Differences in predicted catch composition between two widely used catch equation formulations

2009 ◽  
Vol 66 (1) ◽  
pp. 126-132 ◽  
Author(s):  
Trevor A. Branch
Keyword(s):  
Age Groups ◽  
Correct Choice ◽  
Fishing Gear ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Gear Selectivity ◽  
Different Types ◽  
Catch Composition ◽  
Continuous Formulation ◽  
Discrete Formulation

Fishing gear selectivity varies among different types of fish (e.g., species, age, sex, or length groups), but their relative catch composition also depends on the fishing process. The continuous (Baranov) formulation assumes that fishing mortality and natural mortality occur together during the fishing season and that there are multiple encounters between fish and fishing gear. For this formulation, predicted catch composition depends on fishing mortality, and at high fishing mortality levels the entire population can be caught provided the selectivity is nonzero for all age groups. In contrast, the discrete formulation assumes that fishing mortality occurs separately from natural mortality and that fish encounter at most only one set of fishing gear. The discrete formulation is easier to compute, but the predicted catch composition is independent of fishing mortality, and some of the population remains unexploitable. The correct choice of equations depends on the particular fishery and fishing mortality levels; at low fishing mortality levels the predictions differ little, but at high fishing mortality levels where multiple gear encounters could occur, the continuous formulation is preferable.

Reply to the comment by Francis on “Differences in predicted catch composition between two widely used catch equation formulations”Appears in Can. J. Fish. Aquat. Sci. 66: 126–132.

2010 ◽  
Vol 67 (4) ◽  
pp. 766-768
Author(s):  
Trevor A. Branch
Keyword(s):  
Entire Population ◽  
Fishing Gear ◽  
Fishing Mortality ◽  
Gear Selectivity ◽  
Catch Composition ◽  
Continuous Formulation ◽  
Discrete Formulation ◽  
Model Fits

Francis (2010. Can. J. Fish. Aquat. Sci. 67: 763–765) writes a thoughtful response detailing concerns with my suggestion that the continuous (Baranov) catch formulation is preferable to the discrete catch formulation when fishing mortality is high (T.A. Branch. 2009. Can. J. Fish. Aquat. Sci. 66: 126–132). He suggests the discrete formulation allows for multiple gear encounters and that formulation choice should depend on which formulation better fits the data. Here I first distinguish between gear selectivity and availability and then show that our two views are complementary: the original assumes fish groups with differing gear selectivity but full availability, whereas Francis assumes fish groups fully selected by fishing gear but with differing availability. I maintain that the discrete formulation only models a single instantaneous interaction between fish and fishing gear and therefore only part of the population can be caught if fish groups have equal gear selectivity that is less than 100%, whereas under the same assumptions, the continuous formulation would allow the entire population to be caught. Finally, when the balance between gear selectivity and availability is unknown, I agree that formulation choice could be driven by model fits to the data, although formulation choice could also be based on how the fishery operates.

Comment on “Differences in predicted catch composition between two widely used catch equation formulations”Appears in Can. J. Fish. Aquat. Sci. 66: 126–132.

2010 ◽  
Vol 67 (4) ◽  
pp. 763-765 ◽  
Author(s):  
R. I.C. Chris Francis
Keyword(s):  
Stock Assessment ◽  
Fishing Gear ◽  
Fishing Mortality ◽  
Instantaneous Rate ◽  
Exploitation Rate ◽  
Catch Composition ◽  
Continuous Formulation

Branch (2009. Can. J. Fish. Aquat. Sci. 66: 126–132) described the two most common catch equation formulations in stock assessment models: the continuous (Baranov) one, which represents fishing mortality as an instantaneous rate, F, and the discrete one, in which it is represented as an exploitation rate, u. He claimed that the continuous formulation is preferable at high fishing mortality where a fish could encounter multiple sets of gear within a year. This claim is wrong for two reasons. First, it is based on the false supposition that the discrete catch equations require the assumption that fish encounter at most only one set of fishing gear in a year. Second, it is not possible to determine, for a specific stock assessment, whether one formulation is preferable to another solely on the basis of information about the fishery. The appropriate way to make this decision is to see which fits the data better.

Estimation of Effective Effort from Catch-at-Age Data

1993 ◽  
Vol 50 (11) ◽  
pp. 2421-2428 ◽  
Author(s):  
J. E. Paloheimo ◽  
Yong Chen
Keyword(s):  
Age Groups ◽  
Simulated Data ◽  
Mortality Rates ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
A Value ◽  
Basic Equations ◽  
Highly Correlated ◽  
High Degree ◽  
Two Age Groups

We present a method for estimating effective efforts or fishing mortality rates based on a linearized version of the catch equation. Catch-at-age for at least two age groups over a series of years is required. The method presupposes a value for natural mortality rate (M). The method is validated using simulated data with an appropriate error structure. The algorithm always converges to a set of effective efforts that are compatible with the known catches. Nevertheless, the solution to the basic equations is not unique although the different solutions are typically highly correlated. If the M assumed by the algorithm is the same as the actual M the iterated effective efforts are typically very close to the true effective efforts or fishing mortality rates. If the assumed M is too high or too low the pattern of effective efforts is still recovered to a high degree of accuracy, typically 0.90 < r < 1.00, even though M may be off by as much as 60%. When data for three or more age groups are available the method is extended to at least squares procedure that takes into account the increasing uncertainty of catches with age.

Models of Tag Dynamics with Exchange between Available and Unavailable Populations

1989 ◽  
Vol 46 (8) ◽  
pp. 1356-1366 ◽  
Author(s):  
Ray Hilborn
Keyword(s):  
Loss Rate ◽  
Fishing Effort ◽  
Estimation Methods ◽  
Fishing Gear ◽  
Natural Mortality ◽  
Time Varying ◽  
Skipjack Tuna ◽  
Fishing Mortality ◽  
Release Group ◽  
Parameter Estimation Methods

Four models of the dynamics of an exploited population of fish are presented, and methods for the estimation of the parameters of each model from a mark recapture experiment are developed. The four models are (1) constant loss rate from the population, (2) constant natural mortality, with time varying fishing mortality proportional to fishing effort, (3) constant natural mortality, and time varying vulnerability to fishing gear, and (4) interchange between a vulnerable population and an invulnerable one, with natural mortality occurring in both populations, but fishing mortality occurring only in one. The parameter estimation methods are developed for a single release group recovered over discrete intervals. Each of these models is applied to tagging data on skipjack tuna (Euthynnus pelamis) in the western tropical Pacific.

scholarly journals POPULATION DYNAMICS OF TUNA (EUTHYNNUS AFFINIS, CANTOR 1849) IN WESTERN WATERS OF SOUTH SULAWESI

2020 ◽  
Vol 8 (8) ◽  
pp. 164-172
Author(s):  
Budiman Yunus ◽  
Suwarni ◽  
Basse Siang Parawansa
Keyword(s):  
Population Dynamics ◽  
Mortality Rate ◽  
Age Groups ◽  
Total Mortality ◽  
Assessment Tools ◽  
Natural Mortality ◽  
Age Group ◽  
Fishing Mortality ◽  
Growth Coefficient ◽  
South Sulawesi

This study aims to determine the population dynamics of tuna including age group, growth, mortality, exploitation rate and yield per recruitment. It was conducted from June to August in West Waters of South Sulawesi. By method of age group using Bhattacharya method with FAO-ICLARM Fish Stock Assessment Tools II (FISAT II) program, growth using Von Bertalanffy’s equation, natural mortality (M) using Pauly’s empirical equation, total mortality (Z) using Beverton and Holt’s equations, fishing mortality (F) by the formula Z = F + M, exploitation (E) using Baverton and Holt’s equations and yield per recruitment (Y/R’) using Baverton and Holt’s equations. The results of research of tuna observed were 737 includes 355 male tunas and 382 female tunas. The estimation of total length ranging from 215 mm to 429 mm. Male tunas are classified into 4 (four) of age groups with a length of 236.67, 272.8, 326.04 and 375.53 mm, respectively. Asymptote length (L∞) = 455.00 mm, growth coefficient (K) = 0.33 and theoretical age (t0) of -0.2377 per year. Total mortality rate (Z) = 1.12 per year. Natural mortality (M) = 0.41 per year, fishing mortality (F) = 0.71, exploitation (E) = 0.63 and yield per recruitment (Y/R’) = 0.0691, while male tunas are classified into 5 (five) of age groups with a length of 235.73, 272.86, 326.89, 360.89 and 408.89 mm, respectively. Asymptote length (L∞) = 453.50 mm, growth coefficient (K) = 0.42 and theoretical age (t0) of -0.1853 per year. Total mortality rate (Z) = 1.35 per year. Natural mortality (M) = 0.48 per year, fishing mortality (F) = 0.87, exploitation (E) = 0.64 and yield per recruitment (Y/R’) = 0.0784. Thus, it can be concluded that tuna in West Waters of South Sulawesi have declined and thought occur overfishing.

scholarly journals Are the Acute Effects of THC Different in Aging Adults?

2021 ◽  
Vol 11 (5) ◽  
pp. 590
Author(s):  
Raeghan L. Mueller ◽  
Jarrod M. Ellingson ◽  
L. Cinnamon Bidwell ◽  
Angela D. Bryan ◽  
Kent E. Hutchison
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Age Groups ◽  
Young Group ◽  
Self Administration ◽  
Behavioral Measures ◽  
Younger Adults ◽  
Different Types ◽  
Before And After ◽  
Aging Adults

In recent years of expanding legalization, older adults have reported the largest increase in cannabis use of any age group. While its use has been studied extensively in young adults, little is known about the effects of THC in older adults and whether the risks of cannabis might be different, particularly concerning intoxication and cognition. The current study investigated whether age is associated with the deleterious effects of THC on cognitive performance and other behavioral measures before and after ad libitum self-administration of three different types of cannabis flower (THC dominant, THC + CBD, and CBD dominant). Age groups consisted of young adults (ages 21–25) and older adults (ages 55–70). Controlling for pre-use scores on all measures, the THC dominant chemovar produced a greater deleterious effect in younger adults compared with older adults in tests of learning and processing speed, whereas there were no differences between old and young in the effects of the other chemovars. In addition, the young group reported greater cannabis craving than the older group after using the THC chemovar. Consistent with some reports in the preclinical literature, the findings suggest that older adults may be less sensitive to the effects of THC on cognitive and affective measures.

Spontaneous Glomerulonephritis in Dogs: II. Correlation of Glomerulonephritis with Age, Chronic Interstitial Nephritis and Extrarenal Lesions

1977 ◽  
Vol 14 (2) ◽  
pp. 121-127 ◽  
Author(s):  
R. Müller-Peddinghaus ◽  
G. Trautwein
Keyword(s):  
Interstitial Nephritis ◽  
Membranoproliferative Glomerulonephritis ◽  
Age Groups ◽  
Renal Amyloidosis ◽  
Morphologic Study ◽  
Different Types ◽  
End Stage ◽  
Chronic Interstitial Nephritis ◽  
Slight Damage ◽  
Severe Fibrosis

A morphologic study of 103 dogs, including two with renal amyloidosis, showed that different types of diffuse glomerulonephritis are correlated with different age groups. Membranous and membranoproliferative glomerulonephritis were more common in middle-aged and older animals, whereas mesangial lesions were found predominantly in younger dogs and considered to be early glomerular changes. Glomerulonephritis largely occurred independently of interstitial nephritis. The incidence of interstitial lesions was 71%. Chronic interstitial nephritis was rare in dogs under 1 year old. Glomerulonephritis did not seem to induce interstitial nephritis. Glomerulonephritis occurred not only in kidneys with severe interstitial damage, but also in those with slight damage. This indicated that glomerulonephritis occurred independently of interstitial nephritis. In end-stage kidneys with severe fibrosis, mesangial changes seemed to predominate.

Phone-Related Distracted Walking Injuries as a Function of Age and Walking Environment

2021 ◽  
Vol 65 (1) ◽  
pp. 611-615
Author(s):  
Zheng Haolan ◽  
Isabella M. Campbell ◽  
Wayne C.W. Giang*
Keyword(s):  
Emergency Department ◽  
Surveillance System ◽  
Age Groups ◽  
Injury Surveillance ◽  
Future Research ◽  
Home Environments ◽  
Injury Surveillance System ◽  
Different Types ◽  
Ed Visits ◽  
Walking Environment

Using phones while walking has been a factor that has led to accidents and injuries. However, few studies have analyzed the propensity of injuries due to distracted walking for different age groups and in different types of walking environments. This study aims to examine the number of emergency department (ED) visits due to distracted walking across different age groups and walking environments using a publicly available dataset, the National Electronic Injury Surveillance System (NEISS) database. The results suggest that there were an estimated 29140 distracted walking injuries between the years 2011-2019. Individuals between 11 and 20 years old had the most injuries, followed by 21 to 30, and 31 to 40. Furthermore, the proportion of estimated injuries that occurred in different walking environments differed across age groups. Safety-orient interventions for future research for stairs and home environments were also recommended in the present study.

Phonological Profile of Patients With Velopharyngeal Dysfunction and Palatal Anomalies

2021 ◽  
pp. 1-15
Author(s):  
Ariela Nachmani ◽  
Muhamed Masalha ◽  
Firas Kassem
Keyword(s):  
Cleft Palate ◽  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Age Groups ◽  
Phonological Process ◽  
Phonological Processes ◽  
Process Error ◽  
Submucous Cleft Palate ◽  
Different Types

Purpose This purpose of this study was to assess the frequency and types of phonological process errors in patients with velopharyngeal dysfunction (VPD) and the different types of palatal anomalies. Method A total of 808 nonsyndromic patients with VPD, who underwent follow-up at the Center for Cleft Palate and Craniofacial Anomalies, from 2000 to 2016 were included. Patients were stratified into four age groups and five subphenotypes of palatal anomalies: cleft lip and palate (CLP), cleft palate (CP), submucous cleft palate (SMCP), occult submucous cleft palate (OSMCP), and non-CP. Phonological processes were compared among groups. Results The 808 patients ranged in age from 3 to 29 years, and 439 (54.3%) were male. Overall, 262/808 patients (32.4%) had phonological process errors; 80 (59.7%) ages 3–4 years, 98 (40, 0%) ages 4.1–6 years, 48 (24.7%) 6.1–9 years, and 36 (15.3%) 9.1–29 years. Devoicing was the most prevalent phonological process error, found in 97 patients (12%), followed by cluster reduction in 82 (10.1%), fronting in 66 (8.2%), stopping in 45 (5.6%), final consonant deletion in 43 (5.3%), backing in 30 (3.7%), and syllable deletion and onset deletion in 13 (1.6%) patients. No differences were found in devoicing errors between palatal anomalies, even with increasing age. Phonological processes were found in 61/138 (44.20%) with CP, 46/118 (38.1%) with SMCP, 61/188 (32.4%) with non-CP, 70/268 (26.1%) with OSMCP, and 25/96 (26.2%) with CLP. Phonological process errors were most frequent with CP and least with OSMCP ( p = .001). Conclusions Phonological process errors in nonsyndromic VPD patients remained relatively high in all age groups up to adulthood, regardless of the type of palatal anomaly. Our findings regarding the phonological skills of patients with palatal anomalies can help clarify the etiology of speech and sound disorders in VPD patients, and contribute to general phonetic and phonological studies.

Movement, Growth and natural mortality rate of the Red Spot King Prawn, Penaeus longistylus Kubo, from the Great Barrier Reef Lagoon

1990 ◽  
Vol 41 (3) ◽  
pp. 399 ◽  
Author(s):  
MCL Dredge
Keyword(s):  
Growth Rate ◽  
Mortality Rate ◽  
Great Barrier Reef ◽  
Annual Variation ◽  
Growth Parameters ◽  
Natural Mortality ◽  
Barrier Reef ◽  
Fishing Mortality ◽  
Nursery Areas ◽  
Reef Lagoon

Movement, growth and natural mortality rate of the red spot king prawn, Penaeus longistylus, occurring in waters of the Great Barrier Reef off Townsville, Queensland, were investigated in a series of tagging experiments. Adult P. longistylus did not migrate after leaving nursery areas. Their growth rate was slower than that of the conspecific species P. plebejus, and significant inter-annual variation in growth parameters was observed. The natural mortality rate, assessed by sequential tagging experiments that eliminated the possibility of confounding with the rate of fishing mortality, was estimated to be 0.072 (week-1).

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