Ground truth and target identification for fisheries acoustics

McClatchie, Sam; Thorne, Richard E.; Grimes, Paul; Hanchet, Stuart

doi:10.1016/s0165-7836(00)00168-5

Cited by 95 publications

(56 citation statements)

References 50 publications

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“…Therefore, it is critical to complement the acoustic surveys by using groundtruth methods (trawling, gillnets, seining, etc. ; for a review see McClatchie et al 2000). In the present study, nine detailed acoustic surveys did not provide a clear pattern between day and night results, meaning some other factors that were not monitored were important.…”

Section: Discussioncontrasting

confidence: 58%

Hydroacoustic estimates of fish stocks in temperate reservoirs: day or night surveys?

Draštík

Kubečka

Čech

et al. 2009

Aquat. Living Resour.

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-Day and night acoustic surveys were used to compare fish stock estimates at eight European reservoirs and one flooded mining pit. During both photoperiods of summer, higher fish biomass was observed in the uppermost 4 m of the water column by horizontal beaming than in deeper water by vertical beaming. Comparisons of volume backscattering coefficient (s v ), fish biomass (kg ha −1 ), abundance (ind. ha −1 ) and average fish weight (g) did not show a common pattern among the reservoirs but were found to vary significantly across photoperiods. At most reservoirs, the night surveys had higher estimates than day surveys. However, at several reservoirs the opposite pattern was observed. These patterns could not be explained by the species composition of the fish stocks. Fish size distributions were found to be different between day and night. A higher proportion of 1+ and older fish were found during the night at two of three studied waterbodies. In general, it was not possible to decide whether day or night acoustic surveys gave more reliable fish stock assessments. We advise performing both day and night transects on a given water body before deciding when to conduct the full survey. For a complete fish assessment it is very desirable to combine acoustic mobile surveys with active sampling gear.Key words: Hydroacoustics / Fish biomass / Diel migration / Man-made lake Résumé -Evaluation hydro-acoustique de stocks de poissons en lacs artificiels de la zone tempérée : de nuit ou de jour ? Des campagnes acoustiques nocturnes et durant le jour ont été effectuées pour comparer les estimations de stock de poissons de 8 lacs artificiels et un puits de mine inondée d'Europe centrale. Durant l'été, de jour comme de nuit, des biomasses plus élevées de poissons ont été observées dans la partie haute (jusqu'à 4 m de profondeur) de la colonne d'eau, par sondage acoustique horizontal que dans la partie plus profonde par sondage vertical. Des comparaisons du coefficient de rétro-(réverbération) en fonction du volume d'eau (s v ), de la biomasse de poissons (kg ha −1 ), de leur abondance (ind. ha −1 ) et du poids moyen des poissons (g) ne montrent pas de schémas communs entre ces réservoirs mais varient significativement en fonction de la période du jour ou de la nuit. Pour la plupart des réservoirs, les campagnes nocturnes présentent des estimations plus importantes que celles effectuées de jour. Cependant, le contraire est aussi observé pour certains réservoirs. Ces différences ne peuvent s'expliquer par la composition en espèces des stocks de poissons. La répartition en tailles des poissons est différente entre la nuit et le jour. Une plus grande proportion de plus gros poissons (1+) est trouvée durant la nuit pour deux des trois lacs réservoirs et du lac minier. En général, il n'est pas possible de décider si des campagnes de jour ou de nuit fournissent des estimations plus fiables des stocks de poissons. Nous conseillons d'effectuer des transects de nuit et de jour avant de décider de la période d'évaluation. Pour un...

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Section: Discussioncontrasting

confidence: 58%

Hydroacoustic estimates of fish stocks in temperate reservoirs: day or night surveys?

Draštík

Kubečka

Čech

et al. 2009

Aquat. Living Resour.

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“…This study is based on data collected during the MEDIAS survey, which is of added value given that (1) the data lack spatial bias because the whole anchovy distribution area is covered and not only the fishing grounds; (2) catches are not restricted by depth or mesh size, so the entire population length range is sampled; (3) fisheries acoustics is a direct method based on "ground-truth" information, through which all the anchovy echotraces are identified (McClatchie et al 2000); and (4) the survey period coincides with the anchovy spawning peak (Giráldez andAbad 1995, Palomera 1992) and with the maximum anchovy abundance (Palomera and Sabatés 1990), so it is optimal for stock discrimination (Cadrin et al 2014).…”

Section: Discussionmentioning

confidence: 99%

“…Acoustic data were recorded every nm using a calibrated EK60 (SIMRAD) scientific echosounder working with five split-beam transducers at 18, 38, 70, 120 and 200 kHz frequencies, with a constant vessel speed of 10 knots (nm/h). Anchovy echotraces (fish schools) which were detected on the echogram were identified by "ground-truth" information (McClatchie et al 2000) obtained by pelagic trawl net samples targeted at the echotraces (Simmonds et al 1992). …”

Section: Study Area and Fish Samplingmentioning

confidence: 99%

Anchovy (<em>Engraulis encrasicolus</em>) otoliths reveal growth differences between two areas of the Spanish Mediterranean Sea

2017

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Summary:Anchovy is a commercial species that supports large fisheries in the Mediterranean Sea. In addition, anchovy is an essential element of the pelagic food web, playing a considerable role in connecting the lower and upper trophic levels. Comparisons made regarding length frequency distribution, demographic structure, growth during the first year inferred from otoliths, and the condition factor of anchovy inhabiting the Spanish Mediterranean Sea (General Fisheries Commission for the Mediterranean management units, GSA06-Ebro Delta and 01-Alboran Sea), based on five-year data, clearly showed significant growth differences between areas and evidenced the existence of two independent anchovy stocks in the Spanish Mediterranean Sea. The anchovies inhabiting the Alboran Sea had higher growth than the anchovies inhabiting the Ebro Delta for the same age (one year old). The dramatic decline of the Alboran Sea anchovy could be related to the current management legislation in the Spanish Mediterranean Sea, based mainly on a common minimum catch size (9 cm), which should be revised given that sustainable anchovy exploitation is crucial for the pelagic food web equilibrium.Keywords: anchovy growth; length-frequency distribution; otolith first radius; anchovy stocks; condition factor; fisheries management; Spanish Mediterranean Sea. Otolitos de anchoa (Engraulis encrasicolus) revelan diferencias de crecimiento entre dos áreas del Mediterráneo españolResumen: La anchoa es una especie de interés comercial sometida a gran explotación pesquera en el mar Mediterráneo. Asimismo, esta especie es un elemento esencial de la cadena trófica pelágica dado que actúa como nexo entre los niveles más altos y más bajos de ésta. En este trabajo se han llevado a cabo comparaciones, basadas en un conjunto de datos de 5 años, entre las distribuciones de frecuencias de tallas; la estructura demográfica; el crecimiento durante el primer año, inferido empleando otolitos y el factor de condición de individuos de anchoa recogidos en el Mediterráneo español (unidades de gestión de la General Fisheries Commission for the Mediterranean, GSA06-Delta del Ebro y GSA01-Mar de Alborán), mostrando diferencias significativas entre áreas y evidenciando la existencia de dos stocks de anchoa independientes en el Mediterráneo español. Las anchoas procedentes del mar de Alborán presentaron un mayor crecimiento que aquellas procedentes del Delta de Ebro para la misma edad (1 año). La dramática disminución de la población de anchoa del mar de Alborán podría estar relacionada con la aplicación de una única legislación para todo el Mediterráneo español basada, principalmente, en una misma talla de primera captura (9 cm), que debería ser revisada puesto que la explotación sostenible de la anchoa es de crucial importancia para el equilibrio de la cadena trófica pelágica.Palabras clave: crecimiento de anchoa; distribución de frecuencias de tallas; primer radio del otolito; stocks de anchoa; factor de condición; gestión de pesquerías; mar Mediterráneo español.

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“…Examples of behaviours that alter the availability of fish to acoustic surveys include reaction of fish to sounds and survey vessels (Gerlotto & Fréon 1992, Misund & Aglen 1992, Popper et al 2004, Handegard & Tjøs-theim 2005, De Robertis et al 2008, ICES 2010, De Robertis & Wilson 2011 and diel migrations (Lawson & Rose 1999). Coupling acoustic data with complementary data on size and species composition is often challenging, due to varying sampling selectivity and resolution among sampling methods, but it is necessary for proper interpretation of acoustic data, and comparisons among different complementary techniques can be insightful (McClatchie et al 2000, Yule et al 2007, Williams et al 2010a). …”

Section: Coupling Acoustic Data With Other Sampling Techniquesmentioning

confidence: 99%

Underwater acoustics for ecosystem-based management: state of the science and proposals for ecosystem indicators

Trenkel¹,

Ressler²,

Jech³

et al. 2011

Mar. Ecol. Prog. Ser.

108

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Ecosystem-based management (EBM) requires more extensive information than singlespecies management. Active underwater acoustic methods provide a means of collecting a wealth of ecosystem information with high space-time resolution. Worldwide fisheries institutes and agencies are carrying out regular acoustic surveys covering many marine shelf ecosystems, but these data are underutilized. In addition, more and more acoustic data collected by vessels of opportunity are becoming available. To encourage their use for EBM, we provide a brief introduction to acoustic and complementary data collection methods in the water column, and review current and potential contributions to monitoring population abundance and biomass, spatial distributions, and predator-prey relationships. Further development of acoustics-derived indicators is needed. We review and propose indicators for assessing and monitoring zooplankton, population dynamics of fish and other nekton, and changes in diversity and food-web functioning. Acoustic methods have the potential to make a strong contribution to EBM. Evaluation of new indicators and suitable reference points in different ecosystems are the current challenges.

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Ground truth and target identification for fisheries acoustics

Cited by 95 publications

References 50 publications

Hydroacoustic estimates of fish stocks in temperate reservoirs: day or night surveys?

Hydroacoustic estimates of fish stocks in temperate reservoirs: day or night surveys?

Anchovy (<em>Engraulis encrasicolus</em>) otoliths reveal growth differences between two areas of the Spanish Mediterranean Sea

Underwater acoustics for ecosystem-based management: state of the science and proposals for ecosystem indicators

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