Correlating trawl and acoustic data in the eastern Bering Sea: A first step toward improving biomass estimates of walleye pollock (Theragra chalcogramma) and Pacific cod (Gadus macrocephalus)?

Szalay, Paul G. von; Somerton, David A.; Kotwicki, Stan

doi:10.1016/j.fishres.2007.05.005

Cited by 23 publications

(17 citation statements)

References 13 publications

(22 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Prior to the present study, little was known about the vertical distributions of Pacific cod or the factors that control the distribution of this species (Ciannelli & Bailey 2005, Nichol et al 2007, von Szalay et al 2007. Pacific cod movements observed in the present laboratory study generally confirmed previously observed effects of light, temperature, and food distribution on vertical distribution, and the formation of groups in other gadoid species.…”

Section: Discussionsupporting

confidence: 89%

Vertical distribution of juvenile Pacific cod Gadus macrocephalus: potential role of light, temperature, food, and age

Davis¹,

Ottmar²

2009

Aquat. Biol.

View full text Add to dashboard Cite

Prior to the present study little was known about factors that control daily, seasonal, or ontogenetic changes in the vertical distribution of Pacific cod Gadus macrocephalus, an ecologically and commercially important fish species in the northern Pacific Ocean. Vertical distribution and migration of species in the family Gadidae are primarily controlled by gradients of light, temperature, food, and predators. The role of these factors in the vertical distribution of juvenile Pacific cod (0+ and 1+ yr) was tested by exposing fish to vertical gradients of light, temperature, and food that were constructed in the laboratory to simulate conditions normally found in Pacific cod habitats. Fish avoided high light and cold water. Food introduction in warm isothermal water (9°C) induced fish to feed and form more groups than when food was not present. In cold-thermocline conditions (9 to 3°C, top to bottom), food introduction into the lower third of the tank induced fish to swim deeper, but detections of food, feeding, and the formation of groups were initially inhibited by excursions into cold water. Increasing consumption of food during the hour after feeding indicated that fish adapted to cold water. Fish adapted within an hour of continuous exposure to high light as they swam higher in the water column. The effects of fish age were minor and evident as interactions with environmental condition effects on the number of fish groups. Pacific cod are able to adapt to changing ecological conditions, and their behavioural flexibility in response to food, temperature, and light conditions make prediction of vertical distribution complex. Future field studies of the diel vertical migration of Pacific cod should include concurrent measurements of key environmental factors and consider the ability for fish to quickly adapt to changing conditions.

show abstract

Section: Discussionsupporting

confidence: 89%

Vertical distribution of juvenile Pacific cod Gadus macrocephalus: potential role of light, temperature, food, and age

Davis¹,

Ottmar²

2009

Aquat. Biol.

View full text Add to dashboard Cite

show abstract

“…If there was a systematic bias, then one could equally well conclude that the estimates were too low (i.e.,q e was often .1.0). Furthermore, the Spearman's rank correlation had a value of 0.53, which compares favorably with the results of other studies that have related acoustic backscatter to trawl catch data (von Szalay et al 2007). …”

Section: Trawling Efficiency Of Atlantic Croakers and White Perchsupporting

confidence: 84%

Estimation of Bottom Trawl Catch Efficiency for Two Demersal Fishes, the Atlantic Croaker and White Perch, in Chesapeake Bay

Hoffman

Bonzek²,

Latour³

2009

Mar Coast Fish

View full text Add to dashboard Cite

The use of fisheries‐independent trawl survey data to estimate fish abundance in shallow coastal systems can present challenges for producing reliable population estimates. We used hydroacoustic and trawl data to estimate the catch efficiency of a demersal trawl that is presently used in surveys to support stock assessments in Chesapeake Bay, USA. Specifically, we determined the efficiency of catching Atlantic croakers Micropogonias undulatus and white perch Morone americana, two of the most common species captured in the trawl survey. Monotypic hauls (>90% by abundance) from 2003 to 2004 were used to estimate catch efficiency, defined as the ratio of the observed catch to the number of fish encountered by the trawl, which we estimated by deploying a scientific echosounder directly in front of the trawl net. The catch efficiency estimates ranged from 0.18 to 1.26 for Atlantic croakers (n = 29 tows) and from 0.11 to 0.60 for white perch (n = 7 tows). For Atlantic croakers, Spearman's rank correlation between the total and predicted catch was 0.53. A post hoc analysis of the Atlantic croaker efficiency estimates based on general linear modeling suggests that trawl efficiency is a function of fish behavior, gear geometry, and habitat. Efficiency declined with increasing fish density and increasing trawl width; to lesser extent, an increasing proportion of fines in the sea bed and decreasing depth were also associated with declines in efficiency. We conclude that because catch efficiency is variable, the trawl should be integrated with hydroacoustics to obtain improved population data.

show abstract

“…BSZ limitation should not be crossed the bottom, to obtained accurate echo integration. Bias of demersal fish echo integration, due to backscattering from bottom echo (Von Szalay et al, 2007).…”

Section: Acoustic Datamentioning

confidence: 99%

Factors Influencing the Performance of Trawl Operation in the Waters Area of Tarakan

Priatna¹,

Suprapto²

2018

Indonesian Fisheries Research Journal

View full text Add to dashboard Cite

Any fish on swept area of bottom trawl could not be caught due to some technical factors during towing. However, it could be estimated by integrated of bottom trawl and acoustic survey. This paper describes the determination of some factors that affect the performance of trawl net during the bottom trawl survey in the waters of Tarakan. Surveys were carried out in May, August, and November 2012. A total of 57 stations of simultaneously acoustic-trawl were completed. Data collected from each station include catch composition, and variables of trawling operation (i.e. bottom depth, warp length, trawl door opening, towing speed, towing duration, and acoustic fish density). Principal component analysis was applied to identify variables might impact of trawling performance (i.e. fish density at the waters area, towing speed, towing duration, warp length, horizontal opening of trawl door, density of non-demersal at cod end, and bottom depth). Both towing speed and towing duration were not major component for trawl operation. According to test of significance for four variables (i.e. bottom depth, warp length, horizontal opening, biota nondemersal at cod end) which affected to fish density at waters area, that both of variable (i.e. warp length and bottom depth) were significant as the principal components for the performance of bottom trawl.

show abstract

Correlating trawl and acoustic data in the eastern Bering Sea: A first step toward improving biomass estimates of walleye pollock (Theragra chalcogramma) and Pacific cod (Gadus macrocephalus)?

Cited by 23 publications

References 13 publications

Vertical distribution of juvenile Pacific cod Gadus macrocephalus: potential role of light, temperature, food, and age

Vertical distribution of juvenile Pacific cod Gadus macrocephalus: potential role of light, temperature, food, and age

Estimation of Bottom Trawl Catch Efficiency for Two Demersal Fishes, the Atlantic Croaker and White Perch, in Chesapeake Bay

Factors Influencing the Performance of Trawl Operation in the Waters Area of Tarakan

Contact Info

Product

Resources

About