus identifying recaptures, and to estimate ancestry derived from the stocked strain. Anglers reported catching 16% of individuals marked by biologists. Of Muskellunge reported by anglers, 78% were from the lake where they were initially captured while 22% were reported in the lake opposite their initial capture. Postspawn movements suggested that more individuals migrated from the lake characterized as having preferred spawning and nursery habitat to the lake characterized as having preferred summer habitat and prey. The age- and length-frequency distributions of fish captured by anglers and trap nets were similar, while electrofishing sampled younger and smaller fish, likely because it occurred postspawn when many adults had moved off shore. The best estimate of adult population size was produced by a model incorporating fish length as a covariate. Density was estimated at 0.70 adults per ha or 1.92 adults per littoral ha. Higher percentages of nonlocal ancestry were associated with smaller maximum size potential (<em>L<sub></em>∞</sub> ) in von Bertalanffy growth models. Our study described key population characteristics for a Muskellunge population while demonstrating that anglers could reliably collect several specific types of data that supplement data collected by management agencies.

scholarly journals New directions in assisted breeding techniques for fish conservation

2020 ◽  
Vol 32 (9) ◽  
pp. 807 ◽  
Author(s):  
Nicola Rivers ◽  
Jonathan Daly ◽  
Peter Temple-Smith
Keyword(s):  
Endangered Species ◽  
Germ Cell ◽  
Cell Transplantation ◽  
Fish Species ◽  
Captive Breeding ◽  
Germ Line ◽  
Management Strategies ◽  
Germ Cell Transplantation ◽  
Spawning Periods ◽  
Breeding Techniques

Fish populations continue to decline globally, signalling the need for new initiatives to conserve endangered species. Over the past two decades, with advances in our understanding of fish germ line biology, new exsitu management strategies for fish genetics and reproduction have focused on the use of germ line cells. The development of germ cell transplantation techniques for the purposes of propagating fish species, most commonly farmed species such as salmonids, has been gaining interest among conservation scientists as a means of regenerating endangered species. Previously, exsitu conservation methods in fish have been restricted to the cryopreservation of gametes or maintaining captive breeding colonies, both of which face significant challenges that have restricted their widespread implementation. However, advances in germ cell transplantation techniques have made its application in endangered species tangible. Using this approach, it is possible to preserve the genetics of fish species at any stage in their reproductive cycle regardless of sexual maturity or the limitations of brief annual spawning periods. Combining cryopreservation and germ cell transplantation will greatly expand our ability to preserve functional genetic samples from threatened species, to secure fish biodiversity and to produce new individuals to enhance or restore native populations.

scholarly journals A Critical Analysis of Corona Related Data: What the More Reliable Data Can Imply for Western-Europe

2020 ◽  
Vol 10 (10) ◽  
pp. 3398
Author(s):  
Robert J. Meier
Keyword(s):  
Western Europe ◽  
Real Life ◽  
European Countries ◽  
Initial Increase ◽  
Local Concentration ◽  
Related Data ◽  
Daily Increments ◽  
Human Contact ◽  
Exponential Increase ◽  
Real Life Data

We present a less common type of discussion about COVID-19 data, beginning with the observation that the number of people reported deceased following COVID-19 infection is currently the most reliable dataset to be used. When the available real-life data are visualized for a number of European countries, they reveal the commonly seen exponential increase, though with different absolute rates, and over time different periods. More interesting information is obtained upon inspection of the daily increments in deaths. These curves look very similar to those for China, and seem to indicate that in European countries that have imposed more strict human–human contact measures, in particular Italy and Spain, where we have seen a decrease in daily deaths since early April, it is to be expected it will take 40–50 days from the end of March until this number has fallen to negligible levels. Taking the initial increase in the number of deaths for Germany, and combining this with typical values for the mortality reported in the literature and the published number of daily contacts for the working population, we calculated an initial increase in infections of 20 per day by a single infected person with an average human–human contact number of 22, decreasing to 5.5 after the first 10 days. The high number at the outset is likely related to outbreaks in a high local concentration of people.

scholarly journals Drivers of male sound production and effective communication distances at fish spawning aggregation sites

2020 ◽  
Vol 77 (2) ◽  
pp. 730-745 ◽  
Author(s):  
Timothy J Rowell ◽  
Gerald L D’Spain ◽  
Octavio Aburto-Oropeza ◽  
Brad E Erisman
Keyword(s):  
Environmental Effects ◽  
Sound Production ◽  
Effective Communication ◽  
Data Interpretation ◽  
Reproductive Activity ◽  
Fish Sounds ◽  
Fish Spawning ◽  
Spatio Temporal ◽  
Female Presence ◽  
Spawning Periods

Abstract While monitoring fish sounds has enhanced our understanding of spatio-temporal patterns of spawning and acoustic communication, data interpretation often fails to account for environmental effects on acoustic recordings, resulting in uncertainty of whether measures of detected fish sounds correspond to rates of sound production, specific behaviours, and abundance. In this study, we applied acoustic propagation modelling and detection theory to estimate rates of sound production of territorial, male Gulf grouper (Mycteroperca jordani) from passive acoustic recordings and evaluate effective communication distances. To assess behavioural drivers, environmentally calibrated, hourly estimates of sound production rates were compared to diver observations of courtship, spawning, and numbers of females encountered within male territories. Rates of sound production increased before sunset and were correlated to observed rates of spawning and females encountered, indicating that sound production is largely driven by female presence and increased opportunities to spawn. The mean effective communication distance was estimated to be &lt;21 m, supporting the importance of short-range communication within the observed behaviours. Our findings corroborate that fish sounds can be used to infer measures of reproductive activity and the relative abundance of both sexes during spawning periods once properly calibrated for environmental effects and detection capabilities.

Active and passive dispersal of Centroberyx affinis (Berycidae) and Gonorynchus greyi (Gonorynchidae) larvae on the Sydney shelf

2000 ◽  
Vol 51 (3) ◽  
pp. 229 ◽  
Author(s):  
Kimberley A. Smith
Keyword(s):  
Continental Shelf ◽  
Larval Stage ◽  
Shelf Break ◽  
Outer Shelf ◽  
Size Distributions ◽  
Passive Dispersal ◽  
Larval Size ◽  
Larval Behaviour ◽  
Eastern Australia ◽  
Spawning Periods

Distributions of small and large larvae of Centroberyx affinis (Berycidae) and Gonorynchus greyi (Gonorynchidae) were examined along a shore-normal transect across the Sydney continental shelf, south-eastern Australia during January and April 1994. Both species were abundant, and 3016 individuals of C. affinis and 3184 individuals of G. greyi were taken. Distributions of small and large C. affinis reflected hydrographic variability and suggested passive dispersal. Previous observations of high year-class variability for this species may therefore reflect oceanographic variability during the larval stage. In contrast, the distributions of G. greyi only partially reflected hydrography and appeared to be influenced by larval behaviour at both sizes. Size distributions during each month indicated protracted spawning periods for both species. Spawning by C. affinis may have occurred over the inner shelf although the location was unclear because of the complexity of nearshore currents. Spawning by G. greyi probably occurred over the outer shelf. An increasing influence of larval behaviour with larval size on the distribution of G. greyi restricted larger individuals to the shelf break; this may have been a response to higher productivity in this region.

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