Estimation of Size Selectivity and Movement Rates from Mark–Recovery Data

1994 ◽  
Vol 51 (3) ◽  
pp. 734-742 ◽  
Author(s):  
Alejandro Anganuzzi ◽  
Ray Hilborn ◽  
John R. Skalski
Keyword(s):  
Mortality Rates ◽  
Fishing Mortality ◽  
Size Selectivity ◽  
Movement Rates ◽  
Return Rates ◽  
Size Dependent ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis ◽  
Time Specific ◽  
Dependent Mortality

Size selectivity, movement rates among spatial strata, and size-dependent mortality rates were estimated from mark–recovery data of Pacific halibut (Hippoglossus stenolepis). Growth rates, area- and time-specific fishing mortality on fully vulnerable individuals, and tag return rates were assumed known from other data. We obtained similar estimates from a model that considered movement to take place immediately after tagging and a model that assumed that movement takes place once each year. The inability to distinguish between one-time and annual movement is most likely due to the fact that tagged juveniles were not recovered until 3–5 yr later when they became vulnerable to the adult fishery.

Catch and Release in Marine Recreational Fisheries

2002 ◽  
Keyword(s):  
The United States ◽  
Mortality Rates ◽  
Severe Injuries ◽  
Injury Type ◽  
Return Rates ◽  
Catch And Release ◽  
Pacific Halibut ◽  
Discard Mortality ◽  
Hippoglossus Stenolepis ◽  
Survival Potential

<em>Abstract</em>.—Management of the hook-and-line-only fishery for Pacific halibut <em> Hippoglossus stenolepis </em>in waters off the United States and Canada requires discard to the sea of Pacific halibut bycatch (out of season, undersized, or by fishermen without individual quotas or licenses). Depending on hook type and release methods, survival from longline discards can vary from nearly 100% to none. Conversion in the early 1980s from J-hooks, used by foreign fleets and the domestic halibut fleet, to circle hooks, now used by most domestic longline fishermen, increased survival potential through less damaging hooking locations. Bycatch mortality caused by a fishery was estimated by applying a discard mortality rate to the total halibut discarded. On-board observers collected viability data used to calculate annual fishery-specific Pacific halibut discard mortality rates and collected fisheryspecific bycatch rate data used to estimate total bycatch. Limits on bycatch mortality, which closed fisheries when exceeded, provided an incentive for the longline fleet to practice careful release. Estimated halibut bycatch mortality dropped following careful release regulations. Results of tagging studies on halibut released using careful release demonstrated that the distribution of hook injuries shifted to minor and moderate injuries compared with moderate and severe injuries when careful release did not occur. Tag return rates used to quantify survival by injury type led to criteria describing the injuries.

A sequential Bayesian methodology to estimate movement and exploitation rates using electronic and conventional tag data: application to Atlantic bluefin tuna (Thunnus thynnus)

2009 ◽  
Vol 66 (2) ◽  
pp. 321-342 ◽  
Author(s):  
Hiroyuki Kurota ◽  
Murdoch K. McAllister ◽  
Gareth L. Lawson ◽  
Jacob I. Nogueira ◽  
Steven L.H. Teo ◽  
...  
Keyword(s):  
Auxiliary Information ◽  
Bluefin Tuna ◽  
Mortality Rates ◽  
Fishing Mortality ◽  
Thunnus Thynnus ◽  
Multiple Sources ◽  
The West ◽  
Movement Rates ◽  
Bayesian Methodology ◽  
Atlantic Bluefin Tuna

This paper presents a Bayesian methodology to estimate fishing mortality rates and transoceanic migration rates of highly migratory pelagic fishes that integrates multiple sources of tagging data and auxiliary information from prior knowledge. Exploitation rates and movement rates for Atlantic bluefin tuna ( Thunnus thynnus ) are estimated by fitting a spatially structured model to three types of data obtained from pop-up satellite, archival, and conventional tags for the period 1990–2006 in the western North Atlantic. A sequential Bayesian statistical approach is applied in which the key components of the model are separated and fitted sequentially to data sets pertinent to each component with the posterior probability density function (pdf) of parameters from one analysis serving as the prior pdf for the next. The approach sequentially updates the estimates of age-specific fishing mortality rates (F) and transoceanic movement rates (T). Estimates of recent F are higher than the estimated rate of natural mortality and higher in the east than in the west. Estimates of annual T from the west to the east are higher for larger fish (6% for ages 0–3 to 16% for ages 9+). These estimates are also higher than those obtained from tagging studies before the 1990s and could be associated with changes in stock composition.

An Appraisal of the Size-Dependent Mortality Hypothesis for Larval Fish: Comparison of a Multispecies Study with an Empirical Review

1993 ◽  
Vol 50 (10) ◽  
pp. 2166-2174 ◽  
Author(s):  
Pierre Pepin
Keyword(s):  
Growth Rate ◽  
Larval Fish ◽  
Mortality Rates ◽  
Accurate Information ◽  
Constant Growth Rate ◽  
Size Dependent ◽  
Conception Bay ◽  
Biased Estimates ◽  
Constant Growth ◽  
Dependent Mortality

This study presents an assessment of the size-dependent mortality hypothesis for larval fish from a multispecies survey of Conception Bay, Newfoundland, Canada. Mortality rates are estimated using a length-based method (per millimetre). The results from this survey are consistent with previous studies which indicate that losses decrease with increasing size of fish. However, for each species within this survey, mortality rates are constant. Comparison of mortality rates within species among surveys indicates that as the range of size categories sampled increases, the estimated mortality rates decrease, despite evidence of adequate fit to the length-based model. The findings indicate that previous relationships between size or stage and mortality of larval fish should be reevaluated. Length-based methodology used to estimate mortality rates of larval fish appears to provide biased estimates of this vital characteristic. It is suggested that using size as a proxy for biological age (i.e., assuming a constant growth rate) may be an invalid assumption. Future surveys will need to provide accurate information about the age structure of larvae sampled in order to properly estimate mortality rates.

Estimating larval fish growth under size-dependent mortality: a numerical analysis of bias

2007 ◽  
Vol 64 (3) ◽  
pp. 554-562 ◽  
Author(s):  
Tian Tian ◽  
Øyvind Fiksen ◽  
Arild Folkvord
Keyword(s):  
Growth Rate ◽  
Longitudinal Data ◽  
Growth Rates ◽  
Mortality Rates ◽  
Growth Patterns ◽  
Cross Sectional ◽  
Larval Phase ◽  
Size Dependent ◽  
Recruitment Success ◽  
Dependent Mortality

The early larval phase is characterized by high growth and mortality rates. Estimates of growth from both population (cross-sectional) and individual (longitudinal) data may be biased when mortality is size-dependent. Here, we use a simple individual-based model to assess the range of bias in estimates of growth under various size-dependent patterns of growth and mortality rates. A series of simulations indicate that size distribution of individuals in the population may contribute significantly to bias in growth estimates, but that typical size-dependent growth patterns have minor effects. Growth rate estimates from longitudinal data (otolith readings) are closer to true values than estimates from cross-sectional data (population growth rates). The latter may produce bias in growth estimation of about 0.03 day–1 (in instantaneous, specific growth rate) or >40% difference in some situations. Four potential patterns of size-dependent mortality are tested and analyzed for their impact on growth estimates. The bias is shown to yield large differences in estimated cohort survival rates. High autocorrelation and variance in growth rates tend to increase growth estimates and bias, as well as recruitment success. We also found that autocorrelated growth patterns, reflecting environmental variance structure, had strong impact on recruitment success of a cohort.

scholarly journals A simple length-structured model based on life history ratios and incorporating size-dependent selectivity: application to spawning potential ratios for data-poor stocks

2016 ◽  
Vol 73 (12) ◽  
pp. 1787-1799 ◽  
Author(s):  
Adrian R. Hordyk ◽  
Kotaro Ono ◽  
Jeremy D. Prince ◽  
Carl J. Walters
Keyword(s):  
Life History ◽  
Growth Parameter ◽  
Mortality Rates ◽  
Life History Strategies ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Computationally Efficient ◽  
Size Dependent ◽  
Spawning Potential Ratio ◽  
Recursive Equations

Selectivity in fish is often size-dependent, which results in differential fishing mortality rates across fish of the same age, an effect known as “Lee’s Phenomenon”. We extend previous work on using length composition to estimate the spawning potential ratio (SPR) for data-limited stocks by developing a computationally efficient length-structured per-recruit model that splits the population into a number of subcohorts, or growth-type-groups, to account for size-dependent fishing mortality rates. Two simple recursive equations, using the life history ratio of the natural mortality rate to the von Bertalanffy growth parameter (M/K), were developed to generate length composition data, reducing the complexity of the previous approach. Using simulated and empirical data, we demonstrate that ignoring Lee’s Phenomenon results in overestimates of fishing mortality and negatively biased estimates of SPR. We also explored the behaviour of the model under various scenarios, including alternative life history strategies and the presence of size-dependent natural mortality. The model developed in this paper may be a useful tool to estimate the SPR for data-limited stock where it is not possible to apply more conventional methods.

Size Selectivity of Coho (Oncorhynchus kisutch) Preying on Juvenile Chum Salmon (O. keta)

1986 ◽  
Vol 43 (3) ◽  
pp. 581-586 ◽  
Author(s):  
N. Brent Hargreaves ◽  
Robin J. LeBrasseur
Keyword(s):  
Chum Salmon ◽  
Prey Size ◽  
Pacific Salmon ◽  
Oncorhynchus Kisutch ◽  
Fork Length ◽  
Size Selectivity ◽  
Size Dependent ◽  
Juvenile Chum Salmon ◽  
Dependent Mortality

Predation may be a major source of size-dependent mortality of Pacific salmon (Oncorhynchus spp.) during early sea life. Our experiments conducted in large saltwater enclosures demonstrated that coho (Oncorhynchus kisutch) are size selective when preying on juvenile chum (O. keta) salmon. Yearling coho (112–130 mm fork length) consumed significantly more smaller chum over a range in prey size of 43–63 mm fork length. We hypothesize that the intensity of size selectivity by coho and other predators is variable, depending on the relative sizes of the predators and prey.

The U‐shaped pattern of size‐dependent mortality and its correlated factors in a subtropical monsoon evergreen forest

2021 ◽  
Author(s):  
Ruiling Lu ◽  
Yang Qiao ◽  
Jing Wang ◽  
Chen Zhu ◽  
Erqian Cui ◽  
...  
Keyword(s):  
Evergreen Forest ◽  
Size Dependent ◽  
Correlated Factors ◽  
Shaped Pattern ◽  
Dependent Mortality

scholarly journals Evidence for rapid avoidance of rockfish habitat under reduced quota and comprehensive at-sea monitoring in the British Columbia Pacific halibut fishery

2020 ◽  
Vol 77 (8) ◽  
pp. 1409-1420
Author(s):  
Robyn E. Forrest ◽  
Ian J. Stewart ◽  
Cole C. Monnahan ◽  
Katherine H. Bannar-Martin ◽  
Lisa C. Lacko
Keyword(s):  
British Columbia ◽  
Spatial Clustering ◽  
Clustering Methods ◽  
Quota System ◽  
Encounter Rates ◽  
System A ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis ◽  
Footprint Area ◽  
Management Changes

The British Columbia longline fishery for Pacific halibut (Hippoglossus stenolepis) has experienced important recent management changes, including the introduction of comprehensive electronic catch monitoring on all vessels; an integrated transferable quota system; a reduction in Pacific halibut quotas; and, beginning in 2016, sharp decreases in quota for yelloweye rockfish (Sebastes ruberrimus, an incidentally caught species). We describe this fishery before integration, after integration, and after the yelloweye rockfish quota reduction using spatial clustering methods to define discrete fishing opportunities. We calculate the relative utilization of these fishing opportunities and their overlap with areas with high encounter rates of yelloweye rockfish during each of the three periods. The spatial footprint (area fished) increased before integration, then decreased after integration. Each period showed shifts in utilization among four large fishing areas. Immediately after the reductions in yelloweye rockfish quota, fishing opportunities with high encounter rates of yelloweye rockfish had significantly lower utilization than areas with low encounter rates, implying rapid avoidance behaviour.

Energy and ration requirements of juvenile Pacific halibut (Hippoglossus stenolepis) based on energy consumption and growth rates

1994 ◽  
Vol 44 (6) ◽  
pp. 1023-1031 ◽  
Author(s):  
A. J. Paul ◽  
J. M. Paul ◽  
R. L. Smith
Keyword(s):  
Energy Consumption ◽  
Growth Rates ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis

scholarly journals An integrated tagging model to estimate mortality rates of Albemarle Sound – Roanoke River striped bass

2017 ◽  
Vol 74 (7) ◽  
pp. 1061-1076 ◽  
Author(s):  
Julianne E. Harris ◽  
Joseph E. Hightower
Keyword(s):  
Striped Bass ◽  
Stock Assessment ◽  
Mortality Rates ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Albemarle Sound ◽  
High Reward ◽  
Accuracy And Precision ◽  
Summer Mortality ◽  
Roanoke River

We developed an integrated tagging model to estimate mortality rates and run sizes of Albemarle Sound – Roanoke River striped bass (Morone saxatilis), including (i) a multistate component for telemetered fish with a high reward external tag; (ii) tag return components for fish with a low reward external or PIT tag; and (iii) catch-at-age data. Total annual instantaneous mortality was 1.08 for resident (458–899 mm total length, TL) and 0.45 for anadromous (≥900 mm TL) individuals. Annual instantaneous natural mortality was higher for resident (0.70) than for anadromous (0.21) fish due to high summer mortality in Albemarle Sound. Natural mortality for residents was substantially higher than currently assumed for stock assessment. Monthly fishing mortality from multiple sectors (including catch-and-release) corresponded to seasonal periods of legal harvest. Run size estimates were 499 000–715 000. Results and simulation suggest increasing sample size for the multistate component increases accuracy and precision of annual estimates and low reward tags are valuable for estimating monthly fishing mortality rates among sectors. Our results suggest that integrated tagging models can produce seasonal and annual mortality estimates needed for stock assessment and management.

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