Stock Assessment Problems in Atlantic Herring (Clupea harengus) in the Northwest Atlantic

1985 ◽  
Vol 42 (5) ◽  
pp. 888-898 ◽  
Author(s):  
M. Sinclair ◽  
V. C. Anthony ◽  
T. D. Iles ◽  
R. N. O'Boyle
Keyword(s):  
Stock Assessment ◽  
Population Analysis ◽  
Age Distribution ◽  
Clupea Harengus ◽  
Assessment Process ◽  
Atlantic Herring ◽  
Management Units ◽  
Management Measures ◽  
Stock Assessments ◽  
Assessment Problems

Total annual catches of Atlantic herring (Clupea harengus) in NAFO statistical areas 3–6 have declined steadily since 1968, and have not rebounded after management measures were implemented in the late 1970's (unlike demersal species in the area). The accuracy of the biomass estimates generated by sequential population analysis is evaluated by a retrospective analysis for 3 of the 10 management units for herring fisheries. In each case, the stock assessments have tended to seriously underestimate the declines in stock abundance and overestimate the upswings. Fishing mortalities have exceeded F0.1, but they have rarely exceeded Fmax, the level below which growth overfishing is prevented. Three assumptions in the stock assessment process are evaluated in relation to the 4WX management unit: (1) the various management units are in fact self-sustaining populations; (2) catchability (i.e. fishing mortality per unit of effort) is constant and independent of stock size; and (3) the population is in the stable age distribution. We conclude that at least part of the management failures are due to invalid assumptions in the stock assessment models. An approach that has prevented growth overfishing may well have caused recruitment overfishing. Atlantic herring should be managed on principles suited to salmon rather than those applied to groundfish.

scholarly journals Development of long-term larval indices for Atlantic herring (Clupea harengus) on the northeast US continental shelf

2009 ◽  
Vol 67 (4) ◽  
pp. 617-627 ◽  
Author(s):  
David E. Richardson ◽  
Jonathan A. Hare ◽  
William J. Overholtz ◽  
Donna L. Johnson
Keyword(s):  
Continental Shelf ◽  
Stock Assessment ◽  
Clupea Harengus ◽  
Assessment Process ◽  
Atlantic Herring ◽  
Large Drop ◽  
Index Development ◽  
Northeast Us ◽  
Analytical Approaches

Abstract Richardson, D. E., Hare, J. A., Overholtz, W. J., and Johnson, D. L. 2010. Development of long-term larval indices for Atlantic herring (Clupea harengus) on the northeast US continental shelf. – ICES Journal of Marine Science, 67: 617–627. The incorporation of data from ichthyoplankton programmes into the stock assessment process has lagged far behind the use of data from comparable adult-monitoring programmes. This can in part be attributed to a mismatch between established analytical approaches to larval-index development and the inconsistencies in sampling for many long-term ichthyoplankton datasets. Along the northeast US continental shelf, ichthyoplankton surveys have been carried out by the Northeast Fisheries Science Center (NMFS/NOAA) multiple times annually since 1971, but the spatial and seasonal allocation of sampling has varied substantially. Here, we present a non-linear least-squares approach to larval-index development. We use the age structure and abundance of larvae on each survey to derive the larval index, along with parameters describing the survival of larvae and the seasonal cycle of hatching. Application to Atlantic herring (Clupea harengus) revealed a large drop in the index around 1976, an increase in the index through the late 1980s, and another large drop in 2004. This index was correlated with the stock assessment estimate of Atlantic herring spawning-stock biomass from 1971 to 2003, but differed substantially during 2004. Our results demonstrate that our approach to larval-index development is flexible to the inconsistencies in sampling effort.

Interaction Between Stock Area, Stock Abundance, and Catchability Coefficient

1985 ◽  
Vol 42 (5) ◽  
pp. 989-998 ◽  
Author(s):  
G. H. Winters ◽  
J. P. Wheeler
Keyword(s):  
Stock Assessment ◽  
Population Decline ◽  
Clupea Harengus ◽  
Atlantic Herring ◽  
Population Abundance ◽  
Commercial Catch ◽  
Standard Manner ◽  
Clupea Harengus Harengus ◽  
The Relationship ◽  
Stock Abundance

The relationship between commercial catch-rates and population density upon which many stock assessment models depend assumes that stock area (A) is constant and independent of population abundance. Starting from a theoretical demonstration that the catchability coefficient (q) is inversely proportional to A, we establish the empirical basis of this relationship through comparisons of q and A of various Northwest Atlantic herring (Clupea harengus harengus) stocks and, in more detail, for Fortune Bay herring. For these stocks the relationship was of the form q = cA−b. For Atlantic herring stocks, levels of b were in excess of 0.80. In Fortune Bay herring, reductions in abundance were accompanied by proportional reductions in A, which in turn was inversely correlated with changes in q. School size, measured as catch per set, also declined as population levels declined but the change was not proportional. Published findings indicate that pelagic stocks in particular, and fish stocks in general, exhibit a common response of reductions in A with interactive increases in the q during periods of rapid population decline. We conclude that the conventional assumption of a constant stock area is usually violated due to the systematic interaction between A and population abundance which is reflected in an inverse relationship between stock abundance and q. Calibration of sequential population models should therefore be restricted to research vessel data collected in a standard manner and covering the distributional area of the stock.

scholarly journals “The Elephant in the Room”: Exploring Natural Mortality Uncertainty in Statistical Catch at Age Models

2020 ◽  
Vol 7 ◽  
Author(s):  
Alessandro Mannini ◽  
Cecilia Pinto ◽  
Christoph Konrad ◽  
Paraskevas Vasilakopoulos ◽  
Henning Winker
Keyword(s):  
Stock Assessment ◽  
Assessment Process ◽  
Sensitivity Analyses ◽  
Fish Stock ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Food And Agriculture ◽  
Stock Assessments ◽  
The Mediterranean ◽  
The Impact

The natural mortality rate (M) of a fish stock is typically highly influential on the outcome of age-structured stock assessment models, but at the same time extremely difficult to estimate. In data-limited stock assessments, M usually relies on a range of empirically or theoretically derived M estimates, which can vary vastly. This article aims at evaluating the impact of this variability in M using seven Mediterranean stocks as case studies of statistical catch-at-age assessments for information-limited fisheries. The two main bodies carrying out stock assessments in the Mediterranean and Black Seas are European Union’s Scientific Technical Economic Committee for Fisheries (STECF) and Food and Agriculture Organization’s General Fisheries Commission for the Mediterranean (GFCM). Current advice in terms of fishing mortality levels is based on a single “best” M assumption which is agreed by stock assessment expert working groups, but uncertainty about M is not taken into consideration. Our results demonstrate that not accounting for the uncertainty surrounding M during the assessment process can lead to strong underestimation or overestimation of fishing mortality, potentially biasing the management process. We recommend carrying out relevant sensitivity analyses to improve stock assessment and fisheries management in data-limited areas such as the Mediterranean basin.

scholarly journals Seabird diets as bioindicators of Atlantic herring recruitment and stock size: a new tool for ecosystem-based fisheries management

2018 ◽  
Vol 75 (8) ◽  
pp. 1215-1229 ◽  
Author(s):  
Lauren C. Scopel ◽  
Antony W. Diamond ◽  
Stephen W. Kress ◽  
Adrian R. Hards ◽  
Paula Shannon
Keyword(s):  
Fishery Management ◽  
Gulf Of Maine ◽  
Clupea Harengus ◽  
Data Series ◽  
Atlantic Herring ◽  
Stock Biomass ◽  
Stock Assessments ◽  
Spawning Stock ◽  
Fishery Data ◽  
Ecosystem Based Fisheries Management

Ecosystem-based fishery management requires understanding of relationships between exploited fish and their predators, such as seabirds. We used exploratory regression analyses to model relationships between Atlantic herring (Clupea harengus) in the diet of seabird chicks at nine nesting colonies in the Gulf of Maine and four types of fishery- and survey-derived herring data. We found several strong relationships, which suggests spatial structuring in herring stocks and likely patterns of herring movements before they recruit into the fishery. Some types of herring data seldom used in stock assessments — notably acoustic surveys, fixed-gear landings, and mass-at-age (i.e., weight-at-age) — correlated as strongly with seabird data as more commonly used series, such as mobile-gear landings and modeled spawning stock biomass. Seabird chick diets collected at specific locations thus offer a promising means to assess the size, distribution, and abundance of juvenile herring across a broad area prior to recruitment, which is a major source of uncertainty in fisheries. Common terns (Sterna hirundo) showed the most potential as a bioindicator, correlating well and showing consistent spatial patterns with 11 of 13 fishery data series.

Incorporating Uncertainty into Fishery Models

2002 ◽  
Keyword(s):  
Monte Carlo ◽  
Stock Assessment ◽  
Population Analysis ◽  
Current Method ◽  
Spanish Mackerel ◽  
Virtual Population ◽  
Stock Assessments ◽  
History Of ◽  
Management Advice ◽  
Bootstrap Algorithm

<em>Abstract.—</em> The stock assessment analyses of king and Spanish mackerel fisheries of the southeastern United States have a long history of incorporating uncertainty. The development of this philosophy resulted from a number of unique circumstances, both biological and historical, that encouraged the incorporation of stochastic approaches and risk evaluation to the assessment and management process. The progression from simple discrete decision tree analysis to delta methods to Monte Carlo/bootstrap methods was due not only to advances in assessment technology but also to changing requirements for management. The current method for mackerel stock assessment is a tuned virtual population analysis with uncertainty incorporated via a mixed Monte Carlo/bootstrap algorithm. Through this procedure, uncertainty in the tuning indices, catch-at-age and natural mortality rate are directly incorporated into the advice provided to management. The management advice is given in terms of probability statements, as opposed to point estimates, to reflect this uncertainty in the stock assessments. This approach is a result of the evolution of the assessment and management and provides a pragmatic alternative in the “frequentist versus Bayesian” debate.

scholarly journals Utility of 18-kHz acoustic data for abundance estimation of Atlantic herring (Clupea harengus)

2012 ◽  
Vol 69 (6) ◽  
pp. 1086-1098 ◽  
Author(s):  
Ryan A. Saunders ◽  
Ciaran O'Donnell ◽  
Rolf J. Korneliussen ◽  
Sascha M. M. Fässler ◽  
Maurice W. Clarke ◽  
...  
Keyword(s):  
Stock Assessment ◽  
Clupea Harengus ◽  
Assessment Model ◽  
Target Strength ◽  
Abundance Estimation ◽  
Atlantic Herring ◽  
Acoustic Data ◽  
Substantial Problem ◽  
The Impact ◽  
Age Estimates

Abstract Saunders, R. A., O'Donnell, C., Korneliussen, R. J., Fässler, S. M. M., Clarke, M. W., Egan, A, and Reid, D. 2012. Utility of 18-kHz acoustic data for abundance estimation of Atlantic herring (Clupea harengus) – ICES Journal of Marine Science, 69: 1086–1098. Current acoustic survey protocols for Atlantic herring (Clupea harengus) abundance estimation are principally dependent upon 38-kHz backscatter data. This can constitute a substantial problem for robust stock assessment when 38-kHz data are compromised. Research vessels now typically collect multifrequency data during acoustic surveys, which could be used to remediate such situations. Here, we investigate the utility of using 18- and 120-kHz data for herring abundance estimation when the standard 38-kHz approach is not possible. Estimates of herring abundance/biomass in the Celtic Sea (2007–2010) were calculated at 18, 38, and 120 kHz using the standard 38-kHz target-strength (TS) model and geometrically equivalent TS models at 18 and 120 kHz. These estimates were compared to assess the level of coherence between the three frequencies, and 18-kHz-derived estimates were subsequently input into standard 38-kHz-based population models to evaluate the impact on the assessment. Results showed that estimates of herring abundance/biomass from 18 and 38 kHz acoustic integration varied by only 0.3–5.4%, and acoustically derived numbers-at-age estimates were not significantly (p > 0.05) different from 1:1. Estimates at 120 kHz were also robust. Furthermore, 18-kHz-derived estimates did not significantly change the assessment model output, indicating that 18-kHz data can be used for herring stock assessment purposes.

Environmental Effects on Recruitment, Growth, and Vulnerability of Atlantic Herring (Clupea harengus harengus) in the Gulf of Maine Region

1985 ◽  
Vol 42 (S1) ◽  
pp. s158-s173 ◽  
Author(s):  
V. C. Anthony ◽  
M. J. Fogarty
Keyword(s):  
Larval Development ◽  
Minimum Temperature ◽  
Gulf Of Maine ◽  
Population Analysis ◽  
Clupea Harengus ◽  
Atlantic Herring ◽  
Virtual Population Analysis ◽  
Virtual Population ◽  
Spawning Stock ◽  
Clupea Harengus Harengus

Atlantic herring (Clupea harengus harengus) recruitment in the Gulf of Maine since 1947 has varied by a ratio of 20 to 1. Since heavy fishing began in the mid-1960's, recruitment has fluctuated by only a factor of 9 to 1. The greatest fluctuations in recruitment, therefore, historically occurred in the absence of high fishing mortality. Recruitment predictions and understanding of the causes of fluctuations are extremely important, since strong year classes traditionally have sustained the herring fisheries in the Gulf of Maine. The effect of environmental variables (particularly temperature) on herring recruitment and growth were examined in detail. Vulnerability of Gulf of Maine herring in response to moon phase is also considered. Indices of abundance of Atlantic herring in the Gulf of Maine were calculated for three time periods using three different procedures. Indices of abundance for the periods of 1915–67 and 1951–81 indicated that productivity, or amount of recruitment per amount of spawning stock, was positively related to temperature or other factors (e.g. food availability) related to temperature at intermediate to high levels of spawning stock biomass. For the shorter and most recent time period (1965–81), abundance was calculated by virtual population analysis and an attempt was made to relate temperature effects during several periods in the first year of life to recruitment levels at age 2. The mean, maximum, and minimum water temperatures during (1) September–December (spawning – early larval development), (2) January–April (overwintering and late larval development), and (3) May–August (postlarval) periods were correlated with abundance. Significant effects of mean and minimum temperature during period 2 and minimum temperature during period 3 were observed, suggesting that environmental influences on determination of year class strength occur during late larval – early juvenile phases. Possible reasons for the discrepancy between the long-term analyses bases on abundance indices and the more detailed analyses using population size estimates based on virtual population analysis are discussed. An indication of environmental limitation is also shown by density-dependent growth. Growth appears to be related to both age 2 abundance and summer water temperature. When abundance is great, its effect overcomes the positive effect of temperature (or other factors indicated by temperature). The environment also alters the availability and vulnerability of herring to the inshore fisheries. Young herring are more available and vulnerable to fixed gear during the dark phase of the moon. This effect is pronounced when abundance is low.

Homing of Atlantic Herring (Clupea harengus harengus) in Newfoundland Waters as Indicated by Tagging Data

1984 ◽  
Vol 41 (1) ◽  
pp. 108-117 ◽  
Author(s):  
J. P. Wheeler ◽  
G. H. Winters
Keyword(s):  
East Coast ◽  
Fishing Effort ◽  
Clupea Harengus ◽  
Atlantic Herring ◽  
Stock Management ◽  
Management Units ◽  
Management Objectives ◽  
Rational Distribution ◽  
Clupea Harengus Harengus

An extensive tagging program was carried out on the herring populations along the east coast of Newfoundland during the 1970s as a basis for defining stock management units. The resulting tag recapture data have been examined in relation to the hypothesis that the majority of Atlantic herring (Clupea harengus harengus) return to the same area to spawn in successive years. Our analyses support this hypothesis and indicate that homing rates for Atlantic herring are high (approximately 90%). We concluded that herring fisheries restricted to spawning fish would allow a more rational distribution of fishing effort such that individual spawning stocks could be exploited in varying fashion according to the desired management objectives.

scholarly journals Review of integrated size-structured models for stock assessment of hard-to-age crustacean and mollusc species

2013 ◽  
Vol 70 (1) ◽  
pp. 16-33 ◽  
Author(s):  
Andre E. Punt ◽  
TzuChuan Huang ◽  
Mark N. Maunder
Keyword(s):  
Stock Assessment ◽  
Age Distribution ◽  
Size Composition ◽  
Data Sources ◽  
Multiple Sources ◽  
Surplus Production ◽  
Production Models ◽  
Stock Assessments ◽  
Mollusc Species ◽  
Size At Age

Abstract Punt, A. E., Huang, T., and Maunder, M. N. 2013. Review of integrated size-structured models for stock assessment of hard-to-age crustacean and mollusc species. – ICES Journal of Marine Science, 70:16–33. Crustaceans and molluscs such as crabs, rock lobsters, prawns, abalone, and oysters constitute large and valuable fisheries. However, assessments of these species are hampered because they cannot be production aged, in contrast to many teleosts. The major data sources for these species, in addition to catch and abundance index data, are the size compositions of the catches and of any fishery-independent indices. Assessments of such species have been conducted using age-based methods of stock assessment, as well as surplus production models. However, size-structured methods are now preferred because they can make full use of size-composition data, are able to integrate multiple sources of data, and produce the types of outputs which are needed for management purposes. An advantage of size-based models over age-based models is that all processes can be size-based, and these processes can modify the (unmodelled) size-at-age distribution. We review these methods, highlighting the choices that need to be made when developing integrated size-structured stock assessments, the data sources which are typically available and how they are used for parameter estimation, and contrast a number of such assessments worldwide.

scholarly journals Sources of variation in stomach contents of predators of Atlantic herring in the Northwest Atlantic during 1973–2014

2018 ◽  
Vol 75 (4) ◽  
pp. 1439-1450 ◽  
Author(s):  
Jonathan J Deroba
Keyword(s):  
Stomach Contents ◽  
Clupea Harengus ◽  
Spatial And Temporal Variation ◽  
Atlantic Herring ◽  
Predator Species ◽  
Stock Assessments ◽  
Generalized Additive Mixed Models ◽  
Additive Mixed Models ◽  
Sources Of Variation ◽  
Biased Estimates

AbstractSpatial and temporal variation in stomach-contents data is often unquantified or combined in such a way (e.g. averaged among years) that true signal in diets may be lost. Using a delta approach, this paper fits generalized additive mixed models (GAMMs) to the amount of Atlantic herring (Clupea harengus) identified in predator stomachs using only data from stomachs in which herring occurred, and to the probability that a stomach contained herring. Both the amount of herring in stomachs and the probability of a stomach containing herring varied seasonally, spatially, and among years. Of the random effects in each GAMM, the effect of predator species had the largest variance. An index of herring abundance derived from the stomach-contents data was generally consistent with recent herring stock assessments. The temporal and spatial variation in the stomach-contents data suggested that the effect of averaging or combining stomach-contents data among years, seasons, or areas may lead to falsely precise or biased estimates from multispecies assessments or in estimates of consumption, and may restrain the relevance of static foodweb models.

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