Statistical analysis of catch-at-age data with correlated errors

1995 ◽  
Vol 52 (6) ◽  
pp. 1265-1273 ◽  
Author(s):  
Ransom A. Myers ◽  
Noel G. Cadigan
Keyword(s):  
Statistical Model ◽  
Estimation Error ◽  
Fish Abundance ◽  
Fishing Mortality ◽  
Correlated Errors ◽  
Commercial Catch ◽  
Commercial Fish ◽  
Research Survey ◽  
The World ◽  
Survey Estimates

We extend the statistical model used to estimate abundance from commercial catch-at-age data for many of the major commercial fish species in the world. The model we consider combines commercial catch-at-age data and research survey estimates of fish abundance; we extend the model to allow correlated errors among ages within a year for the survey estimates of fish abundance. We also formulate a method for modeling the fishing mortality on the oldest ages of the fish caught. Estimates are obtained using maximum likelihood. We conclude that the level of correlation among ages is sufficiently large to produce large biases in the standard methods for some stocks. The statistical model that includes correlated errors greatly reduces bias and increases efficiency if the correlation in the estimation error is large.

Estimating trends in fishing mortality at age and length directly from research survey and commercial catch data

1998 ◽  
Vol 55 (5) ◽  
pp. 1248-1263 ◽  
Author(s):  
Alan F Sinclair
Keyword(s):  
Population Analysis ◽  
New Method ◽  
Natural Mortality ◽  
Population Abundance ◽  
Similar Magnitude ◽  
Fishing Mortality ◽  
Commercial Catch ◽  
Relative Population ◽  
Research Survey

Relative fishing mortality (R) is estimated directly as the ratio of commercial catch divided by a research vessel survey index of relative population abundance. If the survey is conducted near the middle of the fishing year, its catchability is constant, and the rate of catch reporting remains constant, R will be proportional to the actual fishing mortality (F). Trends in R will reflect trends in F. A case study is presented where R at age and length are compared with estimates obtained with sequential population analysis (SPA). They were found to be of similar magnitude and trend. This new method would be useful for stocks where SPA is not possible. It would also be a useful addition to analytical assessments where SPA is used; it provides estimates of relative F at length, it is insensitive to changes in natural mortality provided the research survey occurs close to the middle of the fishing year, and it provides useful diagnostics for interpreting SPA results.

scholarly journals North Sea cod recovery?

2006 ◽  
Vol 63 (6) ◽  
pp. 961-968 ◽  
Author(s):  
Joe Horwood ◽  
Carl O'Brien ◽  
Chris Darby
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Mortality Rates ◽  
Fishing Effort ◽  
Current Status ◽  
Fishing Mortality ◽  
Commercial Fish ◽  
Fish Stocks ◽  
Stock Assessments ◽  
Low Levels

AbstractRecovery of depleted marine, demersal, commercial fish stocks has proved elusive worldwide. As yet, just a few shared or highly migratory stocks have been restored. Here we review the current status of the depleted North Sea cod (Gadus morhua), the scientific advice to managers, and the recovery measures in place. Monitoring the progress of North Sea cod recovery is now hampered by considerable uncertainties in stock assessments associated with low stock size, variable survey indices, and inaccurate catch data. In addition, questions arise as to whether recovery targets are achievable in a changing natural environment. We show that current targets are achievable with fishing mortality rates that are compatible with international agreements even if recruitment levels remain at the current low levels. Furthermore, recent collations of data on international fishing effort have allowed estimation of the cuts in fishing mortality achieved by restrictions on North Sea effort. By the beginning of 2005, these restrictions are estimated to have reduced fishing mortality rates by about 37%. This is insufficient to ensure recovery of North Sea cod within the next decade.

scholarly journals Overlooked biological and economic implications of within-season fishery dynamics

2014 ◽  
Vol 71 (2) ◽  
pp. 181-188 ◽  
Author(s):  
Xiaozi Liu ◽  
Mikko Heino
Keyword(s):  
Concentration Profile ◽  
Fishing Effort ◽  
Economic Consequences ◽  
Fish Abundance ◽  
Fishing Pressure ◽  
Fishing Mortality ◽  
Economic Implications ◽  
Special Cases ◽  
Total Stock ◽  
Stock Abundance

Catch equations relate fisheries catch to initial fish abundance and the applied fishing pressure. The Baranov catch equation, often simply referred to as the catch equation, is the commonest one. However, there are exactly three ways of describing seasonal progression of fishing parsimoniously with a single parameter: assume catch rate, fishing effort, or fishing mortality is constant, the last being the assumption underlying the Baranov catch equation. These assumptions imply different dynamics, and only in special cases two of these assumptions can hold true simultaneously. Whether this happens is dictated by the concentration profile (i.e., the dependence of mean fish density where fishing takes place on total stock abundance). We show that the assumed seasonal progression of fishing and the type of the concentration profile have major implications for fishery dynamics as well as biological and economic consequences of fishing, calling for increased awareness of these overlooked assumptions of fishery dynamics. However, in many cases the Baranov catch equation serves as a good approximation, even when its assumption of constant fishing mortality is violated.

The effects of salinity, turbidity and flow on fish biomass estimated acoustically in two tidal rivers

2014 ◽  
Vol 65 (3) ◽  
pp. 267 ◽  
Author(s):  
V. F. Matveev ◽  
A. D. L. Steven
Keyword(s):  
Large Scale ◽  
River System ◽  
Fish Abundance ◽  
Practical Significance ◽  
Small Scale ◽  
Fish Biomass ◽  
Strongly Correlated ◽  
Commercial Catch ◽  
Four Seasons ◽  
Annual Means

Establishing drivers of fish abundance in estuaries is an important task of both theoretical and practical significance. Commercial catch data help explain large-scale variation in fish productivity; however, there is insufficient understanding of small-scale changes. We analysed correlations between acoustically estimated fish biomass (FB) and environmental variables, which included indices of primary productivity and physio-chemistry in a coastal river system during four seasons. Spatial series of FB were obtained for the Logan River (main estuary) and the Albert River (tributary) located in South East Queensland, Australia. Most of the year, FB was significantly higher in the Albert River. Annual means for discharge, salinity and pH were significantly lower, whereas phosphorus concentrations were higher in the Albert River. Out of 15 hydrological variables tested, FB was strongly correlated only with salinity, conductivity and turbidity. In the Albert River, where fish were larger, as indicated by greater target strengths, FB was positively correlated with river discharge. Our results suggest that salinity and turbidity can be important seasonal drivers of fish abundance in communities dominated by Mugil spp. and Nematalosa erebi and that the flow-biomass relationship may appear independent of the effects of primary production.

Demographic and risk analyses of spiny dogfish (Squalus suckleyi) in the Gulf of Alaska using age- and stage-based population models

2011 ◽  
Vol 62 (12) ◽  
pp. 1395 ◽  
Author(s):  
Cindy A. Tribuzio ◽  
Gordon H. Kruse
Keyword(s):  
Input Parameter ◽  
Gulf Of Alaska ◽  
Spiny Dogfish ◽  
Fishing Mortality ◽  
Sustainable Harvest ◽  
Demographic Models ◽  
The World ◽  
Slow Growing ◽  
Cohort Analyses ◽  
Modelling Approach

Demographic models are useful tools for assessing data-limited species and may be an appropriate alternative to cohort analyses for sharks due to their long-lived, slow-growing nature. In this study, age- and stage-based demographic analyses were conducted to examine the intrinsic rebound potential (r) and potential risk of fishing for spiny dogfish (Squalus suckleyi) in the Gulf of Alaska. Monte Carlo simulations were conducted to incorporate input parameter uncertainty. For an unfished population, r was estimated to be 0.02–0.03 year–1. Fishing mortalities (F) of F = 0.04 and 0.03 (age- and stage-based models respectively), resulted in r = 0, indicating that populations fished at higher F are not sustainable. Harvest strategies targeting juveniles (age-based model) and subadults (stage-based model) caused the highest risk of the population falling below defined thresholds (BMSY, B40% and B50%) after 20 years. The age- and stage-based models provided similar estimates of r and sustainable fishing mortality, suggesting that the stage-based model is an appropriate substitute for the age-based model in this case. S. suckleyi and the closely related S. acanthias are often harvested around the world and this modelling approach could be useful to the management of these species and other sharks where data is limited.

A STATISTICAL MODEL OF CLAIM PRICES IN PREDICTION MARKETS

2012 ◽  
Vol 4 (3) ◽  
pp. 85-93
Author(s):  
Russ Ray
Keyword(s):  
Statistical Model ◽  
Financial Markets ◽  
Poisson Distribution ◽  
Prediction Markets ◽  
Inside Information ◽  
Prediction Market ◽  
The World ◽  
Global Agreement ◽  
High Degree

This paper finds that claim prices in prediction markets, a new genre of financial markets, follow a Poisson distribution. The significance of this finding is that as soon as a claim in a prediction market is created and thereafter flushes out expert and inside information from around the world regarding that particular claim, claim prices immediately begin forming bell-shaped distributions, implying global agreement regarding the probabilities of claims being realized. This is an interesting finding, implying a surprisingly high degree of global homogeneity of inside information in predictions markets, even though such information is scattered in disconnected and secretive pockets around the world. This finding could also imply that cultural diversities do not significantly affect the interpretation of information in prediction markets. 

Assessing the impacts of shale gas development on the water-energy nexus across the semiarid Mexico’s northeast

2020 ◽  
Author(s):  
Saul Arciniega-Esparza ◽  
Agustín Breña-Naranjo ◽  
Antonio Hernández-Espriú ◽  
Adrián Pedrozo-Acuña
Keyword(s):  
Remote Sensing ◽  
Water Resources ◽  
Statistical Model ◽  
Water Use ◽  
Shale Gas ◽  
Surface Model ◽  
Eagle Ford ◽  
Limited Region ◽  
Water Energy Nexus ◽  
The World

<p><span>An intensification of water use for hydraulic fracturing (HF) to extract oil and gas from deep shale formations has been observed during the last years across the USA, increasing concerns about water resources management in water-limited regions around the world. At the same time, HF has been associated to several environmental and water quality/quantity impacts in many developed plays of USA, China and Canada, nevertheless, assessing impacts on emergent plays involves several difficulties since future development of HF is generally unknown and because of the lack of local data to evaluate water resources baselines.</span></p><p><span>In this work, we present a framework that combines the use of remote sensing derived data to assess the baseline of water resources and the development and application of a statistical model to project the development of HF activities. Remote sensing and global land surface model products of precipitation (CHIRPS), evapotranspiration (MODIS), recharge (WaterGAP model), infiltration and runoff (MERRA) and water storage (GRACE) were used to estimate water availability and the hydrological response of watersheds and aquifers. Scenarios of HF were generated using a statistical model that simulates HF water requirements, hydrocarbon production, flowback-produced water and economic trends, among others factors that influence the HF development.</span></p><p><span>The proposed framework was applied to evaluate the impacts of HF development on the water energy-nexus at the transboundary Eagle Ford play, located across Mexico’s northeast, a water-limited region that contains substantial reserves of shale gas.</span></p><p><span>Scenarios were generated following two economic projections and assuming water use trends and historical HF development from the Eagle Ford, Barnett and Haynesville plays, in Texas, which are geologically similar to the Mexican Eagle Ford play.</span></p><p><span>Results suggested that the higher impacts on the water-energy nexus in Mexico resulted from reported trends in Eagle Ford, Texas, with ~14,000 wells drilled in ten years and an accumulative water use volume of ~450 millions cubic meters, representing about ~69% of the annual groundwater concessions for municipal use.</span></p><p><span>The framework presented in this work can be used in other plays around the world to assess the impacts of HF on water resources and their implications in its water-energy nexus.</span></p>

scholarly journals Sustained exponential population growth of grey seals at Sable Island, Nova Scotia

2003 ◽  
Vol 60 (6) ◽  
pp. 1265-1274 ◽  
Author(s):  
W.D Bowen ◽  
J McMillan ◽  
R Mohn
Keyword(s):  
Nova Scotia ◽  
Statistical Model ◽  
Aerial Photography ◽  
Environmental Variability ◽  
Grey Seal ◽  
Confidence Limits ◽  
The World ◽  
The Face ◽  
Exponential Population Growth ◽  
Exponential Population

Abstract Grey seal pup production on Sable Island, Nova Scotia, has been monitored since the early 1960s. We estimated pup production on Sable Island in 1997 using aerial photography with a correction for detection of pups on the imagery and a statistical model to account for the proportion of pups not born at the time of the survey. A total of 20 863 pups were counted on the colour positives. When corrected for the proportion of pups seen on the imagery (0.96) and the proportion of pups born before the survey (east colony 0.94, west colony 0.66), estimated total pup production was 25 400 with approximate 95% confidence limits of 23 500 and 26 900. The 1997 estimate indicates that pup production in this population, now the largest grey seal colony in the world, has been increasing exponentially at an annual rate of 12.8% for four decades in the face of considerable environmental variability.

scholarly journals A Statistical Model for Estimation of Fish Density Including Correlation in Size, Space, Time and between Species from Research Survey Data

PLoS ONE ◽  
2014 ◽  
Vol 9 (6) ◽  
pp. e99151 ◽  
Author(s):  
J. Rasmus Nielsen ◽  
Kasper Kristensen ◽  
Peter Lewy ◽  
Francois Bastardie
Keyword(s):  
Statistical Model ◽  
Survey Data ◽  
Space Time ◽  
Fish Density ◽  
Research Survey
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