Age and growth of school mackerel (Scomberomorus queenslandicus) and spotted mackerel (S. munroi) in Queensland east-coast waters with implications for stock structure

1998 ◽  
Vol 49 (2) ◽  
pp. 109 ◽  
Author(s):  
Gavin A. Begg ◽  
Michelle J. Sellin
Keyword(s):  
Fisheries Management ◽  
East Coast ◽  
Stock Assessment ◽  
Growth Patterns ◽  
Age And Growth ◽  
Stock Structure ◽  
Population Parameters ◽  
Geographic Regions

Age and growth of school mackerel (Scomberomorus queenslandicus) and spotted mackerel (S. munroi) in east-coast waters, Queensland, Australia (16˚S to 28˚S), were determined to provide population parameters required for stock assessment and fisheries management. Female school mackerel (L∞ = 651 mm, K = 0.59, t0 = –1.41) were estimated to grow to a greater asymptotic length, but at a slower rate, than males (L∞ = 628 mm, K = 0.71, t0 = –1.26). Growth patterns of school mackerel differed between geographic regions and suggested the existence of separate stocks throughout the east-coast distribution. In contrast, female spotted mackerel (L∞ = 849 mm, K = 0.46, t0 = –1.54) were estimated to reach a greater asymptotic length at a faster rate than males (L∞ = 768 mm, K = 0.23, t0 = –4.33). There was no difference in growth between spotted mackerel from different regions, suggesting that there is a single stock along the Queensland east coast. Identification of school and spotted mackerel populations in Queensland east-coast waters will enable the species to be managed on the basis of stock structure across this range.

Validated estimation of growth and age in the New Zealand abalone Haliotis iris using stable oxygen isotopes

2007 ◽  
Vol 58 (4) ◽  
pp. 354 ◽  
Author(s):  
J. R. Naylor ◽  
B. M. Manighetti ◽  
H. L. Neil ◽  
S. W. Kim
Keyword(s):  
Carbon Isotopes ◽  
Stock Assessment ◽  
Growth Function ◽  
Growth Patterns ◽  
Age And Growth ◽  
Data Sets ◽  
Reproductive Patterns ◽  
Novel Approach ◽  
Isotopic Analyses ◽  
Rational Management

The growth and reproductive patterns of abalone are central to an understanding of the dynamics of their populations, and provide essential input into many of the stock assessment models currently used as the basis of assessing the sustainability of the fisheries. At present, most of this knowledge is obtained by tag-recapture methods, which are time consuming, often expensive and potentially confounding. The aim of the present study was to determine whether variations in the ratios of oxygen and carbon isotopes in the shells of Haliotis iris can be used to determine age, growth and reproductive patterns. Isotopic analyses of H. iris shells indicated that oxygen isotope profiles within the shells reflected ambient water temperature at the time of shell precipitation, and that these profiles could be used to determine age and growth patterns. To match the variation in isotopic ratios with ambient temperature cycles, we also adopted the novel approach of fitting a growth function to the data sets. The method should allow the collection of abalone growth information over the finer scales more appropriate for the rational management of abalone fisheries. Variations in the ratios of carbon isotopes showed no consistent patterns and, unlike some mollusc species, did not appear to be useful predictors of reproductive status at length.

Marine Artificial Reef Research and Development: Integrating Fisheries Management Objectives

2018 ◽  
Keyword(s):  
Standard Deviation ◽  
Gulf Of Mexico ◽  
Fisheries Management ◽  
Artificial Reef ◽  
Growth Patterns ◽  
Red Snapper ◽  
Age And Growth ◽  
Artificial Reefs ◽  
Lutjanus Campechanus ◽  
Management Objectives

<em>Abstract</em>.—Identifying morphometrics, age composition, and growth of Red Snapper <em>Lutjanus campechanus </em>(Poey, 1860) in the Gulf of Mexico is crucial for management of this valuable species. Red Snapper are highly associated with artificial reefs situated off the coast of Texas. Artificial reefs, two in federal waters (offshore) and two in state waters (inshore), were sampled quarterly from December 2014 through December 2016. Characteristic differences in age and growth patterns at inshore and offshore sites and across sampled sites were compared. Mean ± standard deviation was calculated for total length (TL), weight, and biological age. Red Snapper collected averaged 464.5 ± 92.6 mm in TL, 1.62 ± 1.03 kg, and 3.8 ± 1.5 years. Significant differences in TL, weight, and age were observed across sites but not between inshore and offshore locations. In comparing 12 previous Red Snapper length-at-age (0–25 years) studies across the Gulf of Mexico, results were similar except for two studies significantly different from one another, but none with respect to our study. Our findings suggest that Red Snapper populations are young and restricted to one or two spawning years before capture on artificial reefs. Continued management of fisheries associated with these reefs are necessary to increase the stock and eventually lead to robust and sustainable fisheries.

Language and Literacy Predictors of Dialect Density Among School-Age African American Children From Two Geographic Regions

2020 ◽  
Vol 51 (3) ◽  
pp. 807-820
Author(s):  
Lena G. Caesar ◽  
Marie Kerins
Keyword(s):  
African American ◽  
Multiple Regression ◽  
Oral Language ◽  
East Coast ◽  
Geographic Region ◽  
Literacy Skills ◽  
School Age ◽  
Regression Analyses ◽  
Geographic Regions ◽  
American Children

Purpose The purpose of this study was to investigate the relationship between oral language, literacy skills, age, and dialect density (DD) of African American children residing in two different geographical regions of the United States (East Coast and Midwest). Method Data were obtained from 64 African American school-age children between the ages of 7 and 12 years from two geographic regions. Children were assessed using a combination of standardized tests and narrative samples elicited from wordless picture books. Bivariate correlation and multiple regression analyses were used to determine relationships to and relative contributions of oral language, literacy, age, and geographic region to DD. Results Results of correlation analyses demonstrated a negative relationship between DD measures and children's literacy skills. Age-related findings between geographic regions indicated that the younger sample from the Midwest outscored the East Coast sample in reading comprehension and sentence complexity. Multiple regression analyses identified five variables (i.e., geographic region, age, mean length of utterance in morphemes, reading fluency, and phonological awareness) that accounted for 31% of the variance of children's DD—with geographic region emerging as the strongest predictor. Conclusions As in previous studies, the current study found an inverse relationship between DD and several literacy measures. Importantly, geographic region emerged as a strong predictor of DD. This finding highlights the need for a further study that goes beyond the mere description of relationships to comparing geographic regions and specifically focusing on racial composition, poverty, and school success measures through direct data collection.

Nonstationarity of Production Relationships in Exploited Populations

1987 ◽  
Vol 44 (S2) ◽  
pp. s156-s165 ◽  
Author(s):  
Carl J. Walters
Keyword(s):  
Environmental Changes ◽  
Historical Data ◽  
Stock Assessment ◽  
Policy Implications ◽  
Data Sets ◽  
Stock Structure ◽  
Stock Size ◽  
Rate Processes ◽  
And Shifts ◽  
Time Invariant

Stock assessment usually proceeds from the assumption that there are time-invariant relationships between stock size and rate processes such as recruitment, although such relationships are difficult to discern due to noise caused by factors other than stock size. There are good biological reasons not to trust this assumption in exploited populations, where persistent environmental changes and shifts in stock structure may cause various parameters to change. Graphical and statistical procedures can be used to detect this nonstationarity in historical data sets for which stock size has varied so as to repeatedly sample a range of sizes. The policy implications of nonstationarity depend on whether the changes are clearly observable as deviations from known, Song-term baseline responses. If the changes are observable, it is usually best to pretend that the current deviation will persist unless strong constraints on policy change make it necessary to plan for changes that may occur far into the future. If the changes are not observable (the usual case), then it is necessary to make a difficult policy choice between passively waiting for informative stock responses versus actively experimenting with harvest rates so as to quickly get information about responses over a range of stock sizes.

Grenadiers of the World Oceans: Biology, Stock Assessment, and Fisheries

2008 ◽  
Keyword(s):  
Fisheries Management ◽  
Geographic Distribution ◽  
Stock Assessment ◽  
Objective Data ◽  
The Family ◽  
The World ◽  
By Catch ◽  
Wide Geographic Distribution

<em>Abstract.</em>—The Chilean fishes of the family Macrouridae have historically been of little interest to the fisheries community in the SE Pacific. Landings of these fishes have only been officially recorded since 2000. Nevertheless there is evidence that macrourids have been incidentally caught as by-catch since the middle of the 20<sup>th</sup> century. Species of the genera <em>Coelorinchus </em>(formerly known as <em>Caelorinchus</em>), <em>Coryphaenoides</em>, <em>Lucigadus</em>, <em>Macrourus </em>and <em>Nezumia </em>are common as by-catch. It now appears important to apply fisheries management to these species, recording them as a unit, but obtaining objective data for each species. This should include an overall perspective on the species having a wide geographic distribution.

scholarly journals Subsampling populations with spatially structured traits: a field comparison of stratified and random strategies

2019 ◽  
Vol 76 (4) ◽  
pp. 511-522 ◽  
Author(s):  
Patricia Puerta ◽  
Bethany Johnson ◽  
Lorenzo Ciannelli ◽  
Thomas Helser ◽  
Robert Lauth
Keyword(s):  
Age Structure ◽  
Stock Assessment ◽  
Population Parameters ◽  
Pacific Cod ◽  
Geographical Patterns ◽  
Eastern Bering Sea ◽  
Random Strategy ◽  
Gadus Macrocephalus ◽  
Size At Age ◽  
Poor Efficacy

Scientific surveys are widely used for stock assessment, but the estimated population parameters are based on the size-at-age relationship and age structure derived from a small subsample of the catch that is aged. This calls for an assessment of subsampling strategies, especially when population’s life history traits are spatially structured. In the Eastern Bering Sea, Pacific cod (Gadus macrocephalus) size and age are spatially structured, with younger and smaller individuals being more abundant at shallower depths. We conducted parallel subsamplings during Pacific cod surveys to compare two contrasting subsampling strategies: length-stratified and random. Geographical heterogeneity of Pacific cod length resulted in divergent estimates of ages between subsampling strategies. When this spatial variability was taken into account to estimate population parameters, random strategy provided more accurate mean and modal size-at-age and estimated age structure. Bias in the length-stratified subsampling arises from the poor efficacy in capturing the geographical patterns of size observed in the population. However, combining age data samples from multiple years helps to minimize the divergences between the two strategies.

Age and growth of blue grenadier, Macruronus novaezelandiae (Hector), in south-eastern Australian waters

1987 ◽  
Vol 38 (5) ◽  
pp. 625 ◽  
Author(s):  
TJ Kenchington ◽  
O Augustine
Keyword(s):  
Growth Parameters ◽  
Growth Curves ◽  
Growth Patterns ◽  
Age And Growth ◽  
Double Blind ◽  
Blind Test ◽  
Thin Sections ◽  
South Eastern ◽  
Weight Data ◽  
Immature Fish

Blue grenadier, Macruronus novaezelandiae, from south-eastern Australian waters were aged, using their otoliths (whole and in transverse thin sections). The greatest recorded age was 25 years. A double blind test showed that the recorded ages were sufficiently reproducible to use in fitting growth curves (Index of Average Percent Error: 8%), but not sufficiently so to assign individuals to particular year-classes. Von Bertalanffy growth curves were fitted to both length and weight data. For males, Lt = 90.7 (1 - exp[-0.256(t + 1.21)]} and Wt = 2.62 (1 - exp[-0.277(t + 1.39)]}3. For females, Lt = 99.3 {l - exp[-0.203(t + 1.48)]} and Wt = 4.16{1 - exp[-0.157(t + 2.93)]}3. L is the length in centimetres, W is the weight in kilograms and t is the age in years. A comparison with length-frequency modes validated the growth curves for immature fish, but no validation was possible for the adults. The $exes have qignificantly different growth patterns. Their growth parameters are typical of those of commercially exploited, temperate gadoid fishes and show no modification for the deep-water zone inhabited by blue grenadier.

Sign in / Sign up

Export Citation Format

Share Document