Relationships between Common Biological Reference Points Used as Thresholds and Targets of Fisheries Management Strategies

1994 ◽  
Vol 51 (1) ◽  
pp. 110-122 ◽  
Author(s):  
Pamela M. Mace
Keyword(s):  
Life History ◽  
Density Dependence ◽  
Fisheries Management ◽  
Management Strategies ◽  
Mortality Rates ◽  
Reference Points ◽  
Fishing Mortality ◽  
New Methods ◽  
Life History Characteristics ◽  
Target Fishing

Relationships between various biological reference points (BRPs) used to define thresholds and targets of fisheries management strategies were examined for a range of combinations of life history characteristics. Rank orderings of the selected BRPs were strongly influenced by the degree of density dependence in the underlying spawning–recruitment (S–R) relationship. The validity of F0.1, Fmax, F20% (the fishing mortality at which spawning per recruit is 20% of the maximum), and other reference fishing mortality rates as approximations to Fmsy or as thresholds of overfishing is highly dependent on life history characteristics, particular the degree of density dependence in the S–R relationship. It is recommended that F40% be adopted as a target fishing mortality rate when the S–R relationship is unknown and that threshold levels of biomass be related to the estimated or assumed degree of density dependence in the S–R relationship. Two new methods of calculating threshold biomass levels are suggested as alternatives to the familiar 20% B0 rule.

scholarly journals Ecosystem-based reference points under varying plankton productivity states and fisheries management strategies

2019 ◽  
Vol 76 (7) ◽  
pp. 2045-2059 ◽  
Author(s):  
Chuanbo Guo ◽  
Caihong Fu ◽  
Robyn E Forrest ◽  
Norm Olsen ◽  
Huizhu Liu ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Management Strategies ◽  
Reference Points ◽  
Productivity Change ◽  
Pacific Herring ◽  
Fishing Mortality ◽  
Pacific Cod ◽  
Sustainable Fisheries ◽  
Ecosystem Effects ◽  
Plankton Biomass

Abstract In the context of ecosystem-based fisheries management, which should consider changing and uncertain environmental conditions, the development of ecosystem-based biological reference points (EBRPs) to account for important multi-species (MS) interactions, fishery operations, and climate change, is of paramount importance for sustainable fisheries management. However, EBRPs under varying plankton productivity states and fisheries management strategies are seldom developed, and the ecosystem effects of these changes are still largely unknown. In this study, ecosystem-based FMSY (fishing mortality rate at MSY) values were estimated within an end-to-end ecosystem model (OSMOSE) for three focused fish species (Pacific Herring, Clupea pallasii; Pacific Cod, Gadus macrocephalus; Lingcod, Ophiodon elongatus) under three plankton productivity states of differing plankton biomass at high, current, and low levels. In addition, ecosystem effects were compared across different plankton productivity and fisheries management strategies with the latter consisting of two fishery scenarios (i.e. single-species-focused (SS) and MS-focused), various fishing mortality rates, and two harvest policies (with and without harvest control rules, HCRs). Main findings of this study include: (i) plankton productivity change affected the values of ecosystem-based FMSY, which increased as plankton productivity states changed from low to high plankton biomass; (ii) ecosystem-based FMSY for Pacific Herring and Pacific Cod stocks increased when fishery scenarios shifted from SS-focused to MS-focused; (iii) fisheries management incorporating HCR yielded more stable system catch and system biomass; and (iv) high plankton biomass combined with fisheries management using HCR could maintain stable ecosystem production and sustainable fisheries. Based on our findings, we highlight possible adaptive fisheries management strategies in the face of future climate and ocean changes. Overall, EBRPs complement SS stock assessments by incorporating key ecological processes and ecosystem properties, thus providing supporting evidence for better incorporation of ecosystem considerations into scientific advice for sustainable fisheries management.

Biological reference points for fish stocks in a multispecies context

2001 ◽  
Vol 58 (11) ◽  
pp. 2167-2176 ◽  
Author(s):  
Jeremy S Collie ◽  
Henrik Gislason
Keyword(s):  
Life History ◽  
Growth Rates ◽  
Prey Species ◽  
Prey Availability ◽  
Mortality Rates ◽  
Reference Points ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Predator Species ◽  
Life History Parameters

Biological reference points (BRPs) are widely used to define safe levels of harvesting for marine fish populations. Most BRPs are either minimum acceptable biomass levels or maximum fishing mortality rates. The values of BRPs are determined from historical abundance data and the life-history parameters of the fish species. However, when the life-history parameters change over time, the BRPs become moving targets. In particular, the natural mortality rate of prey species depends on predator levels; conversely, predator growth rates depend on prey availability. We tested a suite of BRPs for their robustness to observed changes in natural mortality and growth rates. We used the relatively simple Baltic Sea fish community for this sensitivity test, with cod as predator and sprat and herring as prey. In general, the BRPs were much more sensitive to the changes in natural mortality rates than to growth variation. For a prey species like sprat, fishing mortality reference levels should be conditioned on the level of predation mortality. For a predator species, a conservative level of fishing mortality can be identified that will prevent growth overfishing and ensure stock replacement. These first-order multispecies interactions should be considered when defining BRPs for medium-term (5–10 year) management decisions.

scholarly journals Evaluation of the exploitation of Eastern Baltic cod (Gadus morhua callarias L.) stock in 1976–1997

2003 ◽  
Vol 60 (5) ◽  
pp. 1114-1122 ◽  
Author(s):  
Krzysztof Radtke
Keyword(s):  
Gadus Morhua ◽  
Management Strategies ◽  
Mortality Rates ◽  
Reference Points ◽  
Fishing Mortality ◽  
Safe Level ◽  
Stock Biomass ◽  
Spawning Biomass ◽  
Eastern Baltic ◽  
Baltic Cod

Abstract Big changes occurred in the Eastern Baltic cod biomass and catches in the 1976–1997 period. At present, the Eastern Baltic cod stock spawning biomass (SSB) and catches are approximately five times lower than their highest ever recorded levels observed in the middle of the 1980s. The reasons for the stock decline, namely low recruitment and high fishing mortality, are widely known and well described in the literature. Throughout the whole period, the International Council for the Exploration of the Sea (ICES) made scientific recommendations regarding the exploitation level of the cod stock. The ICES presented and analysed different management strategies based on fishing mortalities which corresponded to biological reference points (BRP) and also recommended total allowable catches (TACs) for cod, taking into account the sustainability of cod resources. In fact, in most years the TAC established by the International Baltic Sea Fisheries Commission (IBSFC) and cod catches (observed exploitation) exceeded the ICES-recommended TAC and thus their scientific advice was neither taken into account by the IBSFC nor by fishermen. This paper evaluates: (1) the would-be state of the Eastern Baltic cod stock if it had been exploited according to ICES-recommended TAC levels, as compared with observed stock exploitation; and (2) the potential effects of management using fishing mortality rates which correspond to BRP on SSB estimates and catch levels, as compared with observed stock exploitation. It is concluded that if ICES advice had been followed, the cumulative cod catches in the 1976–1997 period would have been the same as those observed, but the stock biomass would have been much higher and at a safe level (SSB above 240 000 t). Furthermore, from the comparative analysis of different management strategies based on BRP and the observed strategy, it appears that other management strategies could have been applied which would have produced a higher biomass and greater cumulative catch numbers than those observed.

scholarly journals Incorporating environmental forcing in developing ecosystem-based fisheries management strategies

2019 ◽  
Vol 77 (2) ◽  
pp. 500-514 ◽  
Author(s):  
Chuanbo Guo ◽  
Caihong Fu ◽  
Norm Olsen ◽  
Yi Xu ◽  
Arnaud Grüss ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Management Strategies ◽  
Mortality Rates ◽  
Marine Ecosystems ◽  
Ecosystem Structure ◽  
Fishing Mortality ◽  
Management Options ◽  
Environmental Forcing ◽  
Ecosystem Effects ◽  
Ecosystem Level

Abstract This study incorporated two pathways of environmental forcing (i.e. “larval mortality forcing” and “somatic growth forcing”) into an end-to-end ecosystem model (Object-oriented Simulator of Marine ecOSystEms, OSMOSE) developed for the Pacific North Coast Integrated Management Area (PNCIMA) off western Canada, in order to evaluate alternative fisheries management strategies under environmental changes. With a suite of ecosystem-level indicators, the present study first compared the ecosystem effects of different pathways of environmental forcing scenarios; and then evaluated the alternative fisheries management strategies which encompassed a series of fishing mortality rates relative to FMSY (the fishing mortality rate that produces maximum sustainable yield) and a set of precautionary harvest control rules (HCRs). The main objectives of this study were to (i) explore the ecosystem effects of different environmental forcing scenarios; (ii) identify the impacts of different fishing mortality rates on marine ecosystem structure and function; and (iii) evaluate the ecosystem-level performance of various levels of precautionary HCRs. Results indicated that different pathways of environmental forcing had different ecosystem effects and incorporating appropriate HCRs in the fisheries management process could help maintain ecosystem health and sustainable fisheries. This study provides important information on future fisheries management options within similar marine ecosystems that are facing global changes.

scholarly journals Can stock–recruitment points determine which spawning potential ratio is the best proxy for maximum sustainable yield reference points?

2013 ◽  
Vol 70 (6) ◽  
pp. 1075-1080 ◽  
Author(s):  
Christopher M. Legault ◽  
Elizabeth N. Brooks
Keyword(s):  
Life History ◽  
Mortality Rate ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Sustainable Yield ◽  
Marine Science ◽  
Fishing Mortality ◽  
Scatter Plots ◽  
Stock Recruitment ◽  
Spawning Potential Ratio

Abstract Legault, C. M., and Brooks, E. N. 2013. Can stock–recruitment points determine which spawning potential ratio is the best proxy for maximum sustainable yield reference points? – ICES Journal of Marine Science, 70: 1075–1080. The approach of examining scatter plots of stock–recruitment (S–R) estimates to determine appropriate spawning potential ratio (SPR)-based proxies for FMSY was investigated through simulation. As originally proposed, the approach assumed that points above a replacement line indicate year classes that produced a surplus of spawners, while points below that line failed to achieve replacement. In practice, this has been implemented by determining Fmed, the fishing mortality rate that produces a replacement line with 50% of the points above and 50% below the line. A new variation on this approach suggests FMSY proxies can be determined by examining the distribution of S–R points that are above or below replacement lines associated with specific SPRs. Through both analytical calculations and stochastic results, we demonstrate that this approach is fundamentally flawed and that in some cases the inference is diametrically opposed to the method's intended purpose. We reject this approach as a tool for determining FMSY proxies. We recommend that the current proxy of F40% be maintained as appropriate for a typical groundfish life history.

An Alternative Perspective on Recruitment Overfishing and Biological Reference Points

1987 ◽  
Vol 44 (4) ◽  
pp. 913-918 ◽  
Author(s):  
M. P. Sissenwine ◽  
J. G. Shepherd
Keyword(s):  
Fisheries Management ◽  
Reference Point ◽  
Reference Points ◽  
Fishing Mortality ◽  
Alternative Perspective ◽  
Conventional Models ◽  
Definition Of ◽  
Yield Per Recruit ◽  
Spawning Biomass

Biological reference points are used to guide fisheries management decisions. The reference points most often used are expressed in terms of fishing mortality rate (F). Fmsy relates to the maximization of sustainable yield. In principle, it is a most useful reference point, but in practice it is difficult to estimate. Fmax and F0.1 relate to certain levels of yield per recruit and are easily estimated, but they ignore conservation of the resource. Recruitment overfishing has usually been understood to occur when a population has been fished down to a point where recruitment is substantially reduced or fails. It has not been used as a basis for a biological reference point because the definition is vague and cannot be readily related to fishing mortality. Levels of spawning biomass below which recruitment seems to be reduced have been used, but their determination from available data is usually difficult and controversial. We propose an alternative definition of recruitment overfishing in terms of the level of fishing pressure that reduces the spawning biomass of a year class over its lifetime below the spawning biomass of its parents on average. Conventional models and types of data can be used to determine this level of F, denoted as Frep, which clearly relates to the replacement of spawning biomass and thus to sustainability of a population and yield in the long term.

Sustainability assessment for fishing effects (SAFE) on highly diverse and data-limited fish bycatch in a tropical prawn trawl fishery

2009 ◽  
Vol 60 (6) ◽  
pp. 563 ◽  
Author(s):  
Shijie Zhou ◽  
Shane P. Griffiths ◽  
Margaret Miller
Keyword(s):  
Mortality Rate ◽  
Fishery Management ◽  
Sustainability Assessment ◽  
Cost Effective ◽  
Mortality Rates ◽  
Assessment Method ◽  
Reference Points ◽  
Fishing Mortality ◽  
Point Estimates ◽  
Large Numbers

A new sustainability assessment for fishing effects (SAFE) method was used to assess the biological sustainability of 456 teleost bycatch species in Australia’s Northern Prawn Fishery. This method can quantify the effects of fishing on sustainability for large numbers of species with limited data. The fishing mortality rate of each species based on its spatial distribution (estimated from detection/non-detection data) and the catch rate based on fishery-dependent or fishery-independent data were estimated. The sustainability of each species was assessed by two biological reference points approximated from life-history parameters. The point estimates indicated that only two species (but 21 when uncertainty was included) had estimated fishing mortality rates greater than a fishing mortality rate corresponding to the maximum sustainable yield. These two species also had their upper 95% confidence intervals (but not their point estimates) greater than their minimum unsustainable fishing mortality rates. The fact that large numbers of species are sustainable can be attributed mainly to their wide distributions in unfished areas, low catch rates within fished areas and short life spans (high biological productivity). The present study demonstrates how SAFE may be a cost-effective quantitative assessment method to support ecosystem-based fishery management.

scholarly journals Reproductive hyperallometry and managing the world’s fisheries

2021 ◽  
Vol 118 (34) ◽  
pp. e2100695118
Author(s):  
Dustin J. Marshall ◽  
Michael Bode ◽  
Marc Mangel ◽  
Robert Arlinghaus ◽  
E. J. Dick
Keyword(s):  
Fisheries Management ◽  
Management Strategies ◽  
Reference Points ◽  
Target Level ◽  
Fish Stocks ◽  
Global Food Security ◽  
Common Reference ◽  
Future Assessment ◽  
Traditional Approaches ◽  
Global Food

Marine fisheries are an essential component of global food security, but many are close to their limits and some are overfished. The models that guide the management of these fisheries almost always assume reproduction is proportional to mass (isometry), when fecundity generally increases disproportionately to mass (hyperallometry). Judged against several management reference points, we show that assuming isometry overestimates the replenishment potential of exploited fish stocks by 22% (range: 2% to 78%) for 32 of the world’s largest fisheries, risking systematic overharvesting. We calculate that target catches based on assumptions of isometry are more than double those based on assumptions of hyperallometry for most species, such that common reference points are set twice as high as they should be to maintain the target level of replenishment. We also show that hyperallometric reproduction provides opportunities for increasing the efficacy of tools that are underused in standard fisheries management, such as protected areas or harvest slot limits. Adopting management strategies that conserve large, hyperfecund fish may, in some instances, result in higher yields relative to traditional approaches. We recommend that future assessment of reference points and quotas include reproductive hyperallometry unless there is clear evidence that it does not occur in that species.

Spatiotemporal variation in maturation: a case study with American plaice (Hippoglossoides platessoides) on the Grand Bank off Newfoundland

2020 ◽  
Vol 77 (10) ◽  
pp. 1688-1699
Author(s):  
Nan Zheng ◽  
Matthew Robertson ◽  
Noel Cadigan ◽  
Fan Zhang ◽  
Joanne Morgan ◽  
...  
Keyword(s):  
Life History ◽  
Spatial Variation ◽  
Fisheries Management ◽  
Life History Traits ◽  
Spatial Scales ◽  
Management Strategies ◽  
Spatiotemporal Variation ◽  
Small Scale ◽  
Spatial And Temporal Scales ◽  
Hippoglossoides Platessoides

Fisheries management usually does not explicitly account for spatial variation in life history traits within populations. However, for some stocks this spatial variation may be substantial. We develop a spatiotemporal generalized linear model and fit the model to a long time series of maturation data for American plaice (Hippoglossoides platessoides) on the Grand Bank off Newfoundland and Labrador. The spatiotemporal correlation structure improves estimation of small-scale spatiotemporal variation in maturity across locations and times with limited or few samples. We test how American plaice maturity varies at three different spatial resolutions. We find improvements in model fit when decreasing spatial scales for higher spatial resolution due to high levels of spatial heterogeneity in American plaice maturity at age and size. Modeling variation in life history traits at the appropriate spatial and temporal scales is necessary for understanding population dynamics and developing appropriate fisheries management strategies.

scholarly journals Life history traits and fishing mortality estimations of Caspian vimba, Vimba vimba (L.), in southwestern coastal regions of the Caspian Sea

2017 ◽  
Vol 25 (3) ◽  
pp. 145-155
Author(s):  
Fateme Taridashti ◽  
Javid Imanpour ◽  
Shahram Abdolmalaki ◽  
Mahvash Hadavi
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Caspian Sea ◽  
Life History Traits ◽  
Mortality Rates ◽  
Fishing Mortality ◽  
Coastal Regions ◽  
The Caspian Sea ◽  
Males And Females ◽  
Existing Data

Abstract This study was conducted to complement existing data about the life cycle of Caspian vimba, Vimba vimba (L.), with estimations of age, growth, and mortality rates. To achieve this, 811 specimens were collected between May 2012 and June 2013 at three fisheries catch stations in southwestern regions of the Caspian Sea including Talesh, Bandar Anzali, and Kiashahr. The growth rate in vimba is relatively high at approximately 0.29 year−1 for females and 0.32 year−1 for males. Asymptotic lengths are 245 mm and 233 mm for females and males, respectively. The growth pattern was isometric for both males and females. The overall sex ratio was balanced (1: 0.92). The instantaneous coefficients of total, natural, and fishing mortality were 1.27, 0.4, and 0.8 year, respectively, and the current exploitation ratio was 0.63 year−1. Results showed that the growth rate of males is higher than that of females. Considering the exploitation ratio, it is apparent that the vimba population is experiencing significant legal and illegal exploitation pressure.

Sign in / Sign up

Export Citation Format

Share Document