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.

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.

A multifrequency method to classify and evaluate fisheries acoustics data

2006 ◽  
Vol 63 (10) ◽  
pp. 2225-2235 ◽  
Author(s):  
J Michael Jech ◽  
William L Michaels
Keyword(s):  
Clupea Harengus ◽  
Biological Information ◽  
Classification Algorithms ◽  
Atlantic Herring ◽  
Population Abundance ◽  
Acoustic Data ◽  
Video Images ◽  
Abundance Estimates ◽  
Fisheries Acoustics ◽  
Acoustic Surveys

Acoustic surveys have been conducted on Georges Bank from 1998 to present to estimate Atlantic herring (Clupea harengus) population abundance. Acoustic data were collected with a 12 or 18, 38, and 120 kHz Simrad EK500 scientific echo sounder. A pelagic trawl and underwater video images were used to collect biological information and to verify the species composition of acoustic backscatter. A multifrequency classification method was developed to improve the efficiency and accuracy of classifying species from acoustic echograms. In this method, a volume backscatter (Sv) threshold was applied equivalently to all echograms, and then a composite echogram was created based on which frequencies had Sv greater than or less than the Sv threshold. The results of this method were compared with the standard method of visually scrutinizing regions, and metrics were developed to evaluate the accuracy of classification algorithms relative to current methods, as well as to assess the effects of classification methods on population abundance estimates. In general, this method matched visually scrutinized Atlantic herring regions, but with consistent biases in classifying 38 kHz backscatter. The metrics highlighted spatial and temporal changes in the acoustic landscape, which may be indicative of intra- and inter-annual biological changes.

Performance of a fisheries catch-at-age model (Stock Synthesis) in data-limited situations

2011 ◽  
Vol 62 (8) ◽  
pp. 927 ◽  
Author(s):  
Chantell R. Wetzel ◽  
André E. Punt
Keyword(s):  
Stock Assessment ◽  
Estimation Method ◽  
Assessment Method ◽  
Assessment Model ◽  
Limited Data ◽  
Composition Data ◽  
Spawning Stock ◽  
Age Model ◽  
Age Structured ◽  
The Impact

Limited data are a common challenge posed to fisheries stock assessment. A simulation framework was applied to examine the impact of limited data and data type on the performance of a widely used catch-at-age stock-assessment method (Stock Synthesis). The estimation method provided negatively biased estimates of current spawning-stock biomass (SSB) relative to the unfished level (final depletion) when only recent survey indices were available. Estimation of quantities of management interest (unfished SSB, virgin recruitment, target fishing mortality and final depletion) improved substantially even when only minimal-length-composition data from the survey were available. However, the estimates of some quantities (final depletion and unfished SSB) remained biased (either positively or negatively) even in the scenarios with the most data (length compositions, age compositions and survey indices). The probability of overestimating yield at the target SSB relative to the true such yield was ~50%, a risk-neutral result, for all the scenarios that included length-composition data. Our results highlight the importance of length-composition data for the performance of an age-structured assessment model, and are encouraging for the assessment of data-limited stocks.

Effects of variable mean target strength on estimates of abundance: the case of Atlantic mackerel (Scomber scombrus)

2016 ◽  
Vol 74 (3) ◽  
pp. 822-831 ◽  
Author(s):  
Ben Scoulding ◽  
Sven Gastauer ◽  
David N. MacLennan ◽  
Sascha M. M. Fässler ◽  
Phillip Copland ◽  
...  
Keyword(s):  
Stock Assessment ◽  
Target Strength ◽  
Fish School ◽  
Acoustic Data ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
North East ◽  
The North ◽  
Frequency Split ◽  
Abundance And Distribution

Atlantic mackerel Scomber scombrus is a small pelagic, migratory fish which supports commercial fisheries. These fish school and are detectable using echosounders, yet fishery-independent estimates of their abundance in the North East Atlantic do not consider acoustic data. Accurate estimates of mean target strength (TS) are presently limiting echo-integration surveys from providing useful estimates of Atlantic mackerel abundance and distribution. This study provides TS estimates for in situ mackerel from multi-frequency split-beam echosounder measurements. TS equals −52.79 dB at 18 kHz, −59.60 dB at 38 kHz, −55.63 dB at 120 kHz, and −53.58 dB at 200 kHz, for a mean mackerel total length = 33.3 cm. These values differ from those currently assumed for this species in analyses of acoustic survey data. We investigate the sensitivity of acoustically estimated mackerel biomass around the Shetland Islands, Scotland, in 2014, to various estimates of TS. Confidence limits were obtained using geostatistics accounting for coverage and spatial autocorrelation. Stock biomasses, estimated from 38 and 200 kHz data, differed by 10.5%, and stock distributions were similar to each other and to the estimates from an independent stock assessment. Because mackerel backscatter at 38 kHz is dominated by echoes from the flesh and may have similarities to echoes from fish with swimbladders, and backscatter at 200 kHz is dominated by relatively stable echoes from the backbone, we recommend using 200 kHz data for estimates of Atlantic mackerel biomass.

An ichthyophoniasis epizootic in Atlantic herring in marine waters around Iceland

2018 ◽  
Vol 75 (7) ◽  
pp. 1106-1116 ◽  
Author(s):  
Guðmundur J. Óskarsson ◽  
Jónbjörn Pálsson ◽  
Asta Gudmundsdottir
Keyword(s):  
Clupea Harengus ◽  
Assessment Model ◽  
Seasonal Development ◽  
Spatial And Temporal Variation ◽  
Atlantic Herring ◽  
Disease Mortality ◽  
Analytical Assessment ◽  
Heart Lesions ◽  
Best Fit ◽  
Significant Mortality

A widespread ichthyophoniasis epizootic occurred in the Icelandic summer-spawning herring (Clupea harengus) stock during the years 2008–2014. The spatial and temporal variation in prevalence of heart lesions and the seasonal development of the disease in the stock were explored with an inspection of hearts. The year classes from 2004 to 2006 had generally the highest prevalence of heart lesions, varying from ∼47%–50% in 2009 to ∼31%–34% in 2014. Newly developed disease was apparently occurring in the autumns of 2008–2010 but not in the autumns thereafter. Analyses of the data strongly suggest that the disease caused mortality in 2009–2011 but was insignificant thereafter, and consequently, the epizootic waned after mid-2011. The analytical assessment model used for the stock gave the best fit to the data when applying disease mortality equivalent to 30% of the diseased herring for these 3 years. Thus, we conclude that the widespread ichthyophoniasis epizootic in the stock over these 6 years caused significant mortality in the stock during the first 3 years but less mortality than suggested in other publications.

scholarly journals A Bayesian approach to estimating target strength

2009 ◽  
Vol 66 (6) ◽  
pp. 1197-1204 ◽  
Author(s):  
Sascha M. M. Fässler ◽  
Andrew S. Brierley ◽  
Paul G. Fernandes
Keyword(s):  
Bayesian Approach ◽  
Tilt Angle ◽  
Clupea Harengus ◽  
Target Strength ◽  
Model Parameters ◽  
Fish Length ◽  
Acoustic Data ◽  
Abundance Estimates ◽  
The Mean ◽  
Conventional Models

Abstract Fässler, S. M. M., Brierley, A. S., and Fernandes, P. G. 2009. A Bayesian approach to estimating target strength. – ICES Journal of Marine Science, 66: 1197–1204. Currently, conventional models of target strength (TS) vs. fish length, based on empirical measurements, are used to estimate fish density from integrated acoustic data. These models estimate a mean TS, averaged over variables that modulate fish TS (tilt angle, physiology, and morphology); they do not include information about the uncertainty of the mean TS, which could be propagated through to estimates of fish abundance. We use Bayesian methods, together with theoretical TS models and in situ TS data, to determine the uncertainty in TS estimates of Atlantic herring (Clupea harengus). Priors for model parameters (surface swimbladder volume, tilt angle, and s.d. of the mean TS) were used to estimate posterior parameter distributions and subsequently build a probabilistic TS model. The sensitivity of herring abundance estimates to variation in the Bayesian TS model was also evaluated. The abundance of North Sea herring from the area covered by the Scottish acoustic survey component was estimated using both the conventional TS–length formula (5.34×109 fish) and the Bayesian TS model (mean = 3.17×109 fish): this difference was probably because of the particular scattering model employed and the data used in the Bayesian model. The study demonstrates the relative importance of potential bias and precision of TS estimation and how the latter can be so much less important than the former.

A Bayesian hierarchical formulation of the De Lury stock assessment model for abundance estimation of Falkland Islands' squid (Loligo gahi)

2004 ◽  
Vol 61 (6) ◽  
pp. 1048-1059 ◽  
Author(s):  
Murdoch K McAllister ◽  
Simeon L Hill ◽  
David J Agnew ◽  
Geoffrey P Kirkwood ◽  
John R Beddington
Keyword(s):  
Sampling Error ◽  
Stock Assessment ◽  
Assessment Model ◽  
Abundance Estimation ◽  
Falkland Islands ◽  
Parameter Estimates ◽  
Bayesian Hierarchical ◽  
Stock Assessments ◽  
Catch Rates ◽  
Using Data

In stock assessments of short-lived species, De Lury depletion models are commonly applied in which commercial catches and changing catch rates are used to estimate resource abundance. These methods are applied within fishing seasons to decide when to close the fishery and can be reliable if the data show a distinct decline in response to the catch removals. However, this is not always the case, particularly when sampling error variation masks trends in abundance. This paper presents a Bayesian hierarchical formulation of the De Lury model in which data from previous years are combined hierarchically in the same stock assessment model to improve parameter estimation for future stock assessments. The improved precision in parameter estimates is demonstrated using data for the Falkland Islands' Loligo gahi squid fishery.

Behaviours of Atlantic herring and mackerel in a purse-seine net, observed using multibeam sonar

2016 ◽  
Vol 74 (1) ◽  
pp. 359-368 ◽  
Author(s):  
Maria Tenningen ◽  
Gavin J. Macaulay ◽  
Guillaume Rieucau ◽  
Héctor Peña ◽  
Rolf J. Korneliussen
Keyword(s):  
Incident Angle ◽  
Clupea Harengus ◽  
Purse Seine ◽  
Target Strength ◽  
Spatial Density ◽  
Atlantic Herring ◽  
Backscattering Coefficient ◽  
Fishing Vessel ◽  
Backscattering Strength ◽  
Imaging Sonar

To ensure efficient and sustainable purse-seine fisheries, the catch process must be monitored to better understand the reactions of fish to the gear. In this study, we monitored the behaviours of herring (Clupea harengus) and mackerel (Scomber scombrus) schools during purse-seine capture using a multibeam imaging sonar (Simrad MS70, 75–112 kHz) mounted on a research vessel. The fish behaviours differed between species and purse-seine sets. For both species, the acoustic volume backscattering coefficient increased as 0–80% of the seine was hauled aboard, indicating a corresponding increase in fish spatial density. This increase was significantly greater for herring than mackerel. As 0–40% of the seine was hauled aboard the fishing vessel, schools changed their spatial distribution and volume independent of seine hauling, while for some schools, depth and height decreased. The acoustic volume backscattering strength was up to 25 dB higher in the centre of the school than in the edges. The average lateral target strength was estimated for individual fish in the captured herring schools, and the effect of incident angle on the backscattering strength is considered.

scholarly journals The influence of uncertainty in target strength on abundance indices based on acoustic surveys: examples of the Baltic Sea herring and sprat

2009 ◽  
Vol 66 (6) ◽  
pp. 1404-1409 ◽  
Author(s):  
Svetlana M. Kasatkina
Keyword(s):  
Baltic Sea ◽  
Size Structure ◽  
Stock Assessment ◽  
Clupea Harengus ◽  
Statistical Characteristics ◽  
Target Strength ◽  
The Baltic Sea ◽  
Abundance Indices ◽  
Acoustic Surveys ◽  
The Baltic

Abstract Kasatkina, S. M. 2009. The influence of uncertainty in target strength on abundance indices based on acoustic surveys: examples of the Baltic Sea herring and sprat. – ICES Journal of Marine Science, 66: 1404–1409. In situ, target-strength (TS) measurements at 38 kHz and an analysis of biometric fish characteristics are presented for the Baltic Sea herring (Clupea harengus membras) and sprat (Sprattus sprattus). It is demonstrated that the application of two TS–length functions for the Baltic Sea clupeids, the first for young herring and sprat and the second for adult herring, is reasonable, and the two functions can therefore replace the well-known equation used since 1983. Parameters of the proposed relationships, accompanied by their statistical characteristics, are included in a model to obtain uncertainty in acoustically derived abundance indices. Major components of survey uncertainty, such as spatial variability, species composition, and size structure, are also included in the simulation. The proposed TS functions should permit estimates of more realistic abundance dynamics of Baltic Sea clupeids, by years and age groups, thereby providing important information for stock assessment models.

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