Estimating Fmsy from an ensemble of data sources to account for density dependence in Northeast Atlantic fish stocks

2020 ◽  
Author(s):  
Henrik Sparholt ◽  
Bjarte Bogstad ◽  
Villy Christensen ◽  
Jeremy Collie ◽  
Rob van Gemert ◽  
...  
Keyword(s):  
Maximum Sustainable Yield ◽  
Data Sources ◽  
Fishing Pressure ◽  
Fish Stocks ◽  
Northeast Atlantic ◽  
Density Dependent ◽  
Production Models ◽  
Pool Model ◽  
Age Structured ◽  
The 1960S

Abstract A new approach for estimating the fishing mortality benchmark Fmsy (fishing pressure that corresponds to maximum sustainable yield) is proposed. The approach includes density-dependent factors. The analysis considers 53 data-rich fish stocks in the Northeast Atlantic. The new Fmsy values are estimated from an ensemble of data sources: (i) applying traditional surplus production models on time-series of historic stock sizes, fishing mortalities, and catches from the current annual assessments; (ii) dynamic pool model (e.g. age-structured models) estimation for stocks where data on density-dependent growth, maturity, and mortality are available; (iii) extracts from multispecies and ecosystem literature for stocks where well-tested estimates are available; (iv) the “Great Experiment” where fishing pressure on the demersal stocks in the Northeast Atlantic slowly increased for half a century; and (v) linking Fmsy to life history parameters. The new Fmsy values are substantially higher (average equal to 0.38 year−1) than the current Fmsy values (average equal to 0.26 year−1) estimated in stock assessments and used by management, similar to the fishing pressure in the 1960s, and about 30% lower than the fishing pressure in 1970–2000.

Spatial variation in fishing intensity and its effect on yield

2008 ◽  
Vol 65 (4) ◽  
pp. 588-599 ◽  
Author(s):  
Stephen Ralston ◽  
Michael R O’Farrell
Keyword(s):  
Spatial Variation ◽  
Local Density ◽  
Life Stage ◽  
Maximum Sustainable Yield ◽  
Recruitment Rate ◽  
Sustainable Yield ◽  
Fishing Mortality ◽  
Density Dependent ◽  
Age Structured ◽  
Effect On Yield

Fishing mortality is rarely, if ever, evenly distributed over space, yet this is a common assumption of many fisheries models. To evaluate the effect of spatial heterogeneity in fishing mortality on yield, we constructed age-structured models that allowed for differing levels of fishing in three regions within the boundaries of a stock and explored alternative assumptions about the life stage in which density-dependent compensation operates. If the fishing mortality rate (F) is not excessive (i.e., F ≤ FMSY defined for the spatially homogeneous case; MSY, maximum sustainable yield), simulations demonstrated that minor to moderate spatial variation in fishing intensity does not impact sustainable yield. However, if fishing mortality is excessive (F > FMSY), spatial variation in fishing intensity often improves yield and can actually produce yields in excess of MSY when compensation occurs after dispersal, and the density-dependent recruitment rate is a function of the local density of adults. The yield premium generated in these simulations by postdispersal density dependence is due to a low level of compensatory mortality in heavily fished areas coupled with dispersal of propagules into these areas from lightly fished adjacent regions.

scholarly journals Fisheries Reference Point and Stock Status of Croaker Fishery (Sciaenidae) Exploited from the Bay of Bengal, Bangladesh

2022 ◽  
Vol 10 (1) ◽  
pp. 63
Author(s):  
Partho Protim Barman ◽  
Md. Mostafa Shamsuzzaman ◽  
Petra Schneider ◽  
Mohammad Mojibul Hoque Mozumder ◽  
Qun Liu
Keyword(s):  
Bay Of Bengal ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Production Model ◽  
Fishing Pressure ◽  
Surplus Production ◽  
Stock Status ◽  
Management Measures ◽  
Production Models ◽  
The Monte Carlo Method

This research evaluated fisheries reference points and stock status to assess the sustainability of the croaker fishery (Sciaenidae) from the Bay of Bengal (BoB), Bangladesh. Sixteen years (2001–2016) of catch-effort data were analyzed using two surplus production models (Schaefer and Fox), the Monte Carlo method (CMSY) and the Bayesian state-space Schaefer surplus production model (BSM) method. This research applies a Stock–Production Model Incorporating Covariates (ASPIC) software package to run the Schaefer and Fox model. The maximum sustainable yield (MSY) produced by all models ranged from 33,900 to 35,900 metric tons (mt), which is very close to last year’s catch (33,768 mt in 2016). The estimated B > BMSY and F < FMSY indicated the safe biomass and fishing status. The calculated F/FMSY was 0.89, 0.87, and 0.81, and B/BMSY was 1.05, 1.07, and 1.14 for Fox, Schaefer, and BSM, respectively, indicating the fully exploited status of croaker stock in the BoB, Bangladesh. The representation of the Kobe phase plot suggested that the exploitation of croaker stock started from the yellow (unsustainable) quadrant in 2001 and gradually moved to the green (sustainable) quadrant in 2016 because of the reduction in fishing efforts and safe fishing pressure after 2012. Thus, this research suggests that the current fishing pressure needs to be maintained so that the yearly catch does not exceed the MSY limit of croaker. Additionally, specific management measures should implement to guarantee croaker and other fisheries from the BoB.

Management of evolving fish stocks

1998 ◽  
Vol 55 (8) ◽  
pp. 1971-1982 ◽  
Author(s):  
Mikko Heino
Keyword(s):  
Maximum Sustainable Yield ◽  
Evolutionary Change ◽  
Fish Stock ◽  
Sustainable Yield ◽  
Harvest Rate ◽  
Fish Stocks ◽  
Population Dynamics Model ◽  
Before And After ◽  
Age Structured ◽  
Delayed Maturation

Mortality caused by harvesting can select for life history changes in the harvested stock. Should this possibility be taken into account in the management of renewable resources? I compare the performance of different harvest strategies when evolutionary change is accounted for with the help of an age-structured population dynamics model. Assuming that age of first reproduction is the only evolving trait, harvesting of only mature individuals selects for delayed maturation and results in increased sustainable yields. Unselective harvesting of both mature and immature fish selects for earlier maturation which causes the sustainable yield to decrease. Constant stock size and constant harvest rate strategies perform equally well in terms of maximum sustainable yield, both before and after evolutionary change. The maximum sustainable yield for fixed-quota strategies is lower. All those strategies have similar evolutionary consequences given a similar average harvest rate. Coevolutionary dynamics between fish stock and the stock manager indicate that the evolutionary benefits of selective harvesting are attainable without incurring yield losses in the near future.

scholarly journals Comment on “Impacts of historical warming on marine fisheries production”

Science ◽  
2019 ◽  
Vol 365 (6454) ◽  
pp. eaax5721 ◽  
Author(s):  
Cody Szuwalski
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Maximum Sustainable Yield ◽  
Structured Data ◽  
Sea Surface ◽  
Sustainable Yield ◽  
Surplus Production ◽  
Production Models ◽  
Fitting Production ◽  
Age Structured

Free et al. (Reports, 1 March 2019, p. 979) linked sea surface temperature (SST) to surplus production and estimated a 4% decline in maximum sustainable yield (MSY) since 1930. Changes in MSY are expected when fitting production models to age-structured data, so attributing observed changes to SST is problematic. Analyses of recruitment (a metric of productivity in the same database) showed increases in global productivity.

Corrigendum Estimating Fmsy from an ensemble of data sources to account for density dependence in Northeast Atlantic fish stocks

2021 ◽  
Author(s):  
Henrik Sparholt ◽  
Bjarte Bogstad ◽  
Villy Christensen ◽  
Jeremy Collie ◽  
Rob van Gemert ◽  
...  
Keyword(s):  
Density Dependence ◽  
Data Sources ◽  
Fish Stocks ◽  
Northeast Atlantic

Adaptive Probing Strategies for Age-Structured Fish Stocks

1983 ◽  
Vol 40 (5) ◽  
pp. 559-569 ◽  
Author(s):  
D. Ludwig ◽  
R. Hilborn
Keyword(s):  
Management System ◽  
Optimal Size ◽  
Fishing Mortality ◽  
Fish Stocks ◽  
Surplus Production ◽  
Production Models ◽  
Productive Potential ◽  
Adaptive Probing ◽  
Age Structured ◽  
Stock Abundance

This paper examines methods of preventing a stock of fish from being held far below its optimal size. Such sustained overexploitation could arise because the model used to manage the stock poorly represented the stock dynamics, because there are significant errors in the estimates of stock abundance, or because there is insufficient contrast in catch and fishing mortality to generate reliable estimates of the productive potential of the stock. We develop a method to correct for biases due to errors in estimates of abundance and show that this correction does improve estimates of productivity, but not sufficiently to enable a manager to recognize the presence of overexploitation. We demonstrate that the management system must generate significant contrast in catch and effort, and once the contrast is generated the managers can easily find near optimal abundance of the stock. With reasonable levels of contrast even very simple surplus production models will perform well when managing complex age-structured fish stocks.

scholarly journals Challenges to fisheries advice and management due to stock recovery

2018 ◽  
Vol 75 (6) ◽  
pp. 1864-1870 ◽  
Author(s):  
Rob van Gemert ◽  
Ken H Andersen
Keyword(s):  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Forage Fish ◽  
Fish Stocks ◽  
Density Dependent ◽  
Piscivorous Fish ◽  
Predation Mortality ◽  
Management Procedures ◽  
Dependent Growth ◽  
New Situation

Abstract During the 20th century, many large-bodied fish stocks suffered from unsustainable fishing pressure. Now, signs of recovery are appearing among previously overfished large-bodied fish stocks. This new situation raises the question of whether current fisheries advice and management procedures, which were devised and optimized for depleted stocks, are well-suited for the management of recovered stocks. We highlight two challenges for fisheries advice and management: First, recovered stocks are more likely to show density-dependent growth. We show how the appearance of density-dependent growth will make reference points calculated with current procedures inaccurate. Optimal exploitation of recovered large-bodied fish stocks will therefore require accounting for density-dependent growth. Second, we show how a biomass increase of large-bodied piscivorous fish will lead to a reverse trophic cascade, where their increased predation mortality on forage fish reduces forage fish productivity and abundance. The resulting decrease in maximum sustainable yield of forage fish stocks could lead to conflicts between forage and large-piscivore fisheries. Avoiding such conflicts requires that choices are made between the exploitation of interacting fish stocks. Failure to account for the changed ecological state of recovered stocks risks creating new obstacles to sustainable fisheries management.

Red Snapper: Ecology and Fisheries in the U.S. Gulf of Mexico

2007 ◽  
Keyword(s):  
Gulf Of Mexico ◽  
Maximum Sustainable Yield ◽  
Red Snapper ◽  
Lutjanus Campechanus ◽  
Shrimp Fishery ◽  
Spawning Potential Ratio ◽  
Age Structured ◽  
The 1960S ◽  
Age Structured Model ◽  
The U.S

<em>Abstract.</em>—Red snapper <em>Lutjanus campechanus </em>have been fished in the Gulf of Mexico since before the Civil War. The size and efficiency of the commercial fleet increased greatly during the 1960s, but without a corresponding increase in catch, suggesting that red snapper populations throughout the Gulf of Mexico were by that time fully-exploited and perhaps even overfished. Nevertheless, most assessments of red snapper in the U.S. Gulf of Mexico have been based on data collected since the 1980s owing to a combination of gaps in the catch data and limitations of the models employed. The lack of contrast in the more recent data makes it difficult to develop meaningful estimates of stock status, particularly in relation to abundance-based reference points such as the equilibrium spawning biomass at maximum sustainable yield. This paper presents a flexible age-structured model that includes information dating back to the inception of the fishery. The results suggest that the populations of red snapper in the U.S. Gulf of Mexico are well below the levels corresponding to a spawning potential ratio of 30%. They also suggest the stock will not to recover to that level in the foreseeable future without substantial reductions in both the catch of adults by the directed fleets and the bycatch of juveniles by the offshore shrimp fishery.

scholarly journals Implications of late-in-life density-dependent growth for fishery size-at-entry leading to maximum sustainable yield

2018 ◽  
Vol 75 (4) ◽  
pp. 1296-1305 ◽  
Author(s):  
Rob van Gemert ◽  
Ken H Andersen
Keyword(s):  
Density Dependence ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Fish Stocks ◽  
Density Dependent ◽  
Large Size ◽  
Adult Growth ◽  
Stock Assessments ◽  
Stock Recruitment ◽  
Dependent Growth

Abstract Currently applied fisheries models and stock assessments rely on the assumption that density-dependent regulation only affects processes early in life, as described by stock–recruitment relationships. However, many fish stocks also experience density-dependent processes late in life, such as density-dependent adult growth. Theoretical studies have found that, for stocks which experience strong late-in-life density dependence, maximum sustainable yield (MSY) is obtained with a small fishery size-at-entry that also targets juveniles. This goes against common fisheries advice, which dictates that primarily adults should be fished. This study aims to examine whether the strength of density-dependent growth in actual fish stocks is sufficiently strong to reduce optimal fishery size-at-entry to below size-at-maturity. A size-structured model is fitted to three stocks that have shown indications of late-in-life density-dependent growth: North Sea plaice (Pleuronectes platessa), Northeast Atlantic (NEA) mackerel (Scomber scombrus), and Baltic sprat (Sprattus sprattus balticus). For all stocks, the model predicts exploitation at MSY with a large size-at-entry into the fishery, indicating that late-in-life density dependence in fish stocks is generally not strong enough to warrant the targeting of juveniles. This result lends credibility to the practise of predominantly targeting adults in spite of the presence of late-in-life density-dependent growth.

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