scholarly journals Application of in situ target-strength estimations in lakes: examples from rainbow-smelt surveys in Lakes Erie and Champlain

2003 ◽  
Vol 60 (3) ◽  
pp. 500-507 ◽  
Author(s):  
L.G Rudstam ◽  
S.L Parker ◽  
D.W Einhouse ◽  
L.D Witzel ◽  
D.M Warner ◽  
...  
Keyword(s):  
Lake Erie ◽  
Growing Season ◽  
Target Strength ◽  
Fish Length ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Acoustic Data ◽  
Size Groups ◽  
High Fish

Abstract Acoustic abundance of fish depends directly on the target strength (TS) of the fish surveyed. We analyzed 70 and 120 kHz acoustic data from two lakes with abundant rainbow-smelt (Osmerus mordax) populations. Using repeated surveys through the summer growing season, we derived a relationship between TS (dB) and fish length L (cm) at 120 kHz (TS = 19.9 log10 L − 67.8). Values for 70 kHz were similar. In situ TS increased with fish density, indicating a bias from accepting multiple targets at high fish densities. Correcting for this bias increased estimates of smelt abundance by up to 18% in Lake Erie and up to 100% in Lake Champlain. Multiple modes in the TS distributions observed for older fish do not reflect different size groups, as the same modes can be observed from measurements from a single fish. Smelt released gas bubbles during the evening ascent, and these bubbles had TS (−60 to −58 dB) within the range of TS observed from the fish. Gas-bubble release occurred mostly during the migration. Conducting surveys after the ascent is completed will decrease bias associated with counting bubbles as fish.

Examination of possible taxonomic differences within Lake Erie rainbow smelt, Osmerus mordax (Mitchill)

1983 ◽  
Vol 61 (2) ◽  
pp. 326-338 ◽  
Author(s):  
Hugh R. MacCrimmon ◽  
Barra L. Gots ◽  
Ross R. Claytor
Keyword(s):  
Growth Rate ◽  
Lake Erie ◽  
Growing Season ◽  
Genetic Differences ◽  
Osmerus Mordax ◽  
Growth Data ◽  
Rainbow Smelt ◽  
Eastern Basin ◽  
Random Samples ◽  
Electrophoretic Data

Random samples of rainbow smelt, Osmerus mordax, from commercial summer trawl harvests in the Central and Eastern basins of Lake Erie are examined. Analysis of the meristic, morphometric, and electrophoretic data indicates no statistical evidence of genetic differences between basin populations. However, significant differences in size and growth data between basin populations occur and are attributed to differences in limnological conditions between basins which affect the time of spawning, length of growing season, and growth rate. Thus, these differences indicate an ecophenotypic distinction between the Central and Eastern Basin populations because of between-basin limnological dissimilarities.

Population dynamics of rainbow smelt (Osmerus mordax) in Lakes Ontario and Erie: a modeling analysis of cannibalism effects

2000 ◽  
Vol 57 (8) ◽  
pp. 1594-1606 ◽  
Author(s):  
Brian F Lantry ◽  
Donald J Stewart
Keyword(s):  
Population Dynamics ◽  
Lake Erie ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Time Step ◽  
Rainbow Smelt ◽  
Modeling Analysis ◽  
Daily Time Step ◽  
Annual Time ◽  
Daily Time

We used a stochastic stage-based matrix model (annual time step) and a bioenergetics model (daily time step) to simulate population dynamics, production, consumption, and conversion efficiency for rainbow smelt (Osmerus mordax) populations in Lakes Ontario and Erie. Cannibalism on young-of the-year (YOY) smelt by yearlings was the only scenario that reproduced alternate-year recruitment cycles observed in Lakes Ontario and Erie. Assuming constant survivorship and 5% variation in cannibalism, less than one YOY consumed per yearling smelt per year in both lakes could produce fluctuations greater than those observed. We found that at estimated daily mortality rates and during the pelagic phase of larvae only, 2% of the yearling smelt in Lake Erie and 5.1% in Lake Ontario need to consume one YOY per day to induce the observed abundance fluctuations. Bioenergetics simulations of alternating recruitment produced fluctuations in simulated values for annual gross production of approximately 6-7 and 31-59% for the Lake Ontario and Lake Erie smelt populations, respectively.

Corrigendum to: In situ target strength measurement of the black triggerfish Melichthys niger and the ocean triggerfish Canthidermis sufflamen

2021 ◽  
Vol 72 (3) ◽  
pp. 449
Author(s):  
Julie Salvetat ◽  
Anne Lebourges-Dhaussy ◽  
Paulo Travassos ◽  
Sven Gastauer ◽  
Gildas Roudaut ◽  
...  
Keyword(s):  
Target Strength ◽  
Biomass Estimation ◽  
Tropical Islands ◽  
Acoustic Data ◽  
North East ◽  
Fernando De Noronha ◽  
The Mean ◽  
Tuna Fisheries ◽  
Fish Aggregating Devices

Triggerfish are widely distributed in tropical waters where they play an important ecological role. The black triggerfish Melichthys niger may be the dominant species around oceanic tropical islands, whereas pelagic triggerfish, such as the ocean triggerfish Canthidermis sufflamen, can assemble around fish aggregating devices (FADs) where they are a common bycatch of tuna fisheries. In this study we combined acoustic and optical recordings to provide the first in situ target strength (TS) measurement of black and ocean triggerfish. Data were collected in the Archipelago of Fernando de Noronha off north-east Brazil. The mean TS of a 27.8-cm-long black triggerfish at 70 and 200kHz was –39.3dB re 1m2 (CV=14.0%) and –38.9dB re 1m2 (CV=14.4%) respectively. The mean TS values of ocean triggerfish (with a size range of 39–44cm) at 70 and 200kHz were –36.0dB re 1m2 (CV=15.7%) and –33.3dB re 1m2 (CV=14.0%) respectively. This work opens up the field for acoustic biomass estimates. In addition, we have shown that TS values for ocean triggerfish are within the same range as those of small tunas. Therefore, acoustic data transmitted from FADs equipped with echosounders can introduce a bias in tuna acoustic biomass estimation and lead to increased rates of bycatch.

scholarly journals Methods and results of in situ target-strength measurements of Atlantic cod (Gadus morhua) during combined trawl-acoustic surveys

2009 ◽  
Vol 66 (6) ◽  
pp. 1225-1232 ◽  
Author(s):  
Viacheslav A. Ermolchev
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Biological Data ◽  
Target Strength ◽  
Fish Length ◽  
The Barents Sea ◽  
Total Fish ◽  
Acoustic Surveys

Abstract Ermolchev, V. A., 2009. Methods and results of in situ target-strength measurements of Atlantic cod (Gadus morhua) during combined trawl-acoustic surveys. – ICES Journal of Marine Science, 66: 1225–1232. This paper presents methods for collecting acoustic and biological data, including in situ target-strength (TS) estimates of fish, with results presented for Atlantic cod (Gadus morhua) obtained from combined trawl-acoustic surveys. These include fish in the small, average, and maximum length classes, within the range 5–136 cm (total fish length, LT). The investigations were done using Simrad EK500/EK60 echosounders with split-beam transducers and special post-processing software. Based on an analysis of data collected in the Barents Sea during 1998–2007, a relationship TS = 25.2 log10(LT) − 74.8 was obtained for Atlantic cod at 38 kHz, with TS in dB and LT in centimetres. Seasonally, and for depths between 50 and 500 m, the variability in cod TS was 3.1 dB, decreasing with depth. The largest day–night difference in mean TS was in August–September, with changes as large as 1.0–1.7 dB. In the other seasons, the day–night difference was <1.0 dB.

Energetic consequences of diet shifts in Lake Erie rainbow smelt (Osmerus mordax)

2005 ◽  
Vol 62 (1) ◽  
pp. 145-152 ◽  
Author(s):  
SL Parker Stetter ◽  
L D Witzel ◽  
L G Rudstam ◽  
D W Einhouse ◽  
E L Mills
Keyword(s):  
Lake Erie ◽  
Food Resource ◽  
Fork Length ◽  
Late Summer ◽  
Osmerus Mordax ◽  
Bythotrephes Longimanus ◽  
Rainbow Smelt ◽  
The 1960S ◽  
Diet Shifts ◽  
Bioenergetics Models

The diet of eastern Lake Erie rainbow smelt (Osmerus mordax) has changed since the 1960s, reflecting food resource shifts due to phosphorus reductions and the invasion of exotic species (dreissenid mussels and Bythotrephes longimanus). Since rainbow smelt growth was lower in the 1990s than in the 1960s, we considered diet changes as an explanation. A decrease in the proportion of zooplankton occurred in the summer (May–August) diet of two size classes (63–88 and 89–114 mm fork length) between 1961 and 1999. Within the zooplankton, the proportion of Bythotrephes increased. In spite of these changes, energy density (joules per gram) of the summer (June–August) diet has not changed since 1961. However, during the late-summer and fall, predation on Bythotrephes, and therefore the proportion of indigestible spines in the stomach, increases. Using bioenergetics models, we show that Lake Erie rainbow smelt could achieve 66%–155% greater growth between June and October if Bythotrephes spines were replaced with digestible prey items, resulting in end-of-season weights and lengths similar to the 1985–1990 period. Our results indicate that indigestible Bythotrephes spines may reduce growth by occupying space in the stomach but providing no nutritional value to the fish, thereby reducing the realized daily ration for rainbow smelt.

A Comparison of Spawning, Harvested, and Die-Off Rainbow Smelt, Osmerus Mordax, in Eastern Lake Erie

1981 ◽  
Vol 7 (2) ◽  
pp. 144-154 ◽  
Author(s):  
Samuel Nsembukya-Katuramu ◽  
Eugene K. Balon ◽  
Robin Mahon
Keyword(s):  
Lake Erie ◽  
Osmerus Mordax ◽  
Rainbow Smelt

Occurrence of Glugea hertwigi in Lake Erie Rainbow Smelt (Osmerus mordax) and Associated Mortality of Adult Smelt

1972 ◽  
Vol 29 (11) ◽  
pp. 1639-1641 ◽  
Author(s):  
Stephen J. Nepszy ◽  
Alex O. Dechtiar
Keyword(s):  
Lake Erie ◽  
Parasite Load ◽  
Osmerus Mordax ◽  
Microsporidian Parasite ◽  
Rainbow Smelt ◽  
West Central

The occurrence of cysts of Glugea hertwigi, a microsporidian parasite, in Lake Erie rainbow smelt (Osmerus mordax) has been monitored since 1960 when it was first recorded. Annual sampling has shown that an increasing proportion (up to 87.5% in 1971) of the smelt population has been infected.An unusually severe mortality among adult smelt occurred during early May, 1971, in western and west central Lake Erie. Sampling of dead and obviously stressed smelt revealed that 97.3% of the males and 76.7% of the females were heavily loaded with cysts in the intestines and gonads, respectively. It is suggested that the parasite load contributed to the unusual severity of the normal postspawning mortality.

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.

Comparison of in situ, ex situ, and backscatter model estimates of Pacific hake (Merluccius productus) target strength

2007 ◽  
Vol 64 (12) ◽  
pp. 1781-1794 ◽  
Author(s):  
Mark J Henderson ◽  
John K Horne
Keyword(s):  
Acoustic Energy ◽  
Common Method ◽  
Ex Situ ◽  
Target Strength ◽  
Fish Density ◽  
Fish Length ◽  
Merluccius Productus

To convert acoustic energy into estimates of fish density, the target strength (TS) of a representative fish must be known. TS is a measure of the acoustic reflectivity of a fish, which is variable depending on the presence of a swimbladder, the size of the fish, its behavior, morphology, and physiology. The most common method used to estimate the TS of a fish is a TS-to-length empirical regression, with TS values increasing with fish length. This study uses in situ and ex situ TS measurements and a backscatter model to develop TS-to-length conversions for Pacific hake (Merluccius productus). Results from in situ and ex situ measurements had regression intercepts 4–6 dB lower than the previous Pacific hake TS-to-length regression. These differences suggest that an individual hake reflects 2.5–4 times less acoustic energy than was previously estimated.

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