Hierarchical model-based estimation of population growth curves for redfish (Sebastes mentella and Sebastes fasciatus) off the Eastern coast of Canada

2016 ◽  
Vol 74 (3) ◽  
pp. 687-697 ◽  
Author(s):  
Noel G. Cadigan ◽  
Steven E. Campana
Keyword(s):  
Population Growth ◽  
Stock Assessment ◽  
Growth Curves ◽  
Eastern Coast ◽  
Short Term ◽  
Large Dataset ◽  
Production Models ◽  
Sources Of Variation ◽  
Males And Females ◽  
Sebastes Mentella

Northwest Atlantic (NWA) redfish (Sebastes mentella and Sebastes fasciatus) stocks are currently assessed using survey indicators and age-aggregated production models rather than age-based models because routine age readings are not available due to the difficulty in obtaining reliable measurements for these fish. However, recruitment is highly variable for redfish species so age-aggregated production models are not a good approach to provide short-term harvest advice. Recently a relatively large dataset of validated age readings was published that provide a good basis to model growth and its variability [i.e. population growth curve (PGC)]. In this article we propose a hierarchical random effects growth model that includes between-individual variation to estimate PGCs for 10 NWA redfish stocks and for males and females separately. These growth curves are required to develop age-based stock assessment models. External estimates of measurement error in length and age are included in our model to separate these sources of variation from the PGC variability. The hierarchical approach leads to more realistic growth curves than if each stock and sex are modelled separately. Model results indicated that S. mentella usually grow to larger sizes than S. fasciatus and that females of both these species grow to larger sizes than males. There was little evidence of a change in growth rates over time.

scholarly journals Sources of variation in the feeding ecology of the piked spurdog (Squalus megalops): implications for inferring predator–prey interactions from overall dietary composition

2005 ◽  
Vol 62 (6) ◽  
pp. 1076-1094 ◽  
Author(s):  
J. Matías Braccini ◽  
Bronwyn M. Gillanders ◽  
Terence I. Walker
Keyword(s):  
Spatial And Temporal Variation ◽  
Dietary Composition ◽  
Bootstrap Analysis ◽  
Predator Prey ◽  
Ecological Relationships ◽  
Wide Range ◽  
Opportunistic Predator ◽  
Sources Of Variation ◽  
Males And Females ◽  
Prey Items

Abstract Sources of variation in dietary composition were examined in the piked spurdog (Squalus megalops). The species is an opportunistic predator that consumes a wide range of prey items. When importance of prey was measured by weight or occurrence, S. megalops preyed largely on molluscs and teleosts. However, when number of prey was considered, the main items were crustaceans. A bootstrap analysis showed that considerable variability can be expected in the importance of prey items in the species' overall diet. Regional, seasonal, and ontogenetic differences in dietary composition were found, but there were no differences between mature and immature sharks or between males and females. The spatial and temporal variation in diet exhibited by S. megalops and the intrinsic natural variability of the dietary composition of this opportunistic predator suggest that studies that infer predator–prey interactions from overall diet are likely to miss information on the ecological relationships among species and thus account for only part of these interactions.

scholarly journals Age and growth of franciscana dolphins, Pontoporia blainvillei (Cetacea: Pontoporiidae) incidentally caught off southern Brazil and northern Argentina

2010 ◽  
Vol 90 (8) ◽  
pp. 1493-1500 ◽  
Author(s):  
Silvina Botta ◽  
Eduardo R. Secchi ◽  
Mônica M.C. Muelbert ◽  
Daniel Danilewicz ◽  
Maria Fernanda Negri ◽  
...  
Keyword(s):  
Growth Models ◽  
Growth Curves ◽  
Small Sample ◽  
Age And Growth ◽  
Buenos Aires Province ◽  
Von Bertalanffy ◽  
Southern Brazil ◽  
Data Set ◽  
Males And Females ◽  
Pontoporia Blainvillei

Age and length data of 291 franciscana dolphins (Pontoporia blainvillei) incidentally captured on the coast of Rio Grande do Sul State (RS), southern Brazil, were used to fit growth curves using Gompertz and Von Bertalanffy growth models. A small sample of franciscanas (N = 35) from Buenos Aires Province (BA), Argentina, were used to see if there are apparent growth differences between the populations. Male and female franciscana samples from both areas were primarily (78–85%) <4 years of age. The Von Bertalanffy growth model with a data set that excluded animals <1 year of age provided the best fit to data. Based on this model, dolphins from the RS population reached asymptotic length at 136.0 cm and 158.4 cm, for males and females, respectively. No remarkable differences were observed in the growth trajectories of males and females between the RS and BA populations.

scholarly journals Growth curve of Atlantoscia floridana (van Name) (Crustacea, Isopoda, Philosciidae) from a Brazilian Restinga Forest

2004 ◽  
Vol 21 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Paula Beatriz Araujo ◽  
Georgina Bond-Buckup
Keyword(s):  
Growth Rate ◽  
Growth Curve ◽  
Urban Areas ◽  
Field Data ◽  
Growth Curves ◽  
Rio Grande ◽  
Rio Grande Do Sul ◽  
Differential Growth ◽  
Estimate Life Expectancy ◽  
Males And Females

The terrestrial isopod Atlantoscia floridana (van Name, 1940) occurs from the U.S.A. (Florida) to Brazil and Argentina. In the southernmost Brazilian State, Rio Grande do Sul, the species is recorded in many localities, in urban and in non-urban areas. The growth curve of Atlantoscia floridana based on field data is presented. The specimens were sampled from April, 2000 to October, 2001 at the Reserva Biológica do Lami (RBL), Rio Grande do Sul. Captured individuals were sexed and had their cephalothorax width measured, with the data analyzed with von Bertalanffy's model. The growth curves for males and females are described, respectively, by the equations: Wt = 1.303 [1 - e-0.00941 (t + 50.37)] and Wt = 1.682 [1 - e-0.00575 (t + 59.13)]. The curves showed differential growth between sexes, where females reach a higher Wµ with a slower growth rate. Based on the growth curves it was also possible to estimate life expectancy for males and females.

Exploitation status and stock assessment by pseudo-cohort analysis of the bluefish, Pomatomus saltatrix, in the Gulf of Gabes (Tunisia)

2007 ◽  
Vol 87 (5) ◽  
pp. 1315-1319 ◽  
Author(s):  
Khalifa Dhieb ◽  
Mohamed Ghorbel ◽  
Othman Jarboui ◽  
Abderrahmen Bouaïn
Keyword(s):  
Stock Assessment ◽  
Cohort Analysis ◽  
Fishing Effort ◽  
Individual Growth ◽  
Eastern Coast ◽  
Pomatomus Saltatrix ◽  
Gulf Of Gabes ◽  
Gulf Of Gabès ◽  
Exploitation Status ◽  
The One

The bluefish, Pomatomus saltatrix, is quite abundant in the Gulf of Gabes, off the south-eastern coast of Tunisia. It is commercially exploited by artisanal gears and trawlers all year round, and by purse seine nets from May to August (bluefish fishery season). Catches of bluefish, in the period 1996–2004 fluctuated between 365.6 t and 1240.1 t with an annual average of 805 t. This fluctuation, partially due to the migratory nature of the species, could be also attributed to the fleet activities that sometimes changed at the mercy of the operators. The analysis of the virtual population of bluefish in the Gulf of Gabes showed that, in 2002, the stock that had just recovered rightly after an excessive fishing in 1996–1997 was again subject to a fishing effort that passed its capacity (E=0.71; E>0.5). The biomass (B) estimated to be ~2178.9 t only tolerated the extraction of 713.4 t (more or less one-third of B). However, the three fleets in use removed 1029.1 t with a yield per recruit (Y/R) of 70.5 g. As a result of this over-fishing, the actual stock of bluefish in the Gulf of Gabes was characterized by individuals having a mean total length of 17.88 cm, a size which is much lower than the one at first sexual maturity (23.5 cm). The turnover (D/B) being of 75.23%, it did not allow the reconstitution of the stock. The total removals (~1639 t) due to both natural mortality (M=0.28) and fishing mortality (F=0.675) had to be compensated especially by individual growth (1534.2 t; 93.6%) because of the low weight of the recruits.

scholarly journals An optimized catch-only assessment method for data poor fisheries

2018 ◽  
Author(s):  
Shijie Zhou ◽  
André E Punt ◽  
Anthony D. M. Smith ◽  
Yimin Ye ◽  
Malcolm Haddon ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Stock Assessment ◽  
Assessment Method ◽  
Maximum Sustainable Yield ◽  
Estimated Parameters ◽  
Rate Maximum ◽  
Stock Depletion ◽  
Catch Statistics

Catch statistics are perhaps the most commonly collected data and are widely available for many fisheries. However, it is currently difficult to provide scientific advice for management purposes using only catch data. This article presents a catch-only method for stock assessment of data-poor fisheries. It uses time series of catches and two priors, one for the intrinsic population growth rate derived from life history parameters, and another for stock depletion based on catch trends. The method applies an optimization algorithm to search the potential parameter space. All computations are model or equation based rather than using predefined rules. The utility of this method is demonstrated by applying it to 13 stocks in Australia that are assessed using Stock Synthesis—an assessment package that can make use of a variety of data sources. The estimated parameters, including carrying capacity, intrinsic population growth rate, maximum sustainable yield, and depletion from the catch-only method are broadly comparable with those from the full assessments. The circumstances in which the method may perform poorly, such as longer-term changes in productivity and episodic recruitment, are highlighted.

scholarly journals Short-term stock assessment of Loligo gahi at the Falkland Islands: sequential use of stochastic biomass projection and stock depletion models

2006 ◽  
Vol 64 (1) ◽  
pp. 3-17 ◽  
Author(s):  
Rubén Roa-Ureta ◽  
Alexander I. Arkhipkin
Keyword(s):  
Sex Ratio ◽  
Stock Assessment ◽  
Scaling Factor ◽  
Falkland Islands ◽  
Short Term ◽  
Projection Model ◽  
Biomass Estimate ◽  
Projected Length ◽  
Spatio Temporal ◽  
Stock Depletion

Abstract Roa-Ureta, R. and Arkhipkin, A. I. 2007. Short-term stock assessment of Loligo gahi at the Falkland Islands: sequential use of stochastic biomass projection and stock depletion models – ICES Journal of Marine Science, 64, 3–17. Two short-term stock assessment models are combined to examine the pre-season, in-season, and post-season dynamics of the Loligo gahi fishery off the Falkland Islands over four consecutive fishing seasons. A stochastic biomass projection model (SBPM) projects a pre-season survey-based biomass estimate from the date of the survey to the start of the season. A stock depletion model (SDM) assesses in-season biomass from commercial daily catch-and-effort data. The SBPM projects the SDM biomass estimate at the end of the season to a post-season date of spawning. Combining the SBPM and the SDM helps to clarify the spatio-temporal functioning of the stock and to assess the comparability of survey- and fishery-based estimates of biomass. For the first 2005 season, projected length frequencies indicate two pulses of recruitment onto the fishing grounds. Survey-based projections of biomass were lower than equivalent fishery-based estimates. Over two surveys, the sex ratio was balanced, suggesting full recruitment of both sexes onto the fishing grounds, and the ratio of survey-projected to fishing-estimated biomass was constant. This constant is interpreted as a scaling factor between survey biomass and absolute biomass.

Gonad-infecting species of Philometra (Nematoda: Philometridae) from groupers Epinephelus spp. (Osteichthyes: Serranidae) in the Bay of Bengal, India

2014 ◽  
Vol 59 (4) ◽  
Author(s):  
František Moravec ◽  
Jayaraman Manoharan
Keyword(s):  
Bay Of Bengal ◽  
Marine Fishes ◽  
Eastern Coast ◽  
Males And Females ◽  
Electron Microscopical ◽  
Honeycomb Grouper ◽  
Scanning Electron

AbstractBased on light and scanning electron microscopical studies, two new and one specifically not identified gonad-infecting species of Philometra Costa, 1845 (Nematoda: Philometridae) are described from the ovary of marine fishes of the genus Epinephelus Bloch (Serranidae, Perciformes) in the Bay of Bengal, off the eastern coast of India: P. indica sp. nov. (male and females) from the honeycomb grouper E. merra Bloch, P. tropica sp. nov. (males and females) from the duskytail grouper E. bleekeri (Vaillant) and Philometra sp. (only females) from the cloudy grouper E. erythrurus (Valenciennes). Philometra indica is mainly characterized by the length of spicules 192–195 μm and the gubernaculum 84 μm, the distal tip of the gubernaculum without a dorsal protuberance, and by the presence of five pairs of caudal papillae. Philometra tropica is mainly characterized by the spicules conspicuously ventrally distended at their posterior halves, the distal tip of the gubernaculum with a dorsal protuberance, and the presence of three pairs of caudal papillae.

Testing hypotheses concerning the formation of shell growth marks in marine pelecypods

1991 ◽  
Vol 69 (3) ◽  
pp. 535-546 ◽  
Author(s):  
Edwin Bourget ◽  
Hélène Bérard ◽  
Vibeke Brock
Keyword(s):  
Shell Growth ◽  
Growth Accounting ◽  
Short Term ◽  
Tidal Period ◽  
Growth Increments ◽  
Potential Sources ◽  
Sources Of Variation ◽  
Shell Deposition ◽  
The Individual ◽  
External Growth

This paper reviews the evidence supporting the current hypotheses (daily, tidal, endogenous, and other rhythms of growth) accounting for short-term periodicity in the formation of marks (external growth ridges and internal growth increments) on the shell of marine pelecypod molluscs. With few exceptions our analysis shows too much unexplained variability and the availability of too few studies of potential sources of variation for the proposed cycles of mark formation (circadian, circatidal) to be accepted. Since shell deposition takes the form of marks, which must be discrete in frequency (0, 1, or 2 per given day or tidal period), we submit that individual frequencies must be used to test hypotheses concerning the rhythms of shell growth mark formation, and we propose the use of three criteria: (i) that departure of the individual measured frequency from the expected frequency should not be more than the maximal error in measurements (maximal counting errors made by the observer); (ii) should condition one be violated, then the so-called "missing" or "superfluous" marks should be clearly accounted for; (iii) that potential sources of variation (e.g., age, habitat, locality, season) should not significantly influence the frequency of formation of the marks.

Child Athletes and Athletic Objectification

2017 ◽  
Vol 41 (3) ◽  
pp. 175-190 ◽  
Author(s):  
Nadine Cameron ◽  
Lynne McPherson ◽  
Prue Atkins ◽  
Matthew Nicholson ◽  
Maureen Long
Keyword(s):  
Best Interests ◽  
Western Society ◽  
Psychosocial Needs ◽  
Short Term ◽  
Research Project ◽  
Organized Sport ◽  
Beliefs And Values ◽  
Males And Females ◽  
Good For ◽  
Gendered Expectations

This article examines the risks associated with conceptualizing the child athlete’s body primarily in aesthetic terms and as an instrument of sporting victory, and develops a concept of “athletic objectification.” It draws on a recent research project involving Australian males and females aged between 18 and 25 who participated in organized sport as children. It identifies socially prevalent beliefs and values to which the athletic objectification of children may be partially attributed. These include the orthodoxy that sport is inherently good for children’s development, and the particular valorization of sporting success and gendered expectations that characterize Western society. It concludes with the argument that serving children’s best interests in sport requires that their broader psychosocial needs are given priority above the short-term development of their athletic capacity.

Diurnal resting sites of the nocturnal dasyurid marsupial Sminthopsis douglasi in Bladensburg National Park, Queensland

2017 ◽  
Vol 39 (1) ◽  
pp. 121 ◽  
Author(s):  
P. A. Woolley
Keyword(s):  
National Park ◽  
Climatic Factors ◽  
Short Term ◽  
Term Study ◽  
Resting Sites ◽  
Short Term Study ◽  
Males And Females

An attempt has been made to determine where Julia Creek dunnarts (Sminthopsis douglasi), small nocturnal dasyurid marsupials, rest during the day under differing seasonal conditions. A short-term study was carried out in Bladensburg National Park, near the southern edge of its known distribution on the Mitchell grass downs in Queensland. Radio-collared individuals were located in cracks and holes. None of the males and females (including one with young in the pouch) were found to use the same resting site over periods of up to nine days, suggesting that they may be nomadic. Climatic factors may have affected the size of the dunnart population over the course of the study.

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