Incorporating habitat preference into the stock assessment and management of blue marlin (Makaira nigricans) in the Pacific Ocean

2012 ◽  
Vol 63 (7) ◽  
pp. 565 ◽  
Author(s):  
Nan-Jay Su ◽  
Chi-Lu Sun ◽  
André E. Punt ◽  
Su-Zan Yeh ◽  
Gerard DiNardo
Keyword(s):  
Population Dynamics ◽  
Habitat Preference ◽  
Stock Assessment ◽  
Ecosystem Approach ◽  
Maximum Sustainable Yield ◽  
Blue Marlin ◽  
Makaira Nigricans ◽  
Biological Variables ◽  
Population Dynamics Model ◽  
Spawning Stock

Stock assessments that include a spatial component or relate population dynamics to environmental conditions can be considered one way of implementing an ecosystem approach to fisheries. A spatially-structured population dynamics model that takes account of habitat preference is developed and then applied to Pacific blue marlin (Makaira nigricans), as they prefer certain habitats and migrate seasonally. The model is fitted to fishery catch-rate and size data, along with information on the relative density of the population over space derived from a habitat preference model fitted to oceanographic and biological variables. Results show that blue marlin are more abundant in tropical waters, and females account for most of the biomass. Assessments that allow for environmental factors, movement dynamics and sexual dimorphism indicate that this population is in an over-exploited state, with current spawning stock biomass below the level corresponding to maximum sustainable yield (SMSY) and current fishing mortality exceeding that needed to achieve MSY (FMSY). A risk analysis based on samples from a Bayesian posterior distribution suggests that the population will remain above SMSY after 20 years if exploitation rates are below the level corresponding to FMSY.

scholarly journals Development of a stock–recruit model for simulating stock dynamics for uncertain situations: the example of Northeast Atlantic mackerel (Scomber scombrus)

2011 ◽  
Vol 68 (5) ◽  
pp. 848-859 ◽  
Author(s):  
E. John Simmonds ◽  
Andrew Campbell ◽  
Dankert Skagen ◽  
Beatriz A. Roel ◽  
Ciaran Kelly
Keyword(s):  
Stock Assessment ◽  
Management Plan ◽  
Maximum Sustainable Yield ◽  
Fish Stock ◽  
Northeast Atlantic ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Functional Forms

Abstract Simmonds, E. J., Campbell, A., Skagen, D., Roel, B. A., and Kelly, C. 2011. Development of a stock–recruit model for simulating stock dynamics for uncertain situations: the example of Northeast Atlantic mackerel (Scomber scombrus). – ICES Journal of Marine Science, 68: 848–859. The assumption of a relationship between recruitment and a spawning stock is the cornerstone of the precautionary approach and may constrain the use of a maximum sustainable yield (MSY) target for fisheries management, because the failure to include such a relationship suggests that providing a measure of stock protection is unnecessary. The implications of fitting different functional forms and stochastic distributions to stock-and-recruit data are investigated. The importance of these considerations is shown by taking a practical example from management: the management plan for Northeast Atlantic mackerel (Scomber scombrus), a fish stock with an average annual catch of 600 000 t. The historical range of spawning-stock biomass is narrow, and historical data from a stock assessment explain only a small proportion of the recruitment variability. We investigate how best to reflect the uncertainty in the stock–recruit relationship. Selecting a single model based on simple statistical criteria can have major consequences for advice and is problematic. Selecting a distribution of models with derived probabilities gives a more complete perception of uncertainty in dynamics. Differences in functional form, distribution of deviations, and variability of coefficients are allowed. The approach appropriately incorporates uncertainty in the stock–recruit relationship for FMSY estimation.

Stock assessment of school shark, Galeorhinus galeus, based on a spatially explicit population dynamics model

2000 ◽  
Vol 51 (3) ◽  
pp. 205 ◽  
Author(s):  
André E. Punt ◽  
Fred Pribac ◽  
Terence I. Walker ◽  
Bruce L. Taylor ◽  
Jeremy D. Prince
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Stock Assessment ◽  
Dynamics Model ◽  
Point Estimates ◽  
Population Dynamics Model ◽  
Equilibrium Size ◽  
Assessment Approach ◽  
The Status ◽  
Galeorhinus Galeus

The school shark (Galeorhinus galeus) resource off southern Australia is assessed by use of an assessment approach that takes account of the spatial structure of the population. The population dynamics model underlying the assessment considers the spatial as well as the age-specific characteristics of school shark. It allows for a series of fisheries (each based on a different gear type), explicitly models the pupping/recruitment process, and allows for multiple stocks. The values for the parameters of this model are determined by fitting it to catch-rate data and information from tagging studies. The point estimates of the pup production at the start of 1997 range from 12% to 18% of the pre-exploitation equilibrium size, depending on the specifications of the assessment. Allowing for spatial structure and incorporating tag release–recapture data lead to reduced uncertainty compared with earlier assessments. The status of the resource, as reflected by the ratio of present to virgin pup production and total (1+) biomass, is sensitive to the assumed level of movement between the stocks in New Zealand and those in Australia, with lower values corresponding to higher levels of movement.

Allee effects and compensatory population dynamics within a stock complex

2000 ◽  
Vol 57 (3) ◽  
pp. 513-517 ◽  
Author(s):  
Kenneth T Frank ◽  
David Brickman
Keyword(s):  
Population Dynamics ◽  
Simulation Model ◽  
Stock Assessment ◽  
Complex Structure ◽  
Reference Points ◽  
Allee Effects ◽  
Biophysical Modeling ◽  
Aggregated Data ◽  
Apparent Prevalence ◽  
Spawning Stock

Sparked by the observation that (i) many collapsed stocks have failed to recover despite the apparent prevalence of compensatory population dynamics and (ii) many stocks have a complex structure, we devised a simulation model illustrating that the underlying behavior of substocks is masked when the data are aggregated and evaluated at the scale of the management unit. The model consisted of several substocks within a stock complex, each having its own stock and recruitment (S-R) relationship with Allee effects. Incorporation of Allee effects into the S-R relationship was achieved by specifying a critical spawning stock biomass threshold below which no recruitment occurred. The simulation model revealed that it was possible for the aggregate S-R relationship to appear compensatory, even though no substock exhibited this behavior. If the conclusions we draw from our modeling are correct, biological reference points developed from aggregated data from multiple substocks and used in conventional fisheries management and stock assessment models are likely to be inaccurate and possibly nonconservative. More research in support of the delineation of substock structure, biophysical modeling, and metapopulation theory is advocated.

scholarly journals Evaluation of the robustness of maximum sustainable yield based management strategies to variations in carrying capacity or migration pattern of Atlantic bluefin tuna (Thunnus thynnus)

2007 ◽  
Vol 64 (5) ◽  
pp. 837-847 ◽  
Author(s):  
Laurence T Kell ◽  
Jean-Marc Fromentin
Keyword(s):  
Carrying Capacity ◽  
Management Strategy ◽  
Stock Assessment ◽  
Management Strategies ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Sustainable Yield ◽  
Size Limit ◽  
Atlantic Bluefin Tuna ◽  
Spawning Stock

In this study, we examine the performances of current stock assessment methods with respect to their ability to (i) provide estimates of maximum sustainable yield (MSY), FMSY, and BMSY and (ii) assess stock status and exploitation level relative to MSY targets. The robustness of the current International Commission for the Conservation of Atlantic Tunas (ICCAT) management strategy is then evaluated with respect to uncertainty about the true population dynamics and contrasted with a simpler management strategy based solely on a size limit. Reference points are more robust to dynamic uncertainty than the estimates of absolute values and trends in F and spawning stock biomass. However, their performances depend on the underlying dynamics (they perform better when fluctuations come from changes in the carrying capacity than migration) and on when they are implemented relative to the intrinsic cycle of the population. Reference points based on F were less biased and more precise than those based on biomass and (or) yield. Although F0.1 appeared to be the best proxy for FMSY, it cannot indicate past and current levels of exploitation relative to FMSY when there is uncertainty about the dynamics. Finally, the F0.1 management strategy of ICCAT performed only slightly better than a simpler strategy based on size limit and led to lower catch levels.

scholarly journals Population dynamics of Puntius sophore (Hamilton, 1822) of river Sutlej in Punjab (India)

2021 ◽  
Vol 42 (6) ◽  
pp. 1505-1511
Author(s):  
J. Kumar ◽  
◽  
S.N. Datta ◽  
G. Tewari ◽  
S.S. Hassan ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Extreme Values ◽  
Growth Parameters ◽  
Stock Assessment ◽  
Maximum Sustainable Yield ◽  
Recruitment Pattern ◽  
Fish Market ◽  
Baseline Information ◽  
River Sutlej ◽  
Puntius Sophore

Aim: The aim of the present paper was to describe first and comprehensive picture on length-weight relationship and population dynamics of riverine Puntius sophore. The findings of the investigation will be an imperative part of the ecological database from river Sutlej. Methodology: The length-frequency data of 579 specimens of P. sophore captured from different stretches of river Sutlej were collected fortnightly from Tajpur fish market and Haibowal fish market (Devnagar) during April 2019 to March 2020. All the population parameters were analyzed using FiSAT II analytical package developed by FAO. Results: The estimated length-weight relationships (LWRs) of combined male and female was derived as W=0.1471 L3.0605 (r=0.98). The growth parameters were L∞=123.5 mm, K=1.18 yr-1, to= -0.7672 yr-1, Rn=0.215 and ø'=4.241. The estimated natural mortality coefficient (1.25 per yr) was greater than fishing mortality (1.03 yr-1).The present level of exploitation (E=0.45, U=0.40) of P. sophore stock indicated that stocks were under-exploited. Prediction of maximum length from extreme values at 95% confidence interval was calculated as 112.48-138.24 mm. The recruitment pattern of P. sophore showed peaks during May and June. Interpretation: The P. sophore stock was under-exploited. The fishing intensity may be standardized to obtain optimum yield per recruit and thereby ideal maximum sustainable yield. This baseline information will help in further studies on the stock assessment and formulating strategies for rational exploitation of the species.

Sex-structured population dynamics of blue marlin Makaira nigricans in the Pacific Ocean

2014 ◽  
Vol 80 (5) ◽  
pp. 869-878 ◽  
Author(s):  
Hui-Hua Lee ◽  
Kevin R. Piner ◽  
Michael G. Hinton ◽  
Yi-Jay Chang ◽  
Ai Kimoto ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Pacific Ocean ◽  
Blue Marlin ◽  
Makaira Nigricans ◽  
Structured Population ◽  
The Pacific ◽  
Structured Population Dynamics ◽  
The Pacific Ocean
Sign in / Sign up

Export Citation Format

Share Document